The impact of electrogenic sulfide oxidation on elemental cycling and solute fluxes in coastal sediment

ABSTRACTMost stratified sulfidic holomictic lakes become oxygenated after annual turnover. In contrast, Lake Rogoznica, on the eastern Adriatic coast, has been observed to undergo a period of water column anoxia after water layer mixing and establishment of holomictic conditions. Although Lake Rogoznica's chemistry and hydrography have been studied extensively, it is unclear how the microbial communities typically inhabiting the oxic epilimnion and a sulfidic hypolimnion respond to such a drastic shift in redox conditions. We investigated the impact of anoxic holomixis on microbial diversity and microbially mediated sulfur cycling in Lake Rogoznica with an array of culture-independent microbiological methods. Our data suggest a tight coupling between the lake's chemistry and occurring microorganisms. During stratification, anoxygenic phototrophic sulfur bacteria were dominant at the chemocline and in the hypolimnion. After an anoxic mixing event, the anoxygenic phototrophic sulfur bacteria entirely disappeared, and the homogeneous, anoxic water column was dominated by a bloom of gammaproteobacterial sulfur oxidizers related to the GSO/SUP05 clade. This study is the first report of a community shift from phototrophic to chemotrophic sulfide oxidizers as a response to anoxic holomictic conditions in a seasonally stratified seawater lake.

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Climatic Variabilities Control the Solute Dynamics of Monsoon Karstic River: Approaches from C-Q Relationship, Isotopes, and Model Analysis in the Liujiang River

Water ◽

10.3390/w12030862 ◽

2020 ◽

Vol 12 (3) ◽

pp. 862 ◽

Cited By ~ 1

Author(s):

Jing Liu ◽

Hu Ding ◽

Min Xiao ◽

Zhu-Yan Xu ◽

Yuan Wei ◽

...

Keyword(s):

Chemical Weathering ◽

Carbonic Acid ◽

Dissolved Inorganic Carbon ◽

Climatic Variability ◽

Sulfide Oxidation ◽

Future Climate Change ◽

Climate Change Scenarios ◽

Soil Co2 ◽

Solute Dynamics ◽

The Impact

The dynamics of riverine solutes’ contents and sources reflect geological, ecological, and climatic information of the draining basin. This study investigated the influence of climatic variability on solute dynamics by the high-frequency hydrogeochemical monitory in the Liujiang River draining karst terrain of Guangxi Province, SW (Southwestern) China. In the study river, the content-discharge (C-Q) patterns of riverine solutes indicate that the majority of riverine solutes show similar dilution and near chemostatic behaviors responding to increasing discharge, especially geogenic solutes (such as weathering products from carbonate, silicate, and sulfide oxidation), whereas exogenous solutes (such as atmospheric input to riverine sulfate) and biological solutes (such as soil CO2) show higher contents with increasing discharge. Besides, the biological carbon is the main driver of the chemostatic behaviors of total dissolved inorganic carbon (DIC). The forward model results show that carbonate weathering dominates the water chemistry, and the weathering rates are intensified during high flow period due to additional inputs of weathering agents, i.e., the biologic carbonic acid from dissolution of soil CO2, indicated by δ13CDIC. In addition, there exists the strong capacity of CO2 consumption that is heavily dependent on climatic variables such as precipitation and air temperature in this study river. Our study highlights the impact of climatic variability on solutes dynamics and chemical weathering and thus must be better addressed in C models under future climate change scenarios.

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The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study

Biogeosciences ◽

10.5194/bg-14-285-2017 ◽

2017 ◽

Vol 14 (2) ◽

pp. 285-300 ◽

Cited By ~ 15

Author(s):

Stefano Bonaglia ◽

Astrid Hylén ◽

Jayne E. Rattray ◽

Mikhail Y. Kononets ◽

Nils Ekeroth ◽

...

Keyword(s):

