Concentration Levels And Distribution Characteristics Of Halogenated Methanesulfonic Acids And Regional Ecological Assessment In Hangzhou Bay

In past ten years,emerging contaminants have gradually appeared in people's vision.Continuous detection for them has brought new challenges to environmental pollution control and has become an international research hotspot.Halogenated methanesulfonic acids,a class of emerging contaminants,were firstly discovered in the water in 2016.As organic matters containing halogen atoms,toxicity of these substances and their environmental impacts were urgently needed.At present,there were still a little research papers about the concentration distribution of halogenated methanesulfonic acids in nature.Hangzhou Bay was located in the East China Sea region.It was a famous industrial area and water environment is seriously polluted.Therefore,the presence of halogenated methanesulfonic acids in Hangzhou Bay area and its existence level were highly representative.This paper mainly established a qualitative method and a quantitative method of halogenated methanesulfonic acids.It included suspected screening of halogenated methanesulfonic acids,optimization of pretreatment conditions for water samples and sediment samples,and optimization of quantitative methods.Established methods were used to investigate the concentration level and spatial-temporal distribution of halogenated methanesulfonic acids in water and sediment of Hangzhou Bay during one year.Main conclusions were as followed:?1?This paper used UPLC-QTOF-MS full-scan mode combined with MS/MS method to do suspect screening for samples.There were seven kinds of halogenated methanesulfonic acids to be detected.An analysis method of water sample was SPE-UPLC-QTOF-MS while a method of sediment was ASE-SPE-UPLC-QTOF-MS.Optimal conditions for the SPE process were using Oasis-WAX cartridges.The loading pH was 4 and the ammonia concentration in methanol was 5%.The loading rate and eluting rate were 1 mL/min and 3 mL/min,respectively.Optimal accelerated solvent extraction conditions were using methanol as a extraction solvent,heating for 5 mins,extraction on 90°C and 1500 psi,static extraction for 5 mins,flushing for 60%volume,static extraction for3 times,and nitrogen purge for 120 s.The linear correlation coefficient of the proposed method was 0.9983⁰.9994.LOD and LOQ for CF₃SO₃H and external standard were 0.05 ng⁰.15 ng and 0.20 ng⁰.50 ng.Recoveries of spiked water samples ranged from 70.9%to 110.3%,and recoveries of spiked sediment samples ranged from 81.9%to 92.3%.?2?EC₅₀ value of acute toxicity for CF₃SO₃H was 45.56 mg/L so it was low toxic.Characteristics of CF₃SO₃H were refractory and complex toxic effects,probably to cause potential harm to aquatic ecology.?3?The highest concentration of CF₃SO₃H in water was 3941 ng/L,and the median value was 294 ng/L.There was a regional distribution difference for the concentration of CF₃SO₃H because of pollutant collection.Average concentration of each quarter in water was April>January>July>October,mainly caused by rainfall and river exchange functions.Average concentration of each quarter in sediment was October>July>April>January.Different regional concentrations were mainly caused by water concentrations and seasonal factors?temperature,river movement?.Six kinds of halogenated methanesulfonic acids were quantified by semi-quantitative methods.Concentrations of halogenated methanesulfonic acids in sediment were much lower than that in the water,indicating that halogenated methanesulfonic acids were water soluble.There was no obvious spatial and temporal distribution of concentration in water and sediment.Because every halogenated methanesulfonic acid contains sulfonate so Kow was low.They were more likely to exist in water and concentrations in water were higher than that in sediment.CHCl₂SO₃H was the main halogenated methanesulfonic acid both in water and sediment because chemical reactions in nature were difficult.?4?Abundance changes of phytoplankton at four sampling points were 1.995×10³ cells/L²72.8×10³ cells/L,and density changes of zooplankton were 0.9 ind/L¹72.8 ind/L.Average abundance and density in spring were higher than that in autumn.Both water quality and plankton biodiversity indicated that there were serious pollution problems in Hangzhou Bay,which were consistent with results of water quality indicators.CCA analysis of plankton and environmental factors showed that the composition of plankton in Hangzhou Bay was closely related to environmental factors.The correlation between phytoplankton and pH,DO,TOC,CF₃SO₃H was relatively tight.The community structure of zooplankton was affected by many factors,including pH,DO,TN,TP,NH₃-N,NO₃-N and CF₃SO₃H.Differences existed in different species because of impacts on environmental factors at different levels.