| Shellfish toxins are toxic macromolecular compounds that are transmitted from toxic algae in the ocean to algal-eating fish,shrimp and shellfish through the food chain,and accumulate in their bodies.In recent years,poisoning incidents caused by the consumption of poisonous shellfish have been frequently reported around the world.In order to strengthen the management of shellfish red tide biotoxins and reduce the harm of shellfish biotoxins,this paper takes the Aotou sea area of Guangdong Daya Bay,a high incidence area of shellfish red tide toxins as the research object.From September to August 2021,a one-year on-site monthly sampling and laboratory toxin chemical composition analysis will be carried out to understand the pollution status of red tide toxins in the sea of Daya Bay and its nearby marketed shellfish,The main analysis includes three major shellfish toxins,paralytic shellfish toxin,lipophilic shellfish toxins and amnestic shellfish poisoning,and to reveal the spatial and temporal distribution characteristics of the toxins.Provide theoretical basis for shellfish toxin management.The main findings are as follows:1)By optimizing the sample pretreatment conditions and improving the chemical analysis method,a detection technology(LC-MS/MS)combined with high performance liquid chromatography and mass spectrometry for 25 kinds of shellfish toxins was successfully established.The detection limit of the method for 10 kinds of paralytic shellfish toxins(PSTs)was 2-20μg/kg,the limit of quantification was 4-40μg/kg,the average recovery was 83%-113%,the precision and relative standard deviation(RSD)was 2%～25%;the detection limit for 11 kinds of Lipophilic Shellfish Toxins(LSTs)was 1～10 μg/kg,and the quantification limit was 2～20 μg/kg;The average recovery was 82%～121%,the precision and relative standard deviation(RSD)are 1.2%～23%;the average recovery rate for Amnestic Shellfish Poisoning(ASP)is between 97%～112%,the precision and relative standard deviation(RSD)was 1.4%～7%,and the analysis results showed that the shellfish toxin analysis method established in this paper generally met the requirements of the national testing standard(GB/T 27404-2008).2)In the 150 shellfish samples collected,7 kinds of PSTs components were found,and the order of detection rate was dc STX>GTX5>C1&C2>GTX6> dc NEOSTX>STX>NEO-STX;the order of detected concentrations was GTX5,dc NEOSTX,C1&C2,NEO-STX,GTX6,dc STX,STX.Among the 11 components of Lipophilic Shellfish Toxins(LSTs),4 kinds of toxins,YTX,AZA1,AZA2 and AZA3,were not detected,and the other 7 components of LSTs were detected.The order of detection rate was GYM,h YTX,PTX2,DTX2,SPX1,OA,DTX1,the order of the detected concentrations was h YTX,GYM,PTX2,OA,DTX1,DTX2,SPX1.The detection rate of DA was the highest,reaching 76.7%,and the highest detection concentration was up to 5.34 μg/g.3)In terms of seasonal distribution pattern,the highest detection rate of PSTs was in October,and the detection rate was up to 100%,and the highest detection concentration was in March,reaching up to 120μg/kg.the pattern of LSTs,the highest detection rate was from June to August in 2021,and the detection rate of GYM reached 100%,and the highest detection concentration was up to 66.3 μg/kg.For ASP,the detection rate of DA was 100% in December,2020 and January and June to July,2021,the highest detected concentration was in July,2021(5.34 μg/g).Combined detection rate and concentration,it could identify the seasonal distribution pattern of PSTs was higher in spring and summer than winter and autumn,LSTs in autumn and summer was higher than autumn and spring,DA was higher in summer and winter than autumn and spring.4)Aotou of four shellfish toxin components were detected from the particulates in natural seawater column collected in Daya Bay,namely DA,GYM,PTX2 and GTX5.The highest concentration of DA detected was in September,followed by June and August,indicating significantly higher DA content in summer phytoplankton than in other seasons.Except for some sampling points in December,the detection rate of GYM was 100% in the other months,but the detection concentration was low,and the highest was only 0.13 ng/L.The detection rates of PTX2 were up to 100% in spring and July to August,the highest concentration was 0.5 ng/L,The seasonal distribution in order from high to low is spring,summer,winter and autumn.The detection rate of GTX5 was not high,mainly in the spring and summer seasons,with the highest detection concentration of 5.3 ng/L.5)In terms of shellfish species,the detection rate of PSTs toxoids is the highest in Chamys nobilis,and the order of the detection rate of PSTs in various shellfish is Chamys nobilis,Meretrix meretrix,Perna viridis,Crassostrea rivularis,Atrina pectinata,Paphia undulata,Mactra veneriformis.The detection rate of LSTs toxoids was the highest in Perna viridis,but the detected components were the most in Chamys nobilis,and 7 components of LSTs were detected;the order of the detection rate of LSTs in various shellfish was as follows,Perna viridis,Chamys nobilis,Crassostrea rivularis,Atrina pectinata,Paphia undulata,Meretrix meretrix,Monetaria moneta.The detection rate of DA in ASP toxoid was also the highest in Chamys nobilis,and the lowest detection rate was in Mactra veneriformis and Busycon canaliculatu,all of which were not detected.According to the order of detection rate of ASP,the various shellfish were ranked as Chamys nobilis,Atrina pectinata,Crassostrea rivularis,Perna viridis,Meretrix meretrix,Paphia undulata,Mactra veneriformis = Busycon canaliculatu.Combined with the limit standard of harmful algae biotoxin in marine shellfish in China,the content of the biotoxin in the main marine shellfish collected from Aotou,Daya Bay was low in the present year,and no samples with excessive toxin content threshold were found.The total content of PSTs was 0～120 μg STXeq./kg,The total content of LSTs was 0～66.3 μg YTXeq./kg,and that of DA was 0～5.34 μg/g. |
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