Fate And Bound-residue Formation Of Bisphenol S In An Oxic Soil

Bisphenol analogues(BPs)consist of two phenolic rings,including bisphenol A(BPA),bisphenol F(BPF),bisphenol S(BPS)and bisphenol AF(BPAF).They are widely used in the production of plastics and resins and are endocrine disrupting chemicals(EDCs).Because of the regulation of BPA use,manufacturers use BPS,BPF and BPAF as substitutes for BPA.BPs are frequently detected in river,sediments,soil,indoor dust,and urine.While there are many studies on BPA,studies on the environment fate of other BPs are scarce.We studied the fate of BPS in paddy rice soil under oxic conditions.Firstly,14C-BPS and 13C-BPS were synthesized from 14C-phenol or 13C-phenol and sulfuric acid,which would help further study their fate in the environment.Then,we studied the fate of 14C-labeled BPS in paddy rice soil under oxic condition.During the 28 days’ incubation,BPS dissipated quickly,with a half-life of merely 4.1 days.In active soil,BPS dissipation was accompanied by mineralization(53.6±0.2%)and formation of bound residues(45.1 ± 0.3%).A polar metabolite and a less polar metabolite were found in the organic extracts.The bound residues formed mainly from physical entrapment(50-60%)and ester-linkages(about 30%).Ether-linkages and other covalent bonds like C-N and C-C were much less than ester-linkages.Besides,the amount of radioactivity binding to.humic substances follows the order:humin>humic acid(HA)>fulvic acid(FA).While in sterilized soil,BPS mainly formed extractable residues(72.1±0.6%)and bound residues(28.8±0.7%).The amount of radioactivity bound to humic substances was HA>FA>humin,which was different from that in active soil.Formation of bound residues was reversible.Bound residues could be released due to microbial activity.To our knowledge,this is the first study on the fate of BPS in soil.And our results indicate that in paddy rice soil BPS is not as stable as in river water or sea water.On the contrary,mineralization and bound-residue formation are two major pathways of BPS dissipation in the oxic soil.This will help with the risk assessment of BPS.