Study On The Influence Of River Animals In Different Niches On The Migration And Transformation Of Heavy Mentals In Sediment

Under the background of black and smelly river regulation and urban endogenous pollution regulation,the problem of heavy metal pollution in river sediment has aroused widespread concern.Heavy metals can accumulate in sediment by hydrolysis and complexation,and cause secondary pollution by diffusion and migration.River animals play an important role in river ecosystem,and their feeding,excretion,disturbance and other life activities will have an important impact on the migration and transformation of heavy metals in sediment,while animals in different niches have different effects on heavy metals.In this paper,from the point of view of population and niche,carp,loach and mussel were selected for laboratory ecological simulation experiment,to explore the influence of river animals on the migration and transformation of typical heavy metals Cr,Pb,Zn and Cu which is in sediment,and to evaluate the pollution and risk of sediment and niche animals before and after the experiment,focusing on the change of heavy metal pollution degree and its risk harm to the environment and exposed people.Monitoring and analyzing the changes of environmental factors at the interface of overlying water and sediment in the experimental group,the results show that animal life activities have obvious influence on the environmental factors at the interface of water and sediment,among which the changes of water pH,water DO,sediment pH and sediment organic matter are the most obvious;the content and form of heavy metals in sediment and the content of heavy metals in animals were determined and analyzed,the results showed that carp had the strongest migration,transformation and enrichment of Cr and Zn,and mussel had the strongest migration,transformation and enrichment of Pb and Cu.There were Cr and Zn pollution in carp,Cr pollution in mussel and loach.The correlation between environmental factors and heavy metals was further analyzed and the key environmental factors affecting the migration,transformation and enrichment of heavy metals were explored.The results showed that the changes of heavy metal content and forms were significantly correlated with sediment pH,organic matter,water pH and water DO,indicating that these environmental factors had a significant impact on the migration and transformation of heavy metals in sediment and the enrichment efficiency of heavy metals in animals.There are different degrees of correlation between heavy metals in the sediment of each niche animal group and heavy metals in animals,which indicates that when heavy metal pollution is found,it is also necessary to pay attention to the heavy metal pollution associated with it.On that basic of the above experiments,heavy metal pollution and risk assessment methods were used to evaluate the heavy metals in the sediments and animals before and after the experiment.The results showed that the sediments of the control group and loach group had an impact on the environment,while the sediments of carp group and mussel group changed from having an impact on the environment to being within the environment.Heavy metal pollution in carp and loach changed from light to heavy,and heavy metal pollution in mussel changed from none to heavy.The non-carcinogenic risk index of four heavy metals in sediment is far lower than the risk value,and the target risk coefficient of four heavy metals in animals is also lower than the risk value,which shows that experimental animals will not bring obvious health hazards to the environment and exposed people while affecting the migration and transformation of heavy metals in sediments.