CADMIUM AND ARSENIC SOIL THRESHOLD IN RICE PRODUCTION AREA OF PEARL RIVER DELTA OF GUANGDONG PROVINCE

Heavy metals are harmful to human body. Soil-plant system is an important way for heavy metals to enter the food chain. In our study, we summarize the data published in CNKI, web of science, Wan Fang database and Wei Pu from 2005 to 2017 about heavy metal contamination in soil and rice crop of the pearl river delta region of Guangdong. The database expose that the pollution of Cd in the soil is serious, followed by Cu, Ni, As, Hg. The contamination of Zn, Pb, Cr, was lower as compare to Cd. Concentration of Cd and Pb in rice grains was serious, followed by As and Cr Hg and Cu. When soil organic matter in tillage layer was >20%, the Cd limited value is 0.96 mg/kg. When the organic matter content in soil tillage layer is <20%, the Cd limited value is 1.23 mg/kg. When soil organic matter in tillage layer was >20%, the fitting equation As limit value is 18.86 mg/kg. When soil organic matter in tillage layer was <20%, As limited value is 19.68 mg/kg. National soil environment quality standard (GB15618-2018) the pearl river delta soil have Cd contamination which can produce security rice, As contaminated farmland soil cannot produce safety rice crops, in rice cultivation system.