Baltic Sea ◽

Water Column ◽

Nitrate Reduction ◽

Organic N ◽

Fixed Nitrogen ◽

Coastal Station ◽

Solute Fluxes ◽

The Baltic ◽

The Impact

Abstract. Over the last decades, the impact of human activities on the global nitrogen (N) cycle has drastically increased. Consequently, benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while in oligotrophic systems its understanding is still scarce. Here we report on benthic solute fluxes and on rates of denitrification, anammox, and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with benthic chamber landers during two cruises to the Gulf of Bothnia (GOB), a cold, oligotrophic basin located in the northern part of the Baltic Sea. Rates of N burial were also inferred to investigate the fate of fixed N in these sediments. Most of the total dissolved fixed nitrogen (TDN) diffusing to the water column was composed of organic N. Average rates of dinitrogen (N2) production by denitrification and anammox (range: 53–360 µmol N m−2 day−1) were comparable to those from Arctic and subarctic sediments worldwide (range: 34–344 µmol N m−2 day−1). Anammox accounted for 18–26 % of the total N2 production. Absence of free hydrogen sulfide and low concentrations of dissolved iron in sediment pore water suggested that denitrification and DNRA were driven by organic matter oxidation rather than chemolithotrophy. DNRA was as important as denitrification at a shallow, coastal station situated in the northern Bothnian Bay. At this pristine and fully oxygenated site, ammonium regeneration through DNRA contributed more than one-third to the TDN efflux and accounted, on average, for 45 % of total nitrate reduction. At the offshore stations, the proportion of DNRA in relation to denitrification was lower (0–16 % of total nitrate reduction). Median value and range of benthic DNRA rates from the GOB were comparable to those from the southern and central eutrophic Baltic Sea and other temperate estuaries and coasts in Europe. Therefore, our results contrast with the view that DNRA is negligible in cold and well-oxygenated sediments with low organic carbon loading. However, the mechanisms behind the variability in DNRA rates between our sites were not resolved. The GOB sediments were a major source (237 kt yr−1, which corresponds to 184 % of the external N load) of fixed N to the water column through recycling mechanisms. To our knowledge, our study is the first to document the simultaneous contribution of denitrification, DNRA, anammox, and TDN recycling combined with in situ measurements.

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Rapid cloud removal of dimethyl sulfide oxidation products limits SO2 and cloud condensation nuclei production in the marine atmosphere

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2110472118 ◽

2021 ◽

Vol 118 (42) ◽

pp. e2110472118

Author(s):

Gordon A. Novak ◽

Charles H. Fite ◽

Christopher D. Holmes ◽

Patrick R. Veres ◽

J. Andrew Neuman ◽

...

Keyword(s):

Radiative Forcing ◽

Dimethyl Sulfide ◽

Cloud Condensation Nuclei ◽

Sulfide Oxidation ◽

Radiation Balance ◽

Marine Atmosphere ◽

Condensation Nuclei ◽

Near Surface ◽

Loss Process ◽

The Impact

Oceans emit large quantities of dimethyl sulfide (DMS) to the marine atmosphere. The oxidation of DMS leads to the formation and growth of cloud condensation nuclei (CCN) with consequent effects on Earth’s radiation balance and climate. The quantitative assessment of the impact of DMS emissions on CCN concentrations necessitates a detailed description of the oxidation of DMS in the presence of existing aerosol particles and clouds. In the unpolluted marine atmosphere, DMS is efficiently oxidized to hydroperoxymethyl thioformate (HPMTF), a stable intermediate in the chemical trajectory toward sulfur dioxide (SO2) and ultimately sulfate aerosol. Using direct airborne flux measurements, we demonstrate that the irreversible loss of HPMTF to clouds in the marine boundary layer determines the HPMTF lifetime (τHPMTF < 2 h) and terminates DMS oxidation to SO2. When accounting for HPMTF cloud loss in a global chemical transport model, we show that SO2 production from DMS is reduced by 35% globally and near-surface (0 to 3 km) SO2 concentrations over the ocean are lowered by 24%. This large, previously unconsidered loss process for volatile sulfur accelerates the timescale for the conversion of DMS to sulfate while limiting new particle formation in the marine atmosphere and changing the dynamics of aerosol growth. This loss process potentially reduces the spatial scale over which DMS emissions contribute to aerosol production and growth and weakens the link between DMS emission and marine CCN production with subsequent implications for cloud formation, radiative forcing, and climate.

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Intense Chemical Weathering at Glacial Meltwater-Dominated Hailuogou Basin in the Southeastern Tibetan Plateau

Water ◽

10.3390/w11061209 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1209 ◽

Cited By ~ 3

Author(s):

Xiangying Li ◽

Yongjian Ding ◽

Qiao Liu ◽

Yong Zhang ◽

Tianding Han ◽

...

