| Water is the source of life,but the shortage of water resource has been worsened by water pollution,posing a direct threat to daily lives of human beings.Therefore,it is imperative to carry out water remediation,which request effective montoring of pollutants in water.Active sampling has been traditionally used in water quality monitoring.Water samples were collected in the field sites and transported back to the laboratory for sampling preparation and analysis at regular time intervals.Active sampling method is time-consuming,labor-intensive and with tedious procedures for sample pretreatments,in addition,it can only provides instantaneous concentrations of contaminants in water when sampling,thus it is difficult to reflect water contamination during a long exposure time.Alternatively,passive sampling has been developed to overcome the shortcomings of the traditional active sampling,with the merits of energy-saving,convenient,providing continuous monitoring and gaining time-weighted average concentrations for contaminants in water.So far,passive sampling techniques have been mainly developed for monitoring hydrophobic compounds in water.Comparatively,fewer studies have been performed on polar organics,and the majority of these studies were related to pharmaceuticals and personal care products.Polar organic chemical integrative sampler(POCIS)has been developed as a passive sampling device for polar compounds,and used for endocrine disrupting chemicals,pharmaceuticals,personal care products,and polar insecticides and herbicides.There are few choices of solid phase adsorbents for POCIS,limiting its application in simultanous monitoring multi-class compounds with broad range of polarity.Neonicotinoid and organophosphate insecticides are currently used insecticides,which are highly neurotoxic to aquatic organisms,and have been widely used in urban landscape maintenance and agricultural pest control.In addition,as a replacement of brominated flame retardants,organophosphorus flame retardants have been widely used in recent years and caused serious water pollution urban areas.Therefore,it is neccessay to monitoring these three classes of compounds which have a wide range of polarity,calling for development of new adsorbent materials.In this thesis,the adsorption properties of a series of newly synthesized solid phase adsorbents were investigated and an optimized synthetic adsorbent(SYN)was selected to be used for POCIS.The adsorbent can extract multiple classes of compounds in water simultaneously and significantly reduce matrix effect during chemical analysis in comparison with the commercial adsorbents(HLB).In addition,a flow-through system was designed to maintain a constant concentration for the target compounds in water,which improved the accuracy of calibration parameters.At the optimized test conditions,sampling parameters of new synthetic adsorbent(SYN)and commercial adsorbent(HLB)were gained for target compounds by laboratory calibration tests.At last,syn-POCIS were deployed in Guangzhou reach of the Pearl River and its tributaries and the concentrations and potential ecological risk of neonicotinoids,organophosphate insecticides and organophosphorus flame retardants were assessed.Firstly,a series of adsorbents were synthesized and screened by soild phase extraction method.Upon the selection of the adsorbent and optimization of extraction conditions,insecticide residues in Guangzhou reach of the Pearl River were quantified.The newly synthesized adsorbent was spherical with a diameter,surface area,average pore volume and pore size being ~5 ?m,341 m2/g,0.092 m3/g and 2.22 nm,respectively.The total concentrations of neonicotinoids in Guangzhou reach of the Pearl River were from 51.8 ± 19.4 to 111 ± 35.4 ng/L,while chlorpyrifos and diazinon were the only organophosphate insecticides being detected in water,but their concentrations were below method detection limits and around 20 ng/L,respectively.Fipronil and its metabolites were detectable in the river,yet the concentrations were all less than their method detection limits.Hexachlorocyclohexane,an organochlorine insecticide,was detected in all sampling sites with the concentrations in the range of 13.6 ± 2.88–21.0 ± 2.83 ng/L.Within all insecticides,neonicotinoids showed possible risk to aquatic ecosystem in the study river.Secondly,the samping rates(Rs)of neonicotinoid and organophosphate insecticides were calibrated for the newly synthesized adsorbent syn-POCIS and HLB adsorbent pha-POCIS in the flow-through system.The