Arsenic is considered the primary contaminant of concern in soil ecosystems regarding pollution control and soil ecological risk assessment. Many authors have reported extensive arsenic contamination in paddy soil. The natural sources of arsenic in paddy fields can be attributed to the weathering of rocks and alluvial deposits. Arsenic in paddy soil originates from the weathering of arsenic-bearing minerals like claudetite (As2O3), bearsite (Be2(AsO4·OH·8H2O)), and wallisite [(Cu, Ag) TlPbAs2S5]. Arsenic is released into the soil either by mineral dissolution or changes in surrounding conditions. Arsenic attached to bioavailable and redox-sensitive fractions is easily released. Arsenic contamination in floodplain paddy fields can also result from sediment transportation by river flow and gradual alluvial deposition. Rice cultivation becomes contaminated with arsenic through the application of fertilizers, pesticides, irrigation with arsenic-rich groundwater, and mining operations.
Author(s) Details:
Young-Cheol Chang,
Course of Chemical and Biological Engineering, Division of Sustainable and Environmental Engineering, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585, Japan.