| Carbendazim belongs to the class of benzimidazole drugs,and is a commonly used high-efficiency and low-toxic fungicide.It is widely used in rice production to prevent and cure rice sheath blight,rice blast,malaria Disease.The method of applica-tion is mainly foliar spraying.Carbendazim sprinkled in paddy water will be transferred to the Sediment with the infiltration of water,which will cause pollution to the paddy field water and Sediment.Studies have shown that carbendazim is toxic to aquatic ani-mals.With the promotion of a new type of ecological circular agricultural development model—Integrated farming of rice and aquaculture animal,carbendazim will adversely affect aquatic animals that integrated with rice after entering the water environment.In recent years,Procambarus clarkii has higher economic value and consumer demand.In order to avoid the transfer of carbendazim from aquatic products to the human body through the food chain and bring dietary risks to people,this project takes Procambarus clarkii,which is a high-quality aquatic animal with Chinese characteristics,as the re-search object,the residual characteristics,fate and accumulation effect of carbendazim,a typical fungicide under integrated shrimp in rice field,were investigated.The re-search content and results of this thesis mainly include the following three parts:1.A new method for the determination of carbendazim in water-sediment-Procambarus clarkii by high performance liquid chromatography-triple quadrupole mass spectrometry was established by optimizing the chromatographic and mass spec-trometer instrument parameters and conditions for extracting and purifying the target Water samples were enriched and purified using a mixed cation extraction cartridge(MCX).Sediment,Hepatopancreas,and muscle of Procambarus clarkii was extracted by ethyl acetate under alkaline condition,centrifuged,and the supernatant was concen-trated by rotary evaporation and redissolved,then enriched and purified by mixed-mode cation exchange solid-phase extraction column(MCX).Acetonitrile and water were used as mobile phase and C18 column was used for gradient elution separation.Ioniza-tion was performed using an electrospray positive ion source(ESI+)and detected by tri-ple quadrupole mass spectrometry(MS/MS)in multiple reaction detection(MRM)mode.The results showed that the linearity of carbendazim was good in the range of 0.5-50 ?g/L,and the correlation coefficient(r2)was 0.9985.The limits of quantification of carbendazim in water,sediment,and gills,Hepatopancreas,and muscle tissues were 10 ng/L,0.20 ?g/kg,1.00 ?g/kg,1.00 ?g/kg,and 0.50 ?g/kg.When the spiked levels were 1,2,10,and 100 times the respective limits of quantification,the spiked recover-ies were 83.90%to 108.42%,and the relative standard deviations were 1.02%to 5.70%(n=6).The method can simply and effectively detect the residual amount of car-bendazim in water-sediment-Procambarus clarkii,and has good stability and reliable results.2.Study the fate behavior of carbendazim in paddy water and sediment and its residual characteristics in Protothecus clarkii under integrated shrimp in rice field.The experimental results show that in a field test of 200 g/mu dose of 50%carbendazim suspension(100 g/mu of carbendazim active ingredient)in 16 L of water and applied once,the carbendazim is degradation in Paddy water,Sediment and Protothecus clarkii is faster,and it belongs to easily degradable and difficult to eliminate pesticides.Among them,the residual value of carbendazim in different tissues of paddy water and Proto-thecus clarkii decreased rapidly with the application time.At 90 days after application,low-dose residual values in the paddy water,sediment,and Protothecus clarkii ovary and muscle tissue were 0.11 ± 0.02 ?g/L,3.27±0.21 ?g/kg,1.03 ±0.06 ?g/kg,0.58±0.03 ?g/kg;the final residual value of carbendazim in the gills,liver and pancreas of Procrustus clarkii was below its limit of quantification(1.00?g/kg).The fate behavior of carbendazim in paddy water conforms to the first-order kinetic model.The kinetic equation is Ct=398.16e-0.316t,the correlation coefficient(r2)was 0.9647,and the half-life(T1/2)is 2.19 d.The residual dynamics of carbendazim in the Sediment did not conform to the first-order kinetic model,and the maximum residual amount on the 10th day after application was 123.16 ± 10.55 ?g/kg.Different tissues of Protothecus clarkii show the distribution characteristics of gill>hepatopancreas>muscle tissue.The residual amount of carbendazim in gill,hepatopancreas is significantly higher than that of muscle tissue(P<0.05).The percentage of the three is:gills(43.34%±20.25%),hepatopancreas(39.56%±15.24%),and muscle tissue(17.10%±5.98%).Under the same exposure time,the sum of carbendazim residues in the edible parts(gills,gonads,muscle tissues)of Protothecus clarkii different sex was different but not significantly different(P>0.05).3.Through laboratory exposure simulation experiments,the accumulation of carbendazim in the gill,hepatopancreatine and muscle tissues of the male Procrustus clarkii was studied when exposed to carbendazim at concentrations of 3.70?g/L,18.50?g/L and 370 ?g/L for 10 days respectively,and the double-box dynamic model is used to calculate the Bioconcentration factor(BCF),accumulation rate(ki),release rate(k2),maximum accumulation(Cmax),and half-life(T1/2)and other pollution kinetic parame-ters.The experimental results show that,as a whole,the accumulation of carbendazim in different tissues of Procrustus clarkii did not reach a dynamic equilibrium state at the end of the exposure experiment(10 d).The accumulation amount,Cmax,of carbendazim in different tissue parts is:gill>hepatopancreas>muscle,T1/2 is hepatopancreas/mus-cle>gill,and is positively correlated with exposure concentration and accumulation time.The concentration of carbendazim in muscle tissue is 48.82 to 3381.47 ?g/kg,36.27 to 981.47 ?g/kg,7.80 to 545.13 ?g/kg;Cmax is 287.76 to 4727.88 ?g/kg,232.93 to 1669.21 ?g/kg,117.41 to 868.06 ?g/kg;T1/2 is 2.17 to 5.78 d,2.89 to 7.70 d,3.01 to 6.30 d.Under the same water,the BCF and k1 of the three tissues are gills>hepatopan-creas>muscle tissues,k2 is gills>hepatopancreas/muscle,and are negatively corre-lated with exposure concentration.The BCF of gills,hepatopancreas,and muscle tissues were 12.78 to 77.77,4.51 to 62.95,2.35 to 31.73 respectively;k1 were 1.53 to 24.89,0.41 to 15.11,0.26 to 7.30 respectively;k2 were 0.12 to 0.32,0.09 to 0.24,0.11 to 0.23 respectively.In this study,a novel method was established for the determination of car-bendazim in paddy water-sediment-Procambarus clarkii by high performance liquid chromatography-triple quadrupole mass spectrometry(HPLC-MS/MS)method.The residual characteristics,fate behavior and accumulation characteristics of carbendazim in Procambarus clarkii under integrated shrimp in rice field were revealed.The results of the study have great practical value for improving the ability of monitoring hazards in the culture of Procambarus clarkii,and it has important reference significance for ensuring the safety of crustacean food consumption. |
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