Assessment Of Heavy Metal Pollution In Sediments And Soils Of Poyang Lake Marginal Zone

Taking the edge of Poyang Lake as the research area,the surface sediment,profile sediment,paddy soil and vegetable soil in the basin were collected as the research objects.The contents of Cu,Pb,Zn,Cr,As,Cd and Hg,as well as the physical and chemical properties of soil p H,soil organic matter（SOM）,soil redox potential（Eh）and soil particle composition were determined to analyze the sediment in the edge of Poyang Lake The characteristics of heavy metal pollution,the characteristics,differences and influencing factors of heavy metal pollution in different types of soil,and the adsorption behavior of Cu²⁺in sediment and soil were analyzed to explore the adsorption characteristics and influencing factors of copper ion in sediment and soil.In order to provide reference for the prevention and control of heavy metal pollution in Poyang Lake Basin.Through research and analysis,the following conclusions are obtained:Heavy metals Cu,Pb and Zn are the main accumulation elements in the sediments of Poyang Lake marginal zone.The spatial distribution characteristics of heavy metals in the basin are obvious.Xinjiang River and Raohe River basins are high value areas of heavy metal content,and the content of heavy metal Cd in Xinjiang River Basin is more prominent.In the vertical direction,the content of Cu increased with the increase of depth,the content of Hg showed a zigzag distribution with the change of depth,and the content of other heavy metals had no obvious regularity in the vertical distribution.The accumulation degree of heavy metals in agricultural soil in the watershed is very small;different utilization methods have certain effects on the content of heavy metals in soil,mainly on the content of heavy metals such as Cu,As,Zn and Cr.The accumulation degree of Hg in sediments and soils was the same,while the accumulation degree of the other six heavy metals in sediments was significant,The results show that the surrounding soil has a greater impact on the heavy metal Hg in the lake sediments,but has less impact on Cu,Pb,Zn,Cr,As and Cd.The source of heavy metals in the sediments of Poyang Lake is not only in the marginal zone,but in a wider range of Watershed.The results of heavy metal pollution assessment showed that the pollution degree of the seven heavy metals in the sediment was Cu>Pb>Zn>Hg>Cr>As>Cd.The pollution of Cu and Hg in the soil was the largest,and the potential ecological risk of Cd was the largest.Generally speaking,the soil quality in the study area was good,while the sediment was polluted by a variety of heavy metals.Correlation analysis showed that p H,redox potential（Eh）and heavy metal content were negatively correlated,soil organic matter（SOM）,particle size and heavy metal content were positively correlated,and Cu,Pb,Zn,Cr,As,Cd content were positively correlated.The results of principal component analysis showed that the sources of heavy metals in the study area were mainly industrial sources.The adsorption experiment showed that the adsorption kinetic curve of sediment and soil samples in the basin fitted with elovich equation with the highest coefficient（>0.9）,and the fitting result was the best,which indicated that the adsorption process of Cu²⁺was mainly chemical adsorption,that is,electrical adsorption,and the activation energy changed greatly in the adsorption process.In addition,the adsorption isotherm curve of Cu²⁺on the sample can be well fitted with Freundlich equation,Langmuir equation and Temkin equation,but from the fitting coefficient,Temkin equation is the best,Langmuir equation is the second,and Freundlich equation is the last,which shows that the adsorption of Cu²⁺on the sample under experimental conditions may be dominated by irregular surface adsorption.Compared with the oscillating adsorption,the equilibrium time of static adsorption is longer,the adsorption capacity is smaller,and the fitting degree of kinetic curve and adsorption isotherm curve with empirical formula is poor.It shows that the adsorption capacity of Cu²⁺in the overlying water may not reach saturation in the natural environment similar to the experimental conditions.Relevant.The results showed that Cu content was negatively correlated with adsorption kinetic parameters and adsorption isotherm parameters,indicating that Cu content inhibited adsorption reaction,while organic matter content,p H and eh were positively correlated,indicating that these factors could promote adsorption.