High rates of anaerobic methane oxidation in freshwater wetlands reduce potential atmospheric methane emissions

Segarra, Katherine Eowyn; Schubotz, Florence; Samarkin, V.; Yoshinaga, Marcos Y.; Hinrichs, Kai‐Uwe; Joye, Samantha B.

doi:10.1038/ncomms8477

Cited by 241 publications

(180 citation statements)

References 68 publications

(145 reference statements)

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“…The anaerobic oxidation of CH 4 has rarely been considered as a mechanism for altered CH 4 v www.esajournals.org emissions in wetland sediments (Smemo and Yavitt 2011). Recently, tidal freshwater sediments have been shown to support high rates of anaerobic CH 4 oxidation coupled to SO 4 2À reduction (Segarra et al 2015) and to Fe(III), Mn(IV), and NO 3 À reduction (Segarra et al 2013). The interactions between increased SO 4 2À reduction, methanogenesis, and CH 4 oxidation (aerobic and anaerobic) are likely to vary with sitespecific factors such as soil and water chemistry, O 2 availability, vegetation, and fluctuations in hydrology.…”

Section: Biogeochemical Cyclingmentioning

confidence: 99%

A global perspective on wetland salinization: ecological consequences of a growing threat to freshwater wetlands

et al. 2015

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Abstract. Salinization, a widespread threat to the structure and ecological functioning of inland and coastal wetlands, is currently occurring at an unprecedented rate and geographic scale. The causes of salinization are diverse and include alterations to freshwater flows, land-clearance, irrigation, disposal of wastewater effluent, sea level rise, storm surges, and applications of de-icing salts. Climate change and anthropogenic modifications to the hydrologic cycle are expected to further increase the extent and severity of wetland salinization. Salinization alters the fundamental physicochemical nature of the soil-water environment, increasing ionic concentrations and altering chemical equilibria and mineral solubility. Increased concentrations of solutes, especially sulfate, alter the biogeochemical cycling of major elements including carbon, nitrogen, phosphorus, sulfur, iron, and silica. The effects of salinization on wetland biogeochemistry typically include decreased inorganic nitrogen removal (with implications for water quality and climate regulation), decreased carbon storage (with implications for climate regulation and wetland accretion), and increased generation of toxic sulfides (with implications for nutrient cycling and the health/functioning of wetland biota). Indeed, increased salt and sulfide concentrations induce physiological stress in wetland biota and ultimately can result in large shifts in wetland communities and their associated ecosystem functions. The productivity and composition of freshwater species assemblages will be highly altered, and there is a high potential for the disruption of existing interspecific interactions. Although there is a wealth of information on how salinization impacts individual ecosystem components, relatively few studies have addressed the complex and often non-linear feedbacks that determine ecosystem-scale responses or considered how wetland salinization will affect landscape-level processes. Although the salinization of wetlands may be unavoidable in many cases, these systems may also prove to be a fertile testing ground for broader ecological theories including (but not limited to): investigations into alternative stable states and tipping points, trophic cascades, disturbance-recovery processes, and the role of historical events and landscape context in driving community response to disturbance.

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Section: Biogeochemical Cyclingmentioning

confidence: 99%

A global perspective on wetland salinization: ecological consequences of a growing threat to freshwater wetlands

et al. 2015

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“…The traditional assumption is that aerobic methanotrophy dominates CH 4 cycling in wetlands by oxidizing an estimated 40 to 70% of the gross CH 4 production in these ecosystems (11). Recent findings (12) challenged this conjecture by providing evidence that AOM may consume up to 200 Tg of CH 4 · year Ϫ1 , decreasing their potential CH 4 emission by 50% in these habitats. Most AOM activities observed in wetlands have been related to sulfate reduction (12,13), but other electron acceptors remain feasible.…”

Section: Importancementioning

confidence: 99%

Anaerobic Methane Oxidation Driven by Microbial Reduction of Natural Organic Matter in a Tropical Wetland

