An assessment of trace metals in the soil, vegetation and atmospheric deposition of urban areas in Vancouver by Gladys Azaria Oka Honours Thesis, 2012 Environmental Science, University of British Columbia ii ABSTRACT Urbanization of recent decades has motivated the expansion of urban agriculture as a means to address growing concerns of food security, climate change mitigation and community building, especially in areas facing socio-economic challenges. Community gardens are often relegated to brownfield sites which may have contained some degree of soil contamination prior to remediation. The intrinsic placement of gardens in areas of high industrial exposure poses a concern for atmospheric deposition as another source of contaminants. Metals are of particular interest because they have large anthropogenic contributions and persist in soils for very long periods of time. This study investigates metal concentrations in the native soil and atmospheric deposition of three sites, which represent a range in crop production, site history and industrial exposure. Metal accumulation in the rhizosphere soil, root and shoot of Kentucky bluegrass was assessed. Study sites include the UBC Farm, the 16 Oaks community garden and a brownfield in the Strathcona neighbourhood. Field sampling of topsoil and vegetation took place in the fall. In addition, wet and dry deposition were collected over a period of five months. HCl and aqua regia extraction were performed to determine the labile and total fractions of metals in the soil, vegetation and deposition. During this time Zn, Pb, Ni, Mn and Cu were found at detectable concentrations at all sites. Total metal concentrations were highest at 16 Oaks and lowest at the Farm. Dry deposition was the main mechanism for atmospheric metal contributions and was largest at the Brownfield and lowest at the Farm. Ni and Mn seem to largely originate from parent material while Zn, Pb and Cu may be considerably influenced by atmospheric deposition. High mobility into root and shoot were observed for all metals with large variability at 16 Oaks and the Brownfield. This may be attributed to site heterogeneity, lack of plant preference for accumulation into vegetative parts and large variability in foliar uptake. Future siting of community gardens needs to address the potential additive effects of native soil contamination and atmospheric deposition, as parent material, site history and current deposition trends seem to be complementary to overall soil and vegetative health. iii TABLE OF CONTENTS Abstract…………………………………………………………………………………….... ii Table of Contents……….……………………………………………………………........... iii List of Figures……………………………………………………………………………….. iv List of Tables………………………………………………………………………………... iv Acknowledgements…………………………………………………………………………. v 1. Introduction………………………………………………………………………………. 1 1.1 Community gardens and urban sources of metal contamination………….…...... 1 1.2 Metal distribution and transport in the atmosphere and soil…………………...... 3 1.3 Metal availability in soil……………………………………………………….... 7 1.4 Atmospheric deposition onto vegetation………………………………………... 8 1.5 Study Objectives……………………………………………………………….. 10 2. Methodology……………………………………………………………………………... 12 2.1 Site and soil information……………………………………………………....... 12 2.2 Field sampling: soil, vegetation and atmospheric deposition………………….. 12 2.3 Sample processing, pH, electrical conductivity and loss on ignition…………... 14 2.4 Aqua regia and HCl extraction………………………………………………..... 15 3. Results…………………………………………………………………………………… 16 3.1 Caveats to the data…………………………………………………………...… 16 3.2 Soil Properties………………………………………………………………….. 16 3.3 Metal concentrations in the soil and atmospheric deposition………………….. 17 3.4 Metal accumulation in the rhizosphere soil, root and shoot……………………. 21 3.5 Relationships among soil properties and metals in the soil and vegetation......... 26 4. Discussion…………………………………………………………………………….….. 27 iv 4.1 Metal concentrations in the soil and atmospheric deposition……………….….. 27 4.2 Metal accumulation in the rhizosphere soil, root and shoot……………….….... 30 4.3 Considerations for future siting of community gardens………………………... 31 5. Conclusions……….…………………………………………………………………..…. 33 References Cited………………………………………………………………………….... 34 Appendix………………………………………………………………………………….... 40 LIST OF FIGURES Figure 1. Pathways of metal transport to the human population…………………………... 6 Figure 2. Map of Vancouver with locations of study sites………………………………… 11 Figure 3. Diagram of deposition collector system...…….……………..…………………... 14 Figure 4. Total (and available) metals in soil and atmospheric deposition……………....... 19 Figure 5. Boxplots of soil and vegetation metal concentrations at the UBC Farm………... 23 Figure 6. Boxplots of soil and vegetation metal concentrations at 16 Oaks……………….. 24 Figure 7. Boxplots of soil and vegetation metal concentrations at the Brownfield………... 25 LIST OF TABLES Table 1. Soil properties of the study sites………………………………………………….. 17 Table 2. Mean and standard deviation values of metal concentrations in soil, vegetation and atmospheric deposition…………………………………………………………………....... 20 Table 3.Mean and standard deviation values for bioconcentration factors (BCF) of root and shoot and translocation factors (TF)…………………………………………………….….. 26 Table 4. Standards for comparison with total metal concentrations at the study sites (adapted from B.C. Ministry of Environment 2012)……………..………….…………………….…. 32 v ACKNOWLEDGEMENTS I would like to thank Dr. Les Lavkulich for imparting his wealth of knowledge through humour and kindness; for his open-door policy to answering my multitude of questions; and for his infectious passion in the power of good science. Without his “method to this madness”, this work would not have been possible. I am very grateful to Lis Thomas and Emma Holmes for sharing their knowledge and time to support this project, be it during long afternoons in the lab or field sampling in the rain. I’d like to acknowledge Martin Hilmer for his contribution in developing the deposition collector system which was integral to this project, and Maureen Soon for her accommodation of all the ICP-OES analysis. Thank you to the members of the UBC Farm, the 16 Oaks community garden and the Strathcona neighbourhood for allowing us to sample soil and vegetation with the hope of bettering future spaces of urban agriculture. A special thanks to everyone in the Land and Food System’s Soil Department for creating a space that fosters limitless discussions. 1 1. INTRODUCTION 1.1 Community gardens and urban sources of metal contamination Urbanization is a global phenomenon and one that often consumes valuable lands that constitutes the rural, agricultural and natural landscapes. In 2006, 80% of the national and 85% of the British Columbian population were reported to live in urban centres (Statistics Canada 2012). Population pressure increases the energy demands of the city often leading to increased resource consumption and waste production. Communities are not equally affected by this demand as those with lower socio-economic status are more vulnerable to food insecurity (Barbolet et al. 2005). An urban food strategy addresses concerns of growing poverty and food security by providing local and often organic alternatives for food production (Okvat and Zautra 2011) which reduces the fossil fuel load necessary to grow and transport food, indirectly reducing the amount of waste exported from the city (Nolasco da Silva 2007). The growth of community gardens has been particularly significant in Metro Vancouver due to the lack of access to fresh produce in vulnerable areas such as the Strathcona/DTES, Grandview-Woodlands and Renfrew-Collingwood neighbourhoods (Barbolet et al. 2005). Small, often vacant plots can be used as gardens to supplement diets or provide the primary source of fresh vegetables and fruit. The practice of urban agriculture provides a sustainable use of green spaces; addresses the concerns associated with climate change; and, enhances the social wellbeing and economic value of the community. The creation of habitats for birds and other small animals enhances urban biodiversity, while absorption of air pollutants by plants and trees enhances urban health (US EPA 2011). Climate change mitigation is achieved both directly and indirectly through the uptake of greenhouse gases and through lifestyle change and education. Niinemets and Penuelas (2007) suggest that garden plants may exhibit a disproportionately large contribution to the earth’s carbon balance because urban plants are usually grown with little to no natural predators, at naturally high temperatures, with high available CO2 and nitrogen deposition. As such, urban-grown plants have been observed to have greater photosynthetic rates than rural-grown plants. From a social perspective gardens provide sites for daily interaction, celebration of special events, and educational tours for youth (Saldivar-Tanaka and Krasny 2001). Low-income and immigrant communities are 2 given the opportunity to grow culturally salient food and interact with nature in an accessible and affordable way. Economic benefits can range from costs saved from growing one’s own vegetables to increasing the property value of a neighbourhood in close proximity to a garden (US EPA 2011). In Metro Vancouver, access to land is a significant challenge because of high property values and growing populations (Kaethler 2006). Globally, urban agriculture occupies public land or land leased from a local landlord (Bryld 2003). The expansion of urban agriculture places intense pressure on the remaining available plots of land. As a result, gardens are often relegated to brownfield sites which prior to development may have contained industrial waste and/or exhibit some form of soil contamination (Devine 2007). Several garden sites in Vancouver have even been established on closed-down gasoline stations which have been capped and left standing for several years. Limited land tenure also constrains longer term site remediation. In Vancouver, land tenure is given for approximately five years (Kaethler 2006) which limits the incentive and capacity for gardeners, landowners or the municipal government to invest time and capital to remediate a potentially contaminated soil. As an alternative, raised beds of imported fill from the city or compost from local farms are often used as the growth media after the native soil has been extensively covered with nylon sheeting (pers. comm. Bouchard, Community Gardener 2011). Vegetation grown in raised beds currently dominate community gardens in urban Vancouver. A prominent feature of community gardens is its proximity to urban centres, which often parallel regions of high traffic density, industrial activity, and air pollution. Sezgin et al. (2003) and Li et al. (2001) have reported atmospheric pollution to be a major contributor to heavy metal contamination. Lead often being the most important heavy metal pollutant as it was a significant component of petroleum products (Sezgin et al. 2003) prior to Gasoline Regulations made under the Canadian Environmental Protection Act in 1990 (Environment Canada 2010). In cases of point-source emissions Fakayode and Onianwa (2002) and Moseholm et al. (1992) found topsoil and vegetation to be meaningful sinks for dry and wet deposition of metals. Harrison and Chirgawi (1989a) propose that the extent of metal retention depends on the particle size distribution, weather conditions, plant surface characteristics, the solubility of the chemicals, and the chemicals present on the plant surface. The variability of emission rates and plant uptake (Moseholm et al. 1992) increases the 3 complexity of addressing atmospheric deposition and limits the level of comparability among studies. Urban agriculture is valuable because it has the potential to address the intersection of environmental, social and economic needs within a growing urban population. However, the quality of community gardens as an urban artifact requires investigation into how metal concentrations in the soil and vegetation are affected by the atmosphere and native soil environment. Metals are of particular concern because they persist in soils for very long periods of time since leaching and uptake and removal by crops are generally low (Dudka and Miller 2008). Therefore contaminated sites have the potential to impact plants and humans for a long period of time. While actions can be taken to ameliorate the effects of contaminated native soil, atmospheric deposition of pollutants is largely affected by the intrinsic placement of gardens in or near urban centres. The effect of dry and wet deposition of metals from non-point sources in current and future sites of urban agriculture needs to be determined before claims can be made of the nutritional and ethical value of growing vegetation to support communities facing food insecurity. 