Study Of Water Quality Criteria For Mercury And Lanthanum By Using Interspecies Correlation Estimation Models

Mercury and lanthanum are toxic to aquatic organisms.It is very important to obtain more toxicity data and derive accurate water quality criteria for risk assessment and water quality management.Lack of toxicity data is one of the main limiting factors in current research of water quality criteria.Interspecies correlation estimation(ICE)model can predict toxicity data for more species by using toxicity data of the known species,which is helpful to obtain more toxicity data for water quality criteria research.However,this model is mainly based on the toxicity data of species from North American,it is necessary to verify the applicability of the model to species in different biota.Mercury and lanthanum were chosen as the research objects,and ICE and species sensitivity distribution(SSD)were used as the main research models.The effectiveness of ICE model in predicting the toxicity of species in different biota was validated by using mercury toxicity data,and water quality criteria of mercury and lanthanum were studied.The main conclusions are as follows:(1)The ICE model can be used to predict the toxicity data of mercury for Chinese species.Based on the results of k-s test,comparison of SSDs and values of HC5,there were no significant difference between the toxicity data from native and non-native species,or measured and predicted toxicity data.Moreover,the STHC5 value based on prediction data-SSD curve of mercury is 5.01 ?g·L-1,while STHC5 values based on measured data-SSD is 4.85 ?g·L-1,which is closed to the former value.It suggested that the prediction data from ICE model has good consistency with experimental data and can be used in derivation of mercury water quality criteria.The acute and chronic criteria values of mercury derived based on all the data(including predicted and measured data)are 5.57 ?g·L-1 and 2.67 ?g·L-1,respectively.The acute and chronic criteria values are in the same order of magnitude or basically close to those values obtained by using statistical extrapolation method in other studies,and the results provided by present study can be used as reference values for risk assessment.(2)It is suggested that the predicted toxicity data of lanthanum from ICE had statistical significance,based on k-s nonparametric test results between prediction data and measured data,predicted data and all data,measured data and all data.SSD analysis results showed that HC5 values of the predicted data,the measured data and all data were 460.14 ?g·L-1,37.93 ?g·L-1 and 363.08 ?g·L-1.The differences among these values are no more than one order of magnitude.It indicated that ICE model can be used to predicting lanthanum toxicity values and the toxicity values can be used for deriving water quality criteria.The acute water quality criteria and chronic water quality criteria of lanthanum obtained in the present study were 36.31 ?g·L-1and 10.78 ?g·L-1,respectively.Preliminary risk assessment of lanthanum in different rivers was conducted using lanthanum water quality criteria obtained in this study indicated that the lanthanum in some foreign rivers,the small watershed of South Jiangxi,the Yellow River in Baotou main stream section and the Yangtze river in Wuhan main stream section are not harmful to aquatic organisms.However,lanthanum in the tributaries of Yellow River,Sidaosha River and Kundulun River,have potential risk to aquatic organisms.This study has a positive effect on the development and improvement of water quality criteria system.