Hidden dangers: High levels of organic pollutants in hadal trenches

Water Research, Journal Year: 2024, Volume and Issue: 251, P. 121126 - 121126

Published: Jan. 10, 2024

Language: Английский

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Timekeepers for Trace Elements in the Global Ocean: The Thorium Stopwatches

Oceanography, Journal Year: 2024, Volume and Issue: 37(2)

Published: Jan. 1, 2024

The various isotopes of thorium offer oceanographers tools for tracking particulate matter in the ocean across multiple timescales. To learn about cycling trace elements ocean, this perspective we focus on latest applications thorium’s longest-lived naturally occurring isotopes: 232Th, 230Th, 228Th, and 234Th. From desert dust to marine snow sediment porewaters, measurements can be used derive rates element input removal, using assumptions radioactive disequilibrium. Opportunities exist fine tune improve application these already versatile stopwatches, but GEOTRACES-era data clearly demonstrate their utility.

Language: Английский

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Enriched Regions of ²²⁸Ra Along the U.S. GEOTRACES Pacific Meridional Transect (GP15)

Journal of Geophysical Research Oceans, Journal Year: 2024, Volume and Issue: 129(3)

Published: March 1, 2024

Abstract The half‐life of 228 Ra (5.7 years) aligns well with near‐surface and near‐bottom ocean mixing timescales. Because is sourced from sediments, regions enhanced activity represent water that has recently interacted sediments on the continental margin or seabed. GP15 meridional transect Alaska to Tahiti along152°W encountered several in upper where was enriched. These enrichments follow surface subsurface current patterns pair earlier measurements transient radionuclides reveal origins these enriched regions. An region at stations 1–3 locally but did not extend Alaskan trench station 4. A large shallow between 47° 32°N. west by North Pacific Current; another 11° 5° N also Equatorial Countercurrent. Subsurface (100–400 m) 18 47°N were associated Central Mode Water Intermediate Water. activities six times lower than Atlantic. In deep waters primary enrichment 27°–47°N. Two (32° 37°N) especially enriched, having inventories greater other stations. With two exceptions remaining exhibited averaged those There one 223 (half‐life = 11 days) above Puna Ridge near Hawaii.

Language: Английский

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Meridional Central Pacific Ocean Depth Section for Pb and Pb Isotopes (GEOTRACES GP15, 152°W, 56°N to 20°S) Including Shipboard Aerosols

Journal of Geophysical Research Oceans, Journal Year: 2025, Volume and Issue: 130(1)

Published: Jan. 1, 2025

Abstract Most oceanic lead (Pb) is from anthropogenic emissions into the atmosphere deposited surface waters, mostly during past two centuries. The space‐ and time‐dependent emission patterns of Pb (and its isotope ratios) constitute a global geochemical experiment providing information on advective, mixing, chemical, particle flux processes redistributing within ocean. shares aspects behavior with other elements, for example, atmospheric input, dust solubilization, biological uptake, reversible exchange between dissolved adsorbed sinking particles. evolving distributions allow us to see signals hidden in steady‐state tracer distributions. serves as tool understand trace element dynamics. We obtained high‐resolution (5° station spacing) depth transect concentrations isotopes Alaska (55°N) just north Tahiti (20°S) near 152°W longitude. sections reveal distinct sources (American, Australian, Chinese), transport Australian style water mass formation region Sub‐Antarctic Mode Water which advected northward, columnar contours due particles high‐productivity veils, gradient high northern deep [Pb] low southern that created by release carrying predominantly hemisphere Pb. 208 Pb/ 206 versus 207 relationships show most North Pacific Chinese American sources, whereas South sources.