1.2 Metal distribution and transport in the atmosphere and soil Historically the term “heavy metals” has been used to describe metals which had a density greater than 3.5-7g/cm3 (Duffus 2002). The lack of consensus in establishing a definite threshold density resulted in a general abandonment of this definition. Density has been found to have little significance on the reactivity of a metal providing further support to develop a classification of metals based on their chemical properties. Currently the use of this term in the literature connotes that these metals (or their compounds) are toxic (Appenroth 2010). While some metals may be benign or even beneficial in small concentrations toxicity may occur when a threshold limit is exceeded (Tiller 1989). The term “trace metal” is also commonly used to describe the relative quantity of metal contaminants in the soil. Historically the term was used to describe elements that are ubiquitous but hard to detect (Tiller 1989). Currently, “trace metal” is defined as an element which is present at a concentration of less than 100 parts per million in a sample of soil (Banfalvi 2011). Trace metals are equivalent to micronutrients which are needed in minute quantities for proper growth, development, and physiology of an organism. Essential micronutrients for plant 4 growth include boron, chlorine, copper, iron, manganese, molybdenum and zinc (McKenzie 2001). Bowen (1979) suggests that when the rate of mining of a given element exceeds its natural rate of cycling by a factor of ten or more, the element must be considered a potential pollutant. According to this definition, the following metals may be considered most hazardous to the biosphere: Ag, Au, Cd, Cr, Hg, Mn, Pb, Sb, Sn, Te, W and Zn. However, elements that are considered to be of greatest risk to environmental health do not necessarily overlap; these include: Be, Cd, Cr, Cu, Hg, Ni, Pb, Se, V and Zn (Kabata-Pendias 2001). Accumulation of metals in soil may arise from natural and anthropogenic sources (Figure 1). In igneous rocks, trace metals occur as trace constituents of primary minerals (Alloway 1995). They are incorporated in minerals through isomorphic substitution in the crystal lattice as governed by the ionic charge, ionic radius and electronegativity of the major element and the trace element substituting it. Because sedimentary rocks comprise 75% of the earth’s rocks, secondary minerals may be more relevant for soil parent material. Generally clays and shales tend to have relatively higher element concentrations because of their capacity to adsorp metal ions. Anthropogenic additions of soil amendments directly to a site may be a significant source of metals especially if accumulation has occurred after some years; these may include commercial fertilizers, liming materials, agrochemicals, sewage sludge and irrigation water (He et al.2005). Recycling and/or disposal of metallurgical, municipal and industrial waste can also result in the creation of waste dumps which promote the corrosion of metals and leaching into the underlying soil (Alloway 1995). In addition, urban sites often contain infill following remediation practices such as excavation. Infill results from the demolition of urban structures and may contain a high proportion of processed wood, glass, ceramics, plastic, asphalt, metal and building stone (Craul 1992). Chemically, anthropogenic artifacts may alter the composition of the soil (Bullock and Gregory 1991). These artifacts may release metals directly into the soil or create conditions that are favourable for their (im)mobilization. Metals emitted into the atmosphere are transported through the movement of air masses and can migrate considerable distances from their source. They are deposited in soluble form in rainwater and as particulate matter in dry deposition. Natural emissions of metals include eroded soil particles which may account for approximately 20-30% of the Cu, 5 Pb, Ni, and Zn emitted from natural sources (Nriagu 1989) and only 6% for Cd (Nriagu 1979). The contribution of volcanic emission is enhanced for Cd, accounting for 40-50% of its natural emissions compared to 20-40 % for Pb, Cu, Zn, Ni, and Sb (Nriagu 1989). Nriagu suggests that vegetative exudates are only significant (20%) for the emission of Zn into the atmosphere. Other sources such as sea spray and forest fires represent only minor sources which comprise less than 10% of the total natural emissions (Nriagu 1989). Anthropogenic emission of metals results from the combustion and processing of fossil fuels, metal ores, as well as industrial products (Pacyna and Pacyna 2001). Industrialization in recent decades has led to “mankind [becoming] the key agent in the global atmospheric cycle of toxic metals” (Nriagu 1989). Nriagu reports that anthropogenic emissions exceeded natural rates of Pb and Cd emission by more than an order of magnitude (1979). Cu, Ni, and Zn exhibited anthropogenic increases of approximately 300%, 200%, and 700% of their natural source emissions. The main source of anthropogenic emission of nonferrous heavy metals is primary metal production, with the exception of lead which originates mainly from vehicular pollution. Pacyna and Pacyna (2001) found that some metals enter the atmosphere with exhaust gases as they evaporate from raw material during high-temperature production of industrial goods, combustion of fuels, and incineration of municipal and industrial wastes. Accidental release from landfills or spills to water bodies may also result in volatilization and entrainment of metals. 6 Natural sources Volcanoes Vegetative exudates, forest fires, sea spray Soil amendments, waste materials, urban infill Industrial and vehicular emission Primary metal production Soil Atmosphere Water Volatilization and entrainment / Wet and dry deposition Wet and dry deposition / Re-suspension Transport and sedimentation Eroded soil particles Plants People Uptake / Release from roots Runoff and leaching Consumption Anthropogenic sources Parent material Accidental release During deposition, the particulate fraction released or produced in the atmosphere range from 0.005-500µm (Smith 1977). The fine fraction accounts for particles in the range of 0.01-1µm while the coarse fraction corresponds to particles greater than 10µm in diameter. Artinano et al. (2003) found that particles smaller than 2.5 µm correlate with the dominant particles size in vehicular emissions. The fine fraction consists of gases emitted from high temperature processes such as coal and waste incineration (Allen et al. 2001) which have condensed to form non-volatile products (Smith 1977). Particles in this fraction tend to have long residence times, deposit slowly and travel far distances from the source of emission (Witt et al. 2010). Soil particles, process dust, industrial combustion products, and marine salt particles account for the mid-size range of 1-10 µm (Smith 1977). Associated metals likely have mechanical and high-temperature sources and are transported through the Figure 1. Pathways of metal transport to the human population. 7 advection of air masses (Allen et al. 2001). The coarse fraction corresponds to particles that frequently result from mechanical processes such as the resuspension of soil or road dust (Galloway et al. 1982). These metals likely have short residence times and are quickly removed from the atmosphere (Witt et al. 2010). The size of the metal bearing particle may determine whether wet or dry deposition will dominate (Galloway et al. 1982). Fine particles and gases are transported high into the upper troposphere and can be incorporated into the formation of raindrops. Larger particles include resuspended soil and dust and do not reach high altitudes where rain forms; these particles are inefficiently carried by precipitation and are mainly deposited dry. Smith (1977) identified three main pathways for atmospheric deposition: i) sedimentation due to gravity which is significant for larger particles; ii) impaction due to release from eddy currents; and iii) deposition due to precipitation. In some regions, the atmospheric load of heavy metals, specifically Cd, Pb, V, and Zn is highest during the winter and lowest during the summer (Lee et al. 2007). The distribution of particles is influenced by anthropogenic forces; in regions of moderate to high traffic density fine particles were found to be a minimum in the summer as traffic density declined (Artinano et al. 2003). 1.3 Metal availability in soil While long-distance transport of metals occurs as particulate matter, movement of metals within the soil mass occurs mainly in the aqueous phase. Plants accumulate metals within their roots and shoots through water uptake (Robinson et al. 2006). Metal solubility ultimately determines its availability to be taken up or bio-accumulated by plants. Factors which determine this uptake include pH, redox conditions, adsorption/desorption, the presence of other ions, metal complexation (solution/precipitation), and the type of soil and vegetation present. Not all processes are equally important for each element but all processes are affected by soil pH/redox potential and biological processes (He et al. 2005). Since many metals form cations or oxycations in solubilized forms, they are more likely to be adsorped to particle surfaces at high pH; in contrast, metals that have high charge and form oxyanions are more likely to be adsorped to particle surfaces at low pH. Redox conditions can indirectly affect metal availability by determining which oxidation state is most stable (Robinson et al. 2006). Reddy and Chinthamreddy (1999) found that at low pH and under oxidizing 8 conditions Cr(VI) is more stable than Cr(III); however, most Cr(III) compounds are sparingly soluble at the normal range of pH in soil while some Cr(VI) compounds are very soluble (US EPA 2012). In the soil matrix, ion composition can impact metal mobility. Competing ions can affect the capacity for metals to adsorp to particle surfaces as replacement usually occurs for ions with similar radii (Robinson et al. 2006). Luo and Rimmer (1995) observed in the zinc- copper interaction that the addition of copper increased the amount of readily available zinc to plants; this occurs because copper adsorption replaced sites once occupied by zinc. Precipitation of metals with phosphates or sulfides decreases mobility, while the presence of dissolved organic matter from root exudates increases mobility through chelation by functional groups (Robinson et al. 2006). Metals may also be associated with specific soil minerals which range in their capacity to weather, dissolve, and release metals in solution (Gibson and Farmer 1984). Desboeufs et al. (2005) found that metals dissolved from carbonaceous species often adsorped impurities or salts that were highly soluble with dissolution having little pH dependence. Metals dissolved from the aluminosilicates, specifically bound to Fe/Mn oxides were less soluble with dissolution having high pH dependence. Plants also exhibit preference in associating with metals as some may act as metal excluders or non-excluders (i.e. indicators and hyperaccumulators of metals) (Raskin 1994, Chaudhry et al. 1998). Metal excluders can effectively prevent metals from entering their aerial parts, though accumulation may still occur in the roots. Indicators reflect metal levels in the soil, while hyperaccumulators concentrate metals in their above ground tissues to levels exceeding those present in soil. 1.4 Atmospheric deposition onto vegetation Initially foliar contamination was considered to be preventable by washing vegetation prior to consumption (Motto et al. 1970); however, studies have shown that deposited metals may enter inner plant tissues (Ernst and Cramer 1980). In a laboratory experiment, Harrison and Chirgawi (1989a) and Azimi et al. (2003) discovered that in many cases dry deposition is the dominant mechanism of particle transfer since the net effect of wet deposition is often to 9 cleanse the plant. An exception may apply during particularly rainy periods for the more soluble metals (e.g. Cd, Zn and V). The rate of uptake and accumulation of metals by plants is usually associated with their concentrations in the soil (Harrison and Chirgawi 1989a). Vegetation nurtured in a growth chamber had relative atmospheric contribution of Cd, Cr, Ni, and Pb which ranged from 8-96%. Lower atmospheric contributions indicated greater ease of metal uptake from the soil which was observed for Cd and Zn. Harrison and Chirgawi (1989a and 1989b) found that metals behaved differently in their translocation to unexposed parts of the vegetation. Cd and Pb were found to accumulate preferentially in the leaves as compared to the storage roots while all plant parts efficiently accumulated Zn. Edible portions (i.e. fruiting bodies or storage tissues) of crops tend to accumulate less metals and display lower sensitivity to increases in metal concentrations than vegetative tissues (Motto et al. 1970). Harrison and Chirgawi (1989a) found that the efficiency of uptake was high for Zn and Cd, low for Pb and moderate for Ni and Cr. Urban areas of India demonstrated corresponding trends with maximal uptake for Zn followed by Cu, Cd and Pb (Sharma et al. 2008). Results from field studies of metal uptake were comparable to those in the growth chamber: Cd was excluded from accumulation in the pea fruit; Cr accumulated in the pea leaves but not in the pods or fruit; and Pb demonstrated minimal translocation in the roots and within the plant system. Higher metal concentrations were consistently found in exposed parts as compared to non-exposed parts of the plant. Accumulation of heavy metals in plants may affect absorption and transportation of essential elements, damage plant structure, affect physiological and biological activities and decrease the overall functions of the plant (Cheng 2003). Different vegetative species tend to accumulate different metals, possibly due to differences in leaf surface-to-volume ratios and in surface and uptake characteristics (Harrison and Chirgawi 1989a, Chaudhry et al. 1998). On a short time scale, atmospheric deposition contributes directly to foliar contamination and on a long time scale it contributes to metal contamination in soils. 