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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]

Rare earth element (REE) concentrations were measured for the first time in plankton from the northwestern Mediterranean Sea. The REE concentrations in phytoplankton (60–200 μm) were 5–15 times higher than those in four size fractions of zooplankton: 200–500 μm, 500–1000 μm, 1000–2000 μm and >2000 μm. The concentrations within these zooplankton fractions exhibited the same ranges with some variation attributed to differences in zooplankton taxonomy. The REE concentrations in plankton were poorly related to the reported REE concentrations of seawater, but they correlated well with the calculated REE 3+ , concentrations especially with regard to middle REE (MREEs) and heavy REEs (HREEs). Plankton and seawater revealed different PAAS-normalised REE distributions, with the greatest differences observed in the light REEs. Interestingly, a comparison of PAAS-normalized sediment particles from the study of Fowler et al. (1992) showed concentrations of the same order of magnitude and a similar REE distribution without MREE enrichment. Based on this comparison, we propose a conceptual model that emphasizes the importance of biological scavenging of REEs (especially LREEs) in surface waters. [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]

Abstract: To evaluate the role of submarine groundwater discharge (SGD) as a source of rare earth elements (REEs) in the coastal ocean, we estimated the SGD associated discharge of REEs into two semi-enclosed coastal bays in the southern coast of Korean peninsula. The mass balances of REEs demonstrated that the REE fluxes through SGD were two to three orders of magnitude higher than those through the other sources, such as diffusion from bottom sediments and atmospheric dust fallout. The Nd inputs through the total SGD from the two small coastal bays, Gamak Bay (148km2) and Hampyeong Bay (85km2), were estimated to be 0.7×104–1.3×104 moly−1, which is 0.06–0.3% of the total Nd fluxes from global rivers. In this region, coastal seawater was observed to have a substantially higher middle REE (MREE), which appears to be due to a large discharge of groundwater that is highly enriched with MREE. High MREE bearing waters were observed over the entire shore of the southern coast of Korea, implying that such high SGD-driven REE fluxes are common in coastal area. Our results suggest that the SGD-driven REE fluxes may contribute considerably to the global budget of REEs in the ocean. [Copyright &y& Elsevier]

Abstract: To evaluate the role of submarine groundwater discharge (SGD) as a source of rare earth elements (REEs) in the coastal ocean, we estimated the SGD associated discharge of REEs into two semi-enclosed coastal bays off a volcanic island, Jeju, Korea. The coastal brackish groundwater showed pronounced enrichments of middle REEs (MREE) relative to light REEs (LREE) and heavy REEs (HREE) when normalized against the upper continental crust (UCC), whereas seawater samples outside the bays showed a HREE enrichment pattern. The enrichment of both MREE and HREE was clearly identified in bay waters, resulting from mixing between groundwater and offshore seawater. The mass balances of REEs demonstrated that the REE fluxes through SGD were two to three orders of magnitude higher than those that occurred through the other sources, such as diffusion from bottom sediments and atmospheric dust fallout. The SGD-driven Nd flux from the entire Jeju Island during this summer was approximately 120±60mold−1, which is comparable to the Nd fluxes from major rivers (i.e., Mississippi River). Our results imply that highly permeable oceanic islands are particularly important for REE fluxes to the ocean. [Copyright &y& Elsevier]