The Distribution Of Heavy Metals And Organochlorines Of Sediments From Major Rivers In The Central Part Of Jilin Province

In recent years,the pollution of heavy metals and organochlorine pesticides in sediments of water bodies has become increasingly prominent.The Songhua River is one of the seven major rivers in China,with a wide watershed and abundant water resources.Yinma River,as the second largest tributary of Songhua River,is the main source of water for domestic residents and agricultural irrigation;Yitong River is a tributary of Yinma River.It is also a secondary tributary of the Songhua River.These three rivers constitute the main river system in the central region of Jilin Province.Therefore,studying the distribution characteristics of heavy metals and organochlorine pesticides in the sediments of these three rivers is of great significance to the water environment management of the river basin.This study takes the surface sediments of these three rivers as research objects,studies the mineral composition and chemical composition of sediment samples,analyzes As,Bi,Sb,Hg,Cu,P,Pb,Zn,Ni,Mn,Cr,Cd,etc.The contents of elements,organochlorine pesticides,and total organic matter were compared for the distribution characteristics of heavy metals and organochlorine pesticides in these three rivers.The heavy metal and organochlorine pesticide pollution levels,and pollution sources were analyzed.The X-ray diffraction results showed that the mineral composition of the surface sediment samples of the three rivers was mainly quartz,plagioclase,illite,chlorite,kaolinite,and the mixed-layer illite/smectite.The ranges of oxide content in the sediment samples of the three rivers are similar,and the chemical composition is similar.Statistical analysis showed that the metal content of most of the sediment samples and the clay mineral content were significantly positively correlated,and Bi,Cu,Cr,As,and Sb in the sediment were significantly positively correlated with the total organic matter.The standardization of clay minerals can effectively eliminate the differences in the content of heavy metal elements caused by the difference in mineral separation between samples,and improve the comparability of samples.The analysisIVafter standardization shows that the content of heavy metals in the sediments of Changchun and Jilin urban areas and their adjacent areas is generally higher than that in non-urban areas,and the content of heavy metals in the upstream and downstream areas gradually decreases.The highest points are concentrated between Jiutai District and Longjia Airport.According to the index of geo-accumulation and the potential ecological risk index,the elements of Bi,Hg,Cd,and Zn in the sediment samples of Yitong River and Songhua River were polluted to variable degrees,and the pollution was mainly concentrated in the Changchun and Jilin sections.The pollution level of the Yinma River sediment is relatively low,with Hg as the main pollution sources.The elements with high potential ecological risk index in the sediment are mainly Hg and Cd.The potential ecological risk of the sediment in the Songhua River is the most serious.According to the spatial distribution characteristics of heavy metal pollution in sediments and the comparison of soil element content in farmland,it is suggested that surface sediment pollution may mainly come from domestic wastewater and industrial wastewater.Statistical analysis shows that most of the organic chlorine content in the sediment has a significant positive correlation with the total organic matter,and there is a significant positive correlation between the total organic matter and the mineral content in the sediment.However,there is no significant correlation between the organic chloride content and the mineral content in the sediment.The analysis after standardization shows that the organic chloride content of the sediments in the Changchun and Jilin sections and their adjacent areas is generally higher than that in the non-urban areas.The highest organic chloride content is mainly concentrated in the surrounding areas outside the urban area.Organochlorine content is generally high.According to the sediment quality benchmark method,the contents of ?-666,p,p'-DDT,dieldrin,and endrin are at high ecological risk in more than half of the Songhua River and Yitong River.?-666,heptachlor and endrin are at high ecological risk at more than half of Yinma River.According to the proportion of HCHs isomers in the sediment sample and the ratio of ?-666 and ?-666,the input of most HCHs in the sediment sample may be historical residues,and the pollution may come from pesticides and industrial production.According to the ratio of the sum of theconcentrations of DDD and DDE in the sediment samples to DDT,the source of DDTs in the sediment may be mainly recent input.By comparing the organic chlorine content of the sediment with the soil,the HCHs,heptachlor,dieldrin,and endrin pollution in the Songhua River sediment may mainly originate from the surrounding farmland soil;DDT and aldrin may mainly originate from urban industrial wastewater and domestic sewage.Organic chlorine pollution in the sediments of the Yitong River may come from industrial production,domestic sewage and surrounding farmland soils.Dieldrin pollution in the Yinma River sediments may mainly come from surrounding farmland soils,and aldrin and endrin may originate mainly from industrial wastewater and domestic sewage.