Analysis on heavy metal pollution in major seafoods from Zhoushan Fishery, China

Abstract

Through reviewing data on surveys, tested materials especially on lead in Zhoushan fisheries, with ground lead, cadmium and methyl-mercury were analyzed and evaluated. According to the distribution of Zhoushan fisheries, we randomly selected a certain number of Zhoushan seafood as research objects from four counties or districts. Different kinds of seafood would include sea fish, seawater crustaceans, seawater soft-bodied animals and sea algae. The inedible parts of all the seafood were removed, and then the samples of the edible parts were grinding into homogenate. We measured the contents of lead and cadmium, using graphite furnace atomic absorption spectrometry method. The content of methylmercury was measured, using the gas chromatography (acid extraction method of mercaptoacetic cotton). Data from 2007 to 2009 was analyzed under SPSS software. (1) The average standardized rates were: lead as 3.90% (11/282), cadmium as 11.35% (32/282) and methylmercury as 2.84% (8/282). (2) Results from the comprehensive evaluation on the contents of metals showed the following rankings: seaweed (0.4513 mg/kg), marine molluscs (0.1155 mg/kg), marine crustaceans (0.0486 mg/kg), sea-fish (0.0419 mg/kg). (3) Results from the single-factor variance analysis showed that the accumulation of lead, cadmium and methylmercury in different types of seafood were: lead F = 35.683 (P < 0.001); cadmium F = 25.301 (P < 0.001); methylmercury F = 25.990 (P < 0.001). (4) Data on the safety analysis related to the different types of seafood on lead, cadmium, methylmercury food, the Chi-square tests showed as: lead χ(2) = 10.167, P < 0.05; cadmium χ(2) = 62.940, P < 0.001; methylmercury χ(2) = 20.960, P < 0.001. (5) Seafood in different years on lead, cadmium, methylmercury accumulation comparison, the Spearman correlation test results showed: lead P = 0.000, cadmium P = 0.974, methylmercury P = 0.024. (6) The contents of seafood lead, cadmium and methylmercury in different years that with statistically significant differences were as follows: lead χ(2) = 6.440, P < 0.05; cadmium χ(2) = 34.455, P < 0.001; methylmercury χ(2) = 5.226, P > 0.05. The situation of heavy metal pollution in different kinds of Zhoushan fisheries was different. Algae appeared the worst while sea fish, sea water crustaceans pollution were light, with lead and methylmercury mainly influencing sea algae and cadmium mainly in the sea algae, followed by seawater software class. The rates over standards of different kinds of seafood were different from each other, while the rates over standards of lead, cadmium and methylmercury in sea algae were the highest. Evaluated by pollution index, lead, methylmercury pollution was still low, but cadmium in the sea with mild pollution in algae seafood. In the recent three years, heavy metal lead pollution in seafood were worsened, while the cadmium, methylmercury pollution levels remained basically stable.