Distribution Of Heavy Metals In Sediments Of Liao River Basin And Its Effects On Macrozoobenthos

Liao River Basin undertakes the task of providing abundant water resources for regional economic development.Its water ecological health affects the urban development and economic level of Liaoning Province.Monitoring,analysis and risk assessment of heavy metals in sediment of Liao he River basin are helpful to comprehensively understand the characteristics and problems of heavy metal pollution in rivers,and provide basic data and technical support for heavy metal pollution control in Liao River Basin.At the same time,as the direct habitat of macrobenthos,the study on the response relationship between macrobenthos and heavy metal content in sediments in Liao River Basin can provide a basis for scientific management and policy making of water ecosystem in Liao River Basin,and play an important role in promoting ecological environment construction and harmonious social development.This study of Liao basin sediment copper,lead,zinc,cadmium,nickel and chromium six kinds of heavy metal monitoring and evaluation,and use the geoaccumulation index method,Nemerow Pollution index method,potential ecological risk index method,analysis and evaluation,comprehensive analysis of heavy metal pollution status quo and its ecological risks,a comprehensive grasp of Liaohe basin sediment of heavy metal distribution;The macrobenthos in Liaohe River Basin were monitored,analyzed and biologically evaluated.The diversity index method and BI index were used to evaluate and analyze macrobenthos,so as to understand the distribution and species composition of macrobenthos in Liaohe River Basin.Pearson correlation analysis and canonical correspondence analysis（CCA）were used to investigate the effects of heavy metals on macrobenthos in sediment of Liao River Basin,and to search for species or parameters with significant indicators of heavy metals in sediment.The main results are as follows:（1）The average content of Cu,Pb,Zn,Cd,Ni and Cr in the sediment of Liao River Basin is Zn>Cr>Ni>Cu>Pb>Cd;Cd,Cu,Zn,Ni and Cr are enriched in different degrees,and the dispersion degree is small from the analysis of spatial distribution,but the difference of the spatial distribution of Pb and Ni in dry season is higher than that in normal season and wet season.The I_geoaverage value of heavy metals in the three phases of the earth accumulation index method is Zn＆gt from large to small is Zn>Cu>Cr>Ni>Pb>Cd,most of the points are in the clean-mild pollution level;The evaluation results of Nemero comprehensive pollution index method are similar to those of ground accumulation index method.The potential ecological harm index method shows that Cd is the most polluted heavy metal element,which may be because the toxicity level of heavy metals is not taken into account in the first two evaluation methods.The toxicity level of Zn is 1,and the toxicity level of Cd is 30,and the Ti value of the two metals is large,leading to the difference in evaluation results.Based on the I_geo,P_Nand RI values of heavy metals in sediment of Liao River Basin during normal,wet and dry seasons,the results showed that Sanhedun（6）was the most polluted site,and the contribution of Ni metal was the highest.Therefore,ecological and environmental management should be strengthened at this site.In conclusion,the pollution level of heavy metals in sediment of Liao River basin is low.（2）A total of 146 species belonging to 109 genera and 62 families of 5 phyla,8 classes,21 orders were monitored,which arthropods,mollusks,Annelids,linear animals and flat animals accounted for 81.5%,8.9%,8.2%,0.7%,0.7%,respectively.In the main stream and tributaries of Liao River,94 species,76 genera,45 families,7classes,17 orders,and 4 phyla were found.The dominant species of the Liao river were short veined ichthyophagus and blackflies,and the degree of water pollution in the Liao River was light to moderate by species diversity index.BI index water quality status is clean-slightly polluted;A total of 63 species,51 genera,32 families,7 classes,15 orders,and 4 phyla were collected in the Hun River Basin.Chironomidae was the main species,followed by Bombycidae.The dominant species were Chironomus gifferii and Filamentarius krabb,which filamentarius krabb was a contamination-resistant species.The comprehensive evaluation of biodiversity index showed that the water quality was clean and slightly polluted.The average value of BI index at each point evaluates water quality as light to moderate pollution.A total of 46 species of 3 phyla,6 classes,15 orders,31 families,39 genera were monitored in the Taizi River Basin,and chironomidae accounted for the largest proportion.The dominant species were Hymenoptera achironomidae and the comprehensive evaluation of biodiversity index showed that the water quality was light to moderate pollution.BI index indicated that the water quality at five sites was heavily polluted,and the three biodiversity indices and BI index all indicated that the water quality at site 42（Liujiatai）was polluted.（3）Correlation analysis showed that there were significant positive correlations among Cu,Pb,Zn,Cd,Ni and Cr heavy metals in Liaohe River sediment（P<0.01）,the correlation between Ni and the other five heavy metals is weak,which may be because Ni mainly comes from natural background,and the contents of the other five heavy metals may be controlled by human sources,with homology and common variation trend.CCA sequencing analysis showed that the order of heavy metals’impact on macrobenthos was Pb>Cr>Zn>Cd>Ni>Cu;Sequent analysis of CCA in Liao river and tributaries showed that Ni was positively correlated with Her Otc,Pol Nub and Pal Sin,as well as with Zn,Chi Ant and Zn.Che Bre and Hyd Sp of sensitive species groups showed that Ni was positively correlated with Her Oct,Pol Nub and Pal Sin.Are negatively correlated with heavy metals.CCA sequencing analysis showed that Pol Nub,Bel Pur,Mic Gut and Par Str species were positively correlated with heavy metals in Hun River Basin,which may have a certain tolerance to heavy metals because of their relatively high pollution tolerance.Bae and other four species were negatively correlated with the distribution of heavy metals in Hunhe River Basin.CCA ordination analysis in Taizi River Basin showed that Chi Ant was positively correlated with six heavy metals,Lim Hof was negatively correlated,and other species were less correlated with heavy metals.