In this study, the concentration of lead ([Pb]) in the surface water, sediments, soils and muscles of carp and crab in the upstream and downstream coastal watersheds along the Northern Bohai and Yellow Seas (NBYS) in China was investigated and the risks of Pb were evaluated. The mean [Pb] in the downstream water (2.62 mu g/L) and sediments [24.5 mg/kg, dry mass (dm)] was greater than the Chinese seawater quality standard for class I (1 mu g/L) and the regional background soil concentration (11.5 mg Pb/kg, dm), respectively. Approximately 37 % of the soils, mainly from the upstream regions, had [Pb] greater than the regional background concentration of 21.4 mg/kg, dm. The sites with relatively large [Pb] in the water, sediments and soils were located in the coastal watersheds of Tangshan and Huludao. The large enrichment factors in the sediments (2.41) and soils (2.22) suggested that human activities influenced the soils and sediments in this region more than in the other regions. Relatively large [Pb] was found in the crabs that were obtained from the upstream reaches of the Shuanglong and Daliao Rivers and the downstream reaches of the Luanhe and Liugu Rivers. Most of the crabs from the upstream regions contained greater [Pb] than the permissible limit for human consumption [0.3 mg/kg, wet mass (wm)]. The risk indices of the water, carp and crabs for humans were 0.002, 0.01 and 0.006, respectively. Based on the bioaccumulation factors, biota-sediment accumulation factors (BSAFs) and human risk indices, it was concluded that the human risks associated with crab were lower than those of carp despite the greater accumulation of Pb by the crabs from the water and sediments. Finally, the [Pb] in the sediments was significantly correlated with the [Pb] in the soils, which indicated that the same sources of Pb were responsible for the [Pb] in the sediments and soils in the coastal watersheds of the NBYS in China.
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