Aquatic Geochemistry最新文献

{"title":"The Effects of pH, Temperature, and Humic-Like Substances on Anaerobic Carbon Degradation and Methanogenesis in Ombrotrophic and Minerotrophic Alaskan Peatlands","authors":"Lin Zhang,&nbsp;Xiao Liu,&nbsp;Khrys Duddleston,&nbsp;Mark E. Hines","doi":"10.1007/s10498-020-09372-0","DOIUrl":"https://doi.org/10.1007/s10498-020-09372-0","url":null,"abstract":"<p>Methane production usually increases from the acidic sphagnum-dominated ombrotrophic peatlands to minerotrophic ones with more neutral pH and higher coverage of vascular plants. Along this ombrotrophic–minerotrophic gradient, pH, microbial communities, and properties of dissolved organic matter in porewater all vary greatly. The hydrographic change resulted from permafrost thaw and projected global warming can potentially connect the minerotrophic and ombrotrophic sites via porewater and turn acidic bogs to minerotrophic fens. It is thus very important to investigate how the anaerobic carbon degradation processes respond to changes in fundamental factors like pH, temperature, properties of dissolved organic matter, and microbial communities resulted from such hydrographic change. In this study, one ombrotrophic (pH?=?3.9) and one minerotrophic peatland site were sampled in Fairbanks, Alaska in Sep 2017 and a 42-day-period anaerobic laboratory incubation was conducted to study the changes in anaerobic carbon degradation processes including primary and secondary fermentation, methanogenesis, and acetogenesis when pH, temperature, and porewater were manipulated individually and a combination of two or three of these factors. The results suggested lowering pH would inhibit many anaerobic carbon degradation processes in the minerotrophic peatland except primary fermentation. Elevating pH in the ombrotrophic site did not stimulate its methanogen community, but primary fermentation responded better with increasing pH than with increasing temperature alone. Replacing the porewater in the minerotrophic site with that from the ombrotrophic site with high aromaticity did not inhibit methanogenesis but potentially brought in highly efficient primary fermenters. Acetoclastic methanogenesis, acetogenesis, and syntrophy only exist in the minerotrophic site but not at the ombrotrophic one. Porewater from the minerotrophic site could potentially introduce acetoclastic methanogens and syntrophs to the ombrotrophic site but would not make them active unless both pH and temperature were increased. When ground water connects ombrotrophic and minerotrophic peatlands due to thawing of permafrost, secondary fermenters and acetoclastic methanogens could be introduced to acidic bogs and cooperate efficiently to degrade the stored carbon in ombrotrophic peatlands especially under elevated temperature conditions.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"26 3","pages":"221 - 244"},"PeriodicalIF":1.6,"publicationDate":"2020-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-020-09372-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4237941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Role of a Tidal Flat–Saltmarsh System as a Source–Sink of Mercury in a Contaminated Coastal Lagoon Environment (Northern Adriatic Sea)","authors":"Elisa Petranich,&nbsp;Luca Terribili,&nbsp;Alessandro Acquavita,&nbsp;Elena Pavoni,&nbsp;Leonardo Langone,&nbsp;Stefano Covelli","doi":"10.1007/s10498-020-09373-z","DOIUrl":"https://doi.org/10.1007/s10498-020-09373-z","url":null,"abstract":"<p>The Marano and Grado Lagoon (northern Adriatic Sea, Italy) is contaminated mainly by mercury (Hg) of mining and industrial origin. This work aims to investigate the sedimentary records of Hg of a tidal flat–saltmarsh (TF–S) system and to understand the role played by tidal fluxes in terms of the transport, accumulation and release of Hg due to the periodic flow of the tide. The complex history of the sources of Hg in the area of the TF–S system has resulted in several fluctuations of Hg in sediments over time; due to its higher sedimentation rate (1.3?cm year^?1) than the subtidal areas of the Grado lagoon, the outer area of the TF–S system is more active in terms of accumulation (from 56 to 81?mg?m^?2 year^?1) than the inner area. Fluxes were estimated at the mouth of a principal tidal creek by combining discrete hourly tidal flow measurements with weighed measurements of dissolved (DHg) and particulate (PHg) mercury obtained via water sample collection. Mercury, mainly in particulate form, is drained by the tidal creek from the marsh during a tidal semi-cycle. The highest flux of PHg was recorded during ebb tide in July (1071?mg). The calculation of the quantitative flows of PHg and DHg highlighted a tendency for Hg to be exported from the TF–S to the lagoon channel during a tidal semi-cycle. However, the results obtained here for the Hg fluxes do not allow for the depiction of a constant positive or negative budget as that found in the literature for macro-scale budget calculations at lagoon tidal inlets. A possible explanation for there being no constant trend in the PHg and DHg budget is that our TF–S system is located in a lagoon area where previous findings reported accretion or a balance situation between erosion and sedimentation processes.