Heavy metal characterization of land-based waste dumped at three ocean dumping sites in the Republic of Korea

Distributions and compositional characteristics of per- and polyfluoroalkyl substances (PFASs) in sediments of the regional seas of South Korea

This study investigated the distribution and composition of 28 per- and polyfluoroalkyl substances (PFASs) in surface and core sediments from the regional seas of South Korea. Surface sediments were collected from the Yellow Sea (YS, n = 10), East China Sea (ECS, n = 6), South Sea (SS, n = 5), and East Sea (ES, n = 12), and core sediments were obtained from the ES (n = 3, 0-30 cm). Sediment samples were extracted with methanol by shaking, followed by purification using solid-phase extraction cartridges. The purified extracts were then analyzed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to quantify 11 perfluoroalkyl carboxylic acids, 9 perfluoroalkyl sulfonic acids, 5 precursors, and 3 emerging PFASs. The highest PFAS concentrations in surface sediments were observed in the YS (300 ng g-1 organic carbon (OC)), followed by the ES (150 ng g-1 OC), ECS (120 ng g-1 OC), and SS (14 ng g-1 OC). Core sediment analysis revealed the accumulation of PFASs within the top 10 cm depth at the dumpsite, along with elevated OC contents (2.7-4.4 %) and lighter carbon stable isotope ratios (δ13C, -23 to -22 ‰) indicating the influence of dumped wastes. Principal component analysis classified the sites into three groups based on chemical composition, reflecting regional differences in PFASs usage, transport, and deposition. These findings provide critical insights into the distribution and environmental behavior of PFASs in marine sediments and contribute to developing future regulatory frameworks and pollution management strategies.

Revisiting elemental geochemistry in surface sediments of the Ulleung Basin, East/Japan Sea: Signals from ocean dumping materials

A total of 222 surface sediments were collected in the Ulleung Basin, southwestern East/Japan Sea, from the coast to the basin and analyzed for grain size, total organic carbon, biogenic silica and major and trace elements. The metal concentrations of the surface sediments were highly spatially variable, and their distributions were grouped into four types by factor analysis: waste dumping materials (Cr, Cu, Zn, Sn, Sb, and Pb); detrital materials (Al, Fe, and Cs); suboxic diagenetic materials (Mn, Mo, Co, and Ni); and anoxic diagenetic materials (Cd and U). From core samples collected near the dumping site, approximately the top 10 cm was well mixed in the 210Pbex profiles and highly enriched in the above metals related to dumping materials. The enrichment factor of Sn indicates dumping materials well, and its distribution can be used to estimate the dispersion range of the dumped material in this basin.

Applying new regional background concentration criteria to assess heavy metal contamination in deep-sea sediments at an ocean dumping site, Republic of Korea

It is crucial to establish appropriate background concentrations to discern heavy metal pollution in the marine environment. In this study, we analyzed heavy metals in deep-sea sediment cores to determine regional background concentrations at the East-Sea Byeong Ocean dumping site. The vertical profiles of heavy metals were categorized into three groups based on their contamination characteristics, and regional background levels for 12 metals were determined using pre-1900 averages. The enrichment factor, contamination factor, and pollution load index, calculated using regional background concentrations, indicated significant contamination by Cr, Co, Cu, Zn, Cd, Hg, and Pb during the ocean dumping period. These results differ from those obtained using global average concentrations. This underscores the importance of considering regional characteristics to minimize the risk of misinterpreting anthropogenic impacts. The approach based on local information is considered useful when sediment quality guidelines are absent or inapplicable.