Contamination Characteristics,Health Risk Assessment And Sources Of Arsenic And Heavy Metals In Surface Water From Lake Chaohu

Objective:To investigate the pollution characteristics of arsenic and four heavy metals in surface water of Lake Chaohu,and evaluate the potential health risk in water environment preliminarily to provide basic information for risk management.Methods:To eatablish the methods for determination of arsenic and four heavy metals by Atomic Abosorption Spectrometer（AAS）and Analytical System for Atomic Fluorescence Spectroscopy（HG-AFS）.Basde on the water quality investigation data of the Chaohu Lake,the single factor water quality identififcation index method,health risk assessment model and Species Sensitivity Distributions were employed to evaluate the status of heavy metals.In addition,the main pollution factors and the priority control region were determined.The Person correlation and principal component analysis（PCA）was applied to estimate the sources of arsenic and four heavy metals.Results:（1）The determination method of arsenic and four heavy metals was established by Atomic Abosorption Spectrometer（AAS）and Atomic Fluorescence Spectroscopy（AFS）.The linear range of 0.1-10μg/L with great linear relationship,the limit of detection were 0.01-0.3μg/L,the recovery rate were between 88.64%¹07.51%,and the relative standard deviation（RSD）were 0.11%⁸.85%.（2）The concentration of Cu,Pb,Cd,As and Hg in surface water ranged from0.344-3.585μg/L,ND-3.526μg/L,ND-0.208μg/L,2.459-4.411μg/L and 0.067-0.452μg/L,respectively,with the average concentration of 1.494,1.484,0.088,3.735,0.168μg/L and with the coefficinet of variation of 48.26%,61.14%,42.63%,10.42% and 43.21%.（3）The results of single factor water quality identification index method showed that the main pollution factors of heavy metal pollution in Lake Chaohu was Hg.The concentration of Hg in 86%sampling point exceeded the Class III acccording to standards of the water quality（Environmental quality standards for surface water）and the highest Hg concentration reached 0.452μg/L,beyond the Class I 9.04 times.The concentrations of Cu,Pb,As and Cd all within the Class I acccording to standards of the water quality.（5）The ecological risk of pollution to all the sepecies were in the order of Pb>Cd>Hg>Cu>As using the species sensitivity distribution method.The risk of Cu,Cd,As,Hg in each sampling did not exceed the 5%hazardous Concentration,and the Pb had the highest risk quotient among the arsenic and four heavy metals at each sampling of Lake Chaohu.（4）The results of total health risk（R_T）assessment indicated that Chaohu Lake was classified to moderate pollution level and the polltion of sampling point of Nanfei river estuary was the most serious.The descending order of health risk of pollution was As>Cd>Pb>Hg>Cu,while all were lower than the maximum allowance levels recommended by ICRP(5×10-5/a^-1),and As was the main contributor of the potential health risk elements.（5）The arsenic and four heavy metals in surface water from Lake Chaohu consisits of three principal compents,the first principal componment is Pb and Cd,the contribution rate was 29.763%,the second principal component is Cu and As,the contribution rate is29.340%,the thrid principal component is Hg,the contribution rate is 20.328%,respectively,indicating that the three main sourecs of heavy metals were as follows:industrial wastewater,chemical fertilizers and pesticides from agriculture and municipal solid waste incineration.Conclusions:The survey results show that there was a certain degree of pollution in surface waters of Chaohu Lake,and As、Hg and Pb should be regarded as a key object to conduct a risk prevention and control decision-making management,and the NanFei River estuary should be considered as a high-risk area which needs to be controlled preferentially.