10 1.5 Study objectives This study investigates the significance of metal contributions from the native soil and atmospheric deposition for accumulation of metals in the root and shoot of Kentucky bluegrass. Three sites were selected which exhibit a range of exposure to industrial activity, native soil metal contamination, level of management and production of food crops. Study sites include the UBC Farm at the University, the 16 Oaks community garden in the Shaughnessy neighbourhood, and a brownfield on Hastings Street and Glen Drive in the Strathcona neighbourhood (Figure 2). The main objectives of this study are to provide a preliminary assessment of:  the bulk (wet and dry) atmospheric contribution of metals to the three sites and how they compare with the soil contribution of trace metals;  the preferred pathway for metal accumulation (i.e. in the soil, roots or foliage);  the relationship between pH, organic matter and the accumulation of easily extractable and total metal concentrations in the soil at each site; and  the potential implications of the findings for the future siting of community gardens. The UBC Farm is expected to exhibit the lowest atmospheric deposition of metals and the lowest metal contamination to its native soil as it is located in the sparsely populated South Campus of UBC which has only in recent years experienced large scale development of residence buildings and shopping malls. The soil has been managed in varying degrees for the past 40 years (UBC Farm 2011) thus it is likely that a large proportion of the trace metals would be stably bound in humus, immobilized in solid forms, or leached from the ecosystem. The 16 Oaks community garden is expected to exhibit an intermediate range of metal deposition and native soil contamination. Oak Street and 16th Avenue is a moderately high trafficked intersection; it serves as a major bus route and borders a predominantly residential area. Previous to development of the community garden the site was occupied by a restaurant and a parking lot. During development, discovery of an oil tank and car battery in the soil suggested that some form of metal contamination may persist on the site (Iverson 2006). The Hastings brownfield on the northeast corner of the Georgia Street viaduct is expected to exhibit the highest deposition of metals and the highest metal contamination to its native soil. The viaduct is a high traffic roadway and the Strathcona neighbourhood is 11 Figure 2. Map of Vancouver with locations of study sites (Google Maps 2012). populated by various industries. From 1955 to 1970, the site was used as a scrap metal yard (pers. comm. Florko, City of Vancouver 2011). Following this period the native soil was overlain with various layers of construction fill, however no other attempt has been made to remediate the soil. 12 2. METHODOLOGY 2.1 Site and soil information The UBC Farm is a 24ha university research site which integrates cultivated field areas with hedgerows, orchards, and maturing successional forest stands (UBC Farm 2011). The soils are well-drained and sandy and the southern-facing slope along with the moderate maritime climate favours the cultivation of a wide variety of crops all year long. Edible crops produced include vegetables, fruits, berries, and herbs. The 16 Oaks community garden was established approximately three years ago; prior to that, the site was vacant for approximately ten years (pers. comm. Bouchard, Community Gardener 2011). It is a mostly level site which measures 1336 m2 in area (Iverson 2006). Potentially contaminated soil was excavated and piled in the far southeast corner of the site. Most gardeners have opted to use imported soil from various compost sources as the growth media for their food crops. No edible vegetation is grown in the native soil; various species of flowers and vegetables such as kale, lettuce and squash are grown on raised bed plots. The Brownfield site is 2134 m2 in area and has been vacant for the past forty years (pers. comm. Florko, City of Vancouver 2011). It has a northern aspect and a relief of 2-3 metres from east to west. The top layer of fill contains medium green sand and gravel which overlays a metal-containing sand fill. Below these two layers of fill, the native soil is approximately 1-2.5 metres below the surface. Site observations revealed that the soil is quite heterogeneous and compacted in most areas. The western site is susceptible to flooding during high rainfall periods. The whole site is occupied mainly by grasses (e.g. Scotch broom) and a few trees, with dense, well established blackberry bushes bordering the eastern and northern edge. 2.2 Field sampling: soil, vegetation and atmospheric deposition A stratified-random sampling design was applied to this study because little is known about the distribution of metals within each site and the scope of this study cannot account for the range of extraneous environmental and anthropogenic factors (e.g. local climate and traffic density) that may affect the deposition of metals. The first round of field sampling was conducted on October 4, 2011. Each site was stratified on the basis of differences in 13 vegetative cover. Within each vegetation stratified site, soil samples were collected using a hand trowel. The subsoil (20cm below from the surface), topsoil (top 20cm of the surface) and three composite samples, each compiled from five randomly selected areas were collected. A second round of sampling was conducted on February 14, 2012. On each site, five samples of native topsoil and grass and one sample of subsoil were collected. At the UBC Farm sampling took place adjacent to the orchard and the chicken coup; at the 16 Oaks garden it took place on the southeast corner for native soil sampling and throughout the site for raised bed sampling; and at the Brownfield sampling was completed in the eastern section of the site. For the 16 Oaks garden the three composite samples were taken from three different raised bed plots. Vegetation samples included native grass and berries found on the site. Kentucky Bluegrass (Poa Prantesis), a hardy lawn grass common to cool moist climates in North America, was collected from all sites. At the UBC Farm and the Brownfield site blackberries were selected; the 16 Oaks site contained only strawberries grown on one of the raised bed plots. Sampling took place in the fall and few berries could be collected from all sites. An atmospheric deposition filter and rainwater collector was placed on each of the sites near the location of soil and vegetation sampling. The system included a funnel, which contained a 2µm filter (Whatman, 42) housed in a wire chamber; the funnel was attached to a hose and a four-litre collection bottle (Figure 3). For the purposes of this study, “soluble” elements were classified as those being less than 2µm in diameter. Collection of dry and wet deposition resumed for nearly five months ending at the beginning of March 2012. 14 Funnel Wire chamber Hose Rainwater collector stand Four-litre collection bottle 2µm filter 2.3 Sample processing, pH, electrical conductivity and loss on ignition Soil, vegetation and worms found in the samples were air-dried over a period of two days prior to processing. Sampling of worms was opportunistic by collecting individuals that were discovered during the collection of roots. At the 16 Oaks site moss was interspersed in the grass samples thus roots could not be differentiated between moss and Kentucky bluegrass. During extraction of the roots soil attached to surfaces was washed with distilled water and collected. This sample was used as an approximate measure of rhizosphere soil conditions. Soils were sieved through a 2mm stainless steel sieve and tested for pH, electrical conductivity (EC) and organic matter content. The soil pH was initially measured in water at a 1:2 or 1:5 ratio since many of the soils contained a large fraction of fine particles. Soil pH was measured a second time in a 0.01M CaCl2 solution as described by Hendershot et al. (1993). This method is less sensitive to a range of soil-to-solution ratios and allows for a fair approximation of the field pH for agricultural soils. EC measurements were conducted in distilled water for soil (Rayment and Higinson 1992). Rainwater was collected from sites every 2-3 weeks depending on the amount of rainfall observed; pH of the water was Figure 3. Diagram of deposition collector system. 15 determined for each collection. Loss on ignition was measured at three temperature intervals (Atkinson et al. 1958): losses from ambient to 105°C; losses from 105°C to 350°C; and losses from 350°C to 550°C. Vegetation and worms were also analyzed for loss on ignition; samples were initially dried at 70°C to ensure no losses of organic matter prior to heating the samples to 350°C and 550°C. 2.4 Aqua regia and HCl extraction Aqua regia extraction was completed on all soil and vegetation samples as described by Cheng and Ma (2001). Following loss on ignition approximately 0.500 g of soil and 0.250g (or the maximum possible weight) of vegetation was weighed out, mixed with 15mL of aqua regia solution (1 HNO3: 3HCl) and boiled to dryness. Samples were washed with approximately 20mL 0.1M HCl through a 2 µm filter and made up to 100mL with 10% HNO3. This extraction process approximates the total amount of recoverable elements within the samples with the exception of those bound in aluminosilicate compounds. The elements included in this analysis were Zn, Pb, Ni, Mn, Cu, Cd, Co, Cr, Fe, Al, Mg, Ca, Na, K, and P. HCl extraction was applied to soil, wet and dry deposition, and rhizosphere soil samples. This extraction method (Snape et al. 2004) approximates the labile or mobile phases of metals (eg. water soluble and exchangeable fractions) in the soil or sediment matrix to determine the proportion of metals available for plant uptake. The residual fraction is considered immobile under natural soil conditions. Approximately 5 g of fresh soil were weighed out and equilibriated for 24 hours to 25mL of 0.1M HCl. Rainwater and rhizopshere soil samples were concentrated by boiling the residue dissolved and washing with 1M HCl to ensure that residue remaining in the glassware was minimized. Filters containing dry deposition and a blank filter were dried at 110°C and digested at 550°C. All sediment remaining after digestion was weighed for HCl extraction; the weight of the blank filter was subtracted from the samples. All samples undergoing HCl extraction were washed with approximately 25mL of 0.1M HCl through a 2µm filter and made up to 50mL with 10% HNO3. Hydrogen peroxide (30%) was added in small volumes (1-5mL) to oxidize samples containing high dissolved organic matter. If precipitate formed, samples were re-filtered and made to the appropriate volumes. All samples were analyzed using an inductively coupled 16 plasma atomic emission spectrometer (ICP-OES) to determine the relative concentrations of the elements of interest. 3. RESULTS 3.1 Caveats to the data Five metals were considered for comparison among the three study sites: Zn, Pb, Ni, Mn and Cu; Co, Cd and Cr were not considered as values obtained in the soil, vegetation, and deposition (with the exception of Cr) were below detection limits. Figures and tables in the Results section present data relevant to these five metals. Complete datasets and analysis pertaining to all elements that were included in the ICP analysis can be found in the Appendix. A small number of soil and wet deposition samples contained high Zn and Mn concentrations above the standards set for the ICP measurements. These values may be subject to a range of variation. Soil and rhizosphere soil samples from all three sites exhibited high iron content; oxidation during the aqua regia extraction may result in an underestimation of Fe concentration values. However, Fe is not a metal of concern and the proportion available to plants is sufficiently low. Limited statistical analysis could be performed on the data because of the small sample sizes and the large difference in standard deviations among sites. Data from the two sampling events were compiled as no obvious differences in metal concentrations were observed. Values for the composite samples completed in the first round of sampling were incorporated into measurement of topsoil mean for every site except 16 Oaks. For statistical analysis, data collected for a Land and Food Systems Master’s Theses (Thomas 2012) was included into the calculation of mean and standard deviation values for soil metal concentrations at 16 Oaks and the Hastings brownfield. 