ABSTRACT
Soil organic substances play an important role in global carbon cycle. It is widely recognized that application of organic substances to soil is benefit for carbon sequestration and enhancing soil fertility. However, when the soil is contaminated with arsenic (As), the effects of organic substance application on As mobility in soil and accumulation in rice plants should not be ignored. To understand how organic substances affect As transformation and translocation in the soil-microbe-rice system, both pot and microcosms experiments were carried out, including different dosages of rice straw, straw biochar and humic substances. Results showed that the application of organic substances significantly increased As mobility, enhanced As methylation and volatilization, elevated the accumulation of organic As in rice grains. Our study demonstrated that organic substances could regulate As mobility and transformation in paddy soil through regulating soil microbial community, and the biogeochemical processes of As in paddy soils is associated with iron and organic substances through microorganisms.
