Marine Recalcitrant Dissolved Organic Matter Gained by Processing at Sandy Subterranean Estuaries

Environmental Science & Technology, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 13, 2025

The sandy subterranean estuary (STE) connecting fresh groundwater to saline sea water is characterized by strong geochemical (salinity, redox, and pH) gradients, with evidence emerging for its role as a hot spot consumption of labile substrates. This inspired us conduct study evaluate whether this holds true dissolved organic matter (DOM), especially given the still mysterious origin marine recalcitrant DOM. Here, characterization DOM 21 samples (depth 1-13 m, salinity 3.9‰ 32.4‰) across 65 m transect an STE located in coastal Guangdong, China, has found systematic biotransformation toward "recalcitrant" carboxyl-rich alicyclic molecules (CRAM). fraction CRAM (%CRAM) increases from 33.1% 76.7% increasing degree degradation salinity. Further, processing DOM, including more "biolabile" lower %CRAM released aquitard, active under oxic conditions than reducing conditions. Given large quantities that recirculates through STEs globally, amount (RDOM) entering ocean after likely be considerable. While studies are needed, can gain CRAM-like compounds way.

Language: Английский

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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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Effects of boundary conditions and aquifer parameters on salinity distribution and mixing-controlled reactions in high-energy beach aquifers

Hydrology and earth system sciences, Journal Year: 2025, Volume and Issue: 29(5), P. 1469 - 1482

Published: March 18, 2025

Abstract. In high-energy beach aquifers fresh groundwater mixes with recirculating saltwater and biogeochemical reactions modify the composition of discharging to sea. Changing morphology, hydrodynamic forces, hydrogeological properties control density-driven flow transport processes that affect distribution chemical reactants. present study, modelling a generic 2-D cross-shore transect was conducted. Boundary conditions aquifer parameters were varied in systematic manner suite 24 cases. The objective investigate individual effects boundary on regime, salt distribution, potential for mixing-controlled system temporally variable morphology. Our results show changing morphology causes migration infiltration exfiltration locations along transect, leading transient patterns subsurface, thereby enhancing reactions. shape extent zone where potentially take place, as well spatiotemporal variability freshwater–saltwater interfaces, are most sensitive storm floods, hydraulic conductivity, dispersivity. study advances understanding subsurface flow, transport, mixing dynamic beneath beaches. These regulate nutrient fluxes coastal ecosystems.

Language: Английский

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The DynaDeep observatory – a unique approach to study high-energy subterranean estuaries

Frontiers in Marine Science, Journal Year: 2023, Volume and Issue: 10

Published: June 22, 2023

Subterranean estuaries are connective zones between inland aquifers and the open sea where terrestrial freshwater circulating seawater mix undergo major biogeochemical changes. They reactors that modify groundwater chemistry prior to discharge into sea. We propose subterranean of high-energy beaches particularly dynamic environments, effect boundary conditions propagates tens meters subsurface, leading strong spatio-temporal variability geochemical conditions. hypothesize they form a unique habitat with an adapted microbial community unlike other typically more stable subsurface environments. So far, however, studies concerning have been rare therefore their functioning, importance for coastal ecosystems, as well carbon, nutrient trace element cycling, is little understood. addressing this knowledge gap within interdisciplinary research project DynaDeep by studying combined surface (hydro- morphodynamics) on processes (groundwater flow transport, reactions, microbiology). A estuary observatory was established northern beach island Spiekeroog facing North Sea, serving exemplary site model system. It consists fixed permanent infrastructure such pole measuring devices, multi-level wells electrode chain. This forms base autonomous measurements, regular repeated sampling, field campaigns experimental work, all which integrated via mathematical modelling understand quantify functioning reactor. First results show collecting intended spatially temporally resolved morphological, sedimentological data. Samples data further processed ex-situ experiments modelling. Ultimately, aims at elucidating global relevance these common but overlooked

Language: Английский

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Impact of mineral reactions and surface complexation on the transport of dissolved species in a subterranean estuary: Application of a comprehensive reactive transport modeling approach

Advances in Water Resources, Journal Year: 2024, Volume and Issue: 191, P. 104763 - 104763

Published: June 28, 2024

Subterranean estuaries (STE) are hotspots of biogeochemical reactions. Here, dissolved constituents in waters terrestrial and marine origin transformed before they discharge to the coastal oceans. The involved reactions complex non-linear, calling for application numerical reactive transport modeling (RTM) improve process understanding. aim this study was assess roles organic matter degradation coupled secondary mineral fate species STEs sandy beaches. A comprehensive RTM approach applied purpose, accounting effects ion activities, pH, pe, redox reactions, equilibria (calcite, goethite, siderite, iron sulfide, hydroxyapatite vivianite) as well surface complexation. Results show that STE biogeochemistry associated fluxes very sensitive assumed reaction network. For example, inorganic carbon pH were largely controlled by calcite siderite dynamics, Fe2+ HS- precipitated and/or sulfides. Moreover, PO43- concentrations affected both formation vivianite or This work helped establish relative importance some major processes STE. However, further field studies needed understand which play a role real-world STEs, including an exploration deep subsurface STEs. Such field-based observations will our conceptual understanding, is key developing well-constrained RTMs.

Language: Английский

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Bayesian modelling of sulphate isotopic composition in Pristine, contaminated, and experimental environments for Investigating microbial bacterial reduction

Journal of Hydrology, Journal Year: 2025, Volume and Issue: unknown, P. 132662 - 132662

Published: Jan. 1, 2025

Language: Английский

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Water Table Fluctuations Control Nitrate and Ammonium Fate in Coastal Aquifers

Water Resources Research, Journal Year: 2025, Volume and Issue: 61(1)

Published: Jan. 1, 2025

Abstract Coastal aquifers experience water table fluctuations that push and pull air through organic‐rich soils. This exchange affects the supply of oxygen, dissolved organic carbon (DOC), nitrogen (N) to shallow influences groundwater quality. To investigate fate N species, we used a meter‐long column containing sequence natural topsoil aquifer sediments. A fluctuating head was imposed at bottom with local, nitrate‐rich (16.5 mg/L NO 3 ‐N). We monitored in‐situ redox potential collected pore samples for analysis inorganic species DOC over 16 days. Reactive processes were more complex than anticipated. The remained anaerobic, while mineral sediments beneath alternated between aerobic, when dropped sucked across preferential flow paths, anaerobic conditions, high. fluid reactive transport model shows rises into soils, it limits soils release DOC, which stimulates removal nitrate from by denitrification. At end experiment, introduced seawater mimic storm surge. Seawater mobilized soil horizons, could reach if surge is long enough. These are relevant quality in developed coastal areas anthropogenic sources, as climate change rising seas will drive changes flood dynamics.

Language: Английский

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Spatial and temporal dynamics of groundwater biogeochemistry in the deep subsurface of a high-energy beach

Marine Chemistry, Journal Year: 2024, Volume and Issue: 267, P. 104461 - 104461

Published: Oct. 11, 2024

Language: Английский

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High Energy Systems are Underrepresented in Global Porewater Studies of Sandy Beach Aquifers

Published: Jan. 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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