Elevated sources of cobalt in the Arctic Ocean DOI Creative Commons
Randelle M. Bundy, Alessandro Tagliabue, Nicholas J. Hawco

et al.

Biogeosciences, Journal Year: 2020, Volume and Issue: 17(19), P. 4745 - 4767

Published: Oct. 1, 2020

Abstract. Cobalt (Co) is an important bioactive trace metal that the cofactor in cobalamin (vitamin B12) which can limit or co-limit phytoplankton growth many regions of ocean. Total dissolved and labile Co measurements Canadian sector Arctic Ocean during U.S. GEOTRACES expedition (GN01) International Polar Year (GIPY14) revealed a dynamic biogeochemical cycle for this basin. The major sources were from shelf rivers, with only minimal contributions other freshwater (sea ice, snow) eolian deposition. most striking feature was extremely high concentrations upper 100 m, routinely exceeding 800 pmol L−1 over regions. This plume persisted throughout basin extended to North Pole, where shifted primarily shelf-derived riverine, as rivers entrained Transpolar Drift. Dissolved also strongly organically complexed Arctic, ranging 70 % surface deep ocean, respectively. Deep-water remarkably consistent (∼55 L−1), reflecting those Atlantic water deep-ocean scavenging Co. A model cycling used support hypothesis majority emanating shelf. showed observed due large area well dampened by manganese-oxidizing (Mn-oxidizing) bacteria lower temperatures. appears have occurred 200 additional below depth. Evidence suggests both (dCo) (LCo) are increasing time on shelf, these limited temporal results tracers Arctic. These elevated likely lead net flux out implications downstream biological uptake Deep Water. Understanding current distributions will be constraining changes inputs resulting regional intensification fluxes ice permafrost melt response ongoing climate change.

Language: Английский

Reviews and syntheses: The biogeochemical cycle of silicon in the modern ocean DOI Creative Commons
Paul Tréguer, Jill Sutton, Mark A. Brzezinski

et al.

Biogeosciences, Journal Year: 2021, Volume and Issue: 18(4), P. 1269 - 1289

Published: Feb. 18, 2021

Abstract. The element silicon (Si) is required for the growth of silicified organisms in marine environments, such as diatoms. These consume vast amounts Si together with N, P, and C, connecting biogeochemical cycles these elements. Thus, understanding cycle ocean critical wider issues carbon sequestration by ocean's biological pump. In this review, we show that recent advances process studies indicate total inputs outputs, to from world ocean, are 57 % 37 higher, respectively, than previous estimates. We also update silicic acid inventory value, which about 24 higher previously estimated. changes significant, modifying factors geochemical residence time Si, now 8000 years, 2 times faster assumed. addition, present an updated value global annual pelagic biogenic silica production (255 Tmol yr−1) based on new data 49 field 18 model provide a first estimate benthic due sponges (6 yr−1). Given important modifications, hypothesize modern at approximately steady state =14.8(±2.6) yr−1 outputs =15.6(±2.4) yr−1. Potential impacts change discussed.

Language: Английский

Citations

215
Arctic mercury cycling DOI
Ashu Dastoor, Hélène Angot, Johannes Bieser

et al.

Nature Reviews Earth & Environment, Journal Year: 2022, Volume and Issue: 3(4), P. 270 - 286

Published: March 22, 2022

Language: Английский

Citations

116
Bioactive Trace Metals and Their Isotopes as Paleoproductivity Proxies: An Assessment Using GEOTRACES‐Era Data DOI Creative Commons
Tristan J. Horner, S. Little, Tim M. Conway

et al.

