Column Percolation Tests for Evaluating the Leaching Behavior of Marine Sediment Containing Non-anthropogenic Arsenic
Soils excavated in construction works often contain non-anthropogenic heavy metals and metalloids due to their geologic histories. When leaching concentrations of these substances are high, they are reused after containment, such as core materials of embankment structures. Evaluation of the leaching behaviors of non-anthropogenic heavy metals and metalloids is essential to predict the environmental impact and achieve an optimum containment design. However, applicability of the conventional leaching tests to soils containing non-anthropogenic substances is uncertain, mainly because their chemical forms and leaching processes are different from those in contaminated soils. This paper addresses the leaching behavior of arsenic (As) and other inorganic constituents by performing column percolation tests for a marine sediment sample by employing two different-size columns (\( \phi \) 50 mm × h 300 mm and \( \phi \) 150 mm × h 700 mm) with saturated/unsaturated flow conditions. Long term leaching profiles were analyzed to assess the effects of specimen size and flow conditions. At the middle of the unsaturated larger column, higher As leaching concentrations were observed under neutral condition. However, due to precipitation of As with co-precipitation of iron and aluminum compounds, As leaching was limited at the bottom. As a result, there was no significant difference in As leaching amount obtained in two column percolation tests.
KeywordsLeaching Arsenic Column percolation test
This research was supported by the Environmental Research and Technology Development Fund (5-1606). The authors acknowledge contributions to experimental works by Mr. Rasyid Pratama Indra, a former undergraduate student of Kyoto University.
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