Arsenic contamination is one of the common contaminants in soil, especially, near abandoned mines and metals refinery plants. It is well known that As is a carcinogenic in case of both ingestion and inhalation. Arsenic could be fractionated as exchangeable form, bound to amorphouse Fe and Mn oxides, bound to crystalline Fe/Mn oxides, and residual form, which could be analyzed by sequential extraction. Generally, As could be extracted well in the alkaline condition because of enhanced ion exchange reaction between hydroxide and arsenate/arsenite. However, the extraction changes soil pH a lot and the treated soil is not suitable for agricultural land. Additionally, soil organic matter could be extracted by the alkaline solution, which decreases the soil fertility. In this study, we investigated the extraction of As using a biodegradable organic chelating agent, oxalate, to minimize the loss of soil function as agricultural land. Oxalate was very effective to extract As bound to amorphous Fe/Mn oxides, but did not remove any As bound to crystalline Fe and Mn oxides. The molar ratio of oxalate to As was a key factor to influcence the amounts of As extracted by oxalate. Finally, germiation test was executed to evaluate the soil function as agricultural land.

Oxalate based remediation of arsenic bound to amorphous Fe oxide in soil

247th National Meeting (2014)

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