Analysis On Pollution Characteristics Of Heavy Metals In Farmland Soil Around Jiaozuo Section Of Guangliji River And Its Correlation With River Sediment

In order to understand the characteristics of heavy metal pollution in farmland soil around Guangliji River and its correlation with heavy metals in sediment,this paper takes the farmland soil around Jiaozuo section of Guangliji River and the sediment of Guangliji River as the research object,through sampling and experimental analysis.The pollution status and spatial distribution characteristics of Cr,Ni,Cu,Zn,As,Cd,Pb and Hg in farmland soil and Guangliji River sediment in the study area were analyzed by using ground accumulation index method,single factor pollution index method,Nemero comprehensive pollution index method,potential ecological risk index method and health risk assessment method,and the correlation between farmland soil and river sediment was analyzed.The main results are as follow:(1)In the agricultural soils of the study area,all eight heavy metals accumulated,among which the contents of Cd and Cu exceeded the corresponding screening values,with the exceedance rates of 65.2% and 52.2%,and the maximum exceedance multiples of 107.52 and0.91,respectively,and the Cd content of 17.4% sampling points exceeded the control value,with the maximum exceedance multiple of 9.85.The degree of variation for soil heavy metals was in the following order: Cd>Cu>Pb>Zn>Cr>As>Ni>Hg.The mean value of the integrated pollution index of heavy metals Nemero in the farmland soils of the study area was 9.59,which belongs to the heavy pollution level;the mean size of the single factor pollution index of each heavy metal was in the following order: Cd>Cu>Zn>As>Cr>Ni>Pb>Hg,and the mean value of the single factor pollution index of Cd was 13.40,which belongs to the heavy pollution level,and Cd was the primary pollution factor affecting the quality of farmland soils in the study area.In the farmland soils of the concerned area,the combined pollution levels of heavy metals were all at heavy pollution levels,and their pollution levels were in the following order: No.3farmland plot>No.1 farmland plot>No.2 farmland plot.(2)In the sediment of Guangliji River,Cr,Cu and Cd contents all exceeded the corresponding screening values,with exceedance rates of 58.3%,8.3% and 100.0%,respectively,and maximum exceedance multiples of 2.25,0.48 and 103.26.Among them,the Cd content in 41.7% sediment samples exceeded the control value,and the maximum overstandard multiple was 9.43.The range of variation of Cd ground accumulation index was from 2.47 to 8.14,and the Cd content of all sediment sampling sites was influenced by moderate and above anthropogenic factors.The mean value of the integrated pollution index of heavy metals in the sediment was 19.89,which belonged to the heavy pollution level,and the mean value of the single factor pollution index of each heavy metal was in the following order:Cd>Cr>Zn>Cu>As>Pb>Ni>Hg.The average value of Cd single factor pollution index is 27.84,which is a heavy pollution level,and Cd is the primary pollution factor affecting the environmental quality of the sediment in Guangliji River.(3)The correlation analysis of heavy metal elements showed that there was a moderate correlation between Cr and Ni,Cr and Hg,Ni and Hg,Cu and Zn,Cu and As,Cd and Zn in the farmland soil of the study area,and there was a moderate correlation between Cd and Cr,Cd and Zn in the sediments of Guangliji River.There was a correlation between the heavy metals Cu and Cd in the agricultural soils of the study area and the corresponding heavy metals in the sediment of Guanglizi River,with the most obvious correlation for element Cd,with a correlation coefficient was 0.932,indicating that the Cd in the agricultural soils and the sediment of Guangliji River had similar sources,or that the change of Cd content in the agricultural soils were influenced by the Cd in the sediment of Guangliji River.(4)In the agricultural soils of the study area,the combined potential ecological risk of heavy metals was in the medium-strong ecological risk class,the Cd content was in the very strong ecological risk class,the average ecological risk contribution of Cd was 96.3%,and the individual potential ecological risks of different heavy metals were in the following order:Cd>Cu>As>Ni>Pb>Cr>Hg>Zn.In the sediment of Guangliji River,the average combined potential ecological risk of heavy metals was in the strong ecological risk class,the Cd content was in the very strong ecological risk class,and the average ecological risk contribution of Cd was 97.8%.The combined potential ecological risk of heavy metals in the farmland soil of concered area and the sediment of Guangliji River was in the following order: the sediment of Guangliji River>No.3 farmland plot>No.1 farmland plot>No.2 farmland plot.(5)As and Cd levels pose tolerable carcinogenic health risks to both children and adults in agricultural soils of concerned area and the sediment of Guangliji River.Cr levels pose tolerable carcinogenic health risks to both children and adults in agricultural soils,while Cr levels in sediment of Guangliji River can pose intolerable carcinogenic health risks to both children and adults,and can pose non-carcinogenic health risks to children at the same time.Under different exposure routes,the influential degree of each heavy metal on non-carcinogenic health risk for both adults and children was in the following order: oral input>dermal exposure>respiration;the influential degree of heavy metals on combined non-carcinogenic health risk for both children and adults was in the following order: the sediment of Guangliji River>No.3 farmland plot>No.1 farmland plot>No.2 farmland plot;the combined carcinogenic health risk for both adults and children was in the following order: the sediment Guangliji River>No.1 farmland plot>No.3 farmland plot>No.2 farmland plot.