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"26 3","pages":"245 - 267"},"PeriodicalIF":1.6,"publicationDate":"2020-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-020-09373-z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4233552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radium Isotopes as a Tracer of Water Sources and Mixing in the Vidourle Stream (South of France)","authors":"Arnold Molina-Porras,&nbsp;Michel Condomines,&nbsp;Pierre-Louis Legeay,&nbsp;Vincent Bailly-Comte,&nbsp;Jean Luc Seidel","doi":"10.1007/s10498-020-09371-1","DOIUrl":"https://doi.org/10.1007/s10498-020-09371-1","url":null,"abstract":"<p>This study reports analyses of Ra isotopes in a Mediterranean stream, the Vidourle river, whose upper course drains the granitic and metamorphic basement of the SE part of the French Massif Central (Cévennes) and then flows through the karstified carbonates of Jurassic and Cretaceous ages. In these low-Ra waters (²²⁶Ra activities range from 1.5 to 4.9?mBq/L), all four Ra isotopes were successfully analyzed through gamma spectrometry during a single analysis. ²²⁶Ra activities and (²²⁸Ra/²²⁶Ra) ratios are distinctly higher in waters draining the Variscan basement than in waters affected by dissolution of Mesozoic carbonates, in agreement with U contents and Th/U ratios of both rock types. This results in a general N-S decrease, which parallels the evolution of the ⁸⁷Sr/⁸⁶Sr ratios. (²²⁸Ra/²²⁶Ra) ratios reported vs 1/(²²⁶Ra) display linear relationships suggesting mixing of several water components related to the lithology. Ra might thus have a more conservative behavior than usually assumed, possibly because of the high water/rock ratio and flow rate in karst environment. Short-lived Ra isotopes (²²⁴Ra and ²²³Ra) are often in excess compared to their equilibrium values, due to their supply through alpha-recoil processes. ²²³Ra activities in a Vidourle tributary can be explained by mixing of two water components, with a negligible radioactive decay of ²²³Ra during underground water flow. The calculated minimum flow rates (40–60?m/h) are in agreement with those deduced from artificial tracer experiments.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"26 2","pages":"119 - 136"},"PeriodicalIF":1.6,"publicationDate":"2020-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-020-09371-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4468673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ecosystem-Scale Modeling and Field Observations of Sulfate and Methylmercury Distributions in the Florida Everglades: Responses to Reductions in Sulfate Loading","authors":"William H. Orem,&nbsp;Carl Fitz,&nbsp;David P. Krabbenhoft,&nbsp;Brett A. Poulin,&nbsp;Matthew S. Varonka,&nbsp;George R. Aiken","doi":"10.1007/s10498-020-09368-w","DOIUrl":"https://doi.org/10.1007/s10498-020-09368-w","url":null,"abstract":"<p>The Florida Everglades has one of the most severe methylmercury (MeHg) contamination issues in the USA, resulting from factors including high rates of atmospheric mercury (Hg) deposition and sulfate inputs from agricultural lands. Sulfate loading stimulates microbial sulfate reduction and production of toxic and bioaccumulative MeHg. Controls on regional Hg emissions have been successful in reducing Hg deposition and MeHg production in wetlands in other areas, but this has not been the case for the Everglades as the Hg deposited here appears to come from unknown global sources of emissions. We posit that reductions in sulfate loading to the Florida Everglades can be an effective alternative approach used to reduce MeHg production. This study tested this hypothesis (1) by evaluating temporal trends in MeHg concentrations in response to a reduction in sulfate loading at a site in central Water Conservation Area (WCA) 3 and (2) using ecosystem-scale models to predict the effects of reductions in sulfate loading on sulfate concentrations in surface water and MeHg Risk. At the WCA site, we report a decline in sulfate concentrations (from about 9?mg/L in the late 1990s to levels of &lt;?1?mg/L by 2001) due to changes in water delivery as part of Everglades restoration. Concurrent with the decline in sulfate, declines in MeHg concentrations in surface water and fish and wading bird tissues were observed at this site. These results suggest the efficacy of reducing MeHg production and bioaccumulation in the ecosystem through a reduction in sulfate loading. A previously developed model was used to predict the effects of reductions in sulfate loading (97%, 33%, and 10% reduction scenarios) on sulfate concentrations in surface water and MeHg Risk in the Everglades. The model identified areas of the ecosystem where MeHg Risk is most sensitive to the reductions in sulfate loading. Results show that reductions of &gt;?33% in sulfate loading will significantly benefit the Everglades by reducing MeHg Risk.