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The concentrations of both the total dissolved (< 0.45 μm) and colloidal (10 kDa–0.45 μm) phases of trace elements and rare earth elements (REEs) in coastal groundwater were measured to evaluate the role of colloids in transporting trace elements and REEs to the ocean through submarine groundwater discharge (SGD). Samples were collected from two different hydrogeological conditions, Hampyeong Bay in the southwestern coast of Korea and Jeju Island, Korea. The average colloidal proportions of Al, Mn, Zn, Ni, Cu, Cd, Pb, 210 Po, and 210 Pb were 35–45% of the total dissolved phase, which were relatively higher than those of Cr, Fe, Co, and REEs (10–30%), although hydrogeological conditions were variable. Most of the colloidal trace elements (including 210 Pb and REEs), except Mn, correlate most significantly with Fe, indicating that their presence is dependent on Fe-containing oxide minerals in the subterranean estuary (STE). On the other hand, the colloidal Mn and 210 Po correlated more significantly with dissolved organic carbon (DOC), indicating that dissolved organic matter (DOM) cycling associated with bacterial activity plays an important role in their presence in the colloidal phase in the STE. Our results suggest that the fluxes of trace elements through SGD are greatly dependent on the presence of Fe (for Al, Zn, Ni, Cu, Cd, Pb, and REEs) and DOM (for 210 Po and Mn) in coastal groundwater. [ABSTRACT FROM AUTHOR]

To evaluate the impact of modern glacier melting on the chemical enrichment of Antarctic coastal waters, we measured trace elements, including dissolved iron (Fe) and rare earth elements (REEs), together with dissolved inorganic nitrogen, phosphorous, silicate and dissolved organic carbon (DOC) in ice, snow and coastal seawater of Marian Cove in the northernmost part of Antarctica (62°S). There was an increase in the concentrations of Fe and other trace elements (Al, Mn, Cr, Ni, Co, Pb and REEs) between the bay mouth and the glacier valleys. Good correlations between salinity and these chemical elements indicate that the trend was mainly due to the influence of glacier meltwater (GMW). When the effect of GMW was quantified based on plots of its presence (average 5.7%) in the surface water of the cove, the concentrations of trace elements in seawater increased 18-fold for Fe, eight- to 10-fold for Al and Mn and up to four-fold for Cr, Ni, Co, Pb and REEs by GMW. However, the contribution of GMW to inorganic nutrients and DOC was negligible. The significance of GMW-borne REE contribution in this cove was further evidenced by middle REE enrichment in cove water. Our results suggest that the currently increasing glacier melting in Antarctica has a significant influence on the level of trace elements, particularly Fe, in cove water, which in turn may have a significant impact on the biogeochemistry of coastal seawater in Antarctica. [ABSTRACT FROM AUTHOR]

The distributions of trace elements (Fe, Mn, Co, Cu, Cd, and Ni) were measured, for the first time, in the entire East Sea (22 stations, n = 276, 0–3400 m), which is located in the region directly affected by East Asian monsoon and the downstream of Tsushima Current. In general, the distribution patterns of these trace elements were similar to those in the major oceans. However, relatively higher concentrations of trace elements, except for Ni, were observed in the surface layer due to the pronounced external inputs (atmospheric deposition and/or continental shelf input). In addition, we observed unusually high concentrations of Fe and Mn in the bottom layer of the Ulleung Basin, owing to large benthic inputs. These inputs seem to be associated with the significant production/dissolution of Fe and Mn in organic-rich sediments (> 2.5%) and the subsequent diffusion of dissolved organic matter (DOM)-complexed Fe and Mn into the overlying seawater. In this bottom layer, the concentrations of Fe and Mn approached 13 and 57 nmol kg−1, respectively, which are an order of magnitude higher than those in the oxic deep water of other major oceans. Based on the plots of trace elements against nutrients, the scavenging of Co in the deep East Sea is found to be particularly efficient relative to other major oceans. The concentrations of Co in the deep East Sea (2500–3400 m) are the lowest reported concentrations (2–8 pmol kg−1) compared with those from the same depths in the global oceans, while those in the surface layer are 2- and 5-fold higher than those in the North Pacific and North Atlantic Oceans, respectively. Thus, the distinct distribution patterns of trace elements in this sea reveal the efficient scavenging processes related to the high sinking fluxes of particles under the significant boundary input conditions (atmospheric deposition, continental shelf input, and benthic input). • Pronounced atmospheric/shelf inputs of trace elements were observed in the East Sea. • Significant benthic inputs of Fe and Mn were observed in the East Sea. • Ni and Co showed efficient scavenging in the deep East Sea. [ABSTRACT FROM AUTHOR]