Valenzuela

Prieto-Davó

López-Lozano

et al. 2017

Appl Environ Microbiol

132

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Wetlands constitute the main natural source of methane on Earth due to their high content of natural organic matter (NOM), but key drivers, such as electron acceptors, supporting methanotrophic activities in these habitats are poorly understood. We performed anoxic incubations using freshly collected sediment, along with water samples harvested from a tropical wetland, amended with 13 C-methane (0.67 atm) to test the capacity of its microbial community to perform anaerobic oxidation of methane (AOM) linked to the reduction of the humic fraction of its NOM. Collected evidence demonstrates that electron-accepting functional groups (e.g., quinones) present in NOM fueled AOM by serving as a terminal electron acceptor. Indeed, while sulfate reduction was the predominant process, accounting for up to 42.5% of the AOM activities, the microbial reduction of NOM concomitantly occurred. Furthermore, enrichment of wetland sediment with external NOM provided a complementary electron-accepting capacity, of which reduction accounted for ϳ100 nmol 13 CH 4 oxidized · cm Ϫ3 · day Ϫ1 . Spectroscopic evidence showed that quinone moieties were heterogeneously distributed in the wetland sediment, and their reduction occurred during the course of AOM. Moreover, an enrichment derived from wetland sediments performing AOM linked to NOM reduction stoichiometrically oxidized methane coupled to the reduction of the humic analogue anthraquinone-2,6-disulfonate. Microbial populations potentially involved in AOM coupled to microbial reduction of NOM were dominated by divergent biota from putative AOMassociated archaea. We estimate that this microbial process potentially contributes to the suppression of up to 114 teragrams (Tg) of CH 4 · year Ϫ1 in coastal wetlands and more than 1,300 Tg · year Ϫ1 , considering the global wetland area. IMPORTANCEThe identification of key processes governing methane emissions from natural systems is of major importance considering the global warming effects triggered by this greenhouse gas. Anaerobic oxidation of methane (AOM) coupled to the microbial reduction of distinct electron acceptors plays a pivotal role in mitigating methane emissions from ecosystems. Given their high organic content, wetlands constitute the largest natural source of atmospheric methane. Nevertheless, processes controlling methane emissions in these environments are poorly understood. Here, we provide tracer analysis with 13 CH 4 and spectroscopic evidence revealing that AOM linked to the microbial reduction of redox functional groups in natural organic matter (NOM) prevails in a tropical wetland. We suggest that microbial reduction of NOM may largely contribute to the suppression of methane emissions from

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“…8). Both the highest and lowest CH 4 concentrations are observed in waters < 5 • C. In freshwater environments, the concentration of dissolved CH 4 reflects the balance between CH 4 production and CH 4 consumption by anaerobic or aerobic oxidation (Duc et al, 2010;Dzyuban, 2010;Encinas Fernandez et al, 2014;Kankaala et al, 2007;Martinez-Cruz et al, 2015;Segarra et al, 2015;Smemo and Yavitt, 2011). Methane production is affected by temperature, where higher temperatures result in increased production (Duc et al, 2010).…”

Section: Effects Of Temperature On Chmentioning

confidence: 99%

“…Under warm conditions in 2012, not only were CH 4 concentrations in sediments and anoxic waters elevated but the percentage of CH 4 oxidized was also higher. Several studies suggest that MOx is important for mitigating CH 4 emissions to the atmosphere Milucka et al, 2015;Segarra et al, 2015). However, despite the likelihood that MOx was more efficient in 2012 under warmer conditions, CH 4 concentrations in the stored pool were higher in 2012 than in 2013.…”

Section: Effects Of Stratification On Chmentioning

confidence: 99%

Exceptional summer warming leads to contrasting outcomes for methane cycling in small Arctic lakes of Greenland

2017

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Abstract. In thermally stratified lakes, the greatest annual methane emissions typically occur during thermal overturn events. In July of 2012, Greenland experienced significant warming that resulted in substantial melting of the Greenland Ice Sheet and enhanced runoff events. This unusual climate phenomenon provided an opportunity to examine the effects of short-term natural heating on lake thermal structure and methane dynamics and compare these observations with those from the following year, when temperatures were normal. Here, we focus on methane concentrations within the water column of five adjacent small lakes on the icefree margin of southwestern Greenland under open-water and ice-covered conditions from 2012-2014. Enhanced warming of the epilimnion in the lakes under open-water conditions in 2012 led to strong thermal stability and the development of anoxic hypolimnia in each of the lakes. As a result, during open-water conditions, mean dissolved methane concentrations in the water column were significantly (p < 0.0001) greater in 2012 than in 2013. In all of the lakes, mean methane concentrations under ice-covered conditions were significantly (p < 0.0001) greater than under open-water conditions, suggesting spring overturn is currently the largest annual methane flux to the atmosphere. As the climate continues to warm, shorter ice cover durations are expected, which may reduce the winter inventory of methane and lead to a decrease in total methane flux during ice melt. Under openwater conditions, greater heat income and warming of lake surface waters will lead to increased thermal stratification and hypolimnetic anoxia, which will consequently result in increased water column inventories of methane. This stored methane will be susceptible to emissions during fall overturn, which may result in a shift in greatest annual efflux of methane from spring melt to fall overturn. The results of this study suggest that interannual variation in ground-level air temperatures may be the primary driver of changes in methane dynamics because it controls both the duration of ice cover and the strength of thermal stratification.

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High rates of anaerobic methane oxidation in freshwater wetlands reduce potential atmospheric methane emissions

Cited by 241 publications

References 68 publications

A global perspective on wetland salinization: ecological consequences of a growing threat to freshwater wetlands

A global perspective on wetland salinization: ecological consequences of a growing threat to freshwater wetlands

Anaerobic Methane Oxidation Driven by Microbial Reduction of Natural Organic Matter in a Tropical Wetland

Exceptional summer warming leads to contrasting outcomes for methane cycling in small Arctic lakes of Greenland

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