Geographical Distribution and Risk Assessment of Volatile Organic Compounds in Tributaries of the Han River Watershed

Volatile organic compounds (VOCs), with negative impacts on the aquatic ecosystem, are increasingly released into the environment by anthropogenic activities. Water samples were collected from five areas of the Han River Watershed (HRW) tributaries, South Korea, to detect 11 VOCs, which were classified as halogenated aliphatic hydrocarbons (HAHs) and aromatic hydrocarbons (AHs). Among the 11 VOCs, 1,1-dichloroethylene, 1,1,1-trichloroethane, and vinyl chloride were undetected. The highest concentration compounds were chloroform (0.0596 ± 0.1312 µg/L), trichloroethylene (0.0253 ± 0.0781 µg/L), and toluene (0.0054 ± 0.0139 µg/L). The mean concentration (0.0234 µg/L) and detection frequency (37.0%) of HAHs were higher than those of AHs (0.0036 µg/L, 21.0%, respectively). The Imjin Hantan River area exhibited the highest mean concentration (0.2432 µg/L) and detection frequency (22.9%), because it is located near industrial complexes, thus, highlighting their role as important VOC sources. However, the detected VOCs had lower concentrations than those permitted by the EU, WHO, USA, and South Korea drinking water guidelines. Ecological risks associated with the VOCs were estimated by risk quotient (RQ); consequently, the predicted no-effect concentration was 0.0029 mg/L, and the toluene and styrene RQ values were >1 and >0.5, respectively. The findings may facilitate policymakers in designing pollution control strategies.