Adsorption And Biodegradation Of¹⁴C-BPA And Estrogens In Soil Treatment System

Bisphenol A and steroid estrogens have been commonly detected insewage and causing attention because of their potential risk on environment,animals and human beings. Study of removal of bisphenol A and estrogens bysoil treatment system is meaningful, particularly in non-point pollutedremoted areas. Concentration levels of bisphenol A and estrogens in ruralsewage, removal of BPA and estrogens by soil treatment system, absorptionand biodegradation of BPA in soil, and their relationship with nitrificationwere studied.Attenuation of endocrine disrupting compounds （estrone （E1, natural）,estradiol （E2, natural） and estriol （E3, natural）,17α-ethinylestradiol （EE2,synthetic） and biphenyl-A （BPA, synthetic）） was evaluated in soil trenchsystems along with rural domestic sewage in Erhai Lake Basin. All16sitessampled exhibited more elevated concentrations of natural estrogens thansynthetic EE2and BPA. And E1and E2accounted for87.1%-99.2%of thetotal amount of natural estrogen. The amount of natural estrogens remainingin the soil accounted for approximately4.3%,6.3%and3.8%of the initialinfluent amounts of E1, E2and E3, respectively. Soil trench system caneffectively treat natural estrogens （70.3%）, EE2（63.6%） and BPA （77.8%）.Simulated soil trench system was used in lab to study the removal,residue and transport of BPA and estrogens. Results indicated that the sytemwith stronger nitrification and oxidation soil environment removed BPA andnatural esetrogens more efficiently. The average BPA remaining in soil was67.27ng/g. Remaining of E1, E2and E3in soil are53.04ng/g,12.66ng/g and20.14ng/g respectifully. E2has the lowest amount of remaining while E1has the highest. All substsances remaining amounts rose with the depth, indicatingbiodegradability in araerobic environment.Uniformly¹⁴C labeled BPA was used to study its adsorption,biodegradation and transport in soil and soil trench system. The degradationstudy showed that BPA was rapidly dissipated in soil. Within five days ofincubation, up to11.9%to17.7%of radioactivity applied was detected as¹⁴CO2, and less than8.1%in the remaining soil，indicated that¹⁴C-BPA wasrapidly dissipated in soil and the major route of dissipation of¹⁴C-BPA in soilwas the formation of bound residues that could not be recovered by extraction.The study using small-scale soil bench system showed that removal efficiencyof BPA was85.5%. The amount of¹⁴CO2converted in soil trench system was2.5%. Water samples taken from different depth of the system showed nodetectable¹⁴C-BPA or¹⁴C-metabolites.