Mercury And Arsenic Concentrations Characteristics And Risk Assessment Of Soil-rice System In The Typical Irrigated Regions In The Second Songhua River Basin

The typical paddy irrigated regions in the Second Songhua River(SSR) are the advantageous rice production area in Jilin province,and rice paddy irrigated with water from the SSR. The SSR surrounded by industrialized and residents’ communities that may continuously pour the treated, partially treated, and untreated sewage or effluent and municipal waste water into the river. Historically, the river was heavily polluted by petrochemical industries in Jilin City. The soil-rice system in the typical irrigated regions in the Second Songhua River Basin were investigated to study the contents status, the distribution of each part of the rice and risk assessment of As and Hg with the methods of Nemero integrated accumulation index, potential ecological risk and health risk assessment. The results as follows:1. The results indicated that the concentrations of As and Hg were mostly exceeded the Changchun background values, partly higher the level I of the China Soil Environment Quality Standard, and there were individual samples beyond the level II of the China Soil Environment Quality Standard in YSY and SM irrigated regions, that is, the concentrations of As and Hg in soil were not detrimental to plant growth but anthropogenic activities have caused the accumulation of Hg and As in the paddy soils2. The concentrations of Hg in rice ranged from 0.000045 to0.01mg/kg while As is between 0.00016 and 0.061 mg/kg. and their content are both lower the Food Health Standards. The mean value of Hg content was, in descending order, YSY>SY>QG>SC>YMH>YTH>SM,while the average Concentration of As was YMH>YTH>SM>SY>YSY>SC>QG.3. The content of Hg and As in different organs of paddy crop was as follows, root>stem>leave>rice.4. Distribution characteristics and the statistical analysis of Pearson showed As and Hg had no common source, specifically the anthropogenic impact due to soils irrigated with SSR maybe the main source of Hg, and the source of As may be due to fertilizers or something. There were positive correlations between soil As and organic matter, N, between soil Hg and organic matter, between rice Hg and As, between soil K and rice Hg, rice As. There were negative correlations between soil Hg and p H.5. According to the background value of paddy soils in Jilin and the level I of Chinese official norm, The results of evaluation on accumulation index and potential ecological risk assessment indicated that there was no obvious ecological risk of paddy soils in all irrigation areas, but the Hg accumulation degree of YSY,SM and YMH were high level due to anthropogenic activities.6. In terms of health risk, the rice could have an no obvious effect on human health in all irrigation areas. However, according to the reference dose(RFD) of US EPA, local area had potential risk for the health of human beings.