| A series of environmental problems, such as water resource pollution, aquatic ecosystem destroy as well as food safety, are being caused by pesticides widely used in agriculture after entering aquatic environment through dust deposition, rainfall etc. With the prohibition and limitation of organophosphorous pesticides (OPPs) and organochlorine pesticides (OCPs), "new generation" pesticides labeled "low poison" such as pyrethroids, amides, nitrodiphenylamines and heterozoles, are increasingly used as the alternatives. However, researches about their existence, behavior and pollution effects are of seldom concern. In this dissertation, an accurate and sensitive method for the determination of 36 pesticides in aquatic environment (surface water and sediment), using solid phase extraction (SPE) for extraction, enrichment and cleanup and gas chromatography (GC) for detection, has been established and successfully applied to survey the pesticide pollution status in Jiulong River Estuary and Western Xiamen Bay. The detailed contents and results are as the followings:(1) Development of determination method for 36 pesticides in river water and seawater samplesInstrumental analysis method was established using GC with electron capture detection (GC-ECD) for fast screening and quantitative and gas chromatography-mass spectrometry (GOMS) for identification. Under the optimized conditions, instrumental detection limits were in the range of 0. 09～2. 66μg/L, linearity ranges were between 0. 9～2600μg/L.Oasis? HLB was selected to extract and enrich target pesticides from water samples after comparison of 5 different SPE cartridges. Parameters such as elution solvents, loading speed, penetration volume, cleanup cartridges, pH and salinity were investigated. After optimization, the pH and ionic strength of water samples were found had little effect on recoveries, 1.0 L water was load onto HLB SPE cartridge at the speed of 4 mL/min, 5 g Na2SO4 and LC-NH2 SPE cartridges were coupled to HLB for cleanup, 3 mL acetonitrile followed by 10 mL n-hexane/acetone (1:1, vol.) and 10 mL ethyl acetate were used to elute the target pesticides. Using 2,4,5,6-tetrachloro-m-xylene, cyflufenamid, and acrinathrin as surrogates, PCB103 as internal standard, spiked recoveries and relative standard deviation (RSD, n=3) of 36 target pesticides in fresh water and seawater were 62. 2%～124.1%, 0. 2%～9. 6%and 64. 5%～131. 3%, 0.2%～10.3%, respectively. Method detection limits were between 0.06～0.98 ng/L.(2) Development of determination method for 36 pesticides in surface sediment samplesA method for the determination of target pesticides in surface sediment was proposed with acetonitrile for extraction assisted by homogenization and ultrasound and coupled Carb-NH2 SPE cartridges for cleanup. Under the optimized conditions, except propiconazol, spiking recoveries of 35 target pesticides were between 63. 7%～104. 2%, RSD (n=3) 0. l%～10. 3%, and method detection limits were between 0. 01～0. 56μg/kg (dry weight).(3) Pollution status survey of 36 pesticide residues in Jiulong River Estuary and Western Xiamen BayThe pollution status of 36 target pesticides in Jiulong River Estuary and Western Xiamen Bay was surveyed using the established determination methods. Results showed that 2 OCPs, 8 OPPs, 2 nitrodiphenylamines, 3 amides, 3 heterozoles and 8 pyrethroids pesticides were detected in surface water samples with total concentration between 24.8 ng/L～609. 5 ng/L. 3 OCPs, 5 OPPs, 2 nitrodiphenylamine, 3 amides, 3 heterozoles and 7 pyrethroids pesticides were found in sediment samples with total concentration between 14.1μg/L～122. 6μg/L (dry weight).Compared with other research results, although the concentrations of OCPs and OPPs in the researching area were lower, the results show that many "new generation" pesticides have been found in aquatic environment at certain concentrations reveal that their existence, environmental behaviors and effects should not be ignored and deserve further study.
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