Language: Английский

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The role of scavenging and early diagenesis in controlling hydrothermal fluxes into the ocean along the Endeavour segment of the Juan de Fuca ridge

Chemical Geology, Journal Year: 2025, Volume and Issue: unknown, P. 122675 - 122675

Published: Feb. 1, 2025

Language: Английский

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Dynamics of dissolved trace metals, rare earth elements and Pb isotopes across the eastern margins of the Mediterranean Sea

Marine Chemistry, Journal Year: 2025, Volume and Issue: unknown, P. 104519 - 104519

Published: April 1, 2025

Language: Английский

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Modeling Dissolved Pb Concentrations in the Western Arctic Ocean: The Continued Legacy of Anthropogenic Pollution

Journal of Geophysical Research Oceans, Journal Year: 2025, Volume and Issue: 130(4)

Published: April 1, 2025

Abstract Over the past decade, international GEOTRACES program has greatly expanded coverage of dissolved lead (dPb) observations in western Arctic Ocean including Canada Basin and Canadian Archipelago. However, it is difficult to quantify drivers spatial distribution seasonal variability dPb concentrations using alone. Here, we present a three‐dimensional model with experiments from 2002 2021 assess our current understanding cycling. The illustrates impact historical anthropogenic pollution on Ocean, which accounts for at least 28% addition region, through aerosol deposition net transport other ocean basins. Advected water masses Pacific North Atlantic Oceans convey elevated pollution‐derived play key role, contributing 43% annual budget. Labrador Sea source Baffin Bay via West Greenland Current. Within Bay, simulated track extension warm Water along shelf occasional dense overflows into deep interior. While are low, simulations presented here show that continues Pb budget this consistent recent observational work, demonstrate use as tracer masses.

Language: Английский

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Controls on Dissolved Cu Concentrations and Isotopes in the North Atlantic: The Importance of Continental Margins

Global Biogeochemical Cycles, Journal Year: 2025, Volume and Issue: 39(5)

Published: April 30, 2025

Abstract Copper (Cu) is a marine micronutrient whose distribution and budget remain incompletely understood. Here, we present section of dissolved Cu isotope compositions (δ 65 Cu) across the North Atlantic (GEOVIDE cruise, GEOTRACES GA01). High δ are observed in surface waters co‐vary with carbon uptake rates, indicating light removal by biological activity or complexation heavy organic ligands. Beneath surface, low may be partially caused remineralization. Below 1,500 m, an increase points to particulate scavenging. At greater depths, reversible scavenging, driven high vertical exports, could explain concentrations between deep ocean, mostly eastern part transect. Investigation external sources sinks reveals that anthropogenic aerosols benthic processes locally supply isotopically whilst hydrothermal above Reykjanes ridge does not seem represent significant source. A striking feature 300 m from Iberian margin Icelandic basin, which coincides elevated non‐conservative neodymium fractions (Nd xs ). This comparison suggests inputs source this can transported over long distances. The hotspot internal tides their energy triggers sediment resuspension, leading particle dissolution release. These results suggest continental margins contribute significantly missing ocean.

Language: Английский

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Stable Iron Isotopes Constrain the Sedimentary Input of Dissolved Iron to the Ocean

Global Biogeochemical Cycles, Journal Year: 2025, Volume and Issue: 39(5)

Published: May 1, 2025

Abstract Iron is a key micronutrient for marine biota and potentially one of the main drivers ocean feedback to changing climate. There however no consensus on relative role different external iron sources ocean, hampering our ability predict how oceanic cycle biological carbon pump will react climate change. For last two decades, stable isotopes have been increasingly used in field studies track contributions modeling started help interpreting isotope observations. However, measured isotopic compositions can vary substantially, signatures overlap, leading high uncertainty constraining magnitude sources. This study aims examine sensitivity seawater sedimentary source. An existing box model extended with description its isotopes. Experiments done variable end‐member signature strength source, fractionation through uptake binding organic ligands. The results reveal necessity consider spatially distinct source fractionations so as reproduce observed spatial gradients composition. By assuming input 7.5–15 Gmol Fe , able concentrations dissolved large regions, providing useful constraints complex global biogeochemistry models.

Language: Английский

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The geochemistry of marine particles

Elsevier eBooks, Journal Year: 2024, Volume and Issue: unknown, P. 459 - 477

Published: March 21, 2024

Language: Английский

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