Dynamic Material Flow Analysis And Ecological Risk Assessment Of Perfluorooctane Sulfonate In China

Perfluorooctane sulfonate（PFOS） are regarded as a category of chemicals with persistence,bioaccumulation,and toxicity.Understanding dynamic flows,stocks,and emissions of PFOS on a macro spatial and temporal scale can help provide a scientific basis for their sound management.In this work,a dynamic material flow analysis（d-MFA）model was built to characterize and analyze the cycles of PFOS in China’s mainland for the period 1985-2019.Flows,stocks and environmental emissions were calculated,followed by developing a multimedia environmental model to predict the annual average environmental concentrations of PFOS.Taking advantage of risk quotient method,ecological risk assessment of PFOS was then conducted.Finally,sensitivity and uncertainty of the results were analyzed.Main contents and conclusions for the current study are as follows:（1）A framework for dynamic material flow analysis of PFOS in China was built.Based on mass balance principle,flows,stocks,and environmental emissions were quantified.Results show that domestic production was the primary source of PFOS in China and most of them flew to domestic market in the form of final products,with the remain exported to international market;soil and water were the main sinks of PFOS in China,among which emissions from use stage contributed most（103 tonnes in 2019）.The amount of inflows and outflows were relatively low before 2000,but gradually increased until 2009 when the relevant convention was issued.Since 2005,in-use stocks and emissions of PFOS have grown with years.In addition,stocks in landfill have been climbing from 1985.End-of-Life management was still dominated by traditional ways,such as landfill and incineration,while there was a trend towards green treatments.（2）Based on the environmental emission data quantified by d-MFA,a multimedia environmental model was developed.By utilizing the model,the annual average concentrations of PFOS in each environmental media in China were simulated.Results indicate that the simulated concentrations of PFOS in air,water,soil and sediment all showed an upward trend from 1985 to 2019.It was also found that water was the main sink of PFOS in China,with the maximum concentration can reach 38.1 ng·L^-1,exceeding the Surface Water Environmental Quality Standards for PFOS adopted by European Union(0.65 ng·L^-1).Nevertheless,China currently has no relevant standards for the environmental concentrations of PFOS.The predicted environmental concentrations of PFOS in water,soil and sediment in China were relatively reliable,which can be concluded from the fact that the deviation between the predicted and simulated values were within an order of magnitude.（3）Based on the average annual concentrations data predicted by the multimedia environmental model,risk quotients（RQs）of PFOS were calculated,followed by assessing the ecological risks of PFOS to organisms living in water,soil,and sediment.Results suggest that the anthropogenic releases of PFOS in China have not yet posed significant risks to species in water and sediment during the period 1985-2019.However,they have caused low potential risks to soil organisms since 2006.In 2018,the RQ of PFOS in soil reached the maximum value of 2.83.The results of the current study can provide basic data and theoretical supports for sound management of PFOS in China.