3.2 Soil Properties The general soil characteristics of the Farm, Garden and Brownfield are comparable with low variability within sites (Table 1). EC values are very low and pH is near neutral at 16 Oaks and slightly acidic at the other two sites. Loss on ignition was most significant at the 17 Farm where values doubled the organic matter content of the other two sites. Raised bed samples also contained high organic matter content with high variability likely due to limited sampling and the wide range of compost sources. 3.3 Metal concentrations in the soil and atmospheric deposition Total and available metal concentrations in the subsoil and topsoil were proportional among all sites: Zn concentrations were very low at the UBC Farm and 4-5 times higher at 16 Oaks and the Hastings brownfield; Pb was highest at 16 Oaks and lowest at the UBC Farm; Ni and Mn concentrations converged among all sites; and Cu was only sizable at the Hastings brownfield and the raised bed composite samples (Table 2). Across all sites the order of available metal concentrations was Mn>Zn>Pb>Cu>Ni. Metal availability (%) was approximated by dividing metal concentrations obtained from HCl extraction by values from aqua regia extraction. Values above 100% were eliminated as they may have resulted from random sampling of aluminosilicate particles which were not dissolved by aqua regia, in which case total metal concentrations would be underestimated. Values for availability were similar among sites for Zn, Ni and Mn while Pb and Cu availability was considerably higher at 16 Oaks and the Hastings brownfield. Metal availability ranged from 1-59% for Zn, 2-85% for Pb, 2-45% for Ni; 18-93% for Mn and 1-87% for Cu. Wet deposition metal concentrations were found to be low for all three sites with a relative order of Zn>Cu>Pb>Mn>Ni (Table 2). Differences among sites were minimal and fluxes ranged from 5.2 mg/kg/m2/day for Zn to 0.002 mg/kg/m2/day for Mn. These values are Table 1. Soil properties of the study sites. pH in water pH in 0.01M CaCl2 EC (dS/m) LOI at 350°C (%) SD SD SD SD 5.80 5.16 0.0506 11.7 0.358 0.597 0.0121 2.61 6.20 5.90 0.163 6.92 0.505 0.457 0.111 3.64 7.18 6.74 0.227 20.2 0.201 0.0702 0.135 15.1 5.84 5.14 0.0556 4.95 0.504 0.507 0.0646 1.56 Site Sample 16 Oaks community garden UBC Farm Hastings brownfield Topsoil Raised bed Topsoil Topsoil 9 14 3 9 Sample Size18 several orders of magnitude smaller than fluxes achieved for dry deposition affirming past studies which found dry deposition to be the dominant factor in atmospheric metal contributions (Harrison and Chirgawi 1989a, Azimi et al. 2003). The order of metal concentrations found in dry deposition is the same as in wet deposition. The Hastings brownfield exhibits the highest flux for all metals followed by the Farm (with the exception of Zn) and the 16 Oaks community garden. The difference in flux between each site is approximately two-fold for Pb, Ni and Mn; it is also two-fold for Zn with metal contributions at 16 Oaks surpassing those at the Farm. The large flux of Cu at the Hastings site suggests that a local source is contributing this particular metal. Dry deposition fluxes ranged from 37, 300 mg/kg/m2/day for Zn to 27 mg/kg/m2/day for Ni. Bulk metal deposition collected over the entire study period showed concentrations ranging from 15 to 15,000 times greater than total metal concentrations found in the soil (Figure 4). The greatest difference between metal concentrations found in soil compared to deposition is observed at the UBC Farm followed by the Hastings brownfield and 16 Oaks. 19 0 100 200 300 400 500 600 UBC Farm 16 Oaks Hastings brownfield Co nc en tra tio n ( mg /k g) 0 200 400 600 800 1000 1200 r 16 Oaks Hastings brownfield Co nc en tra tio n ( mg /k g) 0 100 200 300 400 500 600 UBC Farm 16 Oaks Hastings brownfield Co nc en tra tio n (1 04 m g/ kg /m 2 ) Zn Pb Ni Mn Cu Figure 3. a) Total soil metal concentrations; b) available soil metal concentrations; and c) bulk metal contributions from atmospheric deposition. a) b) c) 20 Table 2. Mean and standard deviation values for total and available metals in soil, vegetation and atmospheric deposition. Sample Size Zn Pb Ni Mn Cu SD SD SD SD SD 85.1 44.9 16.4 291 35.4 27.1 16.1 11.4 223 10.5 20.1 3.01 1.76 175 3.16 19.9 1.30 1.20 41.0 1.84 36.3 49.5 3.64 262 18.7 15.5 17.6 2.55 123 8.33 174 53.0 15.0 427 72.4 59.2 12.3 11.8 125 17.5 738 82.2 36.0 1350 150 768 21.3 32.2 841 70.6 Wet deposition (mg/kg/m 2 /day) 1 2.95 0.00860 0.00853 0.00231 0.0128 Dry deposition (mg/kg/m2/day) 1 8460 327 101 71.2 367 Strawberries 1 234 - 47.1 357 103 Worms 1 2810 157 - 290 307 2630 212 38.9 362 254 4020 183 33.9 98.4 272 70.1 14.9 2.09 121 3.56 18.8 20.0 2.27 51.0 3.25 456 219 24.3 407 45.0 356 196 13.6 361 10.3 191 78.1 2.93 193 11.2 153 71.2 1.32 178 9.94 607 436 9.26 376 39.1 633 409 13.6 392 49.8 1360 455 35.8 399 106 969 397 18.5 279 43.3 1330 387 53.3 506 148 989 315 38.2 323 54.9 Wet deposition (mg/kg/m 2 /day) 1 5.22 0.0140 0.00400 0.00420 0.0407 Dry deposition (mg/kg/m2/day) 1 17600 160 27.0 46.1 169 Strawberries 1 652 - 34.1 7360 128 Worms 1 3570 485 12.7 297 91.0 324 143 26.1 260 193 344 134 23.7 147 924 76.8 41.6 4.65 122 87.9 160 75.0 9.25 23.5 51.2 347 164 22.6 585 193 260 95.1 20.1 440 140 843 172 46.0 403 448 219 39.6 11.9 181 133 905 253 63.7 814 290 570 227 44.5 590 192 Wet deposition (mg/kg/m2/day) 1 5.99 0.0135 0.00337 0.00484 0.0303 Dry deposition (mg/kg/m2/day) 1 37500 782 192 120 1310 Blackberries 1 373 24.2 258 716 220 Worms 1 2210 245 - 513 383 mg/kg dry matter UBC Farm 16 Oaks community garden Hastings brownfield Site Sample 9 9 Topsoil (aqua regia) 9 Raised bed (aqua regia) 14 6 5 5 14 3 5 6 5 6 5 5 3 9 Topsoil (HCl extraction) Rhizosphere soil Root Shoot Topsoil (aqua regia) Topsoil (HCl extraction) Rhizosphere soil Shoot Root Raised bed (HCl extraction) Raised bed (aqua regia) Topsoil (HCl extraction) Shoot Root Rhizosphere soil 21 3.4 Metal accumulation in the rhizosphere soil, root and shoot The density of vegetation found on the sites was variable: Kentucky bluegrass was distributed extensively on the Garden and the Farm but was sparse and patchy on the Brownfield site. Rhizosphere soil, root and shoot metal concentrations exhibit similar trends to those found in the soil. Mean concentrations at 16 Oaks and the Hastings brownfield are higher than those at the UBC Farm for Zn and Pb with 16 Oaks exhibiting a larger range of variability; metal concentrations converge for Ni and Mn; and Cu concentration are highest at the Hastings brownfield. Greater variability overall is observed in the grass samples, notably for the UBC Farm which shows the largest mean concentration for Mn. The order of metal concentrations is very similar to available metals in the soil with either Zn or Mn being the most abundant. At all sites, mean metal concentrations in the root and shoot are higher than those found in soil. The variability of rhizosphere soil metal concentrations at 16 Oaks and Hastings closely resembles those of root and shoot; at the UBC Farm, this measure aligns more closely with topsoil metal measurements. Accumulation of Zn, Mn, and Cu at the Farm tends to occur in the shoot while the range of concentrations for Pb and Ni overlap among shoot, root and rhizosphere soil (Figure 5). At the 16 Oaks site all three vegetation measurements overlap with large variability for all metals (Figure 6). Mean metal concentrations in the root and shoot are comparable at the Hastings brownfield with rhizosphere soil metal concentrations tending to be lower (Figure 7). Bioconcentration factor (BCF) of root (Croots/Csoil (available) = ratio of root concentration to soil concentration) and shoot (Cshoots/Csoil (available) = ratio of shoot concentration to soil concentration) and Translocation Factor (TF = Cshoots/Croots = ratio of shoot concentration to root concentration) were calculated (Padmavathiamma 2009) (Table 3). For the UBC Farm BCF values for each metal tended to be higher in the shoots compared to the roots suggesting that at this site accumulation largely occurs in the above- ground exposed parts of the plant. This relationship is not evident at the other two sites where the range of BCF values for root and shoot largely overlap. Mn and Ni show a convergence in BCF of root and shoot among all sites which reflects the convergence in both soil and vegetation concentrations for these two metals. For all sites the BCF for root and shoot of Mn is consistently low while values for Pb and Zn are comparable. The TF did not show any qualitative differences in range among sites or metals which may be an effect of the small 22 sample size of this study. It may infer that for this species of grass metals are not preferentially taken up into the shoots as compared to the roots. Metal concentrations for worms and berries found on the sites must be considered with caution as the sample size is very small. Collection of berries was limited by the period of sampling for this study; approximately 0.100g from all sites were analyzed. Sampling of worms was opportunistic and depended on whatever was present in the topsoil samples.16 Oaks contained the largest number of worms followed by the UBC Farm and the Hastings brownfield. Bioconcentration of all metals seems to be evident in berries and worms. Metal concentrations for berries tend to be lower or to overlap with those found in the shoots; most sizable concentrations are found for Zn, Mn (notably at the 16 Oaks garden) and Cu. This must be considered in future studies as fruiting bodies are generally of greatest interest for human consumption and has been expected to have some capacity for excluding metals (Motto et al.1970). Metal concentrations found in worms is also comparable to those found in the shoots; across all sites Zn concentrations were high and above those found in the shoots. 23 c) d) b) e) a) Figure 4. Boxplot of metal concentrations in soil and vegetation at the UBC Farm for a) Zn, b) Pb, c) Ni, d) Mn and e) Cu. *Note: Two outlier points were removed for Zn and Pb from a grass sample from the first round of sampling. 24 c) b)a) d) e) Figure 5. Boxplot of metal concentrations in the soil and vegetation at the 16 Oaks community garden for a) Zn, b) Pb, c) Ni, d) Mn and e) Cu. 25 b) c) d) e) a) Figure 6. Boxplot of metal concentrations in soil and vegetation samples at the Hastings brownfield for a) Zn, b) Pb, c) Ni, d) Mn and e) Cu. 26 3.5 Relationships among soil properties and metals in the soil and vegetation A correlation matrix was developed for pH, EC, LOI, and metal concentrations in the soil, rhizosphere soil, roots and shoots. A t-test was performed to determine statistically significant correlations. pH and EC values varied within a small range across all sites which limited the capacity to observe their effect on metal availability in soils. Loss on ignition (LOI) was not found to correlate with any metals, which may again reflect the limited range among the sites. The co-occurrence of metals was mainly observed for total Zn and Pb: a significant positive correlation (p<0.05, t>3.182) was found in soil (r=0.93, t=4.32), rhizosphere soil (r=0.89, t=3.43), roots (r= 0.97, t=6.74) and shoots (r= 0.96, t=6.14). As expected available Zn, Pb and Cu in the soil correlated with corresponding metals in the roots (r= 0.88, t=3.24; r=0.94, t= 4.77; r=0.99, t= 10.4). In the rhizosphere soil, Ni was found to correlate with Mn (r=0.95, t=5.16) and Cu (r=0.92, t=4.23); associations with Mn may be related to metal affinity for Mn oxides in the soil. e) Table 3. Mean and standard deviation values for BCF of root and shoot and TF. Site Factor Sample Size Zn Pb Ni Mn Cu BCF root 14.3 26.7 10.8 2.50 28.4 SD 5.21 10.7 10.5 0.568 12.9 BCF shoot 34.4 39.6 21.6 8.52 44.1 SD 10.8 8.84 21.2 4.64 17.2 TF 2.58 1.59 5.83 3.35 1.84 SD 0.917 0.467 6.55 1.40 0.838 BCF root 6.92 5.88 19.7 4.70 12.5 SD 2.35 1.65 15.5 3.33 3.42 BCF shoot 5.84 6.63 23.9 6.26 19.3 SD 2.70 4.10 18.3 4.87 13.0 TF 1.06 1.19 2.66 2.21 1.62 SD 6.92 5.88 19.7 4.70 12.5 BCF root 15.8 8.33 12.1 3.66 7.23 SD 4.40 2.04 3.03 1.80 0.552 BCF shoot 19.2 15.2 13.3 7.28 5.58 SD 9.06 12.9 8.91 6.23 3.23 TF 1.32 1.67 1.15 3.05 0.793 SD 0.829 1.17 0.687 3.62 0.486 UBC Farm 16 Oaks community garden Hastings brownfield 5 5 527 4. DISCUSSION 4.1 Metal concentrations in the soil and atmospheric deposition Natural concentrations of elements in soil can be expected to vary depending on parent material, organic matter, mineralization and soil processes (Dudka and