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The GEOTRACES Intermediate Data Product 2014 (IDP2014) is the first publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2013. It consists of two parts: (1) a compilation of digital data for more than 200 trace elements and isotopes (TEls) as well as classical hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing a strongly inter-linked on-line atlas including more than 300 section plots and 90 animated 3D scenes. The IDP2014 covers the Atlantic, Arctic, and Indian oceans, exhibiting highest data density in the Atlantic. The TEI data in the IDP2014 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at cross-over stations. The digital data are provided in several formats, including ASCII spreadsheet, Excel spreadsheet, netCDF, and Ocean Data View collection. In addition to the actual data values the IDP2014 also contains data quality flags and 1-sigma data error values where available. Quality flags and error values are useful for data filtering. Metadata about data originators, analytical methods and original publications related to the data are linked to the data in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2014 data providing section plots and a new kind of animated 3D scenes. The basin-wide 3D scenes allow for viewing of data from many cruises at the same time, thereby providing quick overviews of large-scale tracer distributions. In addition, the 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of observed tracer plumes, as well as for making inferences about controlling processes. (C) 2015 The Authors. Published by Elsevier B.V

The biogeochemical cycle of zinc (Zn) in the South Atlantic, at 40°S, was investigated as part of the UK GEOTRACES program. To date there is little understanding of the supply of Zn, an essential requirement for phytoplankton growth, to this highly productive region. Vertical Zn profiles displayed nutrient-like distributions with distinct gradients associated with the water masses present. Surface Zn concentrations are among the lowest reported for the world's oceans (< 50 pM). A strong Zn-Si linear relationship was observed (Zn (nM) = 0.065 Si (μM), r 2 = 0.97, n = 460). Our results suggest that the use of a global Zn-Si relationship would lead to an underestimation of dissolved Zn in deeper waters of the South Atlantic. By utilizing Si* and a new tracer Zn* our data indicate that the preferential removal of Zn in the Southern Ocean prevented a direct return path for dissolved Zn to the surface waters of the South Atlantic at 40°S and potentially the thermocline waters of the South Atlantic subtropical gyre. The importance of Zn for phytoplankton growth was evaluated using the Zn-soluble reactive phosphorus (SRP) relationship. We hypothesize that the low Zn concentrations in the South Atlantic may select for phytoplankton cells with a lower Zn requirement. In addition, a much deeper kink at~500m in the Zn:SRP ratio was observed compared to other oceanic regions.

Cobalt scavenging in the mesopelagic ocean and its influence on global mass balance: Synthesizing water column and sedimentary fluxes. AbstractIn the ocean, dissolved cobalt is affected by both nutrient cycling and scavenging onto manganese oxides. The latter process concentrates Co in pelagic sediments, resulting in a small deep water inventory. While the flux of scavenged cobalt to sediments appears steady on timescales greater than 100,000 years, its residence time in the water column is short, approximately 130 years. Using results from recent GEOTRACES expeditions, we show net removal of dissolved Co from the deep ocean on the order of 0.043 pM year -1 , which corresponds to a turnover time of 980 years. Scavenging in deep ocean water masses is too slow to match cobalt accumulation rates in marine sediments, requiring most of the scavenging flux to derive from the mesopelagic ocean (< 1500 m depth) where nutrient cycling is active. Based on differences between the Co:P stoichiometry in particles sinking from the euphotic zone and dissolved Co:P remineralization ratios, we calculate areal scavenging rates in the North Atlantic and South Pacific basins on the order of 1.5 and 0.7 μmol m -2 year -1 , respectively, which agree with long-term accumulation rates in Atlantic and Pacific sediments. In both basins, over 50% of the scavenged flux of cobalt occurs in the upper 500 m, resulting in decadal turnover times in the mesopelagic. An assessment of sources suggests that the marine cobalt cycle is approximately in balance, but that this inventory may be sensitive to long term trends in the intensity of oxygen minimum zones, which account for ~25% of the annual cobalt source to the modern oceans.