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"26 3","pages":"191 - 220"},"PeriodicalIF":1.6,"publicationDate":"2020-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-020-09368-w","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4605964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Incorporation of Rare Earths and Yttrium in Calcite: A Critical Re-evaluation","authors":"Peter Möller,&nbsp;Marco De Lucia","doi":"10.1007/s10498-020-09369-9","DOIUrl":"https://doi.org/10.1007/s10498-020-09369-9","url":null,"abstract":"<p>The reported partition coefficients of REE with calcite are reviewed and critically discussed. In some of the reported experimental sets, REE concentrations are found to be supersaturated with respect to individual REE₂(CO₃)₃ but never to REE(OH)₃. Although the solutions are unsaturated with respect to individual REY carbonates, REY including Y are incorporated in calcite surfaces, where they are overgrown by calcite. Charge balances may be obtained by building {REY–Na-(CO₃)₂}_<i>n</i> or by exchange of 2Ca²⁺ against REY³⁺?+?blank space calcite lattice. These surface compounds may either be homogeneously distributed or clustered. Both the size and frequency of clusters increase with [REY]/[Ca] or [ΣREY³⁺]/[Ca²⁺] in solution. If these surface precipitates are removed into solutions saturated with respect to ΣREE₂(CO₃)₃, they start growing in the aqueous phase. In this case, the apparent <i>D</i>_REY and <i>k</i>_REY values decrease with increasing REY concentrations in solution. In previous studies, only the individual distribution coefficients are reported not considering that the entirety of REY determines their behavior in partitioning. Given enough time, these surface clusters equilibrate with the aqueous phase before being overgrown by calcite. In the double logarithmic plots of {REY}/{Ca} versus [REY]/[Ca] or [REY³⁺]/[Ca²⁺], two relationships evolve characterizing the REY distribution in marine calcite and experimental calcites grown in Mg²⁺-free solutions. The double logarithmic plots of partition coefficients of REY<span>³⁺_<i>i</i></span> in calcite grown from seawater show a slope exceeding unity, whereas those from fluids without Mg²⁺ depict slopes less than unity being both in contrast to the Henderson–Kracek rule.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"26 2","pages":"89 - 117"},"PeriodicalIF":1.6,"publicationDate":"2020-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-020-09369-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4492590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterizing Soil Dissolved Organic Matter in Typical Soils from China Using Fluorescence EEM–PARAFAC and UV–Visible Absorption","authors":"Xiao-quan Qin,&nbsp;Bo Yao,&nbsp;Liang Jin,&nbsp;Xiang-zhou Zheng,&nbsp;Jie Ma,&nbsp;Marc F. Benedetti,&nbsp;Yongtao Li,&nbsp;Zong-ling Ren","doi":"10.1007/s10498-019-09366-7","DOIUrl":"https://doi.org/10.1007/s10498-019-09366-7","url":null,"abstract":"<p>Dissolved organic matter (DOM) strongly participates in a variety of critical environmental and ecological processes and has a large impact on environmental quality. In this study, ultraviolet–visible absorbance spectroscopy and excitation–emission matrices of fluorescence spectroscopy in combination with parallel factor analysis (EEMs–PARAFAC) were applied to characterize a total of 92 DOM samples extracted from four typical soil types under three different land-use regimes across China. DOC concentrations ranged from 6.52?±?1.09 to 25.62?±?4.83?mg?L^?1 and were generally higher in red soil from Guangdong and Guangxi, especially in paddy soil. Three fluorescence components were identified in soil DOM by EEMs–PARAFAC, including high molecular weight UVA humic-like substances (C1), low molecular weight autochthonous humic-like substances (C2), and protein-like substances (C3). DOM from black soil in Heilongjiang, purple soil from Sichuan, and red soil from Zhejiang had more humic-like substances, whereas DOM from yellow soil in Guizhou and red soil from Guangdong and Guangxi had lower degree of aromaticity and higher proportion of microbial-derived protein-like components (C3). Moreover, DOM from paddy soil tended to be more of protein-like components (C3) than that from other land uses and DOM from dryland soil generally had more autochthonous humic-like substances (C2). Our results demonstrated that soil DOM characteristics both varied significantly by soil type and land use, and EEMs–PARAFAC could be a useful approach to characterize the components and sources of heterogeneous DOM in soils.