Soils containing geogenic arsenic (As) are widely distributed in Japan. With the amendment of soil contamination regulations, soils containing geogenic contaminants have been allowed to be utilized as geomaterials in limited conditions. However, a standard evaluation procedure on the long-term leaching behavior of As under anaerobic conditions has not been established. This research compared the leaching behavior of As from environmentally-qualified marine sediments in long-term batch leaching tests under reductive conditions brought about by chemical and biochemical methods to help improve the As leaching investigation procedure. Sodium ascorbate was employed as a chemical reducing agent with different concentrations. Glucose, ethanol, and sodium lactate were selected as biological nutrition sources. Testing results indicated that a reductive environment could significantly promote the leaching of As. The leaching of As was highly correlated with iron leaching. Under the chemical reducing conditions, a reductive environment could be realized in a short term and kept stable for the long term, and ORP varied with the concentration of the reducing agents. The concentration of leached As reached concentrations exceeding the environmental regulation of 0.01 mg/L. Under the biochemical reducing conditions, the leaching of As varied with the nutrition sources, and the release of As was followed by stronger resorption, indicating the effect of bio-activities on the leaching behavior of As.
9th International Congress on Environmental Geotechnics (ICEG2023)
Contaminant Fate and Transport