Geochemical Assessment and Preliminary Source Tracing of Sediment and Water Pollution in Major Korean Rivers

This study assesses sediment and water pollution in major rivers of Korea (Han River, Nakdong River, Geum River, and Yeongsan River) and additional rivers in the Saemangeum and Cheongyang regions. The sources of contamination are traced using geochemical methods. A total of 28 sediment samples and 28 river water samples were collected from six rivers, along with six subsoil samples from non-polluted areas to establish background levels of heavy metals.

The river water samples met Korea’s water quality standards, confirming effective management of these rivers. However, sediment analysis revealed varying contamination levels for different elements. Several sediment samples showed Grade II–III contamination (As: 8 samples, Cd: 4 samples, Cr: 5 samples, Cu: 10 samples, Ni: 14 samples, Pb: 9 samples, Zn: 9 samples). Additionally, As (2 samples) and Cd (1 sample) were classified as Grade IV. Upon overall assessment, 3 of the 28 sediment samples were classified as "very poor" and 8 as "poor," confirming contamination in sediments from six river regions.

Geochemical indices, such as the enrichment factor (EF) and geo-accumulation index (Igeo), indicated clear contamination levels relative to background concentrations, in line with the results of the pollution assessment. However, Pearson correlation analysis between heavy metal concentrations in water and sediment showed no significant linear correlations for most metals (Cd, Cu, Ni, Pb, Zn).

Rare earth element (REE) analysis showed a predominance of light REEs (LREEs) over heavy REEs (HREEs) in all river sediments, consistent with the influence of granitic bedrock in Korea. The highest HREE/LREE ratio was found in ND (Nakdong river) region sediments, suggesting a potential influence from marine environments.

Future work will include isotopic analysis (Cu, Pb, Zn) to more precisely trace contamination sources. Integrating geochemical indices, REE distribution patterns, and isotopic ratios is expected to enhance the accuracy of pollution assessment and source tracing.