Distribution and risk assessment of metals in the aquatic environment following the installation of a low-lying bridge in Yeongrang Lake, Sokcho, Gangwon State, South Korea

In November 2021, a bridge was constructed over Yeongrang Lake by placing large cement blocks on the lakebed, leading to ecological consequences. Thus, this study assessed the distribution of metals to evaluate the risk in the aquatic environment of the lake. Ten metals were monitored in water, sediment, and fish samples across four seasons. The samples were analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES) after treatment with nitric acid. During the sampling period, the distribution of metals in water followed the order of Fe > Cu > Al > Zn > Mn > Pb > Ni > Cr > Cd > V, while in sediment, it was Fe > Al > Mn > Zn > V > Pb > Cu > Cr > Ni > Cd. Cu and Cd levels exceeded the criteria and threshold effect levels set by the U.S. Environmental Protection Agency. Although no significant seasonal variations were observed, the ecological risk was considered significant. Situated near the East Sea, the lake has shown signs of salinization after the construction of the bridge. Cu, Mn, and Zn exhibited the highest bioconcentration factors in both benthic and floating fish. Nevertheless, an improved sampling strategy is necessary to verify the bioconcentration of metals in fish in future studies. The hazard index exceeded 1 in a human risk assessment related to fish consumption. However, the actual risk is anticipated to be lower, considering the fish consumption pattern. This study highlights the importance of management actions in reducing ecological risks.