Keyword(s):

Tibetan Plateau ◽

River Water ◽

River Discharge ◽

Chemical Weathering ◽

Sulfide Oxidation ◽

Solute Flux ◽

The Tibetan Plateau ◽

Denudation Rate ◽

Weathering Processes ◽

The Impact

Climate warming has caused rapid shrinkage of glaciers in the Tibetan Plateau (TP), but the impact of glacier retreat on the chemical denudation rate remains largely unknown at the temperate glacial basins. The chemical weathering processes were examined at a temperate glacial basin (HLG) in the southeastern TP based on comprehensive data from the supraglacial meltwater, proglacial river water, precipitation and groundwater over two glacier melt seasons in 2008 and 2013. The concentrations of major ions and suspended sediments in river water exhibit a pronounced seasonality and display a close relationship with river discharge, suggesting a strong hydrological control on the chemical and physical weathering processes. Runoff chemistry is dominated by carbonate weathering and sulfide oxidation. HCO3−, Ca2+, and/or SO42− are the dominant ions in meltwater, river water, precipitation and groundwater. For river water, HCO3− and Ca2+ primarily come from calcite weathering, and SO42− is mainly derived from pyrite oxidation. Both solute and sediment fluxes are positively related to river discharge (r = 0.69, p < 0.01 for sediments). The solute flux and yields are 18,095–19,435 t·year−1 and 225–241 t·km−2·year−1, and the sediment load and yields are 126,390 t·year−1 and 1570 t·km−2·year−1, respectively. The solute yields, cationic denudation rate (CDR; 2850–3108 Σ*meq+ m−2·year−1) and chemical weathering intensity (CWI; 616–711 Σ*meq+ m−3·year−1) at HLG are higher than those at most basins irrespective of the lithology, suggesting more intense weathering in the TP in comparison to other glacial basins worldwide.

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Cosmogenic nuclide and solute flux data from central Cuba emphasize the importance of both physical and chemical denudation in highly weathered landscapes

10.5194/gchron-2021-31 ◽

2021 ◽

Author(s):

Mae Kate Campbell ◽

Paul R. Bierman ◽

Amanda H. Schmidt ◽

Rita Sibello Hernández ◽

Alejandro García-Moya ◽

...

Keyword(s):

Mass Loss ◽

Landscape Change ◽

Cosmogenic Nuclides ◽

Mineral Dissolution ◽

Solute Flux ◽

Dissolution Rates ◽

Cosmogenic Nuclide ◽

Solute Fluxes ◽

Dissolved Load ◽

The Impact

Abstract. We consider measurements of both in situ produced cosmogenic nuclides and dissolved load flux to characterize the processes and pace of landscape change in central Cuba. The tropical landscape of Cuba is losing mass in multiple ways, making it difficult to quantify total denudation rates and thus to assess the impact of agricultural practices on rates of contemporary landscape change. Long-term sediment generation rates inferred from 26Al and 10Be concentrations in quartz extracted from central Cuban river sand range from 3.7–182 tons km−2 yr−1 (mean = 62, median = 57). Rock dissolution rates (24–154 tons km−2 yr−1; mean = 84, median = 78) inferred from stream solute loads exceed measured cosmogenic nuclide-derived sediment generation rates in 15 of 22 basins, indicating significant landscape-scale mass loss not reflected in the cosmogenic nuclide measurements. 26Al / 10Be ratios lower than that of surface production are consistent with the presence of a deep, mixed, regolith layer in the five basins that have the greatest disagreement between rock dissolution rates (high) and sediment generation rates inferred from cosmogenic nuclide concentrations (low). Our data show that accounting for the contribution of mineral dissolution at depth in calculations of total denudation is particularly important in the humid tropics, where dissolved load fluxes are high, and where mineral dissolution can occur many meters below the surface, beyond the penetration depth of most cosmic rays and thus the production of most cosmogenic nuclides. Relying on cosmogenic nuclide data or stream solute fluxes alone would both lead to underestimates of total landscape denudation in the central Cuba, emphasizing the importance of combining these approaches to fully capture mass loss in tropical landscapes.

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Modelling the impact of Siboglinids on the biogeochemistry of the Captain Arutyunov mud volcano (Gulf of Cadiz)

Biogeosciences Discussions ◽

10.5194/bgd-9-6683-2012 ◽

2012 ◽

Vol 9 (6) ◽

pp. 6683-6714

Author(s):

K. Soetaert ◽

D. van Oevelen ◽

S. Sommer

Keyword(s):

