Toxic effects of three perfluorinated or polyfluorinated compounds(PFCs)on two strains of freshwater algae:Implications for ecological risk assessments

Perfluorinated or polyfluorinated compounds(PFCs)continue entering to the environmental as individuals or mixtures,but their toxicological information remains largely unknown.Here,we investigated the toxic effects and ecological risks of Perfluorooctane sulfonic acid(PFOS)and its substitutes on prokaryotes(Chlorella vulgaris)and eukaryotes(Microcystis aeruginosa).Based on the calculated EC50 values,the results showed that PFOS was significantly more toxic to both algae than its alternatives including Perfluorobutane sulfonic acid(PFBS)and 6:2 Fluoromodulated sulfonates(6:2 FTS),and the PFOS-PFBS mixture was more toxic to both algae than the other two PFC mixtures.The action mode of binary PFC mixtures on Chlorella vulgaris was mainly shown as antagonistic and on Microcystis aeruginosa as synergistic,by using Combination index(CI)model coupled with Monte Carlo simulation.The mean risk quotient(RQ)value of three individual PFCs and their mixtures were all below the threshold of 10^(−1),but the risk of those binary mixtures were higher than that of PFCs individually because of their synergistic effect.Our findings contribute to enhance the understanding of the toxicological information and ecological risks of emerging PFCs and provide a scientific basis for their pollution control.

Do trace metal(loid)s in road soils pose health risks to tourists?A case of a highly-visited national park in China

Nowadays,more people tend to spend their recreational time in large national parks,and trace metal(loid)s in soils have attracted long-term attention due to their possible harm to human health.To investigate the pollution levels,potential sources and health risks of trace metal(loid)s in road soils,a total of eight trace metal(loid)s(including As,Cd,Cr,Cu,Ni,Pb,Zn and Hg)from 47 soil samples along roads were studied in the Huangshan National Park in Southeast China.The results showed that the concentrations of As,Cd,Pb,Zn and Hg appeared different degrees of pollution compared with their corresponding background values.According to the pollution indices,Hg and Cd were recognized as significant pollutants presenting moderate to high ecological risk.Combining principal component analysis and positive matrix factorization model,the results showed that traffic,industrial,agricultural and natural sources were the potential origins of trace metal(loid)s in this area,with contribution rates of 39.93%,25.92%,10.53%and 23.62%,respectively.Non-carcinogenic risks were all negligible,while the carcinogenic risk of As was higher than the limit(1×10^(-6)).Moreover,children were more susceptible to trace metal(loid)s by ingestion which appeared to be a more important exposure pathway than dermal contact and inhalation.The contribution rates of different sources to non-carcinogenic risks and carcinogenic risks were similar among children and adults,while traffic and industrial sources have a significant impact on health risks.This study will give more insights to control the environmental risks of trace metal(loid)s in national parks.