Sinhué Torres-Valdés

Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research | AWI · Marine Biogeosciences Section

The Arctic Ocean is experiencing unprecedented changes because of climate warming, necessitating detailed analyses on the ecology and dynamics of biological communities to understand current and future ecosystem shifts. Here, we generated a four-year, high-resolution amplicon dataset along with one annual cycle of PacBio HiFi read metagenomes from...

The Arctic Ocean is one of the regions where anthropogenic environmental change is progressing most rapidly and drastically. The impact of rising temperatures and decreasing sea ice on Arctic marine microbial communities is yet not well understood. Microbes form the basis of food webs in the Arctic Ocean, providing energy for larger organisms. Prev...

The Arctic Ocean is experiencing unprecedented changes as a result of climate warming, necessitating detailed analyses on the ecology and dynamics of biological communities to understand current and future ecosystem shifts. Here we show the pronounced impact that variations in Atlantic water influx and sea-ice cover have on bacterial communities in...

Plain Language Summary Microscopic algae, growing in the sunlit surface layer of the ocean, provide food for other species and form the basis of the ecosystem. In the Arctic Ocean, their growth is limited by the availability of nutrients. The main source of these nutrients are waters entering from the Atlantic and Pacific Oceans. These nutrient‐ric...

Arctic Ocean properties and processes are highly relevant to the regional and global coupled climate system, yet still scarcely observed, especially in winter. Team OCEAN conducted a full year of physical oceanography observations as part of the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC), a drift with the Ar...

The ocean moderates the world’s climate through absorption of heat and carbon, but how much carbon the ocean will continue to absorb remains unknown. The North Atlantic Ocean west (Baffin Bay/Labrador Sea) and east (Fram Strait/Greenland Sea) of Greenland features the most intense absorption of anthropogenic carbon globally; the biological carbon p...

The Arctic Ocean features extreme seasonal differences in daylight, temperature, ice cover, and mixed layer depth. However, the diversity and ecology of microbes across these contrasting environmental conditions remain enigmatic. Here, using autonomous samplers and sensors deployed at two mooring sites, we portray an annual cycle of microbial diver...

We present results from a coordinated frontal survey in Fram Strait in summer 2016 using an autonomous underwater vehicle (AUV) combined with shipboard and zodiac-based hydrographic measurements. Based on satellite information, we identified a front between warm Atlantic Water and cold Polar Water. The AUV, equipped with oceanographic and biogeoche...

Amino acids (AA) and carbohydrates (CHO) are important components of the marine organic carbon cycle. Produced mainly by phytoplankton as part of the particulate organic carbon (POC) fraction, these compounds can be released into the outer medium where they become part of the dissolved organic carbon (DOC) pool and are rapidly taken up by heterotro...

The North Atlantic Basin is a major sink for atmospheric carbon dioxide (CO2) due in part to the extensive plankton blooms which form there supported by nutrients supplied by the three-dimensional ocean circulation. Hence, changes in ocean circulation and/or stratification may influence primary production and biological carbon export. In this study...

Unprecedented quantities of heat are entering the Pacific sector of the Arctic Ocean through Bering Strait, particularly during summer months. Though some heat is lost to the atmosphere during autumn cooling, a significant fraction of the incoming warm, salty water subducts (dives beneath) below a cooler fresher layer of near-surface water, subsequ...

Change is a constant in the Arctic Ocean, with extreme seasonal differences in daylight, ice cover and temperature. The biodiversity and ecology of marine microbes across these extremes remain poorly understood. Here, using an array of autonomous samplers and sensors, we portray an annual cycle of microbial biodiversity, nutrient budgets and oceano...

The authors regret that we omitted acknowledgement of the ‘iFADO EAPA_165/2016 that covered work at the PAP-SO’. The authors would like to apologise for any inconvenience caused.

Ocean biological processes play an important role in the global carbon cycle via the production of organic matter and its subsequent export. Often, this flux is assumed to be in steady state; however, it is dependent on nutrients introduced to surface waters via multiple mechanisms, some of which are likely to exhibit both intra‐annual and interann...

