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11 páginas, 3 tablas, 7 figuras ; Oceans constitute one of the most important reservoirs for mercury. In order to provide a first insight into the concentrations of Hg species in the Atlantic sector of the Southern Ocean a sampling campaign was carried out south of the Polar Front. Water samples taken at discrete depths from the surface down to 300 m at six stations were analysed for total Hg (HgT), methylmercury (MeHg) and other interpretative parameters such as salinity, temperature, dissolved and particulate organic carbon, dissolved oxygen, chlorophyll and inorganic nutrients. Results showed a high spatial variability in the concentrations of HgT and MeHg. HgT (0.93±0.69 ng L−1) and MeHg (0.26±0.12 ng L−1) levels were similar or higher than those reported in previous works in high latitude studies. The highest values were found at a location (−53°, 10°E) south of the South Polar Front, an area of strong gradients caused by the mixing of different water masses. Vertical profiles showed a great variability even for those stations sampled at the same location or an area dominated by the same oceanographic features. A decrease of HgT and a consequent increase in MeHg with depth was observed in some sites, suggesting the occurrence of Hg-methylation process, while at other stations, a concurrent decrease or increase of both mercury species was observed. In spite of these differences, an overall positive correlation between HgT and MeHg was observed. Differences between vertical profiles of Hg species were attributed to favourable environmental conditions for Hg methylation. The highest proportion of MeHg (% of HgT) was observed in sites with low dissolved oxygen or highest estimated remineralization rates. The results obtained in this study show that the Hg distribution and speciation in the Atlantic sector of the SO is comparable (or in some sites higher) to the ones published for the other open ocean regions. However, the concentrations of MeHg in this area are more dependent on the environmental conditions than on the total concentration of Hg present in the water ; JC, AP and EA acknowledge Fundação para a Ciência e Tecnologia for project UID/QUI/00100/2013 and for the InvFCT2013 grant. LML and JSE were funded by the MINECO of Spain (Grant CGL2010-11846-E) and the Government of the Balearic Islands (AAEE083/09, co-funded by FEDER) ; Peer reviewed

This is the final version of the article. Available from Wiley via the DOI in this record. ; The accumulation of carbon within the Weddell Gyre and its exchanges across the gyre boundaries are investigated with three recent full-depth oceanographic sections enclosing this climatically important region. The combination of carbon measurements with ocean circulation transport estimates from a box inverse analysis reveals that deepwater transports associated with Warm Deep Water (WDW) and Weddell Sea Deep Water dominate the gyre's carbon budget, while a dual-cell vertical overturning circulation leads to both upwelling and the delivery of large quantities of carbon to the deep ocean. Historical sea surface pCO2 observations, interpolated using a neural network technique, confirm the net summertime sink of 0.044 to 0.058±0.010PgCyr-1 derived from the inversion. However, a wintertime outgassing signal similar in size results in a statistically insignificant annual air-to-sea CO2 flux of 0.002±0.007PgCyr-1 (mean 1998-2011) to 0.012±0.024PgCyr-1 (mean 2008-2010) to be diagnosed for the Weddell Gyre. A surface layer carbon balance, independently derived from in situ biogeochemical measurements, reveals that freshwater inputs and biological drawdown decrease surface ocean inorganic carbon levels more than they are increased by WDW entrainment, resulting in an estimated annual carbon sink of 0.033±0.021PgCyr-1. Although relatively less efficient for carbon uptake than the global oceans, the summertime Weddell Gyre suppresses the winter outgassing signal, while its biological pump and deepwater formation act as key conduits for transporting natural and anthropogenic carbon to the deep ocean where they can reside for long time scales. ; NERC ; European Union CarboOcean ; CarboChange

14 pages, 4 tables, 4 figures.-- This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) ; Effective data management plays a key role in oceanographic research as cruise-based data, collected from different laboratories and expeditions, are commonly compiled to investigate regional to global oceanographic processes. Here we describe new and updated best practice data standards for discrete chemical oceanographic observations, specifically those dealing with column header abbreviations, quality control flags, missing value indicators, and standardized calculation of certain properties. These data standards have been developed with the goals of improving the current practices of the scientific community and promoting their international usage. These guidelines are intended to standardize data files for data sharing and submission into permanent archives. They will facilitate future quality control and synthesis efforts and lead to better data interpretation. In turn, this will promote research in ocean biogeochemistry, such as studies of carbon cycling and ocean acidification, on regional to global scales. These best practice standards are not mandatory. Agencies, institutes, universities, or research vessels can continue using different data standards if it is important for them to maintain historical consistency. However, it is hoped that they will be adopted as widely as possible to facilitate consistency and to achieve the goals stated above. ; Funding for L-QJ and AK was from NOAA Ocean Acidification Program (OAP, Project ID: 21047) and NOAA National Centers for Environmental Information (NCEI) through NOAA grant NA19NES4320002 [Cooperative Institute for Satellite Earth System Studies (CISESS)] at the University of Maryland/ESSIC. BT was in part supported by the Australia's Integrated Marine Observing System (IMOS), enabled through the National Collaborative Research Infrastructure Strategy (NCRIS). AD was supported in part by the United States National Science Foundation. AV and FP were supported by BOCATS2 Project (PID2019-104279GB-C21/AEI/10.13039/501100011033) funded by the Spanish Research Agency and contributing to WATER:iOS CSIC interdisciplinary thematic platform. MH was partly funded by the European Union's Horizon 2020 Research and Innovation Program under grant agreement N°821001 (SO-CHIC) ; Peer reviewed

Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – the "global carbon budget" – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFF) are based on energy statistics and cement production data, while emissions from land use and land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) and terrestrial CO2 sink (SLAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2008–2017), EFF was 9.4±0.5 GtC yr−1, ELUC 1.5±0.7 GtC yr−1, GATM 4.7±0.02 GtC yr−1, SOCEAN 2.4±0.5 GtC yr−1, and SLAND 3.2±0.8 GtC yr−1, with a budget imbalance BIM of 0.5 GtC yr−1 indicating overestimated emissions and/or underestimated sinks. For the year 2017 alone, the growth in EFF was about 1.6 % and emissions increased to 9.9±0.5 GtC yr−1. Also for 2017, ELUC was 1.4±0.7 GtC yr−1, GATM was 4.6±0.2 GtC yr−1, SOCEAN was 2.5±0.5 GtC yr−1, and SLAND was 3.8±0.8 GtC yr−1, with a BIM of 0.3 GtC. The global atmospheric CO2 concentration reached 405.0±0.1 ppm averaged over 2017. For 2018, preliminary data for the first 6–9 months indicate a renewed growth in EFF of +2.7 % (range of 1.8 % to 3.7 %) based on national emission projections for China, the US, the EU, and India and projections of gross domestic product corrected for recent changes in the carbon intensity of the economy for the rest of the world. The analysis presented here shows that the mean and trend in the five components of the global carbon budget are consistently estimated over the period of 1959–2017, but discrepancies of up to 1 GtC yr−1 persist for the representation of semi-decadal variability in CO2 fluxes. A detailed comparison among individual estimates and the introduction of a broad range of observations show (1) no consensus in the mean and trend in land-use change emissions, (2) a persistent low agreement among the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) an apparent underestimation of the CO2 variability by ocean models, originating outside the tropics. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding the global carbon cycle compared with previous publications of this data set (Le Quéré et al., 2018, 2016, 2015a, b, 2014, 2013). All results presented here can be downloaded from https://doi.org/10.18160/GCP-2018.

This is the final version of the article. Available from the publisher via the DOI in this record. ; The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water fCO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. Highprofile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) "living data" publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). Individual data set files, included in the synthesis product, can be downloaded here: doi:10.1594/PANGAEA.849770. The gridded products are available here: doi:10.3334/CDIAC/OTG.SOCAT-V3-GRID. ; Research vessel Tiglax in Columbia Bay, Alaska, is shown on the website for SOCAT version 3. The Columbia Glacier can be seen at the head of the bay, as well as calved ice from the glacier. The photo was taken by Wiley Evans. Pete Brown (National Oceanography Centre Southampton, UK) designed the SOCAT logo. IOCCP (via a US National Science Foundation grant (OCE-124 3377) to the Scientific Committee on Oceanic Research), IOC-UNESCO (International Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization), SOLAS and IMBER provided travel and meeting support. Funding was received from the University of East Anglia (UK), the Bjerknes Centre for Climate Research (Norway), the Geophysical Institute at the University of Bergen (Norway) and the University of Washington (US). The US National Oceanic and Atmospheric Administration (NOAA) made important financial contributions via the Climate Observation Division of the Climate Program Office, the NOAA Ocean Acidification Program, the NOAA Pacific Marine Environmental Laboratory (PMEL), the NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML) and the NOAA Earth System Research Laboratory. Funding was also received from Oak Ridge National Laboratory (US), PANGAEA® Data Publisher for Earth and Environmental Science (Germany), the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (Germany), the Antarctic Climate and Ecosystems Cooperative Research Centre (Australia), the National Institute for Environmental Studies (Japan) and Uni Research (Norway). Research projects making SOCAT possible included the European Union projects CarboChange (FP7 264879), GEOCARBON (FP7 283080) and AtlantOS (633211), the UK Ocean Acidification Research Programme (NE/H017046/1; funded by the Natural Environment Research Council (NERC) and the Departments for Energy and Climate Change and for Environment, Food and Rural Affairs (Defra)) and the UK Shelf Sea Biogeochemistry Blue Carbon project (NE/K00168X/1; funded by NERC and Defra). Numerous government and funding agencies financially supported SOCAT, notably the Australian International Marine Observing System, the U.S. Geological Survey, the National Aeronautics and Space Administration (NASA) (US), the European Space Agency, the German Federal Ministry of Education and Research (BMBF projects 01LK1224J, 01LK1101C, 01LK1101E, ICOS-D), the Japanese Ministry of the Environment, the Royal Society of New Zealand via the New Zealand–Germany Science and Technology Programme, the Norwegian Research Council (SNACS, 229752), the Swedish Research Council (project 2004-4034) and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (Formas, project 2004- 797). This is PMEL contribution number 4441. Finally, we thank the two anonymous reviewers for their thoughtful, constructive and insightful reviews