| Due to the rapid development of the pharmaceutical and detergent industries,the growing world population,and increased accessibility to healthcare and pharmaceuticals,pharmaceutical and personal care products（PPCPs）and artificial sweeteners（ASs）,which are closely linked to anthropogenic activities,have emerged as new pollutants after traditional priority pollutants,such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls,and are attracting increasing attention worldwide.In recent years,PPCPs and ASs have been detected in large quantities in sewage,surface water and groundwater.However,there is a lack of systematic studies and a relative lack of knowledge on PPCPs and ASs occurrenced in the aquatic environment of the middle and lower reaches of the Yellow River（Henan section）compared to the developed urbanised areas in China.In this study,an efficient and reliable analytical method for the detection of PPCPs and ASs was developed.74samples,including 9 wastewater treatment plant（WWTP）effluent samples,34 surface water samples and 31 groundwater samples,were collected from the middle and lower reaches of the Yellow River（Henan section）to analyse in detail the occurrence,spatial distribution,sources and potential risks of 24 PPCPs and 4 ASs in the aquatic environment.The adsorption/desorption mechanism of tetracycline antibiotics on sediment was studied through adsorption kinetics and thermodynamics experiments.This study provides authentic and reliable background data for the study of PPCPs and ASs in the middle and lower reaches of the Yellow River（Henan section）,and it is of great significance to screen out"priority controlled pollutants".At the same time,it provides scientific basis for ecological risk assessment and pollution control of surface water and groundwater systems in the study area.The main results of the study are as follows:（1）A highly sensitive analytical method for the simultaneous trace analysis of PPCPs and ASs in water matrices by solid phase extraction-high performance liquid chromatography-triple quadrupole mass spectrometry（SPE-HPLC-MS/MS）was developed and successfully applied to the determination of PPCPs and ASs in WWTP effluents,surface water and groundwater in the middle and lower reaches of the Yellow River（Henan section）.The recoveries of most target compounds were in the range of70%～120%with the relative standard deviations（RSDs）less than 20%.The limits of quantification（LOQs）for PPCPs were 0.009～1.77 ng/L and those for ASs were 0.15～30 ng/L.（2）All 24 targeted PPCPs were detected in surface water,with concentrations in the range from not detected（ND）to 527.4 ng/L.Among these PPCPs,caffeine is found to have the highest concentration and its detection frequency is 100%.The total PPCP concentrations ranged from 136 ng/L to 916 ng/L（median,319.5 ng/L）.Antibiotics,NSAIDs and caffeine were the main contaminants in the surface waters of the study area.Sucralose was dominant in WWTP effluents and had the highest mass loading.Acesulfame,cyclamate,saccharin,and sucralose were consistently detected in surface water at concentrations ranging from 1.364 ng/L（cyclamate）to 7786 ng/L（acesulfame）.The total concentrations of ASs ranged from 308.7 and 10498 ng/L.（3）All 24 target PPCPs were detected in groundwater samples from one or more of the sampling sites.the highest concentration detected in groundwater was BPA at13.08 to 3176 ng/L and the lowest concentration was triclosan at ND～0.6102 ng/L.Endocrine disruptors（mainly BPA）and fluoroquinolone antibiotics were the main contaminants in groundwater in this survey area.The highest concentration detected in groundwater was acesulfame,with a corresponding concentration range of ND～2470ng/L and a detection rate of 80.6%.The total concentrations of ASs detected was between ND and 4863 ng/L.Acesulfame and sucralose are the main pollutants in surface water and groundwater within this survey area.（4）The spatial distribution characteristics of the concentrations of PPCPs and ASs in the main stream and 10 major tributaries of the Yellow River were analysed.The results showed that the pollution levels of PPCPs in the tributaries were more serious than those in the main stream,except for the Yiluo River（including the Yi River and the Luo River）and the Qin River;and the pollution levels of ASs in the tributaries were more serious than those in the main stream,except for the Qin River.Wastewater treatment plant effluent is the main point source of input of PPCPs and ASs to the river.Analysis of the relationship between mean concentrations of PPCPs and ASs in groundwater and surface water showed a weak correlation between PPCPs in surface water and groundwater（r=0.47）and a moderate correlation between ASs（r=0.72）.（5）The ecotoxicological risk assessment indicated that norfloxacin,azithromycin,estrone,and triclosan posed high risks to aquatic organisms（RQ>1）,roxithromycin and oxytetracycline imposed moderate risks（0.1≤RQ<1）,and the tributary Jindi River had the highest mixed risk（MRQ=222）;the risks of the four target ASs to aquatic organisms were negligible（RQ?<?0.1）,and the maximum risk quotient of the MRQ values of all rivers were all much less than 0.1.The results of the human health risk assessment showed that all detected PPCPs had RQs<1 and that the risk to humans from PPCPs in groundwater sources was negligible.（6）The adsorption kinetics showed that the adsorption data fitted ewell with both the pesudo-second-order kinetics model and the Elovich model,indicating that the adsorption process is dominated by chemisorption and is a non-homogeneous diffusion process that undergoes both fast and slow adsorption.The results of the fit of the intra-particle diffusion model indicated that external diffusion was the main controlling rate.By varying the solution-soil ratio conditions,it was found that an increase in the solution-soil ratio did not affect the adsorption equilibrium time of tetracycline and oxytetracycline in the sediment,but caused a significant increase in the adsorption equilibrium time of chlortetracycline in the sediment.（7）The adsorption thermodynamic process showed that all three tetracycline antibiotics（chlortetracycline,tetracycline and oxytetracycline）exhibited strong adsorption,with the highest adsorption affinity for chlortetracycline and the lowest for oxytetracycline.The fitting results of adsorption thermodynamic process showed that Langmuir model could well describe the adsorption behavior of three tetracycline antibiotics on sediment.By varying the temperature conditions,the adsorption was found to be a heat absorption reaction.The average desorption hysteresis indices（HI）for chlortetracycline,tetracycline and oxytetracycline were 14.913,4.241 and 3.162respectively,and the average HI showed that chlortetracycline showed a stronger desorption hysteresis than tetracycline,and tetracycline a stronger desorption hysteresis than oxytetracycline in the test sediment.（8）The p H of the system affects the degree of dissociation of the tetracycline antibiotics.The experimental results revealed that the Kd value of the adsorption coefficient of chlortetracycline reached the maximum value when p H=7.For tetracycline and oxytetracycline,their Kd values on the sediment tended to decrease as the p H of the reaction system gradually increased.The presence of high valence and high concentration of ions significantly inhibited the adsorption process.Mg2+had the strongest inhibitory effect on the adsorption of the three tetracycline antibiotics,with K+having the least inhibitory effect. |
