| Largely used triazole pesticides would do harm on aquatic organisms and then affect aquatic ecosystem after entering aquatic environments through deposition, surface runoff and so on.In this dissertation,an accurate,sensitive method for the simultaneous determination of 9 triazole pesticides(triadimefon,paclobutrazol, hexaconazole,uniconazole,myclobutanil,flusilazol,propiconazol,tebuconazole, difenoconazole) in natural water samples has been developed using solid phase extraction(SPE) for extraction and cleanup and gas chromatography coupled with mass spectrometry(GC-MS) for detection.The method was successfully applied to survey triazole residual status in Jiulong River Estuary,Fujian,China and then further study on abiotic degradation of target pesticides in natural water under natural conditions was carried out.Research results could provide analytical techniques and scientific data for risk assessment of triazoles in aquatic environments.The detailed contents and results are as the followings:(1) Development of simultaneous determination method for 9 target pesticides in natural water using SPE-GC-MSAccurate and sensitive instrumental analysis method for 9 target pesticides was established using GC-MS for qualitation and quantitation.Under the optimized conditions,the instrumental detection limits of 3.3～6.3μg/L and linearity ranges between 25-500μg/L for the target pesticides were achieved.C18 cartridge was selected to enrich target pesticides form water samples. Effects of breakthrough volumn,elution solvent,eluent volume,pH and salinity were investigated.Using simeconazole as internal standard and cyproconazole as surrogate, the recoveries and relative standard deviations(RSD,n=3) of 9 target pesticides sipked in river water and seawater at 0.025μg/L and 0.100μg/L were 68.4%～113.9%, 1.6%～6.9%and 70.3%～115.2%,0.8%～8.2%,respectively.Method detection limits were between 0.002～0.009μg/L.(2) Residual status of 9 target pesticides in surface water of Jiulong River Estuary The residual status of 9 target pesticides in surface water of Jiulong River Estuary was surveyed using the above determination method at Dec.2007(dry season) and May 2008(raing season).Results showed that in 16 sampling stations paclobutrazol(29.3～52.1 ng/L),propiconazol(22.5～47.9 ng/L),myclobutanil (2.8～29.3 ng/L),flusilazol(22.9 ng/L),difenoconazole(5.67 ng/L) were detected at dry season.Paclobutrazol(8.5～126.1 ng/L),propiconazol(16.7～123.2 ng/L), myclobutanil(7.1～160.2 ng/L),flusilazol(4.2～29.9 ng/L),difenoconazole(3.9～6.1 ng/L),triadimefon(47.7～173.3 ng/L) were detected in raing season.Paclobutrazol, propiconazol,myclobutanil were main triazole pollutants in this area.(3) Abiotic degradation of 9 target pesticides in natural water under natural conditionsAbiotic degradation experiment of 9 target pesticides was carried out in ultra-pure water,river water and sea water under outdoor temperature and illumination conditions during Dec.2007 to Feb.2008.Result showed that hydrolysis and photolysis processes of 9 target pesticides in different water matrix accorded with first-order kinetics equation.Half-lives of hydrolysis and photolysis in ultra-pure water,river water and seawater were 239.0～630.0 d,68.6～87.7 d,117.5～210.0 d and 8.8～26.3 d,10.6～41.5 d,15.6～577.5 d,respectively,pH mainly affected hydrolysis rates.Both direct and indirect photolysis simultaneously happened for 9 target pesticides,but direct photolysis was dominant for triadimefon and uniconazole.Particulate and/or dissolved organic matter (DOM) in seawater had stronger promotion effect on degradation rate than in river water,whereas inorganic ions greatly slowed degradation rates.The reasons of frequent detection and relatively high detected concentrations of paclobutrazol,propiconazol and myclobutanil in surface water of Jiulong River Estuary were due to their long abiotic degradation half-lives and continuously land input.Those three triazoles should be paid much more attention to and deserved further study. |
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