We investigate the origin of fresh water on the shelves near Cape Farewell (south Greenland) using sections of three hydrographic cruises in May (HUD2014007) and June 2014 (JR302 and Geovide). We partition the fresh water between meteoric water sources and sea ice melt or brine formation using the δ¹⁸O of sea water. The sections illustrate the pres...

A coordinated effort involving trailblazing science—and icebreaking ships—from many nations is needed to fill gaps in our understanding of the Arctic Ocean and how it’s changing.

The ocean is currently a significant net sink for anthropogenically remobilised CO2, taking up around 24% of global emissions. Numerical models predict a diversity of responses of the ocean carbon sink to increased atmospheric concentrations in a warmer world. Here, we tested the hypothesis that increased atmospheric forcing is causing a change in...

The Weddell Gyre (WG) is one of the main oceanographic features of the Southern Ocean south of the Antarctic Circumpolar Current which plays an influential role in global ocean circulation as well as gas exchange with the atmosphere. We review the state‐of‐the art knowledge concerning the WG from an interdisciplinary perspective, uncovering critica...

The net rate of freshwater input to the Arctic Ocean has been calculated in the past by two methods: directly, as the sum of precipitation, evaporation and runoff, an approach hindered by sparsity of measurements, and by the ice and ocean budget method, where the net surface freshwater flux within a defined boundary is calculated from the rate of d...

Global climate is critically sensitive to physical and biogeochemical dynamics in the subpolar Southern Ocean, since it is here that deep, carbon-rich layers of the world ocean outcrop and exchange carbon with the atmosphere. Here, we present evidence that the conventional framework for the subpolar Southern Ocean carbon cycle, which attributes a d...

The traditionally divergent perspectives of the Arctic Ocean freshwater budget provided by control volume-based and geochemical tracer-based approaches are reconciled, and the sources of inter-approach inconsistencies identified, by comparing both methodologies using an observational data set of the circulation and water mass properties at the basi...

The Labrador Current is an important conduit of freshwater from the Arctic to the interior North Atlantic subpolar gyre. Here we investigate the spatial variability of the freshwater sources over the southern Labrador shelf and slope during May?June 2014. Using measurements of seawater properties such as temperature, salinity, nutrients, and oxygen...

We investigate whether one can detect changes in the freshwater contributions to the North Atlantic subpolar gyre (SPG), in light of the observed recent decrease of salinity in the region. We focus on two important conduits of freshwater from the Arctic to the interior North Atlantic subpolar gyre: the Coastal Labrador Current and the southern Gree...

The ocean's biological carbon pump plays a central role in regulating atmospheric CO2 levels. In particular, the depth at which sinking organic carbon is broken down and respired in the mesopelagic zone is critical, with deeper remineralization resulting in greater carbon storage. Until recently, however, a balanced budget of the supply and consump...

The ocean’s biological carbon pump plays a central role in regulating atmospheric CO2 levels. In particular, the depth at which sinking organic carbon is broken down and respired in the mesopelagic zone is critical, with deeper remineralisation resulting in greater carbon storage. Until recently, however, a balanced budget of the supply and consump...

We ask whether dissolved organic nitrogen (DON) and phosphorus (DOP) could account for previously identified Arctic Ocean (AO) inorganic nutrient budget imbalances. We assess transports to/from the AO by calculating indicative budgets. Marked DON:DOP ratio differences between the Amerasian and Eurasian AO reflect different physical and biogeochemic...

The distribution of noble gases and helium isotopes in the dense shelf waters of Antarctica reflect the boundary conditions near the ocean surface: air-sea exchange, sea ice formation and subsurface ice melt. We use a non-linear least-squares solution to determine the value of the recharge temperature and salinity, as well as the excess air injecti...

Poster presented at Arctic Science Summit Week, Toyama, Japan, 23-30 April, 2015

The horizontal and vertical circulation of the Weddell Gyre is diagnosed using a box inverse model constructed with recent hydrographic sections and including mobile sea ice and eddy transports. The gyre is found to convey 42 +/- 8 Sv across the central Weddell Sea and to intensify to 54 +/- 15 Sv further offshore. This circulation injects 36+/- 13...

