Effects Of Polystyrene Nanoplastics On The Degradation,Transformation And Bioaccumulation Of Bisphenol Analogues

The hazards of fine plastics,including micro-plastics(MPs,diameter of MPs less than 1 mm)and nano-plastics(NPs,diameter of NPs less than 1000 nm)have caused great concern recently.Due to their small diameter,these fine plastics provide large specific area that could adsorb organic pollutants,which may influence their environmental behavior.However,most studies have focused on MPs while few studies paid attention to NPs.Furthermore researches about the coexistance of organic pollutants and MPs are even scarcer.TBBPA and BPA are common plastic additives that could leach out and transport with plastic particles.In this study,we investigated the effects of nanoplastics on the degradation of BPA in the natural fresh water and the effects of nanoplastics on toxicity and bioaccumulation of two important plastic additives(BPA and TBBPA)in daphnia using radioactivity trace technology.In order to explore the effect of nanoplastics on the degradation of BPA,a 96-day laboratory incubation study within fresh water collected from Taihu lake was conducted.Samples were taken at 8,18 and 96 days to measure the radioactivity of CO2 mineralized,organic extractable phase and non-extractable phase,as well as BPA parent compounds and metabolites in organic extracts.Our study showed that with the presence of nanoplastics,the mineralization and degradation of BPA was significantly delayed and inhibited.In addition,the generation of polar metabolites was delayed and nonpolar metabolites increased at the same time.The adsorption results showed that kd of BPA on NPs was relatively low(log Kd=2.42),but possibly the enhanced adsorption of nonpolar metabolites on NPs may actually prolong the existance of nonpolar metabolites and thus alter the degradation of BPA in fresh water.The actue toxicity test of BPA and TBBPA with NPs were performed in order to choose the sutiable concentration for bioaccumulation experiments,including short-term and long-term incubation.The results from short-term incubation showed that BPA had no effect on the biomass of daphnia,and NPs did not affect the bioaccumulation of radioactivity in daphnia body.However,TBBPA did significantly decreased the body weight of daphnia,while the presence of NPs offsetted this negative effect,possibly due to the adsorption of TBBPA on the surface of NPs which decreased the bioavailability of TBBPA to daphnia.After 14 days of long-term incubaiton,NPs significantly increased the radioactivity detected in daphnia body,indicating significant "vector"effect of NPs on TBBPA bioaccumulation.The presence of NPs did not influence the dissipation of TBBPA in daphnia-water system,but did increase the relative amount of polar metabolites-M1.These results indicated that NPs showed less effects on toxicity,bioaccumulation and biodegradation of BPA and TBBPA in short times,however,those effects are likely to happen during at longer periods.By confirming the effect of nanoplastics on the degradation of BPA in natural water and the toxicity and bioaccumulation and biotransformation of TBBPA and BPA in daphnia,this study provided scientific envidence of environmental risks of NPs on the fate of organic pollutants and indicated long-term investigations should be paid more attention suring further investigations.