Global Ocean Sediment Composition and Burial Flux in the Deep Sea

Global Biogeochemical Cycles, Год журнала: 2021, Номер 35(4)

Опубликована: Март 24, 2021

Abstract Quantitative knowledge about the burial of sedimentary components at seafloor has wide‐ranging implications in ocean science, from global climate to continental weathering. The use 230 Th‐normalized fluxes reduces uncertainties that many prior studies faced by accounting for effects sediment redistribution bottom currents and minimizing impact age model uncertainty. Here we employ a recently compiled data set with an updated database surface composition derive atlases deep‐sea flux calcium carbonate, biogenic opal, total organic carbon (TOC), nonbiogenic material, iron, mercury, excess barium (Ba xs ). spatial patterns major component are mainly consistent work, but new quantitative estimates allow evaluations budgets. Our integrated 136 Tg C/yr CaCO 3 , 153 Si/yr 20Tg TOC, 220 Mg Hg/yr, 2.6 Ba /yr. This opal is roughly factor 2 increase over previous estimates, important Si cycle. Sedimentary Fe reflect mixture sources including lithogenic hydrothermal inputs authigenic phases. some commonly used paleo‐productivity proxies (TOC, ) not well‐correlated geographically satellite‐based productivity estimates. compilation provides detailed regional information, which will help refine understanding preservation.

Язык: Английский

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Reviews and syntheses: Review of proxies for low-oxygen paleoceanographic reconstructions

Biogeosciences, Год журнала: 2025, Номер 22(4), С. 863 - 957

Опубликована: Фев. 18, 2025

Abstract. A growing body of observations has revealed rapid changes in both the total inventory and distribution marine oxygen over latter half 20th century, leading to increased interest extending oxygenation records into past. The use paleo-oxygen proxies potential extend spatial temporal range current records, constrain pre-anthropogenic baselines, provide datasets necessary test climate models under different boundary conditions, ultimately understand how ocean responds beyond decadal-scale changes. This review seeks summarize state knowledge about for reconstructing Cenozoic oxygen: sedimentary features, redox-sensitive trace elements isotopes, biomarkers, nitrogen foraminiferal elements, assemblages, morphometrics, benthic carbon isotope gradients. Taking stock each proxy reveals some common limitations as majority functions best at low-oxygen concentrations, many reflect multiple environmental drivers. We also highlight recent breakthroughs geochemistry approaches constraining pelagic (in addition benthic) that are rapidly advancing field. In light emergence new persistent driver problem, need multi-proxy data storage sharing adhere principles findability, accessibility, interoperability, reusability (FAIR) is emphasized. Continued refinements proxy–proxy proxy–model comparisons likely support needs oceanographers paleoceanographers interested paleo-oxygenation records.

Язык: Английский

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Novel Insights into Marine Iron Biogeochemistry from Iron Isotopes

Annual Review of Marine Science, Год журнала: 2022, Номер 15(1), С. 383 - 406

Опубликована: Сен. 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

Язык: Английский

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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

Global Biogeochemical Cycles, Год журнала: 2022, Номер 36(6)

Опубликована: Май 23, 2022

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

Язык: Английский

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Earth system science applications of next-generation SEM-EDS automated mineral mapping

Frontiers in Earth Science, Год журнала: 2022, Номер 10

Опубликована: Ноя. 23, 2022

Sedimentary rocks contain a unique record of the evolution Earth system. Deciphering this requires robust understanding identity, origin, composition, and post-depositional history individual constituents. Petrographic analysis informed by Scanning Electron Microscope - Energy Dispersive Spectroscopy (SEM-EDS) mineral mapping can reveal morphology petrological context each imaged grain, making it valuable tool in Scientist’s analytical arsenal. Recent technological developments, including quantitative deconvolution mixed-phase spectra (producing “mixels”), now allow rapid SEM-EDS-based broad range sedimentary rocks, previously troublesome fine-grained lithologies that comprise most record. Here, we test reliability preferred work flow modern Field-Emission scanning electron microscope equipped with Thermofisher Scientific Maps Mineralogy system, focusing on mud/siltstones calcareous shales. We demonstrate SEM-EDS implements 1) strict error minimization spectral matching approach 2) to produce ‘mixels’ for X-ray volumes robustly identify grains mineralogical data sets comparable conventional diffraction (XRD) ( R 2 > 0.95). The correlation between XRD-derived mineralogy is influenced abundance, processing modes mapped area characteristics. Minerals higher abundance (>10 wt%) show better correlation, likely result increased uncertainty XRD quantification low-abundance phases. Automated greatly reduces proportion unclassified pixels, especially fraction, ultimately improving identification quantification. Mapping larger areas benefits bulk analysis, while customized size shape allows high-resolution situ analysis. Finally, review applications Sciences, via case studies illustrating approaches differentiation various components detrital (allogenic), syndepositional (authigenic) burial diagenetic phases, origin significance lamination, 3) effectiveness appropriateness sequential leaching geochemical studies, 4) utility maps target within specific contexts or geochronological