Global Biogeochemical Cycles, Journal Year: 2021, Volume and Issue: 35(11)

Published: May 24, 2021

Abstract Phytoplankton productivity and export sequester climatically significant quantities of atmospheric carbon dioxide as particulate organic through a suite processes termed the biological pump. Constraining how pump operated in past is important for understanding concentrations Earth's climate history. However, reconstructing history requires proxies. Due to their intimate association with processes, several bioactive trace metals isotopes are potential proxies phytoplankton productivity, including iron, zinc, copper, cadmium, molybdenum, barium, nickel, chromium, silver. Here, we review oceanic distributions, driving depositional archives these nine based on GEOTRACES‐era datasets. We offer an assessment overall maturity each isotope system serve proxy diagnosing aspects ocean identify priorities future research. This reveals that chromium most promise tracers paleoproductivity, whereas molybdenum do not. Too little known about silver make confident determination. Intriguingly, least sensitive may be used track other chemistry, such nutrient sources, particle scavenging, complexation, redox state. These complementary sensitivities suggest new opportunities combining perspectives from multiple will ultimately enable painting more complete picture marine biogeochemical cycles,

Language: Английский

Citations

89
A risk assessment review of mercury exposure in Arctic marine and terrestrial mammals DOI
Runé Dietz, Robert J. Letcher, Jon Aars

et al.

The Science of The Total Environment, Journal Year: 2022, Volume and Issue: 829, P. 154445 - 154445

Published: March 16, 2022

Language: Английский

Citations

47
The Pan‐Arctic Continental Slope as an Intensifying Conveyer Belt for Nutrients in the Central Arctic Ocean (1985–2015) DOI
Laurent Oziel, Vibe Schourup‐Kristensen, Claudia Wekerle

et al.

Global Biogeochemical Cycles, Journal Year: 2022, Volume and Issue: 36(6)

Published: May 26, 2022

Abstract Primary production in the Central Arctic Ocean (CAO) is limited by light and bioavailable nutrients. With decline of sea‐ice cover recent decades, resulting increase availability, nitrate limitation has been speculated to become more prominent. We used an eddy‐permitting biogeochemical model simulation estimate advective fluxes at different spatio‐temporal scales (synoptic, mesoscale sub‐mesoscale) over 1985–2015 period. found that pan‐Arctic continental slope contributes disproportionately Dissolved Inorganic Nitrogen supply this intensifying through two main processes: lateral eddy transport upwelling. Despite increasing intensification ocean dynamics, nutrient decreasing everywhere else central basins indicates CAO still shifting from limitation.

Language: Английский

Citations

43
Size‐Fractionated Compositions of Marine Suspended Particles in the Western Arctic Ocean: Lateral and Vertical Sources DOI
Yang Xiang, Phoebe J. Lam

Journal of Geophysical Research Oceans, Journal Year: 2020, Volume and Issue: 125(8)

Published: July 11, 2020

Abstract We present full water depth sections of size‐fractionated (1–51 μm; >51 μm) concentrations suspended particulate matter and major particle phase composition (particulate organic [POM], including its carbon isotopic [POC‐δ 13 C] C:N ratio, calcium carbonate [CaCO 3 ], opal, lithogenic particles, iron manganese [oxyhydr]oxides) from the U.S. GEOTRACES Arctic Cruise (GN01) in western 2015. Whereas biogenic particles (POM opal) dominate upper 1,000 m, are most abundant type at depth. Minor phases such as (Mn) oxides higher GN01 than any other cruises so far. Extremely depleted POC‐δ C, low ~ −32‰, is ubiquitous surface Ocean a result different growth rates phytoplankton. Moderate penetration C to indicates active sinking large central basin. Lateral transport Chukchi shelf also significance Arctic, evident increases silica POC ratios Mn oxide halocline, well element contents deep waters. Our study supports previous suggestions near absence CaCO Basin. This presents first data set concentration sheds new light on vertical lateral processes that govern distribution this enclosed ocean

Language: Английский

Citations

68
A comparison of marine Fe and Mn cycling: U.S. GEOTRACES GN01 Western Arctic case study DOI Creative Commons
Laramie T. Jensen, Peter L. Morton, Benjamin S. Twining

et al.