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"26 1","pages":"71 - 88"},"PeriodicalIF":1.6,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-019-09366-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4081216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineral Magnetic and Geochemical Mapping of the Wular Lake Sediments, Kashmir Valley, NW Himalaya","authors":"Rayees A. Shah,&nbsp;Hema Achyuthan,&nbsp;Satish J. Sangode,&nbsp;Aasif M. Lone,&nbsp;Mohammd Rafiq","doi":"10.1007/s10498-019-09364-9","DOIUrl":"https://doi.org/10.1007/s10498-019-09364-9","url":null,"abstract":"<p>This study presents major element geochemistry, mineral magnetism and textural analysis of lake-bottom sediments collected from the Wular Lake located in the Kashmir Valley (northwest Himalaya). Connected to the Jhelum River, Wular Lake basin occupies?~?75% watershed area of the valley, covering?~?10,196?km², and makes it the major depo-centre for Kashmir Valley. The sediments represent dominant silt fraction with TiO₂, MgO, Fe₂O₃ and MnO enrichment; and depletion of Na₂O and P₂O₅ with reference to upper continental crust. The average CIA (64.17%) reflects moderate chemical weathering of the catchment source rocks. The mineral magnetic mapping identified distinct domains of restricted/reducing and?well-ventilated/oxic conditions, illustrating spatial environmental variability within the lake-bottom environments. The geochemical and mineral magnetic mapping therefore provides a baseline reference for emerging climate and anthropogenic changes being experienced in the Kashmir Valley.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"26 1","pages":"31 - 52"},"PeriodicalIF":1.6,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-019-09364-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4527520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical Behavior of REE in Stream Water and Sediments in the Gold-Bearing Lom Basin, Cameroon: Implications for Provenance and Depositional Environment","authors":"Mumbfu Ernestine Mimba,&nbsp;Wirmvem Mengnjo Jude,&nbsp;Salomon César Nguemhe Fils,&nbsp;Nozomi Numanami,&nbsp;Melvin Tamnta Nforba,&nbsp;Takeshi Ohba,&nbsp;Festus Tongwa Aka,&nbsp;Cheo Emmanuel Suh","doi":"10.1007/s10498-019-09365-8","DOIUrl":"https://doi.org/10.1007/s10498-019-09365-8","url":null,"abstract":"<p>Stream water and associated bottom sediments were sampled within the Lom Basin, and their rare earth element (REE) concentrations have been used to decipher their provenance and environment of deposition. Stream waters in the lower Lom Basin have variable Post Archean Australian Shale-normalized REE concentrations (0.24–4978?ng/l), positive Ce anomalies (Ce/Ce* ranges from 1.08 to 8.03), a general positive Eu anomaly (Eu/Eu* varies from 0.9 to 15.2, average?=?4.9) and are slightly enriched in the light rare earth elements (LREE/HREE varies from 1.7 to 10.3). Similarly, the sediments are slightly depleted in heavy rare earth elements (HREE), have a predominant negative Ce anomaly, but show a ubiquitous positive Eu anomaly. The dissolved REE content is controlled by the near-neutral pH of the stream water and adsorption onto Fe and Mn oxyhydroxides. The variable LREE/HREE ratios and Eu anomalies observed in the sediments indicate that these sediments are sourced mainly from felsic rocks with little mafic input. Moreover, Ce anomalies and redox-sensitive trace elemental ratios of Ni/Co, V/(V?+?Ni), V/Cr, Cu/Zn and V/Ni revealed the sediments were deposited under oxic to reducing conditions. Variations in the concentration of REE in the stream water and sediment indicate that Fe and Mn oxyhydroxides are important sinks for the HREE. The newly generated data will guide future studies and environmental policy makers.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"26 1","pages":"53 - 70"},"PeriodicalIF":1.6,"publicationDate":"2019-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-019-09365-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4527523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry of the Lake Chad Tributaries Under Strongly Varying Hydro-climatic Conditions","authors":"A. Mahamat Nour,&nbsp;C. Vallet-Coulomb,&nbsp;C. Bouchez,&nbsp;P. Ginot,&nbsp;J. C. Doumnang,&nbsp;F. Sylvestre,&nbsp;P. Deschamps","doi":"10.1007/s10498-019-09363-w","DOIUrl":"https://doi.org/10.1007/s10498-019-09363-w","url":null,"abstract":"<p>The Lake Chad Basin (LCB) is one of the main endorheic basins in the world and has undergone large-level and surface variations during