Pollutant Characteristic Distribution And Ecological Risk Assessment Of River And Lake Sediment In Huaining County,Anhui Province

Huaining county is located in anqing in anhui northwest corner,in recent years due to the rapid development of the county and population growth,resulting in a large number of production and living sewage discharged into lakes and river in the wastewater contains large amounts of nitrogen and phosphorus and heavy metal pollutants,all kinds of pollutants in river sediment accumulation precipitation,when the accumulation to a certain degree,pollutants released into the water again,cause secondary pollution to water,the impact on local ecosystems and human health.In this study,the sediment of two river channels(river Y and river Q)and an ecological lake(lake S)in two urban areas of huaining county,anqing,were sampled at 10 points in July and 6 points in the ecological lake respectively in December,2019,and the contents of total nitrogen,total phosphorus,organic matter and heavy metals were determined and analyzed.The organic index,organic nitrogen index and pollution index were used to analyze the distribution characteristics of total nitrogen and total phosphorus content,and the organic matter was evaluated by the nutrient composition grade of the second national soil survey.By adopting single factor evaluation method,ecological risk index method,internal ROM the comprehensive pollution index method,pollution load index method of 10 kinds of heavy metals(iron,manganese,chromium,nickel,copper,arsenic,cadmium,mercury,lead,zinc)lakes eight kinds of heavy metals(chromium,nickel,copper,arsenic,cadmium,mercury,lead,zinc)to evaluate the pollution degree and the potential environmental risk.The results showed that the contents of total nitrogen and organic matter in channel Y and channel Q were high,and many points presented the highest nutritional status,the total nitrogen concentration of sediment in channel Q>Y the total phosphorus concentration in channel Y and channel Q was slightly lower than that in other urban rivers,and the organic matter content in channel Q >Y.The pollution index method was used to evaluate the total phosphorus,and the number of severe pollution points in Y>Q,and the number of severe pollution points in Q>Y.The organic index and organic nitrogen index were used to evaluate the contents of total nitrogen,organic index and organic nitrogen index at 10 points in Y river and Q river.The heavy metal content of the river was analyzed,and arsenic and cadmium were not detected in Y river and Q river,indicating that arsenic and cadmium pollution were not existed.The pollution factors are lead,nickel and mercury.Through the single-factor evaluation method,pollution-free river accounts for the majority.In terms of pollution degree,Y > Q river.Through the ecological risk index method,the overall risk degree of the two rivers is medium or below.The main potential risks in river Y are lead and mercury,and the main potential risks in river Q are mercury and nickel.By nemero comprehensive pollution index method,pollution degree of Y > Q river channel pollution degree;According to the pollution load index method,the pollution degree of channel Y and channel Q is relatively high.Amongthe 10 points,4 are in the state of strong pollution risk,4 are in the state of moderate pollution,and 2 are in the state of light pollution.The pollution of manganese,mercury and nickel is serious.The heavy metal content in lake was evaluated and analyzed.The single factor evaluation method indicated that the sediment at each point S of lake was less polluted by heavy metals.According to the ecological risk index method,the risk intensity of each heavy metal in lake S sediment is Cd =Hg <Pb <Zn < Cr <Cu < As<Ni,and the harm degree of each heavy metal to each point is S1 According to the nemero comprehensive pollution index method,the comprehensive pollution index of heavy metals at each point in lake S sediment is S2 < S5 < S4 = S1 < S3 < S6,and the corresponding evaluation level is pollution-free.According to the pollution load index method,the heavy metal pollution index of sediment at each point of lake S.Finally,the sources of pollutants in rivers and lakes are analyzed,and the countermeasures are put forward.