Spatial and temporal trends in polychlorinated naphthalenes in sediment from Ulsan and Onsan Bays of Korea: Potential sources and ecotoxicological concerns

Few studies have been conducted on spatial and temporal trends in polychlorinated naphthalenes (PCNs) in coastal environments. Here, we describe 18 PCN congeners found in surface and dated sediment samples collected from highly industrialized bays of Korea. Measurable levels of PCN congeners were detected in all sediment samples, suggesting concurrent and historical contamination. The highest PCN concentrations were observed in sediment from rivers, streams, and the inner portions of the bays, which are surrounded by industrial complexes and commercial harbors. CNs 73, 66/67, and 52 were dominant in surface and dated sediment samples. Congener patterns and diagnostic ratios revealed that PCN contamination is originated from combustion processes and the use of polychlorinated biphenyl (PCB) technical mixtures. PCN concentrations in dated sediment increased from the 1980s to the mid-2000s and then decreased to 2015. Although the toxic equivalent (TEQ) levels of PCNs in our study did not exceed sediment quality guidelines proposed by international authorities, the cumulative risks from the TEQ concentrations of polychlorinated dibenzo-p-dioxins, furans, PCBs, and PCNs can be expected for benthic organisms.

Automated summary

Few studies have been conducted on the spatial and temporal trends of polychlorinated naphthalenes (PCNs) in coastal environments. This study investigated the presence of 18 PCN congeners in sediment samples from industrialized bays in Korea, and found measurable PCN levels in all samples. The highest levels were observed in sediment from areas surrounded by industrial complexes and commercial harbors. Congener patterns and diagnostic ratios suggested that PCN contamination originated from combustion processes and the use of PCB technical mixtures. The PCN concentrations in dated sediment showed an increase from the 1980s to the mid-2000s, followed by a decrease until 2015. Although the levels of PCNs did not exceed international sediment quality guidelines, cumulative risks for benthic organisms may still exist due to the presence of other contaminants.