Pollution characteristics and potential health risk of persistent organic pollutants in mudflat sediments at the north coast of Hangzhou Bay in Jinshan section

Objective To analyze the composition of persistent organic pollutants(POPs) in the intertidal sediments at the north shore of Hangzhou Bay in the Jinshan section and to assess their potential health risk.

Methods Four sampling sites(S1, S2, S3, and S4) were selected along the intertidal zone of the north shore of Hangzhou Bay in the Jinshan section, which is upstream of the centralized drinking water source. The gas chromatography-mass spectrometry technique was used to analyze the composition of polycyclic aromatic hydrocarbons(PAHs) and polychlorinated biphenyls(PCBs) in the intertidal sediments. The effect range-low method(ERL) and the effect range-median method(ERM) were used to evaluate the potential risk of POPs in sediments.

Results The concentration range of 16 PAHs at 4 sampling sites was 2.39-249.40 ng/g, with an average value of 44.3 ng/g at S1, 38.2 ng/g at S2, 36.7 ng/g at S3, and 39.5 ng/g at S4, respectively. Among these, benzo(b)fluoranthene had the highest detection rate(60%). In all samples, the highest total PAH concentration was 249.40 ng/g, which was found at the depth of 42-44 cm of the S1 site. The concentration range of 18 PCBs was 1.12-34.90 ng/g, with an average value of 10.6 ng/g at S1, 11.3 ng/g at S2, 9.2 ng/g at S3, and 12.4ng/g at S4, respectively. Among these, PCB153(97.5%) and PCB180(92.5%) had higher detection rates, and the highest total PCB concentration was 34.90 ng/g, found at a depth of 14-16 cm of the S2 site.

Conclusions The POP pollution level in the intertidal sediments at the north shore of Hangzhou Bay in the Jinshan section was low, with a small potential risk for PCBs and a very low potential risk for PAHs. However, the residual and accumulation should still be continuously monitored.