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Evaluation of extraction and pretreatment of soil manganese and associated elements

University of British Columbia

The manganese content of soils from the Lower Fraser Valley has been previously investigated. The studies conducted were conflicting in the total amounts of manganese in the soils. Also there was no attempt in the earlier studies to relate manganese to some of the other oxides in the soils. This study was undertaken to elucidate further the chemistry of manganese in the soils of the Lower Fraser Valley and to evaluate extractants and effects of soil pretreatment on the amount of manganese extracted. Iron, aluminum and silicon, which are commonly associated with soil manganese, were also included in the study. The total manganese concentrations obtained were higher than previously reported, even though the soils were derived from the same area. The distribution of total iron within the soil pedon was closely related to that of manganese. Conventional extractants for amorphous inorganic and organic oxides were evaluated with reducing and chelating agents, for their ability to extract manganese, together with aluminum, iron and silicon. The extractants used were sodium pyrophosphate, acid ammonium oxalate, disodiumEDTA, hydroxylamine hydrochloride and hydroquinone. Hydroquinone was only effective in extracting manganese, while sodium pyrophosphate, disodiumEDTA, acid ammonium oxalate and hydroxylamine hydrochloride extracted larger amounts of manganese, iron and aluminum. Only hydroxyl-amine hydrochloride and acid ammonium oxalate extracted silicon from the samples. All extractants, with the exception of sodium pyrophosphate, were consistent with each other in showing similar distributions of the different elements within the soil pedon. Successive extraction analysis indicated that the elements extracted by hydroxylamine hydrochloride were those derived from the organic and inorganic complexed forms. This study also showed that the preceding extractants may alter the soil system, thus questioning the reliability of successive extraction analysis. The effect of soil pretreatments on the extractability of manganese, iron, aluminum and silicon was also investigated. Some differences were observed between in-situ extraction and air-drying treatments. Freezing and storing moist, contributed to significantly high results. There was no consistency for the effect of the pretreatments on the different soils.

Text

2010-01-27

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http://hdl.handle.net/2429/19179

Soil Science

University of British Columbia

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