Microbial and biogeochemical processes in Big Soda Lake, Nevada

Abstract

Summary Meromictic, alkaline lakes represent modern-day analogues of lacustrine source rock depositional environments. In order to further our understanding of how these lakes function in terms of limnological and biogeochemical processes, we have conducted an interdisciplinary study of Big Soda Lake. Annual mixolimnion productivity (ca. 500 g m −2 ) is dominated by a winter diatom bloom (600f annual) caused by upward transport of ammonia to the epilimnion. The remainder of productivity is attributable to chemoautotrophs (30%) and photosynthetic bacteria (10%) present at the oxic-anoxic interface from May to November. Studies of bacterial heterotrophy and particulate fluxes in the water column indicate that about 900f annual productivity is remineralized in the mixolimnion, primarily by fermentative bacteria. However, high rates of sulphate reduction (9–29 mmol m −2 yr −1 ) occur in the monimolimnion waters, which could remineralize most (if not all) of the primary productivity. This discrepancy has not as yet been fully explained. Low rates of methanogenesis also occur in the monimolimnion waters and sediments. Most of the methane is consumed by anaerobic methane oxidation occurring in the monimolimnion water column. Other bacterial processes occurring in the lake are also discussed. Preliminary studies have been made on the organic geochemistry of the monimolimnion sediments. Carbon-14-dating indicates a lower depositional rate prior to meromixis and a downcore enrichment in 13 C of organic carbon and chlorophyll derivatives. Hydrous pyrolysis experiments indicate that the sediment organic matter is almost entirely derived from the water column with little or no contribution from terrestrial sources. The significance of the organics released by hydrous pyrolysis is discussed.

Geochemical characterization of soil organic matter and variability of a postglacial detrital organic supply (chaillexon lake, france)

“…derived from the phytol of chlorophyll as opposed to the presence of notable amounts of this pigment revealed by the pronounced green colouration of the organic extracts can be explained by a high preservation of the organic inputs, ensured by rapid burial. n-Alkane distributions dominated by odd C atom numbered n-alkanes in the n-C 27 to n-C 31 range signify the inheritance from higher terrestrial plants (Tissot and Welte, 1984;Oremland et al, 1988;Vandebroucke, 1980;Wetzel, 1983;Disnar and Harouna, 1994). The marked predominance of this family of compounds in the saturatedunsaturated fractions agrees with pyrolysis data indicating the prevalence of detrital input in the primary sedimentary organic stock.…”

Microbiology of Lonar Lake and other soda lakes

“…Rift valley soda lakes, Mono Lake Grant et al (1999), Humayoun et al (2003), Rees et al (2004) Investigations on methanogenesis and methanotrophy Big Soda Lake, Mono Lake, Transbaikal soda lakes Oremland et al (1982Oremland et al ( , 1993, Iversen et al (1987), Khmelenina et al (2000) Characterization of microbes associated with arsenic cycle Mono Lake, Searles Lake Reviewed in Oremland et al (2004Oremland et al ( , 2005 Characterization Antony et al (2010Antony et al ( , 2012b Investigations on nitrogen cycle and the characterization of microbes associated with this cycle Big Soda Lake, Mono Lake, Siberian soda lakes, Mongolian soda lakes, Rift valley soda lakes Oremland et al (1988Oremland et al ( , 1990, Sorokin (1998), Sorokin et al (1998Sorokin et al ( , 2001, Ward et al (2000), Carini and Joye (2008) Characterization of diversity of chemoor photoautotrophic Bacteria Mono Lake, Kulunda steppe soda lakes, Wadi al Natrun soda lakes, Soap Lake Giri et al (2004), Kovaleva et al (2011), Asao et al (2011 environments, such as Rift valley soda lakes, Lonar Lake and Mono Lake (Jones et al, 1998;LeCleir et al, 2007;Joshi et al, 2008). Halo(alkali)philic microorganisms use several different types of organic solutes as osmolytes (Ciulla et al, 1997).…”

Short-Chain Organic Acids in Interstitial Waters from Mariana and Bonin Forearc Serpentines: Leg 125

“…As shown in Figures 4 and 5, a sympathetic variation exists between organic acid concentration and dissolved methane and ethane. Methane, ethane, and propane are produced by both microbial (Oremland, 1975(Oremland, , 1981Oremland et al, 1987;Oremland, Cloern, Sofer, et al, 1988;Oremland, Whiticar, Strohmeier, et al, 1988) and thermal mechanisms (Tissot and Welte, 1984). Both methane and ethane also have been shown to evolve abiotically during the process of serpentinization (Abrajano et al, 1988;T.…”