Over 100-year sedimentary record of polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds (OCs) in the continental shelf of the East China Sea

Historical records of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were analyzed in two dated sediment cores (DH05 and DH11) collected from the continental shelf of the East China Sea (ECS) to investigate the influence of anthropogenic activities on marine sediment over the past century. The concentrations and fluxes of 15 PAHs were in the range of 28.6-96.5 ng g−1 and 7.6-35.2 ng cm−2 yr−1 in DH05 (1920s-2009), 18.8-76.4 ng g−1 and 13.9-30.9 ng cm−2 yr−1 in DH11 (1860s-2009). The sedimentary records of PAHs in the two cores generally reflected the economic development and energy consumption change in China. Identification of sources suggested that PAHs in ECS were predominantly from petrogenic origin and various combustion sources. A change of source from low- and moderate-temperature combustion to high-temperature combustion process was observed. Although a production ban of technical HCH and DDT was imposed in China in 1983, their sedimentary fluxes display increasing trends or strong rebounds from 1980s to 1990s as recorded in the core profiles. High proportions of DDD + DDE and γ-HCH suggested those OCPs mainly derived from early residuals. Temporal trends of PCBs presented relative high levels from 1970s to 1980s and high proportions of PCB congeners with 3-6 chlorines atoms indicated industrial sources.