Geochimica et Cosmochimica Acta, Journal Year: 2020, Volume and Issue: 288, P. 138 - 160

Published: Aug. 17, 2020

Language: Английский

Citations

53
DOM degradation by light and microbes along the Yukon River-coastal ocean continuum DOI Creative Commons
Brice Grunert, Maria Tzortziou, Patrick J. Neale

et al.

Scientific Reports, Journal Year: 2021, Volume and Issue: 11(1)

Published: May 13, 2021

The Arctic is experiencing rapid warming, resulting in fundamental shifts hydrologic connectivity and carbon cycling. Dissolved organic matter (DOM) a significant component of the global cycle, perturbations to DOM cycling are expected with warming. impact photochemical microbial degradation, their interactive effects, on composition remineralization have been documented soils rivers. However, role microbes, sunlight interactions alteration coastal ocean has not considered, particularly during spring freshet when loads high, photoexposure can be quite limited residence time within river networks low. Here, we collected samples along salinity gradient Yukon River delta, plume peak discharge immediately after explored UV exposure, transformations effects quantity composition. Our results show: (1) significantly processing pathways terrestrial DOM, including increasing relative humification by microbes > 10%; (2) produce humic-like material that optically distinguishable from humics; (3) size-fractionation community indicates size-dependent for observed through modeled PARAFAC components fluorescent either direct or effects. Field observations indicate apparent conservative mixing gradient; however, changing likely due activity. Finally, our findings show potential transformation alteration, responsible majority dissolved remineralization.

Language: Английский

Citations

47
Novel Insights into Marine Iron Biogeochemistry from Iron Isotopes DOI
Jessica N. Fitzsimmons, Tim M. Conway

Annual Review of Marine Science, Journal Year: 2022, Volume and Issue: 15(1), P. 383 - 406

Published: Sept. 13, 2022

The micronutrient iron plays a major role in setting the magnitude and distribution of primary production across global ocean. As such, an understanding sources, sinks, internal cycling processes that drive oceanic is key to unlocking iron's carbon cycle climate, both today geologic past. Iron isotopic analyses seawater have emerged as transformative tool for diagnosing sources ocean tracing biogeochemical processes. In this review, we summarize end-member isotope signatures different source fluxes highlight novel insights into provenance gained using tracer. We also review ways which fractionation might be used understand iron, including speciation changes, biological uptake, particle scavenging. conclude with overview future research needed expand utilization cutting-edge

Language: Английский

Citations

35
Dissolved Cd, Co, Cu, Fe, Mn, Ni, and Zn in the Arctic Ocean DOI
Loes J. A. Gerringa,

Micha J.A. Rijkenberg,

Hans A. Slagter

et al.

Journal of Geophysical Research Oceans, Journal Year: 2021, Volume and Issue: 126(9)

Published: Aug. 27, 2021

Abstract During the Polarstern (PS94) expedition, summer 2015, part of international GEOTRACES program, sources and sinks dissolved (D) Cd, Co, Cu, Fe, Mn, Ni, Zn were studied in central Arctic Ocean. In Polar Surface Water which TransPolar Drift (TPD) is situated, salinity δ 18 O derived fractions indicated a distinct riverine source for silicate DCo, DCu, DFe, DMn, DNi. Linear relationships between DMn meteoric fraction depended on distance, likely due to Mn‐precipitation during transport. upper 50 m Makarov Basin, outside TPD core, DNi, DCd, DCu enriched by Pacific waters, whereas DFe seemed diluted. DZn relatively high Barents Sea led enrichment Atlantic water flowing into Nansen Basin. Deep concentrations all metals significantly lower Basin compared Amundsen, Eurasian, Basins. The Gakkel ridge hydrothermal input higher continental slope convection are explanations metal Eurasian Although scavenging rates Basins, residence time longer therefore can decrease with time. This study provides baseline assess future change, additionally identifies processes driving trace distributions. Our results underline importance fluvial as well shelf internal cycling, notably scavenging, distribution bio‐active

Language: Английский

Citations

36