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 reveal that deep water trans...

Full-depth measurements of δ(18)O from 2008 to 2010 enclosing the Weddell Gyre in the Southern Ocean are used to investigate the regional freshwater budget. Using complementary salinity, nutrients and oxygen data, a four-component mass balance was applied to quantify the relative contributions of meteoric water (precipitation/glacial input), sea-ic...

We investigated the relationship between picoeukaryote phytoplankton (<2 μm) and the deep layer of new production (NO3− uptake) in the nitracline of the eastern subtropical North Atlantic Ocean. Indices of NO3− uptake kinetics obtained within the lower 15% of the euphotic zone demonstrate that subsurface NO3− uptake maxima are coincident with local...

The horizontal and vertical circulation of the Weddell Gyre is diagnosed using a box inverse model constructed with recent hydrographic sections and including mobile sea ice and eddy transports. The gyre is found to convey 42 ± 8 Sv (1 Sv = 106 m3 s-1) across the central Weddell Sea and to intensify to 54±15 Sv further offshore. This circulation in...

We provide a data set assemblage of directly observed and derived fluxes of sedimenting material (total mass, POC, PON, bSiO2, CaCO3, PIC and lithogenic/terrigenous fluxes) obtained using sediment traps. This data assemblage contains over 5900 data points distributed across the Atlantic, from the Arctic Ocean to the Southern Ocean. Data from the Me...

We present observation based estimates of the transport of dissolved inorganic carbon (DIC) across the four main Arctic Ocean gateways (Davis Strait, Fram Strait, Barents Sea Opening and Bering Strait). Combining a recently derived velocity field at these boundaries with measurements of DIC, we calculated a net summertime pan-Arctic export of 231±4...

A general pattern in water mass distribution and potential shelf-basin exchange is revealed at the Laptev Sea continental slope based on hydrochemical and stable oxygen isotope data from summers 2005-2009. Despite considerable interannual variations, a frontal system can be inferred between shelf, continental slope and central Eurasian Basin waters...

The balance between N2 fixation and diffusive NO3 supply is a key determinant for assessing the importance of both processes for new production in subtropical waters. Here we report observations of integrated N2 fixation rates from the eastern subtropical North Atlantic Ocean with coincident estimates of diffusive NO3 supply. We find the average ra...

The balance between N2 fixation and diffusive NO3− supply is a key determinant for assessing the importance of both processes for new production in subtropical waters. Here we report observations of integrated N2 fixation rates from the eastern subtropical North Atlantic Ocean with coincident estimates of diffusive NO3− supply. We find the average...

We provide a data set assemblage of directly observed and derived fluxes of sedimenting material (total mass, POC , PON , BSiO2, CaCO3, PIC and lithogenic/terrigenous fluxes) obtained using sediment traps. This data assemblage contains over 5900 data points distributed across the Atlantic, from the Arctic Ocean to the Southern Ocean. Data from the...

A general pattern in water mass distribution and potential shelf-basin exchanges is revealed at the Laptev Sea continental slope based on hydrochemical and stable oxygen isotope data from summers 2005–2009. Despite considerable interannual variations, a frontal system can be inferred between shelf, continental slope and central Eurasian Basin water...

study provides the first physically based mass-balanced transport estimates of dissolved inorganic nutrients (nitrate, phosphate, and silicate) for the Arctic Ocean. Using an inverse model-generated velocity field in combination with a quasi-synoptic assemblage of hydrographic and hydrochemical data, we quantify nutrient transports across the main...

We provide a compilation of downward fluxes (total mass, POC, PON, BSiO2, CaCO3, PIC and lithogenic/terrigenous fluxes) from over 6000 sediment trap measurements distributed in the Atlantic Ocean, from 30 degree North to 49 degree South, and covering the period 1982-2011. Data from the Mediterranean Sea are also included. Data were compiled from di...

Full-depth measurements of ?18O from 2008 to 2010 enclosing the Weddell Gyre in the Southern Ocean are used to investigate the regional freshwater budget. Using complementary salinity, nutrients and oxygen data, a four-component mass balance was applied to quantify the relative contributions of meteoric water (precipitation/glacial input), sea-ice...