Miller 2008). Nair and Cottenie (1971) found that the total concentrations of Zn, Cu, Ni, Mn and Pb are closely related to their total contents in the parent material from which they are derived. According to a City of Vancouver parent material classification map developed by Iverson (2006) the three sites originate from three different parent materials: glacial till at the UBC Farm; glacial marine at the 16 Oaks garden; and marine at the Hastings brownfield. The main difference between the three classifications is particle size distribution and drainage capacity with soils ranging from sandy and well-drained in glacial till to fine-textured and poorly-drained with increasing marine influence (Iverson 2006). Baker (1950) found that soils of the Lower Fraser Valley had higher Mn concentrations than soils in other areas of the province which likely explains the high concentration of Mn at all sites. This has been attributed to the presence of marine parent materials. The relatively low Ni concentrations may be a result of the extraction process applied as over 50% of Ni in soils may be associated with the residual fraction (HF and HClO4 soluble) remaining after aqua regia extraction (McGrath 1995). The results of this study suggest that different parent material reflect similar total metal concentrations for Ni and Mn. Ni and Mn tend to be associated with accumulations of translocated clays and hydrous oxides in the subsoil (Alloway 1995). Since metal concentrations in the topsoil and subsoil were similar within sites, this suggests that redistribution may have occurred in the soil profiles. As such it is likely that pedogenic processes and metal content in the parent material do not vary significantly across sites and are the main factors determining soil concentrations of metals with low atmospheric or anthropogenic contributions. The divergence in values for Zn, Pb and Cu may be attributed to specific site history and local urban-industrial conditions at the 16 Oaks and Hastings site. While natural emissions of Zn, Ni, Cu and Pb are comparable, worldwide anthropogenic contributions of Zn and Pb are 15-20 times greater than that of Ni and Cu (Nriagu 1979). Within the soil 28 profile, Zn, Pb and Cu are often found concentrated at the soil surface as a result of cycling through vegetation, atmospheric deposition and adsorption by soil organic matter (Alloway 1995). This may be of concern as recent findings suggest that regardless of metal forms and under similar soil conditions, metals of anthropogenic origin will be more mobile and bioavailable than metals of lithogenic and pedogenic origin (Kabata-Pendias 2001). Since pH is one of the main factors determining metal mobility, the close agreement of near neutral to slightly acidic pH values (>5.5) at all three sites indicates that current soil conditions are generally not conducive to increasing metal availability to plants. Most metals are increasingly soluble as soils become more acidic and hydrogen ions displace cations adsorped to soil colloids; any net positive charge on the soil colloid acts to repel metal cations (He et al. 2008). It is likely that metal speciation across sites may be quite comparable and may explain the overlaps in range of metal availability (%) for all metal except for Pb and Cu. Cu is specifically adsorped in soils making it one of the least mobile trace metals (Baker and Senft 1995) as well Pb is reported to be the least mobile trace metal (Kabata-Pendias 2001). Therefore if metals are not in available forms they are likely to persist in soils for long periods of time. The residence time of Zn, Ni, Cu and Pb in temperate soils are 1000 to 3000 years (Bowen 1979). The presence of compost at the UBC Farm and at 16 Oaks may influence the bioavailability of metals depending on its properties. Zinati et al (2001) found that MSW- compost was able to supply larger amounts of plant available Cu and Zn compared to composted sewage sludge because in the former Cu and Zn were bound to organic forms and in the latter they were bound to Fe-Mn oxides. Zn and Pb comprise the largest fraction of metals present in compost. As such, the application of compost at these sites may have contributed to the total metal concentrations in the topsoil. The source of compost and the rate of application at the two sites are not known but may be meaningful to consider at a later time. The consensus in the literature suggests that organic matter has the potential to bind metals in stable organic forms limiting their solubility and bioavailability (Smith 2009). Pb is the most strongly bound and Ni the weakest with Zn and Cu showing intermediate sorption capacities. In addition to organic matter, Pb has been observed to have high affinity to Mn oxides, Fe-Al hydroxides and clay mineral (Kabata-Pendias 2001). The interaction of Pb and Mn may suggest that over time as Mn oxides develop, Pb availability at these sites may 29 decline. Pb and Cu were observed to have low % availability at the UBC Farm indicating that the influence of organic matter on metal mobility requires a long period time to take effect and may be evident for only some metals. Calculated enrichment factors for total deposition at various non-urban and urban locations in Europe and North America reported the following sequence Pb>Zn=Cu>Ni >Mn (Cawse 1976). A higher enrichment factor indicates greater importance of atmospheric deposition as a source of these metals in soils and plants. This ordering generally approximates what was observed in wet and dry deposition in this study except that Pb concentrations were less than Zn and Cu concentrations. This may be attributed to the discontinued use of Pb in gasoline products post 1970s as vehicle emissions was the largest atmospheric contribution of Pb. High Zn and Cu contributions may reflect the industrial nature of the areas, as these metals are indicators of contamination from street dust; they are found in gasoline, oil lubricants, and industrial and incinerator emissions (Li et al. 2001). Metals in street dust have been found to have higher concentrations (Wei and Yang 2010) and mobility than metals in urban soils because of their adsorption to coarse-sized, feasibly weathered calcite minerals (Li et al. 2001). The UBC site unexpectedly had the second highest metal concentrations with the exception of Zn even though it has the lowest traffic density of the three sites. This may be due to the fact that large scale construction was occurring in close proximity (~200m) from the sampling area. In this study, measurement of dry deposition corresponds to particles larger than 2µm and may include re-suspended soil particles, road dust and industrial combustion products which due to their relatively large size tend to deposit close to the emission source. This may suggest that close-range anthropogenic actions may be more meaningful for the deposition of all metals, other than Zn, even when traffic and industrial activity is relatively low. The low concentrations observed for wet deposition may reflect the distribution of metals in the fine-sized fraction which may suggest that high temperature emissions do not contribute significantly to deposition in these areas. The different order of metal concentrations in soil and deposition may indicate that atmospheric contributions is most meaningful for Zn and Pb which are already abundant in the soils at 16 Oaks and the Hastings brownfield. Enrichment of these metals in the soil may have occurred through long term atmospheric deposition in addition to specific soil conditions. While Mn availability is sizable in soils, atmospheric contribution of this metal is 30 relatively small. Ni concentrations are low in both soils and deposition which suggests that it is not a metal of concern at these three sites. Cu concentrations in the soil and deposition are mainly meaningful at the Hastings brownfield and may demonstrate the integration of site history and the current deposition trends in the area. 4.2 Metal accumulation in the rhizosphere soil, root and shoot Rhizosphere soil conditions are mainly relevant for the purposes of chelation to increase metal mobility and uptake (Laurie and Manthey 1994). At the interface of roots and soil, exudates are excreted which release amino acids containing many functional groups to bind available metals. While metals dissolved in soil solution in ionic, chelated or complexed forms are preferred, uptake of available ions is largely dependent on total ion concentrations in the soil (Kabata-Pendias 2001). This may explain why rhizosphere metal concentrations are approximately between soil and root metal concentrations: in the rhizosphere metal mobility is enhanced but bioconcentration has not occurred. Since the level of management on the three sites differs significantly it is likely that exudate content may vary among sites depending on microorganism associations and the conditions of plant growth. Thus mobilization of metals for uptake is subject to heterogeneity within and among sites resulting in sizable ranges of metal concentrations for rhizosphere soil and roots. Translocation of metals from roots into shoots depends on the mobility of the metal as well as the preference of the plant. Foliar uptake of metal deposition is influenced largely by the morphology of the leaves which is again affected by conditions of plant growth (Laurie and Manthey 1994). Furthermore, shoots may translocate metals to roots if excesses are present. The complexity of the root-shoot interaction limits the capacity to fully understand the factors that are significant at each study site even when examining a single species of grass. The large range for shoot metal concentrations at all sites is likely a consequence of the many variables involved in metal uptake. With increasing soil heterogeneity at a site the variability in root and shoot will be increasingly magnified. The relative accumulation of metals in roots and shoots are largely a reflection of soil metal concentrations which may indicate limited plant preference for accumulation in specific vegetative parts. Higher concentrations tend to occur in the shoots, although this is not evident at all sites. As a consequence of the limited sample size, it cannot be determined whether there are meaningful differences in uptake between 31 metals. 16 Oaks showed the largest variability in root and shoot concentrations which may suggest that this site is highly heterogeneous in both soil and atmospheric metal contribution. The bioaccumulation of trace metals in green plants is generally as follows Zn>Cu>Pb>Mn>Ni (Kabata-Pendias 2001). This trend was not observed in measurements of BFC of root and shoot with the exception of Mn. This may simply indicate that Kentucky bluegrass takes up Mn according to its physiological needs and does not tend to accumulate it. Despite the relative immobility of Pb it was found to have BCF of root and shoot values comparable to Zn which is known to accumulate efficiently in all plant parts (Davies 1995). Koeppe (1977) proposes that uptake of Pb is highly dependent on physiological status. Under conditions of optimal growth Pb precipitates on the root cell wall and does not accumulate in the shoots. There is also a seasonal component by which Pb content in grass shoots increases during autumn and winter when plants are not in their period of active growth (Mitchell and Reith 1966). This study examined Kentucky bluegrass during what may be its senescent stages. The strong positive correlation between Zn and Pb in soils, rhizosphere soil, roots and shoots may simply reflect the parallel mobility of Pb to Zn in these sites. At the UBC Farm the high BCF of shoot relative to root may be attributed to the combination of very low soil metal concentrations in coordination with relatively high atmospheric deposition on the site. This was not evident at the other sites where trends for soil metal concentrations closely aligned with trends for atmospheric deposition of metals. 