Global Ocean Sediment Composition and Burial Flux in the Deep Sea

Hayes, Christopher T.; Costa, Kassandra M; Anderson, Robert F.; Calvo, Eva María; Chase, Zanna; Демина, Л. Л.; Dutay, Jean-Claude; German, Christopher R.; Heimbürger‐Boavida, Lars‐Eric; Jaccard, Samuel L.; Jacobel, Allison W; Kohfeld, Karen E.; Кравчишина, М. Д.; Lippold, Jörg; Mekik, Figen; Missiaen, Lise; Pavia, F. J.; Paytan, Adina; Pedrosa-Pàmies, Rut; Petrova, Mariia V.; Rahman, Shaily; Robinson, Laura F.; Roy‐Barman, Matthieu; Sánchez-Vidal, Anna; Shiller, Alan M.; Tagliabue, Alessandro; Tessin, Allyson; Hulten, Marco van; Zhang, Jing

doi:10.1029/2020gb006769

Cited by 67 publications

(49 citation statements)

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“… Hemispheric mercury gradients in different Pacific Ocean reservoirs. The boxplots illustrate the hemispheric gradient of ( A ) atmospheric Hg 0 model estimates (nanograms ⋅ meters −3 ) extracted at tuna sampling locations (see Materials and Methods ), ( B ) observed total Hg concentrations (picomolar) in seawater ( 12 , 34 , 38 , 53 , 54 , 56 ), ( C ) observed MeHg concentrations at peak (picomolar) in seawater ( 12 , 34 , 53 – 57 ), ( D ) standardized total Hg concentrations (micrograms ⋅ grams −1 , dw) in skipjack tuna (this study), and ( E ) observed total Hg concentrations (nanograms ⋅ grams −1 , dw) in marine sediments ( 2 , 73 – 78 ). ** indicates significant differences between the northern and southern hemispheres (Kruskal–Wallis test; P < 0.01).…”

Section: Resultsmentioning

confidence: 99%

Evidence that Pacific tuna mercury levels are driven by marine methylmercury production and anthropogenic inputs

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Itai

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Pacific Ocean tuna is among the most-consumed seafood products but contains relatively high levels of the neurotoxin methylmercury. Limited observations suggest tuna mercury levels vary in space and time, yet the drivers are not well understood. Here, we map mercury concentrations in skipjack tuna across the Pacific Ocean and build generalized additive models to quantify the anthropogenic, ecological, and biogeochemical drivers. Skipjack mercury levels display a fivefold spatial gradient, with maximum concentrations in the northwest near Asia, intermediate values in the east, and the lowest levels in the west, southwest, and central Pacific. Large spatial differences can be explained by the depth of the seawater methylmercury peak near low-oxygen zones, leading to enhanced tuna mercury concentrations in regions where oxygen depletion is shallow. Despite this natural biogeochemical control, the mercury hotspot in tuna caught near Asia is explained by elevated atmospheric mercury concentrations and/or mercury river inputs to the coastal shelf. While we cannot ignore the legacy mercury contribution from other regions to the Pacific Ocean (e.g., North America and Europe), our results suggest that recent anthropogenic mercury release, which is currently largest in Asia, contributes directly to present-day human mercury exposure.

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Section: Resultsmentioning

confidence: 99%

Evidence that Pacific tuna mercury levels are driven by marine methylmercury production and anthropogenic inputs

Médieu

Point

Itai

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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“…Using a compilation of Th-normalized mass AR (Hayes et al, 2020(Hayes et al, , 2021, a minimum estimate of the global marine Ba output flux in >1,000 m water depth, via the burial of pBa xs , is ∼19 ± 10 Gmol year −1 . The inventory of dBa in the ocean is ∼150 Tmol.…”

Section: Marine Barium Cyclementioning

confidence: 99%

Dissolved and Particulate Barium Distributions Along the US GEOTRACES North Atlantic and East Pacific Zonal Transects (GA03 and GP16): Global Implications for the Marine Barium Cycle

Rahman

Shiller

Anderson

et al. 2022

Global Biogeochemical Cycles

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Processes controlling dissolved barium (dBa) were investigated along the GEOTRACES GA03 North Atlantic and GP16 Eastern Tropical Pacific transects, which traversed similar physical and biogeochemical provinces. Dissolved Ba concentrations are lowest in surface waters (∼35–50 nmol kg−1) and increase to 70–80 and 140–150 nmol kg−1 in deep waters of the Atlantic and Pacific transects, respectively. Using water mass mixing models, we estimate conservative mixing that accounts for most of dBa variability in both transects. To examine nonconservative processes, particulate excess Ba (pBaxs) formation and dissolution rates were tracked by normalizing particulate excess 230Th activities. Th‐normalized pBaxs fluxes, with barite as the likely phase, have subsurface maxima in the top 1,000 m (∼100–200 μmol m−2 year−1 average) in both basins. Barite precipitation depletes dBa within oxygen minimum zones from concentrations predicted by water mass mixing, whereas inputs from continental margins, particle dissolution in the water column, and benthic diffusive flux raise dBa above predications. Average pBaxs burial efficiencies along GA03 and GP16 are ∼37% and 17%–100%, respectively, and do not seem to be predicated on barite saturation indices in the overlying water column. Using published values, we reevaluate the global freshwater dBa river input as 6.6 ± 3.9 Gmol year−1. Estuarine mixing processes may add another 3–13 Gmol year−1. Dissolved Ba inputs from broad shallow continental margins, previously unaccounted for in global marine summaries, are substantial (∼17 Gmol year−1), exceeding terrestrial freshwater inputs. Revising river and shelf dBa inputs may help bring the marine Ba isotope budget more into balance.

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“…This dissolution not only includes the 11-21 Gt/a of the riverine solid sediment flux (adding 3.8 Gt/a of Si; Viers et al, 2009) but also the 0.6-2.4 Gt/a of the rock coast input solid sediment flux (results from this work, upscaled at the global scale, see Supplementary Material). Since Si is a limiting element in much of the ocean, a larger Si flux would rapidly be assimilated by the local biology (Fripiat et al, 2011), accelerating its uptake from ocean water and sedimentation (0.15 Gt/a or 5.3 Tmol/a; Hayes et al, 2021). In the case of the Fe cycle, the mass budget imbalance is not as clear, but increasing the rock coast sediment flux by a factor 3 to 12 would make it a major Fe source (extrapolating from Raiswell et al, 2006, 12-30% of the Fe reaching the continental shelf would come from coastal erosion).…”

Section: Discussionmentioning

confidence: 99%

Rock coast erosion: An overlooked source of sediments to the ocean. Europe as an example

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Prémaillon

Dewez

et al. 2022

Earth and Planetary Science Letters

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Rock coast erosion: an overlooked source of sedimentsto the ocean. Europe as an example

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Global Ocean Sediment Composition and Burial Flux in the Deep Sea

Abstract: Seafloor sediments contain information about many large-scale processes in the ocean such as surface biological productivity, particle export and degradation, hydrothermal activity, and material transport from

Cited by 67 publications

References 123 publications

Evidence that Pacific tuna mercury levels are driven by marine methylmercury production and anthropogenic inputs

Evidence that Pacific tuna mercury levels are driven by marine methylmercury production and anthropogenic inputs

Dissolved and Particulate Barium Distributions Along the US GEOTRACES North Atlantic and East Pacific Zonal Transects (GA03 and GP16): Global Implications for the Marine Barium Cycle

Rock coast erosion: An overlooked source of sediments to the ocean. Europe as an example

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