Extremely low summer sea-ice coverage in the Arctic Ocean in 2007 allowed extensive sampling and a wide quasi-synoptic hydrographic and δ¹⁸O dataset could be collected in the Eurasian Basin and the Makarov Basin up to the Alpha Ridge and the East Siberian continental margin. With the aim of determining the origin of freshwater in the halocline, fra...

With the aim of determining the origin of freshwater in the halocline, fractions of river water and sea-ice meltwater (or brine influence from sea-ice formation) in the upper 150 m were quantified by a combination of salinity and δ18O and nutrients in the Eurasian basins and the Makarov Basin. Our study indicates which layers of the Arctic Ocean ha...

The Gulf Stream provides a `nutrient stream,' an advective flux of nutrients carried in sub-surface waters, redistributing nutrients from the tropics to the mid latitudes. There is a dramatic downstream strengthening in the full depth, volume and nitrate transport diagnosed from synoptic measurements along three sections: 32 Sv and 300 kmol s-1 at...

A series of transects carried out in 2002-2009 across the Laptev Sea continental margin show consistent cross-slope differences of the lower halocline water (LHW). Over the slope the LHW core is on average warmer and saltier by 0.39C and 0.26 practical salinity unit, respectively, relative to the off-slope LHW. Underlying Atlantic water (AW) thermo...

Extremely low summer sea-ice coverage in the Arctic Ocean in 2007 allowed extensive sampling and a wide quasi-synoptic hydrographic and d18O dataset could be collected in the Eurasian Basin and the Makarov Basin up to the Alpha Ridge and the East Siberian continental margin. With the aim of determining the origin of freshwater in the halocline, fra...

In May and June 2005, a transatlantic hydrographic section along 36°N was occupied. A velocity field is calculated using inverse methods. The derived 36°N circulation has an overturning transport (maximum in the overturning streamfunction) of 16.6 Sv (1 Sv ≡ 106 m3 s-1) at 1070 m. The heat transport across the section, 1.14 ± 0.12 PW, is partitione...

A synthesis is provided of dissolved organic nitrogen (DON) and phosphorus (DOP) distributions over the Atlantic Ocean based upon field data from eight recent transects, six meridional between 50°N and 50°S and two zonal at 24° and 36°N. Over the entire tropical and subtropical Atlantic, DON and DOP provide the dominant contributions to total nitro...

Poster summarising results/findings associated with our paper Torres-Valdes et al (2009) GBC of the same title, which was ”in press” at the time.

Copyrighted by American Geophysical Union. We investigate the freshwater composition of the shelf and slope of the Arctic Ocean north of the New Siberian Islands using geochemical tracer data (δ¹⁸O, Ba, and PO₄*) collected following the extreme summer of 2007. We find that the anomalous wind patterns that partly explained the sea ice minimum at thi...

Microstructure and hydrographic observations, during September 2007 in the boundary current on the East Siberian continental slope, document upper ocean stratification and along-stream water mass changes. A thin warm surface layer overrides a shallow halocline characterized by a ~40-m thick temperature minimum layer beginning at ~30 m depth. Below...

Microstructure and hydrographic observations, during September 2007 in the boundary current on the East Siberian continental slope, document upper ocean stratification and along-stream water mass changes. A thin warm surface layer overrides a shallow halocline characterized by a ~40-m thick temperature minimum layer beginning at ~30 m depth. Below...

The NERC-funded Arctic Synoptic Basin-wide Oceanography (ASBO) program is among the projects under the International Polar Year (IPY) that runs from 2007-09. ASBO is cooperating with the International Arctic Research Center at the University of Alaska, and the latter coordinated with two Russian research ships. In the consortium, researchers are qu...

We investigate the distribution of urea and its uptake by phytoplankton during 3 meridional transects of the Atlantic Ocean between 50 degrees N and 500 S. Significant relationships were identified between Urea uptake and Prochlorococcus abundance (p < 0.01) in the northern sub tropical Atlantic, where Prochlorococcus appears likely to dominate ure...