A Study On The Pollution Characteristics And Accumulation Specificity Of Cadmium And Arsenis In Scylla Paramamosain

With the rapid development of modern industry and agriculture,heavy metal such as cadmium and arsenic were released into the aquatic environment through various channels had seriously affected the quality and safety of aquatic organisms.Aquatic products had been identified as one of the main sources of cadmium and arsenic exposure in humans diet.The scylla paramamosain is an important marine crustacean in China,with an annual output of hundreds of thousands of tons.Crustaceans have a higher ability to accumulate heavy metals than other aquatic organisms due to their unique habitat and omnivorous characteristics,excessive heavy metals had been reported in Scylla paramamosain.However,there were few studies on the analysis of arsenic occurrence and the accumulation characteristics of cadmium and arsenic in Scylla paramamosain.Arsenic exists in a variety of forms in aquatic organisms.The toxicity of arsenic was closely related to its species.Therefore,if you want to scientifically and reasonably evaluate the edible risk and safety of arsenic in Scylla paramamosain,the identification and analysis of arsenic species was particularly important.In this study,the high-performance liquid chromatography-inductively coupled plasma mass spectrometry（HPLC/ICP-MS）was used to study common six arsenic species in Scylla paramamosain.The kinetics of bioaccumulation and the accumulation specificity of heavy metals cadmium and arsenic in Scylla paramamosain were exploerd.The contents of cadmium and arsenic in different tissues and organs of Scylla paramamosain were detected in China’s coastal area,and the occurrence species of arsenic were analyzed.The main research results as follows:（1）A method was established to determine six arsenic species in scylla paramamosian using high performance liquid chromatography in conjunction with inductively coupled plasma mass spectrometry,including arsenite（AsⅢ）、arsenate（AsⅤ）、methyl arsenic acid（MMA）、dimethyl arsenic acid（DMA）、arsenic choline（As C）、arsenobetaine（As B）.The extraction solvent and time,optimum mobile phase,p H value and elution method were obtained,and target compounds were quantified using standard addition method.The study determined that the extraction method was ultrasonic bath for 30 minutes with 0.5 mmol·L^-1 ammonium carbonate-methanol（V:V=99:1）.And the extraction was filtered with microporous membrane after degreasing with n-hexane.The HPLC separation was performed on an anion exchange column with 50 mmol·L^-1 ammonium carbonate-methanol（V:V=99:1）as mobile phase under gradient elution mode.The target compounds were qualitatively and quantitatively analyzed by ICP-MS.The methodological verification results showed that good linear range of As B ranging from 5 to 500μg·L^-1 and other five arsenic species ranging from 0.5 to 20μg·L^-1 were obtained.The recoveries ranged from 76%to 118%.The relative standard deviations were between 1.49 and 9.45%,and the detection limits were from 0.01 to 0.05 mg·kg^-1.The standard addition method was creatively used in this study for the quantitative analysis of different arsenic species in scylla paramamosian,the certified reference material of tuna fish tissue（BCR-627）was used to ensure the accuracy of the method.The results show that the mainly arsenic species was As B in scylla paramamosian sample.The method had simple pretreatment process and good separation,and was suitable for quantitative analysis of different arsenic species in crabs.（2）We stimulated kinetic parameters using semi-static two-compartment kinetic model to reveal the accumulation and bioelimination characteristics of arsenic and cadmium in muscle,hepatopancreas and gills of Scylla paramamosain.Parameters including uptake rate constant（k₁）,release bioelimination rate constant（k₂）,bioconcentration factor（BCF）,maximum bioaccumulation at equilibrium(C_Amax)and biological half-lives(T_1/2),were obtained through non-linear curve fitting.The results showed that the BCF of arsenic and cadmium in the tissues ranged from 46.61 to 158.3 and 9.241 to2886 respectively.The T_1/2 of arsenic and cadmium in the tissues ranged from 7.416 to14.61 days and 6.630 to 19.19 days respectively.No significant difference was shown between the modeling output and the laboratory data,which validated this model in the kinetics stimulation of bioconcentrations of arsenic and cadmium by Scylla paramamosain.The results showed that significant positive correlations existed between the concentration of arsenic,cadmium in studied tissues（muscle,hepatopancreas and gills）and accumulation time as well as the exposure concentration of heavy metals.The concentration of arsenic and cadmium in different tissues were:hepatopancreas>gills>muscle.The bioaccumulation factor of cadmium was much higher than that of arsenic in Scylla paramamosain.The bioaccumulation process of Scylla paramamosain exposed in different concentrations of arsenic and cadmium agree with the two-compartment kinetic model prediction.（3）In order to research the differences of As and Cd enrichment in various tissues and organs of Scylla paramamosain.Determination of As,i As and Cd content in 74batches of biological samples collected from Shanghai and Zhejiang markets.The national standard limit method,pearson correlation,and one-way analysis of variance（between and within groups）were used to evaluate the measurement results.The results showed that the excessive rate ofthe content of i As were 0%in chest muscles,cheliped and legs’muscles,hepatopancreas and gills of Scylla paramamosain,but the excessive rate of Cd was 55%in hepatopancreas.Total As content showed distribution trend of hepatopancreas>chest muscles>cheliped and legs’muscles>crab gill;The content of i As showed a distribution trend of crab gills>hepatopancreas>cheliped and legs’muscles>chest muscles distribution;total content of Cd showed distribution trend of hepatopancreas>cheliped and legs’muscles>gills>chest muscles.There was no correlation between the pollution sources of As and Cd（P>0.05）.The enrichment ability of Cd was significantly related to gender in hepatopancreas（P<0.05）,and the enrichment ability of Cd male blue crabs was stronger than female in hepatopancreas（P<0.05）.Univariate analysis of variance found that the gills were significantly related to the enrichment of As in the hepatopancreas,chest muscles,and leg muscles（P<0.05）.The hepatopancreas of the blue crab were significantly different from the content of Cd in the leg muscles,chest muscles and gills（P<0.05）.In this survey the litter content of i As in samples,and the excessive rate was high of Cd in the lhepatopancreas,which had potential consumption risks.These issues should be taken seriously by relevant departments.