Optimization Of Analytical Methods For Endocrine Disrupting Chemicals And Degradation In Manure Composting Process

Endocrine Disrupting Chemicals?EDCs?are widely distributed in the environment and threaten the health of humans and animals by interfering with the endocrine system.At present,there are many methods for determination of EDCs in water samples and their effects differ greatly,besides,there are few studies on EDCs in water samples and manure composting process in agricultural non-point source pollution area.Therefore,it is significant to conduct the following research.In this paper,5 typical EDCs in the environment:estrone?E1?,estradiol?E2?,17?-estradiol?EE2?,estriol?E3?and bisphenol A?BPA?were selected as objects.Based on the analysis of EDCs in the environment by SPE?solid-phase extraction?-GC?gas chromatography?-MS?mass spectrometry?,an optimized pretreatment method was established.Specifically the SPE technology and derivatization process were optimized,including the selection of SPE cartridges,the pH adjustment of water samples,the selection of derivatization reagents and derivatization heating methods.The conclusion was drawn that when the pH of water sample was adjusted to 3.0,the analyte recovery was the highest with 63.50%-112.00%with HC-C18 SPE cartridge used for SPE.When BSTFA reagent containing 1%TMCS was used in combination with pyridine as the derivatization reagent,then heating in an oven at 70?for40 min,analytes got the best derivatization results.The detection limits of E1,E2,EE2,E3 and BPA were 3.2 ng/L,1.5 ng/L,1.9 ng/L,0.9 ng/L and0.6 ng/L,and the recovery rate 104.3%,98.5%,98.4%,98.4%and 98.0%.Concentrations of 5 EDCs in the main lakes into Erhai Lake together with influents and effluents in urban sewage treatment plants around Erhai Lake were determined.The results showed that all 5 EDCs were detected.The estradiol equivalents?EEQ?of E1,E2 and E3 were 0.13-76.10 ng/L,the concentrations of EE2 and BPA were 5-22 ng/L and 4-35 ng/L.The removal rates of E1,E2 and E3 in sewage treatment plants were 67.13%-92.21%.The detection rate of EE2 was only 60%with the lowest removal rate of 50%.The maximum removal rate of BPA was 98.15%.To explore the E1,E2 and EE2 degradation during composting and the effects of O₂ and EM agent on the degradation,composting of cow and pig manure was simulated in the lab.The state of compost was revealed by determining the index of compost.Results showed that concentration of E1in composting increased first and then decreased,the average degradation rates of cow and pig manure were 52.91%and 67.29%respectively,and the degradation rate of EM agent and aerobic treatment was 66.97%and72.67%.The trend of E2 in the composting process was declining.The average degradation rates of cow and pig manure were 74.09%and66.96%.The concentration of EE2 kept decreasing and remained stable until the end of the compost.The average degradation rate of cow and pig manure was 92.37%and 85.26%.Different treatments had little effect on the EE2 degradation.By fitting the degradation curves,it was found that the degradation of E2 and EE2 complied with the kinetic first-order equation.