Extensive Oxygen Consumption in the Intertidal Infiltration Zone of Beach Aquifers—The Impact of Seasonal Input, Filtration Efficiency, and Morphodynamics

Journal of Geophysical Research Biogeosciences, Journal Year: 2025, Volume and Issue: 130(2)

Published: Feb. 1, 2025

Abstract Seawater infiltration into the permeable sands of beach aquifers creates a high input biogeochemical reactants driven by tides and waves. The upper sand layer acts as filter, retaining particulate organic matter (POM), which is degraded bacteria under predominantly oxic conditions. seasonal variation seawater POM oxygen (O 2 ) entering zone, combined with filtration efficiency highly morphodynamic layer, determines turnover subsequent redox gradients along porewater flowpaths. We investigated these effects quantifying O consumption rates directly from incubations sediments taken transect in zone at Spiekeroog Beach, Germany. carried out two‐monthly year‐long sampling campaign spatial resolution measurements down to 1 m depth. In summer, up 106 μM hr −1 were found first decimeters significant decline over depth, indicating efficient retention reactive surface layer. Seasonal carbon sand's suspendable particulates indicates rapid little storage. winter, decreased significantly below 11 . Integrated estimated mineralization varies between 15 (winter) 143 (summer) mmol C −2 d yearly average 73 CO production 35 kg per meter shoreline characterizes high‐throughout system OM remineralization especially but

Language: Английский

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Influence of hydrogeological and numerical parameters on the simulation of an upper saline plume and fresh submarine groundwater discharge

Journal of Hydrology, Journal Year: 2025, Volume and Issue: unknown, P. 133439 - 133439

Published: May 1, 2025

Language: Английский

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Interstitial microbial communities of coastal sediments are dominated by Nanoarchaeota

Frontiers in Microbiology, Journal Year: 2025, Volume and Issue: 16

Published: Feb. 18, 2025

Microbial communities in subsurface coastal sediments are highly diverse and play an important role nutrient cycling. While the major fraction of microorganisms sandy lives as epipsammon (attached to sand grains), only a small thrives interstitial porewaters. So far, little is known about composition these free-living microbial communities. In beach, investigated this study, we compared archaeal bacterial community structures within corresponding porewaters applying 16S rRNA gene sequencing. We found that prokaryotes had proportion 0.2-2.3% bulk communities, depending on pore space. The showed overlap with attached 4-7% ASVs, comprised unique 75-81% ASVs exclusively They were more than respective sediment-attached much higher archaea-to-bacteria ratio. archaea mainly affiliated Nanoarchaeota DPANN superphylum, relative abundance up 50% included several species related Candidate Phyla Radiation (CPR). Both prokaryotic lineages have cell sizes, comprising not-yet cultured unidentified metabolic functions. Our findings supported by investigation adjacent tidal flat, showing similar trend. Thus, our results indicate presence distinct sediments. This natural enrichment members CPR provides opportunity for targeted metagenomic analyses or even isolating groups further characterization.

Language: Английский

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Organo-mineral interactions modulate organic carbon retention and mobility in a deep subterranean estuary of a high-energy beach

Frontiers in Water, Journal Year: 2025, Volume and Issue: 7

Published: May 12, 2025

Permeable sandy sediments beneath high-energy beaches act as potent biogeochemical reactors with high organic matter turnover rates. Despite their significant role in nutrient and Fe cycling coastal environments, capacity to trap mobilize dissolved (DOM) remains poorly understood. This study analyzed the molecular composition of water- acid-leachable sedimentary down 24 meters depth an exemplary subterranean estuary (STE) site a beach on Spiekeroog Island, German North Sea. We also investigated DOM coprecipitation 3+ (oxy)hydroxides aqueous phase STE porewaters containing reduced 2 + , exposed atmospheric oxygen. employed fluorescence spectroscopy ultrahigh-resolution mass spectrometry for our analysis. Seawater porewater were more complex oxidized than leached from sediments. Sediment leaching ultrapure water predominantly yielded aliphatic, oxygen-rich, presumably labile compounds marine possibly autochthonous origin. In contrast, subsequent 0.5 M hydrochloric acid (HCl) leachates was molecularly diverse, enriched aromatic likely terrigenous refractory nature. Notably, contained substantial fraction compounds. Approximately 10% total carbon (TOC) leachable (DOC) both treatments. Leachable DOC concentrations up two orders magnitude higher DOC, while TOC three higher. These findings indicate that deep are important reservoirs. Elevated treatments associated finer, clay-rich sediments, lower levels coincided coarser suggests oxides/hydroxides adsorption sites within mineral matrix While Fe-DOM aerated samples induced distinct alterations, removal analytical uncertainties, fractionation varied across sampling campaigns. Thus, phases at redox interfaces (>5 m) STEs appears limited influenced by transport-driven geochemical changes. propose Fe-rich minerals clay fractions facilitate preservation refractory, DOM, whereas loosely bound, fractions—susceptible rapid microbial respiration—may be readily mobilized advective flow STEs.

Language: Английский

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Reactive transport modeling to reveal the impacts of beach morphodynamics, storm floods and seasonal groundwater recharge on the biogeochemistry of sandy subterranean estuaries

Advances in Water Resources, Journal Year: 2024, Volume and Issue: 196, P. 104884 - 104884

Published: Dec. 26, 2024

Language: Английский

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