4.3 Considerations for future siting of community gardens None of the soil metal concentrations found at the Farm were above the metal standards for agricultural land (the most stringent soil standards) set by the B.C. Ministry of Environment (2012) under the Environmental Management Act for Contaminated Sites Regulation. These generic or matrix numerical standards are based on a standard measurement protocol which is likely an assessment of total instead of available metals (Table 4). Matrix numerical standards were found for Zn, Pb and Cu and selected for human health protection, since this study focuses on sites of urban agriculture for human consumption. Mean values for total Pb and Zn concentrations at the 16 Oaks garden and the Hastings brownfield were above these standards but are subject to a large range of variability. The main complication with urban soils is determining the background soil 32 quality. Often the lack of detailed site history confounds what can be considered anthropogenic contributions. For the Lower Mainland, the B.C. Ministry of Environment developed regional background soil quality estimates, based on aqua regia extraction, which can be used as a reference point for the metal concentrations found on the three study sites (Table 4). Based on these estimates metal concentrations at the UBC Farm can be considered at or below soil background levels while 16 Oaks and the Hastings brownfield exhibit elevated levels for Zn and Pb and Zn, Pb and Cu respectively. The lack of standards set for Mn may indicate that it has not been a metal of interest or concern in the past. Current atmospheric quality standards are designed for human respiratory health and not for the assessment of contaminant deposition onto soil or vegetation. No standards have been set for metal concentrations in vegetation grown on potentially contaminated sites. Future siting of community gardens must address some of the concerns that arise in integrating food production with an urban environment. While not all metal are relevant to all sites the importance of parent material, site history and current deposition trends are complementary in determining soil and vegetative health. In this study, a current Garden had the highest cumulative soil metal concentrations even in comparison to a current Brownfield. While atmospheric deposition at this site was lower than at the Brownfield, the additive load may be significant for metals that are already abundant in these soils. Even if raised beds are used, it is not clear whether bioconcentration in shoots result mainly from metal translocation from the roots or from absorption at the foliar surface; this is likely subject to the metal(s) of Table 4. Standards for comparison with total metal concentrations at the study sites (adapted from B.C. Ministry of Environment 2012). Metal Contaminated site standards for agricultural land Background soil estimates for the Lower Mainland Zn 300 200 Pb 100 60 Ni 150 80 Mn N/A N/A Cu 1500 45 mg/kg dry matter33 concern and the type of vegetation considered. The level of complexity involved in metal uptake and the long residence time of metals should not be underestimated. Therefore environmental standards that are in place need to be considered in the light of local context. 5. CONCLUSIONS The preliminary assessment of three urban sites of current or future agricultural production in Vancouver revealed the significance of parent material, site history and current deposition trends to overall soil and vegetative health. Total soil metal concentrations were highest at 16 Oaks followed by the Hasting brownfield and the UBC Farm. Bulk deposition was highest at the Brownfield followed by the Farm and the Garden. Ni and Mn concentrations seemed to originate from the parent material while Zn, Pb and Cu were likely elevated due to anthropogenic contributions which were only evident at 16 Oaks and the Hastings brownfield. Atmospheric deposition collected over the five month period was up to four orders of magnitude greater than the total metal concentrations in soil. Zn concentrations seem to be most related to high traffic density while local anthropogenic actions may be more important for the other metals. Accumulation of metals tended to be higher in the shoots with large variability in general. Metal concentrations in the rhizosphere soil were intermediate between those found in topsoil and the roots. Zn and Pb was correlated in soils, rhizosphere soil, roots and shoots which may reflect the high level of mobility for Pb in Kentucky bluegrass. 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First sampling event: 5 November 2011 Site Sample EC (dS/m) pH in water pH in 0.01M CaCl2 Organic Matter (%) UBC Farm Topsoil 0.040 5.23 6.63 11.6 UBC Farm Composite 1 0.055 5.52 5.27 8.57 UBC Farm Composite 2 0.070 5.71 4.83 7.73 UBC Farm Composite 3 0.065 6.09 4.99 15.6 UBC Farm Subsoil 0.050 5.59 4.72 7.33 16 Oaks Topsoil 0.060 5.24 5.54 4.90 16 Oaks Raised bed composite 1 0.120 7.12 6.73 29.1 16 Oaks Raised bed composite 2 0.180 7.01 6.67 28.8 16 Oaks Raised bed composite 3 0.380 7.40 6.81 2.73 16 Oaks Subsoil 0.045 6.00 5.79 2.73 Hastings brownfield Topsoil 0.040 5.75 4.72 4.22 Hastings brownfield Composite 1 0.055 5.95 5.96 4.63 Hastings brownfield Composite 2 0.070 5.49 4.90 4.32 Hastings brownfield Composite 3 0.045 5.43 4.68 6.54 Hastings brownfield Subsoil 0.025 5.69 4.65 3.59 Second sampling event: 14 February 2012 UBC Farm Topsoil 1 0.030 5.51 4.63 13.0 UBC Farm Topsoil 2 0.050 5.70 4.75 11.7 UBC Farm Topsoil 3 0.050 6.12 4.98 10.1 UBC Farm Topsoil 4 0.045 6.01 4.99 14.6 UBC Farm Topsoil 5 0.050 6.34 5.34 12.6 UBC Farm Subsoil 0.030 5.97 5.21 7.14 16 Oaks Topsoil 1 0.075 6.14 5.89 3.30 16 Oaks Topsoil 2 0.130 6.23 5.71 4.52 16 Oaks Topsoil 3 0.170 6.22 5.86 5.13 16 Oaks Topsoil 4 0.150 6.09 6.10 7.19 16 Oaks Topsoil 5 0.075 6.25 5.50 5.07 16 Oaks Subsoil 0.050 6.53 5.81 2.73 Hastings brownfield Topsoil 1 0.075 6.2 5.36 4.87 Hastings brownfield Topsoil 2 0.030 6.22 5.05 5.89 Hastings brownfield Topsoil 3 0.070 6.25 5.07 4.12 Hastings brownfield Topsoil 4 0.055 5.35 5.04 5.74 Hastings brownfield Topsoil 5 0.060 5.88 5.47 4.22 Hastings brownfield Subsoil 0.025 6.12 5.22 1.7541 Table A2. Mean and standard deviation values of soil properties. EC (dS/m) pH in water pH in 0.01M CaCl2 Organic Matter (%) SD SD SD SD 0.0506 5.80 5.16 11.7 0.0121 0.358 0.597 2.60 0.0400 5.78 4.96 7.24 0.0141 0.269 0.346 0.134 0.110 6.03 5.77 5.02 0.0459 0.391 0.228 1.26 0.227 7.18 6.74 20.2 0.136 0.201 0.0702 15.1 0.0475 6.26 5.80 2.73 0.00350 0.375 0.014 0.00 0.0556 5.84 5.14 4.95 0.0151 0.352 0.403 0.887 0.0250 5.90 4.94 2.67 0.00 0.304 0.403 1.30 2SubsoilHastings brownfield 2Subsoil16 Oaks 9Topsoil and compositeHastings brownfield 6Topsoil16 Oaks 3Raised bed composite16 Oaks Site Sample Sample Size UBC Farm UBC Farm Topsoil and composite 9 2Subsoil42 First sampling event: 5 November 2011 Site Sample Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P UBC Farm Topsoil 122 42.6 9.01 141 32.2 13800 16600 3230 3080 273 972 1090 UBC Farm Composite 1 70.4 35.0 6.12 144 47.2 13000 15400 2820 2990 185 768 1540 UBC Farm Composite 2 50.7 21.8 7.88 110 23.0 12700 15500 2640 3590 305 740 926 UBC Farm Composite 3 85.4 45.1 14.8 230 37.9 17100 18500 3310 3360 183 1000 1550 UBC Farm Subsoil 66.9 42.0 17.9 393 28.0 19600 17300 3790 3500 63.3 803 882 16 Oaks Topsoil 335 170 11.3 182 40.9 13500 14400 3960 8510 732 711 612 16 Oaks Raised bed composite 1 318 110 21.1 475 102 21800 16600 7880 34200 691 3460 3480 16 Oaks Raised bed composite 2 295 103 17.6 297 92.8 18300 15600 6690 36500 621 2260 2560 16 Oaks Raised bed composite 3 7270 424 78.0 313 568 43000 13800 8880 2070 672 892 286 16 Oaks Subsoil 383 109 25.0 463 135 26600 18000 3500 46600 1230 5400 5660 Hastings brownfield Topsoil 1010 499 72.6 446 381 72600 10200 3410 3300 399 847 325 Hastings brownfield Composite 1 571 202 36.6 185 303 23900 12500 3590 3700 316 1020 453 Hastings brownfield Composite 2 227 92.7 15.9 122 163 18400 14500 4630 3200 353 1010 452 Hastings brownfield Composite 3 148 55.3 23.2 160 120 14000 14200 3550 2640 117 1190 405 Hastings brownfield Subsoil 124 45.5 9.54 258 118 15600 11900 3150 2140 337 940 363 Second sampling event: 14 February 2012 UBC Farm Topsoil 1 90.4 40.7 37.4 147 27.1 18100 20500 2730 3780 72.1 862 1340 UBC Farm Topsoil 2 63.8 50.8 9.24 207 31.9 14700 18200 2730 3120 38.9 704 1250 UBC Farm Topsoil 3 67.4 39.9 9.57 370 38.2 16700 17500 2730 3030 79.2 813 875 UBC Farm Topsoil 4 133 81.8 21.6 785 55.2 27000 34300 5180 7000 348 1580 2630 UBC Farm Topsoil 5 83.1 46.1 31.6 488 26.0 17600 20900 3150 5970 133 968 1740 UBC Farm Subsoil 80.2 40.3 26.4 341 26.5 21000 26100 4250 3740 158 1210 1370 16 Oaks Topsoil 1 339 130 18.9 191 35.7 25300 24400 4960 3950 354 1580 400 16 Oaks Topsoil 2 558 184 25.6 335 40.8 23800 23800 4650 4300 569 1480 563 16 Oaks Topsoil 3 606 229 13.7 186 35.8 16400 19300 3990 4980 389 1320 526 16 Oaks Topsoil 4 1320 734 56.7 217 62.8 24300 25900 4560 9940 1210 1360 975 16 Oaks Topsoil 5 314 123 16.5 113 38.0 26200 28400 5410 5480 325 1830 499 16 Oaks Subsoil 262 108 18.6 219 31.6 17800 20000 4090 3090 70.8 1080 439 Hastings brownfield Topsoil 1 160 83.7 24.9 196 164 17200 15700 3240 3210 107 1070 412 Hastings brownfield Topsoil 2 321 136 26.3 593 258 28600 26000 5710 5380 493 1910 670 Hastings brownfield Topsoil 3 133 59.8 14.4 287 93.2 17900 16000 3180 2850 122 1090 362 Hastings brownfield Topsoil 4 182 81.4 9.23 196 156 17500 19900 4860 3520 214 1450 381 Hastings brownfield Topsoil 5 170 79.0 11.9 157 100 13000 16400 4090 4400 224 1250 370 Hastings brownfield Subsoil 419 170 49.6 312 170 25500 15700 3700 3270 130 935 362 (mg/kg dry matter) Table A3. Element concentrations from aqua regia extraction of individual soil samples from the study sites. 43 Table A4. Mean and standard deviation values for element concentrations from aqua regia extraction of soil. Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P SD SD SD SD SD SD SD SD SD SD SD SD 85.1 44.9 16.4 291 35.4 16700 19700 3170 3990 180 934 1440 27.0 16.1 11.4 223 10.5 4350 5800 794 1460 110 265 534 73.6 41.2 22.2 367 27.3 20300 21700 4020 3620 111 1010 1130 9.40 1.20 6.01 36.8 1.06 990 6220 325 170 67.0 288 345 579 262 23.8 204 42.3 21600 22700 4590 6190 596 1380 596 384 234 16.9 72.9 10.3 5280 5040 560 2450 338 375 199 2630 212 38.9 362 254 27700 15300 7820 24200 661 2200 2110 4020 183 33.9 98.5 272 13400 1420 1100 19200 36.2 1280 1640 323 109 21.8 341 83.3 22200 19000 3800 24800 650 3240 3050 85.6 0.710 4.53 173 73.1 6220 1410 417 30800 820 3050 3690 325 143 26.1 260 193 24800 16200 4030 3580 260 1200 426 291 141 19.4 158 99.2 18600 4560 868 845 138 314 101 272 108 29.6 285 144 20600 13800 3420 2710 234 938 363 208 88.0 28.3 38.2 36.8 7000 2690 389 799 146 3.54 0.707 Hastings brownfield Topsoil and composite 9 Hastings brownfield Subsoil 2 16 Oaks Raised bed composite 3 16 Oaks Subsoil 2 UBC Farm Subsoil 2 16 Oaks Topsoil 6 UBC Farm Topsoil and composite 9 Site Sample Sample Size (mg/kg dry matter)44 Table A5. Element concentrations from HCl extraction of individual soil samples from the study sites. First sampling event: 5 November 2011 Site Sample Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P UBC Farm Topsoil 72.2 5.47 1.44 176 2.32 172 4130 141 1670 34.7 227 71.3 UBC Farm Composite 1 17.3 4.13 1.21 234 3.49 238 4170 159 2450 31.3 231 183 UBC Farm Composite 2 10.6 2.81 0.730 97.7 1.99 142 4000 137 2210 34.9 199 116 UBC Farm Composite 3 18.7 4.08 0.960 214 3.42 161 3870 186 1870 36.8 163 124 UBC Farm Subsoil 7.69 3.88 0.830 183 3.19 300 4100 143 2140 34.8 93.6 56.2 16 Oaks Topsoil 456 240 5.14 147 35.6 979 2580 629 5020 553 186 119 16 Oaks Raised bed composite 1 53.8 3.69 0.780 149 1.82 207 321 1100 11600 296 1170 356 16 Oaks Raised bed composite 2 65.8 2.93 0.780 153 1.55 240 453 1200 12800 56.5 563 195 16 Oaks Raised bed composite 3 90.6 38.0 4.71 62.6 7.31 1020 1360 299 2240 119 53.9 64.1 16 Oaks Subsoil 42.1 2.51 0.630 124 2.37 108 211 1400 12500 87.7 1650 279 Hastings brownfield Topsoil 56.6 28.0 3.54 136 104 736 1300 376 1330 41.3 108 93.4 Hastings brownfield Composite 1 215 172 9.65 122 183 786 1880 247 1700 80.6 87 38.5 Hastings brownfield Composite 2 84.7 35.3 4.79 134 97.9 589 1910 311 1900 43.6 129 71.8 Hastings brownfield Composite 3 63.1 28.8 4.28 143 95.1 573 1650 334 1630 37.0 130 73.4 Hastings brownfield Subsoil 241 233 22.3 226 276 1180 1920 211 889 46.1 48.9 21.3 Second sampling event: 14 February 2012 UBC Farm Topsoil 1 9.49 1.40 2.00 133 2.30 16.8 2240 68.4 1190 17.0 55.2 22.4 UBC Farm Topsoil 2 11.6 2.52 1.83 163 1.60 67.3 3020 95.2 1590 26.2 97.8 57.3 UBC Farm Topsoil 3 9.45 2.70 2.40 195 7.76 64.4 3150 109 1670 38.9 116 35.5 UBC Farm Topsoil 4 14.2 2.24 0.700 186 2.98 32.7 2720 133 1450 22.3 79.9 45.3 UBC Farm Topsoil 5 17.1 1.78 4.55 172 2.56 38.3 2420 160 1300 36.7 141 74.1 UBC Farm Subsoil 5.25 1.83 2.19 108 3.19 4.62 2440 47.8 1270 11.0 42.4 11.0 16 Oaks Topsoil 1 102 34.7 1.40 69.1 9.85 1030 1400 412 732 93.4 74.4 10.2 16 Oaks Topsoil 2 144 90.0 1.93 85.3 9.29 595 1520 310 802 94.5 163 9.95 16 Oaks Topsoil 3 289 70.3 2.37 77.8 6.17 319 1360 242 717 148 120 8.17 16 Oaks Topsoil 4 409 129 3.88 82.0 11.0 172 1400 209 742 222 141 13.9 16 Oaks Topsoil 5 88.0 28.8 1.63 117 6.03 776 1630 172 872 67.6 138 0.520 16 Oaks Subsoil 132 44.5 1.34 65.8 9.09 406 1890 180 979 106 68.5 30.9 Hastings brownfield Topsoil 1 63.6 35.8 4.42 110 75.8 457 1230 320 672 30.4 122 58.7 Hastings brownfield Topsoil 2 64.4 19.3 3.95 109 63.4 308 981 271 545 26.6 87.9 30.4 Hastings brownfield Topsoil 3 43.2 19.1 5.05 107 50.5 534 1360 314 736 40.6 92.9 63.8 Hastings brownfield Topsoil 4 59.5 24.2 3.35 142 85.5 569 1540 359 843 35.8 116 39.3 Hastings brownfield Topsoil 5 40.6 11.8 2.84 99.5 36.4 323 1090 253 594 24.1 61.8 31.6 Hastings brownfield Subsoil 94.2 52.9 10.7 78.3 51.8 332 1730 154 902 29.6 45.5 31.7 (mg/kg dry matter)45 Table A6. Mean and standard deviation values for element concentrations from HCl extraction of soil. Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P SD SD SD SD SD SD SD SD SD SD SD SD 20.1 3.01 1.76 174 3.16 104 3300 132 1710 31.0 146 81.0 19.9 1.30 1.20 40.9 1.84 76.8 758 36.2 410 7.52 64.0 51.2 6.47 2.86 1.51 146 3.19 152 3270 95.4 1700 22.9 68.0 33.6 1.72 1.45 0.960 53.0 0.00 209 1170 67.3 615 16.8 36.2 32 248 98.8 2.72 96.4 13.0 645 1650 329 1480 196 137 27.0 160 78.4 1.48 29.7 11.2 349 467 170 1730 183 38.2 45.3 70.1 14.9 2.09 122 3.56 489 711 866 8880 157 596 205 18.8 20.0 2.27 51.1 3.25 460 566 494 5780 124 559 146 132 44.5 1.34 65.8 9.09 406 1890 180 979 106 68.5 30.9 63.6 29.7 0.500 41.2 4.75 211 1190 863 8150 12.9 1120 175 76.7 41.6 4.65 123 88.0 542 1440 309 1100 40.0 104 55.6 53.4 49.5 2.00 16.7 42.2 162 330 45.0 534 16.6 23.0 21.9 168 143 16.5 152 164 756 1820 183 896 37.8 47.2 26.5 104 127 8.20 104 158 600 134 40.3 9.19 11.7 2.40 7.35 2SubsoilHastings brownfield Subsoil16 Oaks 9 2 Topsoil and compositeHastings brownfield 6Topsoil16 Oaks 3Raised bed composite16 Oaks 9Topsoil and compositeUBC Farm 2SubsoilUBC Farm (mg/kg dry matter) Site Sample Size Sample46 Table A7. Proportion of elements extracted using HCl as compared to aqua regia in individual soil samples from the study sites. First sampling event: 5 November 2011 Site Sample Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P UBC Farm Topsoil 59.3 12.8 16.0 - 7.18 1.25 24.9 4.36 54.3 12.7 23.3 6.53 UBC Farm Composite 1 24.5 11.8 19.8 - 7.40 1.84 27.0 5.62 82.0 16.9 30.1 11.9 UBC Farm Composite 2 20.9 12.9 9.22 89.0 8.66 1.12 25.8 5.19 61.7 11.4 26.9 12.5 UBC Farm Composite 3 21.9 9.04 6.47 93.2 9.01 0.940 20.9 5.62 55.5 20.1 16.3 8.03 UBC Farm Subsoil 11.5 9.24 4.66 46.6 11.4 1.53 23.6 3.78 61.2 54.9 11.6 6.37 16 Oaks Topsoil - - 45.4 80.4 87.0 7.24 17.9 15.9 59.0 75.6 26.2 19.5 16 Oaks Raised bed composite 1 16.9 3.35 3.68 31.4 1.79 0.950 1.93 13.9 34.0 42.9 33.9 10.2 16 Oaks Raised bed composite 2 22.3 2.84 4.42 51.3 1.67 1.31 2.89 17.9 35.1 9.09 24.9 7.61 16 Oaks Raised bed composite 3 1.25 8.98 6.04 20.0 1.29 2.39 9.83 3.37 - 17.7 6.04 22.4 16 Oaks Subsoil 11.0 2.31 2.52 26.6 1.76 0.410 1.17 40.0 26.9 7.10 30.5 4.93 Hastings brownfield Topsoil 5.61 5.61 4.87 30.5 27.2 1.01 12.7 11.0 40.2 10.3 12.7 28.7 Hastings brownfield Composite 1 37.7 85.2 26.4 66.0 60.4 3.29 15.0 6.87 45.9 25.5 8.54 8.51 Hastings brownfield Composite 2 37.3 38.0 30.1 - 59.9 3.20 13.1 6.71 59.5 12.3 12.7 15.9 Hastings brownfield Composite 3 42.5 52.0 18.4 88.9 79.5 4.08 11.6 9.38 61.6 31.6 10.9 18.1 Hastings brownfield Subsoil - - - 87.6 - 7.59 16.2 6.69 41.4 13.7 5.20 5.88 Second sampling event: 14 February 2012 UBC Farm Topsoil 1 10.5 3.45 5.35 90.5 8.50 0.0900 10.9 2.50 31.4 23.6 6.40 1.67 UBC Farm Topsoil 2 18.2 4.97 19.8 79.0 5.00 0.460 16.6 3.48 51.0 67.4 13.9 4.56 UBC Farm Topsoil 3 14.0 6.78 25.1 52.6 20.3 0.390 18.0 3.99 55.2 49.2 14.3 4.05 UBC Farm Topsoil 4 10.6 2.74 3.26 23.7 5.39 0.120 7.92 2.56 20.7 6.42 5.05 1.72 UBC Farm Topsoil 5 20.6 3.87 14.4 35.4 9.83 0.220 11.6 5.09 21.7 27.7 14.6 4.26 UBC Farm Subsoil 6.55 4.55 8.29 31.6 12.1 0.0200 9.35 1.12 34.1 6.96 3.50 0.800 16 Oaks Topsoil 1 30.0 26.6 7.40 36.3 27.6 4.07 5.73 8.31 18.5 26.4 4.71 2.55 16 Oaks Topsoil 2 25.9 49.0 7.55 25.4 22.8 2.50 6.38 6.67 18.6 16.6 11.0 1.77 16 Oaks Topsoil 3 47.7 30.6 17.20 41.7 17.2 1.94 7.02 6.07 14.4 38.0 9.09 1.55 16 Oaks Topsoil 4 31.0 17.6 6.83 37.8 17.5 0.710 5.41 4.57 7.46 18.4 10.4 1.43 16 Oaks Topsoil 5 28.0 23.4 9.85 - 15.9 2.96 5.73 3.18 15.9 20.8 7.54 0.100 16 Oaks Subsoil 50.5 41.2 7.19 30.0 28.8 2.28 9.46 4.41 31.7 - 6.34 7.04 Hastings brownfield Topsoil 1 39.9 42.8 17.8 56.3 46.3 2.65 7.85 9.86 20.9 28.6 11.4 14.2 Hastings brownfield Topsoil 2 20.1 14.2 15.0 18.4 24.6 1.07 3.78 4.74 10.1 5.39 4.60 4.53 Hastings brownfield Topsoil 3 32.5 31.9 35.2 37.2 54.1 2.98 8.54 9.88 25.8 33.4 8.51 17.6 Hastings brownfield Topsoil 4 32.7 29.7 36.3 72.3 55.0 3.26 7.76 7.38 23.9 16.8 8.05 10.3 Hastings brownfield Topsoil 5 23.9 14.9 23.8 63.4 36.3 2.48 6.66 6.18 13.5 10.7 4.96 8.53 Hastings brownfield Subsoil 22.5 31.0 21.6 25.1 30.6 1.30 11.0 4.18 27.6 22.8 4.86 8.74 1. All values greater than 100% eliminated from statisitcal analysis. Percent Available (%)47 Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P SD SD SD SD SD SD SD SD SD SD SD SD 22.3 7.59 13.3 66.2 9.03 0.714 18.2 4.27 48.2 26.2 16.8 6.14 14.8 4.14 7.58 28.7 4.52 0.605 7.00 1.22 20.0 19.8 8.57 3.99 9.02 6.90 6.48 39.1 11.8 0.775 16.5 2.45 47.6 30.9 7.55 3.58 3.50 3.32 2.57 10.6 0.494 1.07 10.1 1.88 19.2 33.9 5.73 3.94 32.5 29.4 15.7 44.3 31.3 3.24 8.03 7.45 22.3 32.6 11.5 4.48 8.71 11.9 15.0 21.0 27.6 2.25 4.87 4.50 18.4 22.4 7.55 7.40 13.5 5.06 4.71 34.2 1.58 1.55 4.88 11.7 34.6 23.2 21.6 13.4 10.9 3.41 1.21 15.8 0.261 0.749 4.31 7.50 0.778 17.6 14.2 7.90 30.8 21.8 4.86 28.3 15.3 1.34 5.32 22.2 29.3 7.10 18.4 5.98 27.9 27.5 3.30 2.40 19.1 1.32 5.86 25.2 3.39 - 17.1 1.49 30.2 34.9 23.1 54.1 49.2 2.67 9.66 8.00 33.5 19.4 9.15 14.0 11.8 24.0 10.2 23.6 17.6 1.03 3.62 2.10 19.1 10.5 3.03 7.18 22.5 31.0 21.6 56.4 30.6 4.44 13.6 5.44 34.5 18.2 5.03 7.31 - - - 44.2 - 4.45 3.68 1.77 9.76 6.43 0.240 2.02 Hastings brownfield Topsoil and composite 9 Hastings brownfield Subsoil 2 16 Oaks Raised bed composite 3 16 Oaks Subsoil 2 UBC Farm Subsoil 2 16 Oaks Topsoil 6 UBC Farm Topsoil and composite 9 Site Sample Sample Size Percent Available (%) Table A8. Mean and standard deviation values for proportion of available elements in soil. 48 Site Sample EC (dS/m) pH in water pH in 0.01M CaCl2 Organic Matter (%) 16 Oaks Topsoil 1 0.050 5.63 5.31 2.77 16 Oaks Topsoil 2 0.125 5.20 4.70 2.26 16 Oaks Topsoil 3 0.055 5.90 5.34 4.38 Hastings brownfield Topsoil 1 0.120 6.88 6.46 8.32 Hastings brownfield Topsoil 2 0.285 4.94 4.81 3.28 Hastings brownfield Topsoil 3 - 5.98 5.42 7.17 Hastings brownfield Topsoil 4 0.390 7.19 6.90 9.85 Hastings brownfield Topsoil 5 0.255 6.47 6.17 15.2 Table A9. Soil properties of individual samples from two of the study sites (Thomas 2012). EC (dS/m) pH in water pH in 0.01M CaCl2 Organic Matter (%) SD SD SD SD 0.077 5.58 5.12 3.14 0.042 0.353 0.361 1.11 0.263 6.29 5.95 8.76 0.111 0.882 0.835 4.33 Site Samp e Topsoil16 Oaks Topsoil Hastings brownfield Table A10. Mean and standard deviation values for soil properties (Thomas 2012), 49 Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P 16 Oaks Topsoil 1 160 125 20.0 700 41.1 24200 19000 3950 4120 114 573 584 16 Oaks Topsoil 2 266 136 24.3 513 60.5 26100 23100 5530 16300 559 1460 1220 16 Oaks Topsoil 3 209 135 31.3 1230 49.0 24500 19300 3170 8750 170 1230 1260 Hastings brownfield Topsoil 1 803 296 43.6 468 249 42100 14500 4870 4080 1080 913 770 Hastings brownfield Topsoil 2 270 138 29.7 400 181 34600 12300 3440 2990 833 894 268 Hastings brownfield Topsoil 3 1080 371 90.1 470 3610 46100 12300 3550 3930 582 981 410 Hastings brownfield Topsoil 4 62.5 180 21.7 318 45.8 17800 15400 3400 4570 121 669 222 Hastings brownfield Topsoil 5 158 64.5 13.2 347 71.0 19300 15200 4020 4610 995 1050 167 Site Sample (mg/kg dry matter) Table A11. Element concentrations from aqua regia extraction of individual soil samples from two of the study sites (Thomas 2012). Table A12. Mean and standard deviation values of element concentrations from aqua regia extraction of soil (Thomas 2012). Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P 212 132 25.2 813 50.2 24900 20500 4220 9720 281 1090 1020 53.2 6.22 5.67 371 9.73 1060 2310 1200 6140 243 461 380 475 210 39.6 401 832 32000 13900 3860 4040 723 901 367 444 123 30.3 68.7 1560 13000 1510 621 655 387 143 242 5 Site Sample 16 Oaks Topsoil 3 (mg/kg dry matter)Sample Size Hastings brownfield Topsoil 50 Table A14. Mean and standard deviation values of element concentrations from HCl extraction of soil (Thomas 2012). Table A13. Element concentrations from HCl extraction of individual soil samples from two of the study sites (Thomas 2012). Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P 16 Oaks Topsoil 1 88.4 70.9 4.52 453 15.3 528 2670 448 1370 173 615 42.8 16 Oaks Topsoil 2 60.1 22.0 3.05 162 5.02 428 1990 571 1000 174 351 120 16 Oaks Topsoil 3 16.1 2.41 547 2.19 132 1580 659 800 121 438 93.6 H stings brownfield Topsoil 1 404 208 12.2 171 193 1460 1840 351 1030 113 2900 39.9 Hastings brownfield Topsoil 2 82.4 71.1 6.39 146 103 1020 1310 374 692 61.6 387 69.5 Hastings brownfield Topsoil 3 561 224 38.2 179 130 1540 1890 455 1060 98.2 4060 52.1 Hastings brownfield Topsoil 4 15.9 17.7 3.08 137 17.6 730 2040 459 1030 48.1 88.7 50.7 Hastings brownfield Topsoil 5 48.7 39.6 2.91 118 42.7 765 2040 371 1040 63.4 292 85.6 (mg/kg dry matter) Site Sample Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P 78.1 36.3 3.33 387 7.51 362 2080 559 1060 156 468 85.5 15.7 30.1 1.08 201 6.91 206 548 106 288 30.2 134 39.3 222 112 12.6 150 97.2 1100 1820 402 968 76.9 1550 59.6 245 96.7 14.8 24.8 69.9 380 299 50.9 155 27.4 1820 18.0 Site Sample (mg/kg dry matter)Sample Size Topsoil 16 Oaks Topsoil Hastings brownfield 3 551 Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P 16 Oaks Topsoil 1 55.3 56.7 22.5 64.8 37.2 2.18 14.0 11.3 33.2 - - 7.32 16 Oaks Topsoil 2 22.6 16.1 12.6 31.6 8.29 1.64 8.58 10.3 6.16 31.2 24.0 9.87 16 Oaks Topsoil 3 41.2 11.9 7.70 44.5 4.48 0.538 8.22 20.8 9.14 71.6 35.6 7.40 Hastings brownfield Topsoil 1 50.3 70.2 28.0 36.5 77.5 3.47 12.7 7.20 25.1 10.4 - 5.19 Hastings brownfield Topsoil 2 30.5 51.6 21.5 36.5 56.8 2.94 10.6 10.9 23.1 7.40 43.3 25.9 Hastings brownfield Topsoil 3 51.8 60.3 42.4 38.1 3.59 3.34 15.3 12.8 26.8 16.9 - 12.7 Hastings brownfield Topsoil 4 25.5 9.86 14.2 43.0 38.6 4.11 13.3 13.5 22.5 39.9 13.3 22.8 Hastings brownfield Topsoil 5 30.8 61.4 22.1 34.0 60.2 3.97 13.4 9.24 22.5 6.37 27.9 51.3 Site Sample Percent Available (%) Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P 39.7 28.2 14.3 47.0 16.7 1.45 10.3 14.1 16.2 51.4 29.8 8.20 16.4 24.7 7.57 16.7 17.9 0.839 3.25 5.75 14.8 28.6 8.21 1.45 37.8 50.7 25.6 37.6 47.3 3.56 13.1 10.7 24.0 16.2 28.2 23.6 12.3 23.7 10.6 3.34 28.1 0.477 1.67 2.58 1.90 13.9 15.0 17.6 Percent Available (%)Sample Size 16 Oaks Topsoil Hastings brownfield Topsoil 5 3 Site Sample Table A16. Mean and standard deviation values for proportion of available elements in soil (Thomas 2012). Table A15. Proportion of elements extracted using HCl as compared to aqua regia in individual soil samples from two of the study sites (Thomas 2012). 52 Table A17. Element concentrations from aqua regia extraction of individual root and shoot samples from the study sites. First sampling event: 5 November 2011 Site Sample Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P UBC Farm Shoot 1 82.3 2260 - 26.8 802 264 1260 698 40700 64200 703 301000 47300 16 Oaks Shoot 2 89.0 1760 178 63.8 508 177 5230 4510 10000 70700 2400 113000 9190 Hastings brownfield Shoot 3 82.5 326 83.3 145 858 104 13000 7720 11500 39000 8180 162000 32300 Second sampling event: 14 February 2012 UBC Farm Shoot 1 81.5 315 62.6 14.1 1300 87.0 7620 7670 10200 19800 1440 200000 27700 UBC Farm Shoot 2 88.1 285 62.0 7.24 748 81.2 10400 9830 15800 41500 1820 226000 36000 UBC Farm Shoot 3 94.0 294 105 97.7 1580 152 9610 7100 14000 46100 2770 257000 31200 UBC Farm Shoot 4 71.8 751 104 34.2 2920 197 19600 15600 29700 61000 3170 413000 61800 UBC Farm Shoot 5 80.9 520 77.2 35.8 762 118 16000 16300 13100 26900 1520 234000 40500 16 Oaks Shoot 1 67.2 641 221 44.9 480 113 33000 36700 8240 17300 1280 49000 8460 16 Oaks Shoot 2 66.9 550 181 7.19 88.5 85.3 7630 25800 6720 15200 1240 65900 9270 16 Oaks Shoot 3 67.1 2990 924 121 1070 230 62000 60800 14400 33400 3040 34200 11500 16 Oaks Shoot 4 61.6 1590 625 50.7 539 108 29500 30100 7680 18300 2220 82900 12900 16 Oaks Shoot 5 91.4 430 196 32.4 349 174 14400 9780 4460 29800 1170 189000 23700 Hastings brownfield Shoot 1 73.3 482 108 22.7 380 160 18600 16000 5290 14800 1160 55500 7630 Hastings brownfield Shoot 2 90.9 1930 702 32.1 1860 616 51400 25400 8250 47400 - 226000 18500 Hastings brownfield Shoot 3 87.8 726 192 53.3 172 166 4560 13600 3420 20700 935 97600 10700 Hastings brownfield Shoot 4 85.7 892 228 49.1 656 397 17200 19100 5700 25300 1880 136000 11400 Hastings brownfield Shoot 5 79.5 1080 204 79.5 958 297 24800 17700 8290 37200 1940 220000 21400 UBC Farm Roots in topsoil 1 63.3 218 59.2 13.5 334 73.2 21700 27400 3540 11800 581 7530 4920 UBC Farm Roots in topsoil 2 55.8 137 43.4 33.4 456 63.3 14800 18600 2710 8470 388 5790 3510 UBC Farm Roots in topsoil 3 49.1 87.4 45.3 7.66 541 48.0 21800 22300 3060 9320 251 2090 1920 UBC Farm Roots in topsoil 4 56.6 206 71.9 17.7 540 92.0 23700 26300 3630 11200 426 4630 4440 UBC Farm Roots in topsoil 5 60.5 221 45.3 2.72 262 85.3 22200 26000 3590 16000 584 7110 5080 UBC Farm Roots in subsoil 51.4 131 61.7 12.4 574 65.9 28100 30800 4160 9340 360 4090 3070 16 Oaks Roots in topsoil 1 35.8 631 157 62.5 165 73.2 25000 25300 4270 6680 436 3890 1320 16 Oaks Roots in topsoil 2 58.8 1500 445 42.7 791 142 53200 50000 10900 19300 1680 20200 5790 16 Oaks Roots in topsoil 3 28.6 1120 380 12.4 185 89.9 25500 29000 4790 8590 795 3040 1240 16 Oaks Roots in topsoil 4 64.0 2970 1130 32.4 593 161 36400 34300 5440 17900 2190 10600 4720 16 Oaks Roots in topsoil 5 44.0 607 167 29.3 260 63.5 34400 32400 4270 9320 511 6130 1830 Hastings brownfield Roots in topsoil 1 54.7 828 184 63.8 584 583 30600 20100 3870 11400 