the last decades, particularly during the Sahelian dry period in the 1970s and the 1980s. The Chari–Logone River system covers 25% of the LCB but accounts for up to 82% of the Lake Chad water supply. The aim of this study is to investigate the dissolved phase transported by the Chari–Logone system, in order (1) to elucidate the origin and the behavior of major elements and the weathering processes in the watershed; (2) to estimate the total dissolved flux, its variability over the last decades and the driving factors. To do so, samples were collected monthly between January 2013 and November 2016 at three representative sites of the basin: in the Chari River in “Chagoua,” in the Logone River in “Ngueli” just before the confluence of both rivers, and at a downstream site in “Douguia,” 30?km after the confluence. Concentrations in major elements displayed significant seasonal variations in the Chari and Logone waters. At the seasonal time scale, the comparison between the concentrations of chemical elements and the flow rates showed a hysteresis loop. This hysteresis behavior corresponds to a variable contribution over time of two water bodies, fast surface water, and slow groundwater, the latter carrying higher concentrations and Ca/Na ratio, which may result from the contribution of pedogenic carbonate weathering to the dominant signature of silicate weathering. At the annual time scale,?similar average concentrations are observed in the Chari and Logone Rivers, despite contrasted annual runoff. In addition, an interannual stability of ionic concentrations was observed in the Chari–Logone River during the flood regime, both during the years covered by our monitoring (2013–2016) and during the pre-drought period (1969, 1972 and 1973). This situation corresponds to a chemostatic behavior, where the annual river discharge is the main factor controlling the interannual variation of chemical fluxes.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"26 1","pages":"3 - 29"},"PeriodicalIF":1.6,"publicationDate":"2019-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-019-09363-w","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5129556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Bacterial Sulfate Reduction Inhibition on the Production and Stable Isotopic Composition of Methane in Hypersaline Environments","authors":"Cheryl A. Kelley,&nbsp;Brad M. Bebout,&nbsp;Jeffrey P. Chanton,&nbsp;Angela M. Detweiler,&nbsp;Adrienne Frisbee,&nbsp;Brooke E. Nicholson,&nbsp;Jennifer Poole,&nbsp;Amanda Tazaz,&nbsp;Claire Winkler","doi":"10.1007/s10498-019-09362-x","DOIUrl":"https://doi.org/10.1007/s10498-019-09362-x","url":null,"abstract":"<p>The aim of this research was to investigate the competition between methanogens and sulfate-reducing bacteria in hypersaline environments. Samples of photosynthetic microbial mats, both soft mats (salinities of 55–126?ppt) and gypsum-hosted endoevaporite mats (salinities of 77–320?ppt), were obtained from hypersaline environments in California, USA, Mexico and Chile. Methane production was determined from the increase in headspace methane concentration within incubation vials containing mat samples. At the end of the incubation period, the δ¹³C values of produced methane were measured. Soft microbial mat vials containing molybdate, a specific inhibitor of bacterial sulfate reduction, exhibited dramatically higher methane production rates and higher (enriched in ¹³C) methane δ¹³C values than the controls. This suggests that the inhibition of sulfate reduction allowed the methanogens at these sites to use the competitive substrates (H₂ and/or acetate) made available. Further, the higher δ¹³C values of the produced methane suggest that substrates (both competitive and non-competitive) were used to near completion. At the endoevaporite sites, which have much higher salinities than the soft mat sites, methane production was not significantly different and the methane δ¹³C values either remained the same or decreased (depleted in ¹³C) with added molybdate. We suggest that substrate availability increased enough to allow for somewhat greater isotopic fractionation resulting in the lower methane δ¹³C values that were observed, but not enough to significantly increase measured production rates. Where no changes in either methane production rates or δ¹³C values occurred, we hypothesize that salinity itself was inhibiting sulfate reduction and thus controlling microbe populations and rates of metabolism.</p>","PeriodicalId":8102,"journal":{"name":"Aquatic Geochemistry","volume":"25 5-6","pages":"237 - 251"},"PeriodicalIF":1.6,"publicationDate":"2019-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s10498-019-09362-x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5064166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}