Язык: Английский

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The paleoenvironmental evolution of the Cambrian Miaolingian Epoch in South China

Palaeogeography Palaeoclimatology Palaeoecology, Год журнала: 2025, Номер 661, С. 112713 - 112713

Опубликована: Янв. 2, 2025

Язык: Английский

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Stromatolites as geochemical archives to reconstruct microbial habitats through deep time: Potential and pitfalls of novel radiogenic and stable isotope systems

Earth-Science Reviews, Год журнала: 2021, Номер 218, С. 103683 - 103683

Опубликована: Май 19, 2021

Understanding the origin and evolution of life on Earth potentially other planets in our solar system is fundamental interest for humanity. For longest time Earth's history, evolved microbial communities. It is, however, still incompletely understood how, when where such habitable environments formed how communities adopted to drastic changes atmosphere-hydrosphere-lithosphere systems through deep time. Stromatolites, i.e., lithified mats that occur sedimentary successions from at least 3.4 billion years ago until today, hold geochemical key understanding may also provide a blueprint planetary studies. This review targets potential pitfalls emerging established isotope applications stromatolites based improved newly developed analytical technical capabilities last decades. We comprehensive overview present data interpretation radiogenic (UPb, RbSr, SmNd) stable (O, C-N-S, Fe, Mo, Cr, U, Cd) stromatolites. Although behaviour fractionation processes different are understood, proxies used better understand reconstruct habitats stromatolite-forming Primarily, isotopes directly date determine source elements ancient stromatolite environments, while redox conditions, metal availability, (biogenic) cycling habitats. insights into each application show their unique future perspectives bridge gap between geochemistry microbiology beyond.

Язык: Английский

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Climate change driven effects on transport, fate and biogeochemistry of trace element contaminants in coastal marine ecosystems

Communications Earth & Environment, Год журнала: 2024, Номер 5(1)

Опубликована: Окт. 4, 2024

Язык: Английский

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Assessment of C, N, and Si Isotopes as Tracers of Past Ocean Nutrient and Carbon Cycling

Global Biogeochemical Cycles, Год журнала: 2021, Номер 35(7)

Опубликована: Май 22, 2021

Abstract Biological productivity in the ocean directly influences partitioning of carbon between atmosphere and interior. Through this cycle feedback, changing has long been hypothesized as a key pathway for modulating past atmospheric dioxide levels hence global climate. Because phytoplankton preferentially assimilate light isotopes major nutrients nitrate silicic acid, stable (C), nitrogen (N), silicon (Si) seawater marine sediments can inform on nutrient cycling, by extension relationship with biological Here, we compile water column C, N, Si from GEOTRACES‐era data four regions to review geochemical proxies oceanic cycling based isotopic composition sediments. External sources sinks well internal (including assimilation, particulate matter export, regeneration) are discussed likely drivers observed isotope distributions ocean. The potential measurements sedimentary archives record aspects C is evaluated, along uncertainties limitations associated each proxy. Constraints during late Quaternary glacial‐interglacial cycles over Cenozoic examined. This highlights opportunities future research using multielement proxy applications emphasizes importance such reconstructing changes oceans climate system.

Язык: Английский

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Combined cadmium and chromium isotopes record a collapse of bioproductivity across the Cretaceous—Paleogene boundary in the Danish basin

Chemical Geology, Год журнала: 2024, Номер 654, С. 122058 - 122058

Опубликована: Март 25, 2024

Cadmium (Cd) isotope signatures (δ114Cd) deduced from modern and ancient marine deposits are often used as a proxy for bioproductivity micronutrient cycling, whereas chromium (Cr) (δ53Cr) potential oxygenation. The Cretaceous—Paleogene (K/Pg) boundary records one of Earth's five big mass extinctions, which contains geochemical fingerprints the Chixculub asteroid impact is coeval with Deccan Trap volcanism. Here we present first time combined record Cd Cr isotopes Danish Basin to interrogate effects on across K/Pg boundary. δ114Cd values range between −0.28‰ 0.27‰ defining an average 0.05‰ ± 0.24 (2σ, n = 87). Authigenic δ53Cr 0.06‰ 1.06‰ define 0.59‰ 0.51 81). An abrupt jump, layer, consistently positively fractionated recorded in Late Maastrichtian white chalks towards less heterogeneous Early Danian carbonates, likely indicates decrease surface water bioproductivity. This accompanied by redox fluctuations column consequence environmental changes either related event and/or volcanic eruptions this Assuming efficient removal through consumption adsorption primary producers, or incorporation into skeleton/shells calcifiers, using fractionation factor reconstruct conditions during Masstrichtian—Early that compatible those oceans, varying 0.17 0.72‰. Overall, Cr-Cd over consistent scenario characterized climate-induced nutrient availability concomitant responses production levels, ultimately proceeding activities influenced ocean's chemistry. We anticipate our results point further studies other stratigraphic sections worldwide reveal extensive Cd-Cr its corresponding collapse decreasing ocean

Язык: Английский

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