concentrations of neonicotinoid and organophosphate insecticides in the flow-through system kept constant,with the relative standard deviations being 3.3%?24.9% and 5.5%?27.3%,respectively,throughout the whole process of calibration.Both neonicotinoid and organophosphate insecticides showed linear adsorption to the POCIS,with r2 values of 0.876?0.993 and 0.781?0.979 for neonicotinoids to syn-POCIS and pha-POCIS,respectively,and 0.964?0.990 and 0.854?0.986 for organophosphates insecticides,respectively.The sampling rates of the insecticides by syn-POCIS were generally lower than those by pha-POCIS,with an exception for chlorpyrifos and tebupirimfos.Specifically,the sampling rates of the insecticides by syn-POCIS were in the range of 0.028?0.216 L/day,with standard deviations being in the range of 0.007?0.062 L/day,and the sampling rates of the insecticides by pha-POCIS were in the range of 0.045?0.214 L/day,with standard deviations being in the range of 0.009?0.026 L/day.Chemical concentrations and water flowrate had little impacts on the sampling rates of the insecticides by both syn-POCIS and pha-POCIS.Linear relationships between log Kow and sampling rates by syn-POCIS and pha-POCIS were observed for neonicotinoid and organophosphate insecticides with r2 being 0.31 and 0.79,respectively.Thirdly,calibration parameters(Rs)of organophosphorus flame retardants by syn-POCIS and pha-POCIS were obtained in the flow-through system.Water concentrations of organophosphorus flame retardants were constant during the whole calibration process with relative standard deviations of 4.2%?30.4%.The sorption of organophosphorus flame retardants to both POCIS was linear,with r2 values of 0.936?0.999 and 0.929?0.999 for syn-POCIS and pha-POCIS,respectively.The sampling rates of organophosphorus flame retardants by syn-POCIS and pha-POCIS were 0.065?0.264 and 0.081?0.311 L/day with standard deviations of 0.018?0.063 and 0.015?0.088 L/day,respectively.The sampling rates of organophosphorus flame retardants by syn-POCIS and pha-POCIS were little influenced by chemical concentrations and water flowrate.The sampling rates of organophosphorus flame retardants by syn-POCIS and pha-POCIS were non-linearly correlated to chemical log Kow,and the correlation coefficients were 0.75 and 0.62,respectively.At last,both syn-POCIS and pha-POCIS were used to measure the time weighted average concentrations of neonicotinoids,organophosphate insecticides and organophosphorus flame retardants in Guangzhou reach of the Pearl River and its tributaries after the sampling parameters were calibrated.Acetamiprid,thiamethoxam and imidacloprid were the dominant neonicotinoid insecticides,chlorpyrifos was the most dominant organophosphate insecticides,and tris(2-chloroethyl)phosphate,tris-(2-chloroisopropyl)phosphate,tris(2,3-diclorpropryl)phosphate,tri-isobutyl phosphate,tri-butyl phosphate and tri-phenyl phosphate were the main organophosphorus flame retardants.These compounds were 100% detected in all field samples.The concentrations target contaminants were comparable when using syn-POCIS and pha-POCIS with the average ratios of the concentrations in the range of 0.74?1.77 and r2 value of 0.82.Compared to active sampling with SPE,water concentrations of most of target contaminants using syn-POCIS were within two-fold deviation,and the average ratios of the concentrations were 0.50?1.86 with r2 being 0.81.Elevated concentrations of neonicotinoid insecticides and organophosphorus flame retardants were detected in Guangzhou reach of the Pearl River and its tribuatries,with the concentrations of neonicotinoids,organophosphate insecticides and organophosphorus flame retardants being in the ranges of 73.1 ± 6.90?354 ± 30.0?1.00 ± 0.12?8.83 ± 2.18 and 211 ± 21.4?404 ± 55.5 ng/L,respectively,likely causing risk to aquatic ecosystem.Overall,a novel adsorbent has been synthesized and selected as solid adsorption phase material,POCIS calibration parameters were determinated using a homemade flow-through system,and finally the concentrations and distribution of neonicotinoid insecticides,organophosphate insecticides and organophosphorus flame retardants in Guangzhou reach of the Pearl River and its tributaries were quantified.Analytical results are similar when syn-POCIS,commercialized pha-POCIS and active sampling SPE methods were used.The development of new adsorbent expands the choice of POCIS adsorbents and provides an effective way for monitoring polar contaminants in water. |
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