Abstract:
In order to study the pollution level of heavy metals in the surface seawater of the central fishing ports in the Yellow Sea and the Bohai Sea during the fishing off period and fishing period, sampling stations were set up in 11 central fishing ports along the coast of the Yellow and Bohai Sea in May and October 2020 to conduct water sample analysis. The content and pollution characteristics of 6 heavy metals including Zn, Pb, Cd, Hg and As were evaluated and analyzed,then, the main sources of heavy metals were explored and their ecological risks were assessed. The results showed that the range of concentrations of Cu, Zn, Pb, Cd, Hg and As during the fishing off season were 1.26~4.46 μg/L, 4.10~22.72 μg/L, 1.18 ~16.76 μg/L, 0.54~7.80 μg/L, 0.02~0.08 μg/L and 0.02~0.86 μg/L respectively. While which in the fishing season were 0.60~4.62 μg/L, 4.92~10.61 μg/L, 0.16~2.95 μg/L, 0.14~2.95 μg/L, 0.03~0.11 μg/L and 0.16~1.37 μg/L respectively. All the average concentrations of Cu, Zn, Pb, Cd, Hg and As of each fishing port were lower than the fourth categories of national seawater quality standards (GB 3097-1997). The concentrations of heavy metals in the surface seawater of the fishing port along the coastal of the Yellow Sea is slightly lower than that in the Bohai Sea. Compared with the East China Sea and the South China Sea, the concentration of Cu, Pb and Cd in the Yellow Sea and Bohai Sea is at a high level, the content of Zn and Hg is at a medium level, while the content of As is at a low level. It is found that Zn and As come from land discharging, while Cu come from both the land discharging and marine antifouling paint during the fishing off period and fishing period. However, Pb in surface seawater is related to the atmospheric deposition and fuel exhaust in the fishing pot zoon. Even though the comprehensive pollution index of heavy metals in the surface seawater of the central coastal fishing port is in the natural background range, and the ecological risk index (
ERI) values (0.84~1.45) of heavy metals in the surface seawater of the coastal central fishing port are also in low risk or risk-free categories to the ecological, the Hazard Quotient (
HQi) values of Cu, Zn, Pb and Cd are greater than 1, which were identified as potential heavy metals to be concerned.