Accelerated microbial organic matter mineralization following salt-water intrusion into tidal freshwater marsh soils

Weston, Nathaniel B.; Vile, Melanie A.; Neubauer, Scott C.; Velinsky, David J.

doi:10.1007/s10533-010-9427-4

Cited by 277 publications

(226 citation statements)

References 65 publications

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“…2a and c). Similarly, other studies have documented short-term increases in potential CO 2 production, CO 2 emissions, and/or the production of dissolved inorganic C following saltwater intrusion (Chambers et al, 2011Weston et al, 2011;Marton et al, 2012;Jun et al, 2013), with the duration of the response being < 3 weeks (Chambers et al, 2011) up to 6 months (Weston et al, 2011). In contrast, short-to moderate-term saltwater intrusion typically results in decreased rates of CH 4 production and emissions, which also occurred in our study ( Fig.…”

Section: Initial Biogeochemical Effects Of Saltwater Intrusionsupporting

confidence: 88%

“…This response is supported both by thermodynamic theory (i.e., sulfate reduction is energetically favorable over methanogenesis) (Schlesinger, 1997) and the experimental results of several other saltwater intrusion studies (e.g., Weston et al, 2006;Chambers et al, 2011;Marton et al, 2012;Morse et al, 2012;Neubauer, 2013a). However, Weston et al (2011) reported contrasting results, and documented a large, sustained increase in CH 4 emissions that persisted for 5 months following simulated saltwater intrusion. One proposed explanation for this inconsistency is that soil characteristics or other site properties may mediate system responses to saltwater intrusion.…”

Section: Initial Biogeochemical Effects Of Saltwater Intrusionmentioning

confidence: 61%

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Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon

2013

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Abstract. Environmental perturbations in wetlands affect the integrated plant-microbial-soil system, causing biogeochemical responses that can manifest at local to global scales. The objective of this study was to determine how saltwater intrusion affects carbon mineralization and greenhouse gas production in coastal wetlands. Working with tidal freshwater marsh soils that had experienced ∼ 3.5 yr of in situ saltwater additions, we quantified changes in soil properties, measured extracellular enzyme activity associated with organic matter breakdown, and determined potential rates of anaerobic carbon dioxide (CO 2 ) and methane (CH 4 ) production. Soils from the field plots treated with brackish water had lower carbon content and higher C : N ratios than soils from freshwater plots, indicating that saltwater intrusion reduced carbon availability and increased organic matter recalcitrance. This was reflected in reduced activities of enzymes associated with the hydrolysis of cellulose and the oxidation of lignin, leading to reduced rates of soil CO 2 and CH 4 production. The effects of long-term saltwater additions contrasted with the effects of short-term exposure to brackish water during three-day laboratory incubations, which increased rates of CO 2 production but lowered rates of CH 4 production. Collectively, our data suggest that the long-term effect of saltwater intrusion on soil CO 2 production is indirect, mediated through the effects of elevated salinity on the quantity and quality of autochthonous organic matter inputs to the soil. In contrast, salinity, organic matter content, and enzyme activities directly influence CH 4 production. Our analyses demonstrate that saltwater intrusion into tidal freshwater marshes affects the entire process of carbon mineralization, from the availability of organic carbon through its terminal metabolism to CO 2 and/or CH 4 , and illustrate that long-term shifts in biogeochemical functioning are not necessarily consistent with short-term disturbance-type responses.

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Section: Initial Biogeochemical Effects Of Saltwater Intrusionsupporting

confidence: 88%

Section: Initial Biogeochemical Effects Of Saltwater Intrusionmentioning

confidence: 61%

Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon

2013

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“…5). These simple comparisons do not include important long-term constraints on the concentration of carbon within a wetland soil (Kirwan and Mudd, 2012), changes in carbon quality (Ball and Drake, 1997), interactions between multiple components of global change (Langley and Megonigal, 2010) or various feedbacks between climate, biota, and sea-level rise (Wolf et al, 2007;Weston et al, 2011;Kirwan and Mudd, 2012). How temperature sensitivities of labile carbon decomposition relate to the more refractory carbon that is important for long-term carbon burial, is poorly understood (Fang et al, 2005;Craine et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Temperature sensitivity of organic-matter decay in tidal marshes

2014

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Abstract. Approximately half of marine carbon sequestration takes place in coastal wetlands, including tidal marshes, where organic matter contributes to soil elevation and ecosystem persistence in the face of sea-level rise. The longterm viability of marshes and their carbon pools depends, in part, on how the balance between productivity and decay responds to climate change. Here, we report the sensitivity of labile soil organic-matter decay in tidal marshes to seasonal and latitudinal variations in temperature measured over a 3-year period. We find a moderate increase in decay rate at warmer temperatures (3-6 % per • C, Q 10 = 1.3-1.5). Despite the profound differences between microbial metabolism in wetlands and uplands, our results indicate a strong conservation of temperature sensitivity. Moreover, simple comparisons with organic-matter production suggest that elevated atmospheric CO 2 and warmer temperatures will accelerate carbon accumulation in marsh soils, and potentially enhance their ability to survive sea-level rise.

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“…In contrast, the freshwater sediments used in this simulation had lower sulfate availability, and the sulfatereducing bacteria abundances were an order of magnitude lower than methanogens. In some cases, however, sulfate reduction can increase without a corresponding decrease in CH 4 production (Hopfensperger et al, 2014), especially if seawater intrusion increases both sulfate and organic matter availability (Weston et al, 2011).…”

Section: Seawater Addition Experimentsmentioning

confidence: 99%

Regulators of coastal wetland methane production and responses to simulated global change

et al. 2017

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Abstract. Wetlands are the largest natural source of methane (CH 4 ) emissions to the atmosphere, which vary along salinity and productivity gradients. Global change has the potential to reshape these gradients and therefore alter future contributions of wetlands to the global CH 4 budget. Our study examined CH 4 production along a natural salinity gradient in fully inundated coastal Alaska wetlands. In the laboratory, we incubated natural sediments to compare CH 4 production rates between non-tidal freshwater and tidal brackish wetlands, and quantified the abundances of methanogens and sulfate-reducing bacteria in these ecosystems. We also simulated seawater intrusion and enhanced organic matter availability, which we predicted would have contrasting effects on coastal wetland CH 4 production. Tidal brackish wetlands produced less CH 4 than non-tidal freshwater wetlands probably due to high sulfate availability and generally higher abundances of sulfate-reducing bacteria, whereas non-tidal freshwater wetlands had significantly greater methanogen abundances. Seawater addition experiments with freshwater sediments, however, did not reduce CH 4 production, perhaps because the 14-day incubation period was too short to elicit a shift in microbial communities. In contrast, increased organic matter enhanced CH 4 production in 75 % of the incubations, but this response depended on the macrophyte species added, with half of the species treatments having no significant effect. Our study suggests that CH 4 production in coastal wetlands, and therefore their overall contribution to the global CH 4 cycle, will be sensitive to increased organic matter availability and potentially seawater intrusion. To better predict future wetland contributions to the global CH 4 budget, future studies and modeling efforts should investigate how multiple global change mechanisms will interact to impact CH 4 dynamics.

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Accelerated microbial organic matter mineralization following salt-water intrusion into tidal freshwater marsh soils

Cited by 277 publications

References 65 publications

Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon

Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon

Temperature sensitivity of organic-matter decay in tidal marshes

Regulators of coastal wetland methane production and responses to simulated global change

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