Environmental Quality Assessment of Soil-rice System in Typical Paddy Fields in Southern China
In order to study the content of heavy metals in paddy soil-rice system in typical areas of southern China.Soil,rice and irrigation water samples were collected from six typical paddy fields in Jinxian County,Jinxi County,Yushui District,Gao'an City,Anfu County and Xingguo County of Jiangxi Province.The contents of lead,cadmium,arsenic and mercury in soil and rice and soil nutrients were analyzed.The content of heavy metals in soil-rice system was evaluated by single factor pollution index and Nemero com-prehensive index.Results show that the mean values of soil pH,organic matter,total nitrogen,total phosphorus,total potassium,a-vailable nitrogen,available phosphorus and available potassium are 5.48,32.99 g/kg,2.06 g/kg,0.54 g/kg,16.04 g/kg,156.71 mg/kg,14.00 mg/kg and 94.98 mg/kg,respectively.The total average contents of lead,cadmium,arsenic and mercury are 35.46,0.18,7.21,0.17 mg/kg in the soil of the study area.The single factor pollution index is less than 1,the Nemero comprehensive pollu-tion index is 0.56,and the soil environmental quality grade is clean.While the soil cadmium content is 0.37 mg/kg in Yushui,excee-ding the limit standard(0.30 mg/kg),and the soil environmental quality is alert.The total average contents of lead,cadmium,arsenic and mercury are 0.06,0.17,0.24,0.008 6 mg/kg in brown rice of the study area.The single factor pollution index is less than 1,and the average Nemero comprehensive pollution index is 0.77.The environmental quality grade of brown rice is alert.The cadmium contents in brown rice of Xingguo and Yushui are 0.22、0.35 mg/kg,which exceeds the limit standard(0.20 mg/kg).The environmental quality grades are warning limit and mild pollution,respectively.Correlation analysis show that cadmium in brown rice is significantly positively correlated with cadmium and lead in soil,while negatively correlates with arsenic in soil.The arsenic in brown rice is significantly posi-tively correlated with arsenic and available phosphorus in soil.In short,heavy metal cadmium is the most important potential pollution el-ement for rice safety in the survey area,and it is necessary to focus on rice food safety in Xingguo and Yushui.
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