ALBERT

Description: Recent studies suggest that transport and water mass mixing may play a dominant role in controlling the distribution of dissolved rare earth element concentrations ([REE]) at least in parts of the North and South Atlantic and the Pacific Southern Ocean. Here we report vertically and spatially high-resolution profiles of dissolved REE concentrations ([REE]) along a NW-SE transect in the West Pacific and examine the processes affecting the [REE] distributions in this area. Surface water REE patterns reveal sources of trace element (TE) input near South Korea and in the tropical equatorial West Pacific. Positive europium anomalies and middle REE enrichments in surface and subsurface waters are indicative of TE input from volcanic islands and fingerprint in detail small-scale equatorial zonal eastward transport of TEs to the iron-limited tropical East Pacific. The low [REE] of North and South Pacific Tropical Waters and Antarctic Intermediate Water are a long-range (i.e., preformed) laterally advected signal, whereas increasing [REE] with depth within North Pacific Intermediate Water result from release from particles. Optimum multiparameter analysis of deep to bottom waters indicates a dominant control of lateral transport and mixing on [REE] at the depth of Lower Circumpolar Deep Water (?3000 m water depth; ~75-100% explained by water mass mixing), allowing the northward tracing of LCDW to ~28°N in the Northwest Pacific. In contrast, scavenging in the hydrothermal plumes of the Lau Basin and Tonga-Fiji area at 1500-2000 m water depth leads to [REE] deficits (~40-60% removal) and marked REE fractionation in the tropical West Pacific. Overall, our data provide evidence for active trace element input both near South Korea and Papua New Guinea, and for a strong lateral transport component in the distribution of dissolved REEs in large parts of the West Pacific.

Description: Dataset containing surface snow measurements of snow specific surface area (SSA), snow density and snow accumulation. Surface samples were taken from the surface 2.5cm of snow. SSA measurements were determined using an Ice Cube measuring device (Zuanon, 2013). Snow density was measured from the SSA samples with a fixed volume. Snow accumulation describes the change in surface height at each sample site. All measured parameters have 10 daily samples taken at 10m intervals over a 90m transect. Sampling was carried out daily between May and August of 2016-2019, at approximately 24hr time intervals. All measurements were taken at the East Greenland Ice Core Project site (EastGRIP) situated in the accumulation zone of the Greenland Ice Sheet.

Description: Hydrographic data and dissolved seawater Neodymium isotopes and concentrations from twelve stations along a transect in the West Pacific between South Korea and Fiji (R/V Sonne cruise SO223T).

Description: We present spatially highly resolved distributions of dissolved seawater REE concentrations ([REE]) along three transects in the zonal (extra-)equatorial current system and the Solomon Strait of the Tropical Western Pacific. Seawater samples were collected using Niskin bottles and filtered through AcroPak500 filter cartridges (0.8/0.45 μm pore size) directly from the Niskin bottles or in the onboard laboratory of R/V L'Atalante cruise CASSIOPEE (GEOTRACES compliant data GPc05) in July-August 2015. We use seawater [REE] in combination with direct physical oceanographic observations to characterize the geochemical composition, origin and pathways of the complex surface and upper layer currents of the Tropical Western Pacific and to quantify the input fluxes of REEs in our study area.

Description: The Rare Earth Elements (REEs) have been widely used to investigate marine biogeochemical processes as well as the sources and mixing of water masses. However, there are still important uncertainties about the global aqueous REE cycle with respect to the contributions of highly reactive basaltic minerals originating from volcanic islands and the role of Submarine Groundwater Discharge (SGD). Here we present dissolved REE concentrations obtained from waters at the island-ocean interface (including SGD, river, lagoon and coastal waters) from the island of Tahiti and from three detailed open ocean profiles on the Manihiki Plateau (including neodymium (Nd) isotope compositions), which are located in ocean currents downstream of Tahiti. Tahitian fresh waters have highly variable REE concentrations that likely result from variable water-rock interaction and removal by secondary minerals. In contrast to studies on other islands, the SGD samples do not exhibit elevated REE concentrations but have distinctive REE distributions and Y/Ho ratios. The basaltic Tahitian rocks impart a REE pattern to the waters characterized by a middle REE enrichment, with a peak at europium similar to groundwaters and coastal waters of other volcanic islands in the Pacific. However, the basaltic island REE characteristics (with the exception of elevated Y/Ho ratios) are lost during transport to the Manihiki Plateau within surface waters that also exhibit highly radiogenic Nd isotope signatures. Our new data demonstrate that REE concentrations are enriched in Tahitian coastal water, but without multidimensional sampling, basaltic island Nd flux estimates range over orders of magnitude from relatively small to globally significant. Antarctic Intermediate Water (AAIW) loses its characteristic Nd isotopic signature (-6 to-9) around the Manihiki Plateau as a consequence of mixing with South Equatorial Pacific Intermediate Water (SEqPIW), which shows more positive values (-1 to -2). However, an additional Nd input/exchange along the pathway of AAIW, eventually originating from the volcanic Society, Tuamotu and Tubuai Islands (including Tahiti), is indicated by an offset from the mixing array of AAIW and SEqPIW to more radiogenic Nd isotope compositions.