Pollution Characteristics Of Artificial Sweeteners In Dalian Coastal Seawater And Wastewater Treatment Plants

Artificial sweeteners are a kind of artificial or semi-synthetic food additives,which are almost not metabolized in human body,have high intensity sweetness and low calories,so they are called nonnutritional artificial sweeteners(NAS).Studies have shown that NAS has ecotoxic effects and exists widely in wastewater treatment plants and natural water environment,which makes it a new pollutant and attracts attention.Saccharin sodium(SAC)has been reported to increase the risk of bladder cancer in rats,aspartame(ASP)in high doses has been associated with cancer risk,and sucralose(SUC)can disrupt genes responsible for sucrose uptake in sugarcane,inhibiting sucrose uptake and transport in plants.They are widely produced,consumed and ubiquitous in aquatic environments.Because of high consumption,long-term monitoring of concentration levels is important for effective assessment of potential risks to the environment and public health.In this study,eight typical NAS,SAC,SUC,ASP,Cyclamate(CYC),Acesulfame(ACE),Alitame(ALI),Advantame(ADV)and Neotame(NEO),were selected.Three wastewater treatment plants in the coastal and main urban areas of Dalian were selected as the research subjects.Field site investigation to collect environmental water samples,testing the NAS in close to shore,and the level of concentration in the wastewater treatment plant,analyzed the NAS in Dalian inshore concentration distribution,seasonal changes,based on the research of the wastewater treatment plant in and out of the water,the analysis of the NAS of seasonal changes in the wastewater treatment plant,estimation of NAS input and emissions.Finally,the ecological risk assessment of NAS near the Dalian coast was carried out.The method was based on the combination of solid phase extraction and high performance liquid chromatography-mass spectrometry with 0.1% formic acid in water and 0.1% formic acid in acetonitrile as mobile phases and positive and negative ion scanning modes.The limits of detection were 1 ng/L?188 ng/L,the limits of quantification were 3 ng/L? 625 ng/L,and the spiked recoveries were 78%?108%.The method can meet the requirements for the detection and analysis of trace NAS in the environment.The study showed that NAS contamination was prevalent in the nearshore of Dalian,six NAS species were detected in water samples from the nearshore of the Yellow Sea with concentrations ranging from ND(not detected)to 866 ng/L,and two NAS species were detected in water samples from the nearshore of the Bohai Sea with concentrations ranging from ND to 112 ng/L.The number and concentration levels of NAS detected in the nearshore of the Bohai Sea were lower than those in the nearshore of the Yellow Sea,and the seasonal variations in the nearshore of the Yellow Sea showed that the seasonal variations in the Yellow Sea nearshore showed that the concentration levels of SAC,ACE,CYC and SUC were significantly higher in summer than in winter,NEO showed higher levels in winter than in summer,and ASP did not show significant seasonal variations.Wastewater from Wastewater treatment plants is an important way for pollutants to enter the sea,and three Wastewater treatment plants in the main urban area of Dalian were selected for field investigation in the study.The results showed that four NAS,SAC,ACE,CYC and SUC,were detected in the effluent of Dalian urban wastewater treatment plant.The concentration range is ND?11.69 ?g/L.SUC is the most important NAS in wastewater treatment plants.The concentration values in and out of SUC are 6.59 ?g/L and 5.17?g/L,respectively.The wastewater treatment plant can effectively remove CYC,SAC and ACE,and the removal rate is 88%?96%.The removal rate of SUCs was only 36%.WWTP 1 and WWTP 3 showed higher concentrations of SAC and CYC in spring,and WWTP 2 showed higher concentrations in summer.All three wastewater treatment plants showed low concentrations of SAC and CYC in winter.The results of wastewater analysis show that the average consumption of NAS in the influent of the wastewater treatment plant in this study is relatively low.The highest average consumption of NAS is 2.04 g/d/1000 p for SUC,the lowest is 0.45 g/d/1000 p for ACE,and the highest is 1.66 g/d/1000 p for SUC.The lowest average emission of CYC is 0.01 g /d/1000 p,and the average consumption and emissions of wastewater treatment plants are generally smaller than those of other countries and regions.The results of ecological risk assessment showed that the 6 NAS detected at present were not likely to cause ecological risk to Dalian coastal aquatic organisms.