Study On Several Elements And Edible Safety Of Major Seaweeds In Fujian

In recent years,exceeded toxic metals were continuously detected from seaweeds of Fujian province,resulting in recalls of the seaweed products,which have seriously negative impacts on seaweed industry and the professionals engaged in seaweeds cultivation and processing.Thus,studies on the toxic metals in seaweeds were necessary to food security and to protect of the development of seaweed industry.This study focused on the three common edible seaweeds in Fujian province,Porphyra haitanensis,Laminaria japonica Aresch and Enteromorpha prolifera,and the results were listed as follows:Ⅰ.The investigation of toxic metals in seawater,ocean sediment and seaweeds indicated that the contents of toxic metals of Cu,Pb,Zn,Cd,Cr,Hg,and As varied widely among different seaweed farming areas,even more than 10 times.There were no obvious regular changes among different samples of ocean sediment from various regions,as well as seawater.The contents of toxic metals among P.haitanensis,L.japonica Aresch and E.prolifera were different in various sea areas of Fujian province,in which aluminum had highest contents.There no significant diversities between the content of toxic metals in the fresh seaweed and that in the processed seaweed,which indicated that the toxic metal pollution were avoided during the procession of seaweed.Ⅱ.Enrichment regularity of toxic matels in living seaweeds were studied for the first time.Enrichment regularity of toxic metals of Cd,Pb and AI in P.haitanensis,L.japonica Aresch and E.prolifera were investigated using bidirectional dynamic model and logistic model.Both the enrichment regularities of Cd,Pb,AI in P.haitanensis and Cd,Pb in E.prolifera complied with the bidirectional dynamic model,and the regression model reached high significance level,while the enrichment rate Ka reached significance level.The enrichment of AI in E.prolifera complied with logistc regression analyses,and the enrichment of Al in both P.haitanensis and E.prolifera were better than that of Cd and Pb.The content of toxic elements of Cu,Zn,Pb and Cd in L.japonica Aresch increased during the first 70 days of aquaculture,but was almost unchanged during later stage.The content of Al was in a state of greater volatility of 111～401 mg·kg-1 during aquaculture,which had a regularity of fluctuation rising trend.Ⅲ.The speciation of five toxic metals,Pb,Cd,Al,Hg and As were analyzed.The main existance form of arsenic in seaweed was organic arsenic,while the content of inorganic arsenic was below 1 mg*kg’1.The predominant form of Cd in three kinds of seaweeds was NaCl-extractable,which had the highest percentage of 68.9%～81.7%;the predominant form of Al was NaCl-extractable,followed by ethanol-extractable and acetic acid-extractable.Although the total content of Al was relatively higher,most Al was insoluble,which accounted for the highest value of total volume could reach 89.80%.The methyl mercury had little proportion in the total mercury,which were extracted from the seaweed of different areas,different types and different harvest times.Ⅳ .Enrichment metabolism and toxicity metabolism of toxic metals from seaweeds were studied in animals for the first.Short-time enrichment metabolism and cumulative toxicity metabolism were tested on toxic metals of Al,Cd and Pb in P.haitanensis using animal experiments in mice,and the expression quantity of detoxicated related genes were analyzed using real-time fluorescent quantitative PCR.The result of metabolism of excessive toxic metals in P.haitanensis showed no significant impacts on organism,and the results of cumulative toxicity indicated that P.haitanensis group had less impact on mice weight,visceral index and the enrichment of harnful elements comparing to reagent group.The expression quantity of GST and CAT genes in reagent group were much higher than that in P.haitanensis group,while the expression quantity of MT and HSP70 genes were higher in P.haitanensis group than the other.The impacts of toxic elements from P.haitanenssi to animals could be almost ignored.Ⅴ.Exposure assessment of Pb,Cd,Al,As in three seaweeds were conducted,and the result indicated that children with the highest EDI scores,followed by middle-aged people then young adults.The daily intake of Al in seaweeds of Fujian province by various age group were much lower than PTDI,while the daily intake of Cd were relatively higher,and the average daily intake of Al by children accounted for the largest proportion of total PTDI.In a word,The intake of toxic metals of Fujian seaweeds is under the limited value.In suumary,the standard threshold value of Pb,Cd,Al,As in seaweeds were proposed based on studies that conducted on pollution condition of seaweeds aquaculture areas,seaweeds structure characteristics,total volume of toxic metals,enrichment regularity of toxic metals,morphological analysis of toxic metals and toxicity of toxic metals in seaweeds.