424 6390 2220 Hastings brownfield Roots in topsoil 2 43.1 856 198 52.0 201 431 37800 22600 4090 10800 478 6200 1520 Hastings brownfield Roots in topsoil 3 59.9 971 188 34.4 594 398 29900 26200 5420 13300 596 9960 2510 Hastings brownfield Roots in topsoil 4 75.5 1070 188 41.1 261 567 35200 32900 6690 14400 716 12400 2910 Hastings brownfield Roots in topsoil 5 53.1 491 102 38.7 374 259 26400 23700 4340 11400 353 5720 1530 Hastings brownfield Roots in subsoil 42.3 396 200 26.0 395 175 118000 15000 2580 4710 1.20 1280 515 (mg/kg dry matter)Organic Matter (%)53 Table A18. Element concentrations from HCl extraction of individual rhizosphere soil samples from the study sites. Second sampling event: 14 February 2012 Site Sample Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P UBC Farm Rhizosphere soil in topsoil 1 40.0 61.6 2.63 418 31.8 4380 9770 186 3480 162 682 1560 UBC Farm Rhizosphere soil in topsoil 2 57.1 65.2 7.26 282 22.3 8060 7960 1270 2640 210 1240 985 UBC Farm Rhizosphere soil in topsoil 3 38.7 57.7 4.33 333 12.9 4860 7950 717 2560 168 579 1020 UBC Farm Rhizosphere soil in topsoil 4 31.4 39.1 3.70 147 12.1 4280 4140 630 1180 130 363 465 UBC Farm Rhizosphere soil in topsoil 5 14.3 23.6 0.260 131 14.6 1490 3080 105 2300 79.9 460 778 UBC Farm Rhizosphere soil in subsoil 20.0 48.6 5.07 468 61.7 5340 20600 83.9 5740 271 866 1860 16 Oaks Rhizosphere soil in topsoil 1 1490 717 32.8 1050 125 51500 24400 8100 24200 1630 2240 3840 16 Oaks Rhizosphere soil in topsoil 2 112 193 0.0700 139 13.6 5320 2610 167 4350 266 897 717 16 Oaks Rhizosphere soil in topsoil 3 169 156 0.260 86.9 8.81 1420 1160 135 2740 106 367 323 16 Oaks Rhizosphere soil in topsoil 4 1070 1020 5.54 366 41.7 7890 5370 423 8460 520 1520 1520 16 Oaks Rhizosphere soil in topsoil 5 195 96.5 7.57 236 6.8 6930 7580 2320 2980 203 689 452 Hastings brownfield Rhizosphere soil in topsoil 1 312 121 20.9 412 186 15800 10100 4460 4980 594 1380 531 Hastings brownfield Rhizosphere soil in topsoil 2 126 78.8 5.34 196 72.6 1800 1510 210 2420 142 692 433 Hastings brownfield Rhizosphere soil in topsoil 3 127 137 4.34 326 96.8 2730 2250 343 5060 352 1420 846 Hastings brownfield Rhizosphere soil in topsoil 4 758 326 53.3 1300 427 41500 26400 13100 13800 1480 3930 1220 Hastings brownfield Rhizosphere soil in topsoil 5 410 157 29.4 688 180 22900 16700 7160 8830 814 1990 902 Hastings brownfield Rhizosphere soil in subsoil 1180 2470 143 1510 567 32000 45400 1510 34500 2320 2350 7500 (mg/kg dry matter)54 Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P SD SD SD SD SD SD SD SD SD SD SD SD 83.1 738 82.2 36.0 1350 150 10700 9530 20600 43200 1900 272000 40800 7.48 768 21.3 32.2 840 70.6 6440 5830 12000 17800 913 77000 12400 57.1 174 53.0 15.0 427 72.4 20800 24100 3310 11400 446 5430 3970 5.38 59.2 12.3 11.8 125 17.5 3470 3630 405 2930 141 2190 1300 - 36.3 49.4 3.64 262 18.7 4610 6580 582 2430 150 665 962 - 15.5 17.6 2.55 123 8.35 2340 2840 469 828 48.4 343 401 73.9 1330 388 53.3 506 148 25300 27900 8580 30800 1890 89000 12500 12.8 990 315 38.3 322 54.8 21200 20200 3380 20900 775 56100 5730 46.2 1370 456 35.9 399 106 34900 34200 5930 12400 1120 8770 2980 15.0 971 398 18.5 279 43.2 11400 9480 2820 5800 775 7030 2120 - 607 437 9.25 376 39.2 14600 8220 2230 8550 545 1140 1370 - 633 410 13.6 392 50.0 20800 9380 3400 9050 626 744 1460 83.3 906 253 63.6 814 290 21600 16600 7080 30700 2820 150000 17000 6.31 570 227 44.4 590 192 16100 5880 2860 12400 3030 67400 9100 57.3 843 172 46.0 403 448 32000 25100 4880 12300 513 8130 2140 11.9 219 39.5 11.9 181 133 4520 4880 1170 1520 144 2920 611 - 347 164 22.7 584 192 16900 11400 5050 7020 676 1880 786 - 260 95.0 20.1 439 140 16400 10400 5370 4430 515 1230 314 Hastings brownfield Rhizosphere soil in topsoil 6 UBC Farm Shoot 6 UBC Farm Roots in topsoil 5 UBC Farm Rhizosphere soil in topsoil 6 16 Oaks Roots in topsoil UBC Farm Rhizosphere soil in topsoil 6 16 Oaks Shoot 6 5 UBC Farm Shoot 6 UBC Farm Roots in topsoil 5 Site Sample Sample Size (mg/kg dry matter)Organic Matter (%) Table A19. Mean and standard deviation values of element concentrations in vegetative samples. 55 Site Date collected pH Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P UBC Farm 21-Nov-2011 5.58 2.19 0.00532 0.00599 0.00575 0.0112 0.0466 0.0815 0.092 0.235 0.527 0.136 0.0217 UBC Farm 14-Dec-2011 5.44 1.32 0.00562 0.00367 0.000812 0.00900 0.00736 0.0573 0.182 0.269 1.40 0.105 0.0138 UBC Farm 4-Jan-2011 5.25 1.46 0.00334 0.00106 0.000233 0.00258 - 0.0166 0.0506 0.166 0.544 0.0438 0.0234 UBC Farm 13-Jan-2012 5.43 1.41 0.00432 0.01571 0.000901 0.0115 - 0.215 0.683 0.197 0.674 0.0675 0.0255 UBC Farm 3-Feb-2012 4.45 1.96 0.00651 0.00327 0.000250 0.00665 - 0.0694 0.132 0.256 1.26 0.0966 0.0213 UBC Farm 14-Feb-2012 4.95 0.597 0.00338 0.000260 - 0.00665 - 0.0560 - 0.272 0.103 0.0154 0.0101 UBC Farm 2-Mar-2012 - 4.31 0.0101 0.00831 0.00240 0.00992 0.0854 0.296 0.154 0.441 1.79 0.181 0.0315 16 Oaks 19-Nov-2011 5.69 2.2 0.00554 0.00341 0.00691 0.0149 0.0312 0.0484 0.0351 0.358 0.550 0.187 0.0163 16 Oaks 10-Dec-2011 5.6 1.4 0.00507 0.00529 0.00400 0.0927 0.0256 0.0856 0.109 0.475 1.25 0.176 0.0239 16 Oaks 29-Dec-2011 5.22 2.00 0.00405 0.00101 0.00188 0.00584 - 0.0368 0.0688 0.491 0.910 0.0881 0.0128 16 Oaks 13-Jan-2012 5.74 1.54 0.00497 - - 0.00957 - 0.0547 0.0932 0.208 0.796 0.0731 0.0164 16 Oaks 3-Feb-2012 5.55 5.79 0.0112 0.00330 0.001900 0.0136 - 0.269 0.281 0.510 3.76 0.203 0.127 16 Oaks 14-Feb-2012 5.19 3.94 0.113 0.000400 0.00173 0.0171 0.0262 0.280 0.101 0.391 1.41 0.273 0.0414 16 Oaks 2-Mar-2012 - 5.36 0.0175 0.00356 0.001500 0.0196 - 0.180 0.134 0.353 1.87 0.169 0.0497 Hastings brownfield 19-Nov-2011 5.49 4.46 0.0076 - - 0.0300 - 0.128 0.00611 0.343 1.46 0.0946 0.0426 Hastings brownfield 10-Dec-2011 5.3 5.17 0.01065 0.00935 0.0129 0.0371 0.0265 0.0701 0.0985 0.631 0.900 0.249 0.0211 Hastings brownfield 29-Dec-2011 4.85 2.59 0.00499 0.00215 0.00223 0.0157 - 0.0321 0.180 0.384 1.84 0.145 0.0152 Hastings brownfield 13-Jan-2012 5.23 3.09 0.00546 0.000440 0.00163 0.00639 - 0.0212 0.0500 0.200 0.813 0.0572 0.00722 Hastings brownfield 3-Feb-2012 4.85 6.53 0.0127 0.000930 0.00305 0.0158 0.202 0.557 0.299 0.439 4.51 0.259 0.0419 Hastings brownfield 14-Feb-2012 4.66 2.35 0.00545 0.000220 0.0008 0.0129 0.0613 0.216 0.0335 0.420 0.319 0.0376 0.0104 Hastings brownfield 2-Mar-2012 - 1.33 0.0109 0.00128 - 0.0111 - 0.124 - 0.454 0.297 0.0294 0.0352 (mg/kg dry matter) Table A21. Total element concentrations in wet deposition over the entire collection period. Table A20. Element concentrations from HCl extraction of wet deposition collections from the three sites. Average pH Site SD Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P 5.18 0.420 5.50 0.237 5.06 0.322 UBC Farm Hastings brownfield 16 Oaks (mg/kg in dry matter) 25.5 22.2 13.2 0.0144 0.0170 0. 382 0.0577 0.0596 0.0386 0.0179 0.173 0.0830 0.955 0.7930.1390.05760.01 3 0.823 2.79 10.5 1.17 0.287 0.1470.6456.31.741.29 1.150.2890.1290.0206 0.1740.87210.12.870.66756 Table A22. Total and average flux of elements in wet deposition per unit area at the study sites. Table A23. Total element concentrations from HCl extraction of dry deposition for the entire collection period. Site Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P 413 1.20 1.19 0.323 1.80 4.35 24.7 40.4 54.2 197 20.1 4.60 2.95 0.00860 0.00853 0.00231 0.0128 0.0310 0.177 0.288 0.387 1.40 0.144 0.0328 694 1.86 0.529 0.559 5.41 2.59 29.8 25.7 86.9 329 36.5 8.97 5.22 0.0140 0.00400 0.00420 0.0407 0.0195 0.224 0.193 0.654 2.47 0.274 0.0674 797 1.80 0.448 0.643 4.02 9.03 35.8 20.8 89.7 316 27.2 5.41 5.99 0.0135 0.00337 0.00484 0.0303 0.0679 0.269 0.156 0.674 2.38 0.204 0.0407 1. Area of funnel: 0.0320m2 UBC Farm 16 Oaks Hastings brownfield Average Flux (mg/kg dry matter/m 2 /day ) Total Flux (mg/kg dry matter/m 2 ) Zn Pb Ni Mn Cu Cr Fe Al Mg Ca Na K P UBC Farm 37900 1460 452 319 1650 - 14100 21900 3440 12400 5390 6510 6970 16 Oaks 75200 683 115 196 719 207 5780 7280 2140 18000 1550 1820 2390 Hastings brownfield 160000 3330 819 512 5600 757 17800 30400 4040 35600 10500 7100 5290 (mg/kg dry matter) Site 57 Table A24. Total and average flux of elements in dry deposition per unit area at the study sites. Sample Zn Pb Ni Mn Cu Cr Fe Al Mg Ca Na K P 1180000 45700 14100 9960 51400 - 441000 684000 107000 387000 168000 203000 218000 8460 327 101 71.2 367 - 3150 4880 767 2760 1200 1450 1550 2350000 21300 3590 6130 22500 6460 180000 227000 66800 563000 48800 56700 74700 17600 160 27.0 46.1 169 48.5 1360 1710 502 4230 366 426 562 4980000 104000 25600 16000 175000 23600 555000 947000 126000 1110000 327000 222000 165000 37500 782 192 120 1310 178 4170 7120 949 8360 2460 1670 1240 Total Flux (mg/kg dry matter) Average Flux(mg/kg dry matter/m 2 /day) UBC Farm Hastings brownfield 16 Oaks Table A25. Total and average flux of elements in bulk (wet and dry) deposition per unit area at the study sites. Zn Pb Ni Mn Cu Cr Fe Al Mg Ca Na K P 1180000 45700 14100 9960 51400 - 441000 684000 107000 386000 168000 203000 218000 8460 327 101 71.2 367 - 3150 4880 767 2760 1200 1450 1550 2340000 21300 3590 6130 22400 6460 180000 227000 66800 563000 48400 56600 74700 17600 160 27.0 46.1 169 48.5 1360 1710 502 4230 364 426 562 4980000 104000 25600 16000 175000 23600 555000 947000 126000 1110000 327000 222000 165000 37500 782 192 120 1310 178 4170 7120 949 8360 2460 1660 1240 1. Area of funnel: 0.0320m2 Hastings brownfield Site Total Flux (mg/kg dry matter/m 2 ) Average Flux (mg/kg dry matter/m 2 /day) UBC Farm 16 Oaks 58 Sample Zn Pb Ni Mn Cu Fe Al Mg Ca Na K P UBC Farm Blackberries 84.3 234 19.9 47.1 357 103 2060 1900 20000 35700 637 275000 35500 16 Oaks Straw erries 7.6 652 - 34. 7360 28 124 286 171 690 1240 1 6 274 Hastings brownfield Blackberries 85.9 373 24.2 258 716 2 0 820 747 36600 5 600 71 290000 46800 Organic Matter (%) (mg/kg dry matter) Site Zn Pb Ni Mn Cu Cd Fe Al Mg Ca Na K P UBC Farm 56.5 3570 485 12.6 297 91.0 43.4 26300 23200 5100 11900 9240 17600 19300 16 Oaks 62.5 2210 245 - 513 383 - 30400 25500 5850 20600 12400 71000 45300 Hastings brownfield 51.2 2810 157 - 290 307 31.6 21600 15800 2690 10800 12400 21800 23000 Site Organic Matter (%) (mg/kg dry matter)Table A27. Element concentrations from aqua regia extraction of bulk worm sampling from the study sites. Table A26. Element concentrations from aqua regia extraction of bulk berry sampling from the study sites. 59 Table A28. Significant correlations for Zn, Pb, Ni, Mn and Cu in soil and vegetative samples. df=3; p<0.05 for two-tailed test: t>3.182 or t< -3.182 Correlation r t Zn in soil (AR) Pb in soil (AR) + 0.974 7.40 Na in soil (AR) + 0.952 5.40 Na in soil (HCl) + 0.949 5.21 Zn in roots + 0.927 4.27 Pb in roots + 0.976 7.77 Na in roots + 0.882 3.24 Zn in rhizosphere soil Pb in rhizosphere soil + 0.892 3.43 Ca in rhizosphere soil + 0.919 4.03 Zn in roots Na in soil (AR) + 0.881 3.24 Pb in roots + 0.968 6.74 Na in roots + 0.902 3.62 Zn in shoots Pb in shoots + 0.962 6.14 Fe in shoots + 0.904 3.66 Pb in soil (AR) Na in soil (AR) + 0.939 4.72 Na in soil (HCl) + 0.907 3.73 Zn in roots + 0.908 3.76 Pb in roots + 0.977 7.88 Pb in soil (HCl) EC in soil + 0.888 3.34 Zn in soil (AR) + 0.945 5.04 Na in soil (HCl) + 0.914 3.92 Zn in roots + 0.877 4.52 Pb in roots + 0.934 4.77 Na in roots + 0.909 3.78 Pb in roots Na in soil (AR) + 0.926 4.24 Na in soil (HCl) + 0.904 3.67 Na in roots + 0.885 4.05 Pb in shoots Fe in shoots + 0.920 3.30 Ni in rhizosphere soil Mn in rhizosphere soil + 0.948 5.16 Cu in rhizosphere soil + 0.926 4.23 Cu in rhizosphere soil + 0.932 4.45 Fe in rhizosphere soil + 0.908 3.74 Mg in rhizosphere soil + 0.994 15.5 Na in rhizosphere soil + 0.917 3.97 K in rhizosphere soil + 0.929 4.36 Mn in rhizosphere soil Fe in rhizosphere soil + 0.936 4.61 Al in rhizosphere soil + 0.966 6.42 Mg in rhizosphere soil + 0.939 4.72 Na in rhizosphere soil + 0.950 5.26 K in rhizosphere soil + 0.928 4.32 Cu in soil (HCl) Cu in roots + 0.986 10.4 Cu in rhizosphere soil Mg in rhizosphere soil + 0.902 3.61 K in rhizosphere soil + 0.915 3.94 1. AR- aqua regia extraction 2. HCl- HCl extraction Significant associations for metals60 Table A29. Significant correlations for other elements in soil and vegetative samples. df=3; p<0.05 for two-tailed test: t>3.182 or t< -3.182 Correlation r t LOI in soil P in soil (AR) + 0.915 3.92 Fe in rhizosphere soil Al in rhizosphere soil + 0.947 5.14 Ca in rhizosphere soil + 0.937 4.64 Na in rhizosphere soil + 0.981 8.74 Al in soil (HCl) Ca in soil (HCl) + 1.00 62.6 Al in rhizosphere soil Na in rhizosphere soil + 0.918 4.00 Ca in rhizosphere soil Na in rhizosphere soil + 0.946 5.07 Mg in soil (AR) K in soil (AR) + 0.978 8.12 Mg in roots Al in roots + 0.909 3.78 K in roots + 0.899 3.55 Mg in rhizosphere soil Fe in rhizosphere soil + 0.913 3.88 Al in rhizosphere soil + 0.938 4.71 Na in rhizosphere soil + 0.911 3.84 K in rhizosphere soil + 0.910 3.81 Na in soil (HCl) EC in soil + 0.910 3.28 Na in rhizosphere soil K in rhizosphere soil + 0.896 3.49 P in soil (AR) P in shoots + 0.912 3.85 P in shoots K in shoots + 0.922 4.12 1. AR- aqua regia extraction 2. HCl- HCl extraction Significant associations for other elements