Combined Pollution Characteristics And Preliminary Safety Risk Assessment Of Pesticides In Surface Water From Jiulongjiang River,Jinjiang River And Minjiang River In Fujian Province

Pesticides play great roles in ensuring the production and supply of agricultural products,but they also cause serious food safety and environmental pollution problems.In production and use,pesticides enter water environment through various ways,threatening drinking water safety and aquatic ecosystem safety.China has approved the production and use of more than 400 kinds of pesticides,which shows development tedencies from high toxicity to low toxicity,high residue to low residue and fat soluble to water soluble.However,little attention has been paid on the combined pollution of various pesticides in waters.In this paper,pretreatment methods-LLE and SPE,and detection techniques-GC-MS and LC-MS/MS were combined to establish a simultaneous determination method system for 349 pesticides commonly used in China in surface waters.This method system was then applied to the monitoring of main drinking water(Minjiang River,Jinjiang River and Jiulongjiang River)in Fujian Province,aiming to investigate the combined pollution characteristics of pesticides in the surface waters,and to assess safety risk preliminarily.The main research contents and results are as follows:1.Establishment of a simultaneous determination method system for 349 pesticides in surface waterA method system for simultaneous determination of 349 pesticides in surface water was established through combining GC-MS and LC-MSMS detection techniques with LLE and SPE pretreatment method according to polarity(fat solubility and water solubility).240 pesticides with low-polarity were analyzed by LLE+GC-MS,and 109 strong polar and ionic pesticides were analyzed by SPE+LC-MS/MS.For 240 pesticides analyzed by LLE+GC-MS,more than 90%targets were in good linear ranges with R2>0.99 and instrumental detection limits were 0.5?10.0 ?g/L under optimized conditions.Surrogate method as a quantitative method,at 20 ng/L spiking level,recoveries of 192 pesticides were in the range of 44.5%?128.6%with RSD(n=4)0.8?30.4%.At 100 ng/L spiking level,recoveries of 223 pesticides were in the range 46.2%?124.6%with RSD(n=4)1.5%-36.6%.The limits of determination were between 0.1?10 ng/L.For 109 pesticides analyzed by SPE+LC-MS/MS,more than 90%targets were in good linear ranges with R2?0.99 and instrumental detection limits were 0.01?20.0 ?g/L under optimized conditions.Surrogate method as a quantitative method,at 20 ng/L spiking level,recoveries of 94 pesticides were in the range of 45.4%?128.4%with RSD(n=4)0.8?30.4%.At 100 ng/L spiking level,recoveries of 89 pesticides were in the range 40.8%?127.9%with RSD(n=4)1.5%?19.8%.The limits of determination were between 0.1?10 ng/L.The above method is sensitive,accurate and reliable,and fully meets the relevant requirements for the detection of various pesticides in surface water.2.Study on the combined pollution characteristics of pesticides detected in the main drinking water sources of Fujian provinceUsing the established method above,combined pollution of various pesticides in 55 surface water samples from Jiulongjiang River,Jinjiang River and Mingjiang River were monitored from May to November in 2018.Results showed that the pesticides detected in Fujian waters were more diverse and complicated compared with other domestic and foreign researches.46 pesticdes of 16 categories were detected in Jiulongjiang River,25 pesticdes of 12 categories were detected in Jinjiang River and 29 pesticdes of 13 categories were detected in Mingjiang River.The concentrations of pesticides detected in the three waters were in the range of 42.2 ng/L-2022.1 ng/L,63.1 ng/L-343.9 ng/L,and 231.0 ng/L-443.3 ng/L,respectively.The characteristics of pesticides detected in the three rivers as follows:(1)Besides traditional pesticides,emerging pesticides such as azoles,anilines,methoxy acrylates,neonicotinoids,ureas and pyrimidines also contributed greatly to the total concentration.(2)Overall,the most specie and the highest concentration were both detected in Jiulongjiang River,followed by Minjiang River,and azole pesticide was the category with highest total amount in both Jiulongjiang River and Mingjiang River,while aniline pesticide showed the highest total amount in Mingjiang River.(3)The total amount of detection in each station of the three rivers showed a certain regularity.In Jiulongjiang River,the total amount increased from upstream to downstream,and the concentration and categories of detection were both higher in tributary stations.In Jinjiang River,the detection concentration in the middle and lower reaches was significantly higher than upstream.In Minjiang River,the total amount showed little difference in each station,due to high proportion of azoles pesticides to 70%in this region.(4)Some emerging pesticides should be paid more attention.For example,nicotine pesticides of lothianidin and thiamethoxam were detected in half of the stations in the three rivers;Benzofenap belonging to azoles pesticides was detected with low concentration but high frequency(Cmax:139.6 ng/L,100%).Others,such as pyrimethanil,dimethomorph and kresoxim-methyl,were detected with low concentration but high frequency(<10.0 ng/L,100%)in Jinjiang River and Mingjiang River.(5)Detected pesticides with high concentration of over 200 ng/L in the Jiulongjiang River were carbendazim,fluconazole and terbutin,and carbendazim and the maximum of carbendazim was as high as 911.8 ng/L.Propham with 172.5 ng/L was detected only in Jinjiang River.Most concentrations of detected pesticides in Mingjiang River were lower than 100.0 ng/L except for benzofenap 139.6 ng/L.3.Preliminary safety risk assessment of pesticides detected in main drinking water sources in Fujian ProvinceAccording to China's"Technical Rules for Evaluation of Safety Status of Drinking Water Sources in Urban Cities"and relevant water quality standards at home and abroad,preliminary safety risk assessments were carried out on pesticides detected in three main drinking water sources in Fujian Province.In terms of maximum concentration of the pesticides,10 pesticides such as carbendazim,terbutazone,acetochlor,omethoate,ect.in Jiulongjiang River all exceeded the regulated limits,the same situation happened to propham in Jinjiang River and benzofenap in Mingjiang River.The aquatic ecological risk of pesticides was initially evaluated by RQ quotient.Results showed that most detected pesticides were at low risk level except for carbendazim between medium and high risk in three rivers.Compared with Jinjiang River and Mingjiang River,Jiulongjiang River detected more high-risk pesticides,such as amide chlorantraniliprole,acetochlor,omethoate and dichlorvos.This study provides a technique reference for the analysis and monitoring of various pesticides in water,and provides scientific data for risk assessment and pesticide management.