Screening Of Emerging Pollutants And Adsorption Behavior Of Bisphenols In Luoma Lake And Its Inflow Rivers

There are various types and sources of emerging pollutants,with characteristics such as biological toxicity,environmental persistence,and bioaccumulation.Low concentration of emerging pollutants may also pose a threat to the ecological environment and human health.Luoma Lake is an important regulation and storage area of the east line of the South-to-North Water Transfer Project,and it is also the drinking water source of Xuzhou and Suqian.Therefore,it is of great significance to study emerging pollutants in Luoma Lake and its rivers.In this study,non-target screening of emerging pollutants,quantitative analysis of emerging pollutant sources,establishment of detection methods of bisphenols,occurrence characteristics of bisphenols,ecological risk,estrogen risk and adsorption and desorption behavior of low concentration bisphenols in lake sediment were studied on Luoma Lake and its inflow rivers.The main results are as follows:(1)A rapid non-target screening method for emerging pollutants in water environment by high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry was established.The single mobile phase of 0.05%(v/v)formic acid+2 mmol/L ammonium acetate-acetonitrile was determined to complete the screening of positive and negative ion modes,which realized the rapid screening of emerging pollution in a short time.The established high-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry non target screening method and the existing gas chromatography quadrupole time-of-flight mass spectrometry non target screening method were applied to the screening of emerging pollutants in the water environment of Luoma Lake and its inflow rivers.13 categories of 75 emerging pollutants were screened in surface water,and 12 categories of 55emerging pollutants were screened in sediment.After multiple runs of the PMF model and combined with the investigation information of pollution sources in the study area,3 sources of emerging pollutants were identified as large-scale aquaculture,domestic sewage,and industrial wastewater.(2)The detection method of solid phase extraction and high-performance liquid chromatography tandem mass spectrometry were established for 7 bisphenols in water.The detection methods of accelerated solvent extraction,solid phase extraction purification and high-performance liquid chromatography tandem mass spectrometry were established for 7 bisphenols in sediment.The separation of the 7 bisphenols was achieved in 8 min by gradient elution with 0.05%ammonia aqueous solution and acetonitrile as the mobile phases.The pretreatment of water samples was performed by solid phase extraction with the following optimized parameters:1000 m L of water samples,p H=3,hydrophilic-lipophilic balance cartridge(HLB),flow rate of 8.0m L/min,10%methanol aqueous solution as rinsing,and elution volume of 9 m L.The pretreatment method for sediment was accelerated solvent extraction with optimized parameters:the extraction solvent is acetonitrile,the extraction temperature is 100°C,and the number of cycles is 3 times.The recoveries of 7 bisphenols in water samples were 77.1-106.2%,the detections were 0.05～1.5 ng/L,and the relative standard deviations were 3.6-9.2%.The recoveries of 7 bisphenols in sediment were 74.9-102.8%,the detection limits were0.01-0.3 ng/g,and the relative standard deviations were 6.2-10.3%.The detection limits of BPB,BPS and BPAF in water and BPF,BPS,BPZ,BPAF and BPAP in sediment in this study were lower than those in previous studies.(3)The distribution characteristics and pollution levels of bisphenols in Luoma Lake and its inflow rivers were revealed.According to the detection of bisphenols,5bisphenols were detected in surface water and 7 bisphenols were detected in sediment.The concentration of bisphenols in surface water was the highest in flood season.Spatially,the concentration of bisphenols in inflow rivers was higher than that in Luoma Lake.There were no significant differences in the spatial distribution and seasonal variation of the concentrations of bisphenols in sediment(p>0.05).Although the use of BPA had been restricted,the highest concentrations of BPA had been detected in surface water and sediment,followed by BPF.The concentrations of BPA and BPF ranged from1.2×10~2-3.1×10~2 ng/L and 87.4-2.3×10~2 ng/L in surface water in flood season,respectively.The concentrations of BPA and BPF ranged from 11.9-38.0 ng/g and 11.0-27.3 ng/g in sediment in flood season,respectively.(4)The entropy method was used to assess the ecological risk of bisphenols in Luoma Lake and its inflow rivers.BPA in dry season,BPA and BPF in normal season,and BPA in flood season had moderate risks to fish and green algae in some sampling points.6 bisphenols had low or no risk to fish,daphnia,and green algae during three water seasons in sediment.The 17β-estradiol equivalent method was used to evaluate the estrogenic activity of bisphenols in surface water and sediment of Loma Lake and its inflow rivers,and there was no estrogenic risk in water and sediment.(5)To reveal the adsorption and desorption regularity and distribution behavior of low concentration BPA and BPF in sediment.The adsorption of BPA and BPF on sediment conforms to the quasi-second-order kinetic model and Freundlich isotherm model,and the adsorption of BPA and BPF on sediment at low concentrations is characterized by multi-layer non-uniform adsorption,with chemical adsorption as the main adsorption and physical adsorption as the auxiliary adsorption.Rapid adsorption plays a dominant role in sediment adsorption of low concentrations of BPA and BPF.The equilibrium adsorption time of BPA and BPF on sediment were 48 h and 24 h,and the equilibrium adsorption amounts were 1.998 and 1.977μg/g,respectively.The adsorption of BPA and BPF on sediment is a spontaneous endothermic process,and the disorder degree of solid-liquid interface increases while the orderliness decreases.Compared to sediment particle size and temperature,the concentration of humic acid has a greater impact on the adsorption of BPA and BPF by sediment.The desorption process was consistent with the quasi-first-order kinetic model.Rapid desorption played a dominant role in desorption of BPA and BPF on sediment.The desorption equilibrium times were 24 h and 12 h,and the equilibrium desorption amounts were1.146 and 0.857μg/g,respectively.According to fugacity model,the diffusion trend of BPA and BPF at the interface between water and sediment is from sediment to water.