Distribution and Source Identification of PAHs and PCBs in Surface Sediments from the Nakdong River Estuary, South Korea

Abstract

The Nakdong River, located in the southeastern region of the Korean Peninsula, is the largest river system in South Korea (river length, 510 km drainage area, 23,384 km2, 127°29’&#8211 129°18’E, 35°03’&#8211 37°13’N). In general, over 60% of the regon’s total annual precipitation (1,000&#8211 1,200 mm) falls in summer (from June to September). A survey of hazardous chemicals in the sediments of the Nakdong River estuary was conducted during the spring of 2015. We investigated the concentrations and distribution of the 16 priority polycyclic aromatic hydrocarbons (16-PAHs) and 19 priority polychlorinated biphenyls (19-PCBs) in the brackish surface sediments (Ulsukdo, Jinwoodo, and Sinjado). PAHs constitute a group of hydrophobic organic compounds (HOCs), that are related to incomplete oxidation during combustion and also to the uncontrolled environmentalpollution that is present in may locations. The toxicity of PCB mixtures is low, but they pose a cancer risk in humans. Concentration of PAHs ranged from 10.76-40.21 ng/g-dry (mean value, 24.79 ng/g-dry N = 4). The levels of PCBs ranged from 197.0-630.0 pg/g-dry (mean value, 402.5 pg/g-dry N = 4). Concentration of PCBs approached the response level (630 pg/g-dry) at one sites. These contamination levels were far below the Sediment Quality Guidelines (SQG) of the National Oceanic and Atmospheric Administration (NOAA), which are used for environmental quality assessments. Low-molecularweightPAHs were dominant in the sediment samples. These results were used to assess the potential sources of PAH and PCB contamination in Nakdong River estuary sediments. We determined that PAHs originated from the combustion of fossil fuel and biomass, and were related to PAH contributions in most sediment samples. The isomer patterns in sediment and PCB products were similar.