Transport Model ◽

Sulfide Oxidation ◽

Mud Volcano ◽

Biogeochemical Model ◽

Anaerobic Oxidation Of Methane ◽

Anaerobic Oxidation ◽

Oxidation Of Methane ◽

Sediment Biogeochemistry ◽

Reaction Transport ◽

The Impact

Abstract. A 2-Dimensional mathematical reaction-transport model was developed to study the impact of the mud-dwelling frenulate tubeworm Siboglinum sp. on the biogeochemistry of a sediment (MUC15) at the Captain Arutyunov mud volcano (CAMV). By explicitly describing the worm in its surrounding sediment, we are able to make budgets of processes occurring in- or outside of the worm, and to quantify how different worm densities and biomasses affect the anaerobic oxidation of methane (AOM) and sulfide reoxidation (HSox). The model shows that, at the observed densities, the presence of a thin worm body is sufficient to keep the upper 10 cm of sediment well homogenized with respect to dissolved substances, in agreement with observations. By this "bio-ventilation" activity, the worm pushes the sulfate-methane transition (SMT) zone downward to the posterior end of its body, and simultaneously physically separates the sulfide produced during the anaerobic oxidation of methane from oxygen. While there is little scope for the AOM to take place in the tubeworm's body, 70% of the sulfide that is produced by sulfate reduction processes or that is advected in the sediment is preferentially shunted via the organism where it is oxidised by endosymbionts providing the energy for the worm's growth. The process of sulfide reoxidation, occurring predominantly in the worm's body is thus very distinct from the anaerobic oxidation of methane, which is a diffuse process that takes place in the sediments in the methane-sulfate transition zone. We show how the sulfide oxidation process is affected by increasing densities and length of the frenulates, and by upward advection velocity. Our biogeochemical model is one of the first to describe tubeworms explicitly. It can be used to directly link biological and biogeochemical observations at seep sites, and to study the impacts of mud-dwelling frenulates on the sediment biogeochemistry under varying environmental conditions. Also, it provides a tool to explore the competition between bacteria and fauna for available energy resources.

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Lake Bacterial Assemblage Composition Is Sensitive to Biological Disturbance Caused by an Invasive Filter Feeder

mSphere ◽

10.1128/msphere.00189-17 ◽

2017 ◽

Vol 2 (3) ◽

Cited By ~ 8

Author(s):

Vincent J. Denef ◽

Hunter J. Carrick ◽

Joann Cavaletto ◽

Edna Chiang ◽

Thomas H. Johengen ◽

...

Keyword(s):

Global Change ◽

Functional Group ◽

Group Representation ◽

Taxonomic Composition ◽

Direct Effects ◽

Dreissenid Mussels ◽

Elemental Cycling ◽

Anthropogenic Global Change ◽

Bacterial Assemblages ◽

The Impact

ABSTRACT Freshwater bacteria play fundamental roles in global elemental cycling and are an intrinsic part of local food webs. Human activities are altering freshwater environments, and much has been learned regarding the sensitivity of bacterial assemblages to a variety of these disturbances. Yet, relatively few studies have focused on how species invasion, which is one of the most important aspects of anthropogenic global change, affects freshwater bacterial assemblages. This study focuses on the impact of invasive dreissenid mussels (IDMs), a globally distributed group of invasive species with large impacts on freshwater phyto- and zooplankton assemblages. We show that IDMs have direct effects on lake bacterioplankton abundance, taxonomic composition, and inferred bacterial functional group representation. One approach to improve forecasts of how global change will affect ecosystem processes is to better understand how anthropogenic disturbances alter bacterial assemblages that drive biogeochemical cycles. Species invasions are important contributors to global change, but their impacts on bacterial community ecology are rarely investigated. Here, we studied direct impacts of invasive dreissenid mussels (IDMs), one of many invasive filter feeders, on freshwater lake bacterioplankton. We demonstrated that direct effects of IDMs reduced bacterial abundance and altered assemblage composition by preferentially removing larger and particle-associated bacteria. While this increased the relative abundances of many free-living bacterial taxa, some were susceptible to filter feeding, in line with efficient removal of phytoplankton cells of <2 μm. This selective removal of particle-associated and larger bacteria by IDMs altered inferred bacterial functional group representation, defined by carbon and energy source utilization. Specifically, we inferred an increased relative abundance of chemoorganoheterotrophs predicted to be capable of rhodopsin-dependent energy generation. In contrast to the few previous studies that have focused on the longer-term combined direct and indirect effects of IDMs on bacterioplankton, our study showed that IDMs act directly as a biological disturbance to which freshwater bacterial assemblages are sensitive. The negative impacts on particle-associated bacteria, which have been shown to be more active than free-living bacteria, and the inferred shifts in functional group representation raise the possibility that IDMs may directly alter bacterially mediated ecosystem functions. IMPORTANCE Freshwater bacteria play fundamental roles in global elemental cycling and are an intrinsic part of local food webs. Human activities are altering freshwater environments, and much has been learned regarding the sensitivity of bacterial assemblages to a variety of these disturbances. Yet, relatively few studies have focused on how species invasion, which is one of the most important aspects of anthropogenic global change, affects freshwater bacterial assemblages. This study focuses on the impact of invasive dreissenid mussels (IDMs), a globally distributed group of invasive species with large impacts on freshwater phyto- and zooplankton assemblages. We show that IDMs have direct effects on lake bacterioplankton abundance, taxonomic composition, and inferred bacterial functional group representation.

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