Pollution Status Of A Section SY River And Its Health Risk Assessment

Objective:Concentration of pollutant in river water, sediment, crops, vegetables, drinking water and hair of the residents in local in a section of SY river in high flow period and low flow period in2011were detected in this study in order to explore the content of the pollutant in the environment and situation of exceed standards of it. Health risk assessment model and the potential ecological risk model were established and used to evaluate the pollution situation of the whole selected river basin and the pollutants exposure pathways and exposure levels to residents in local. To provide a theoretical basis for further pollution management in the section, and at the same time to provide a reliable data basis for the further population health effects assessment.Methods:According to the requirements of technical Code of Environmental Monitoring(water environment section), the hygienic quality status of the river water, sediment, the crops and the vegetables, the drinking water and the hair of the residents were monitored. The river water quality was evaluated using the index of water quality. Health risks associated with drinking water were assessed using the health risk assessment model. The ecological hazard of sediment and soil was assessed by the potential ecological risk index. The unqualified rate of heavy metal content in crops and the hair of local residents was counted, which was used to assess the environmental quality in this watershed.Results:1The results of single factor index evaluation of SY river showed that, some pollution factors including BOD5,NO2-N, CODMn, NH3-N, F-, CN-, Hg, As, Pb, Cr6+and Cd exceed the state standard in high flow period and in low flow period in2011.The results of comprehensive index evaluation of the SY river showed that the water quality of three selected sections in SY river were polluted seriously, and the share rate of Hg, NH3-N, BOD5,volatile phenol and Cd exceed5percent. 2The ecological risk assessment results of river sediment showed that the potential ecological risk index of Hg was the highest one, Hg in the river sediment would have population strong ecological risk. but other metals and As would have slight ecological risks. The total potential ecological risk index of4heavy metals and As showed that the sediments of three river sections would have moderate ecological risks.3There was significant difference in the content of NH3-N,cyanide,Cd,DMP, DEP, and DEHP in drinking water of two villages by comparing the drinking water quality between Baiguo and Hongshan village, and the Baiguo village was significantly more serious higher than Hongshan village(P<0.05).The result of unqualified rate of drinking water showed that the content of As, Hg, fluoride and volatile phenols exceeded the standard. Health risk assessment results showed that Cr6+has a highest per-capita cancer risk in the drinking water of two villages, and per-capita cancer risk of Cr6+was higher than the level of the ICRP recommended maximum acceptable risk. The per-capita cancer risk of Cr6+,As and Cd in the drinking water of two villages was higher than the level of the ICRP recommended maximum acceptable risk, and the pollution situation of the drinking water is severe.4The content of As and4heavy metals in the soil of two villages exceeded the standard, the unqualified rate of the Baiguo village was more higher than that of Hongshan village. There was no significant difference in the content of As and4heavy metals between the surface soil and the deep soil (P>0.05).The ecological risk assessment results showed that Hg in the soil of two villages would have strong population ecological risk, while other metals and As would have slight ecological risk, the total ecological risk of two villages are respectively moderate ecological risk.5The content of As, Pb and Cd in crops of Baiguo village was significantly higher than that of Hongshan village, and there was significant difference (P<0.05). The content of Pb and Cd in vegetables of Baiguo village was significantly higher than that of Hongshan village, and there was significant difference (P<0.05). Conclusion: There is severe water pollution in SY river, in the high flow period and low flow period in2011. The carcinogenic annual risk of Cr6+is the highest in drinking water in2011. The content of Hg in soil and in sediment badly exceeded the State standard. The content of other metal and As all had exceeded the state standard in various degrees. Hg in the soil and the sediment would have serious ecological risk. Heavy metals and As in the crops and the vegetables had badly exceeded the state standard, the condition of crops and vegetables pollution of the Baiguo village was more severe than Hongshan village.