The effect of biogeochemical processes on pH

Soetaert, Karline; Hofmann, A.F.; Middelburg, Jack J.; Meysman, Filip J. R.; Greenwood, Jim

doi:10.1016/j.marchem.2006.12.012

Cited by 235 publications

(260 citation statements)

References 49 publications

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“…The second aspect, however, has received far less attention. Improving and extending previous work by Jourabchi et al (2005) and Soetaert et al (2007), we have recently presented an extension of the conventional pH modelling approach, developing a procedure that allows to quantify how different biogeochemical processes contribute to the overall proton cycling in an aquatic ecosystem (Hofmann et al, 2008a). This method basically splits the total rate of change of protons into individual contributions of the processes that are driving the pH change (details are given 1540 A. F. Hofmann et al: pH modelling with time variable acid-base constants below).…”

Section: Introductionsupporting

confidence: 61%

pH modelling in aquatic systems with time-variable acid-base dissociation constants applied to the turbid, tidal Scheldt estuary

et al. 2009

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Abstract.A new pH modelling approach is presented that explicitly quantifies the influence of biogeochemical processes on proton cycling and pH in an aquatic ecosystem, and which accounts for time variable acid-base dissociation constants. As a case study, the method is applied to investigate proton cycling and long-term pH trends in the Scheldt estuary (SW Netherlands, N Belgium). This analysis identifies the dominant biogeochemical processes involved in proton cycling in this heterotrophic, turbid estuary. Furthermore, information on the factors controlling the longitudinal pH profile along the estuary as well as long-term pH changes are obtained. Proton production by nitrification is identified as the principal biological process governing the pH. Its acidifying effect is mainly counteracted by proton consumption due to CO 2 degassing. Overall, CO 2 degassing generates the largest proton turnover in the whole estuary on a yearly basis. The main driver of long-term changes in the mean estuarine pH over the period 2001 to 2004 is the decreasing freshwater flow, which influences the pH directly via a decreasing supply of dissolved inorganic carbon and alkalinity, and also indirectly, via decreasing ammonia loadings and lower nitrification rates.

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Section: Introductionsupporting

confidence: 61%

pH modelling in aquatic systems with time-variable acid-base dissociation constants applied to the turbid, tidal Scheldt estuary

et al. 2009

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“…During the day, the profiles fluctuated considerably, with the core showing highest photosynthetic activity (core 3) having highest pH values in the overlying water (pH o8.8) resulting from CO 2 consumption during photosynthesis (Revsbech et al, 1983;Des Marais et al, 1989). In the sediment, pH decreased to pH 6-7 as typical for anaerobic carbonate-buffered sediments (Soetaert et al, 2007).…”

Section: Geochemistrymentioning

confidence: 87%

Calcite-accumulating large sulfur bacteria of the genus Achromatium in Sippewissett Salt Marsh

et al. 2015

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Large sulfur bacteria of the genus Achromatium are exceptional among Bacteria and Archaea as they can accumulate high amounts of internal calcite. Although known for more than 100 years, they remain uncultured, and only freshwater populations have been studied so far. Here we investigate a marine population of calcite-accumulating bacteria that is primarily found at the sediment surface of tide pools in a salt marsh, where high sulfide concentrations meet oversaturated oxygen concentrations during the day. Dynamic sulfur cycling by phototrophic sulfide-oxidizing and heterotrophic sulfate-reducing bacteria co-occurring in these sediments creates a highly sulfidic environment that we propose induces behavioral differences in the Achromatium population compared with reported migration patterns in a low-sulfide environment. Fluctuating intracellular calcium/sulfur ratios at different depths and times of day indicate a biochemical reaction of the salt marsh Achromatium to diurnal changes in sedimentary redox conditions. We correlate this calcite dynamic with new evidence regarding its formation/mobilization and suggest general implications as well as a possible biological function of calcite accumulation in large bacteria in the sediment environment that is governed by gradients. Finally, we propose a new taxonomic classification of the salt marsh Achromatium based on their adaptation to a significantly different habitat than their freshwater relatives, as indicated by their differential behavior as well as phylogenetic distance on 16S ribosomal RNA gene level. In future studies, whole-genome characterization and additional ecophysiological factors could further support the distinctive position of salt marsh Achromatium.

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“…The reduced constituents (e.g. NH 4 þ , HS 2 , Fe 2þ , Mn 2þ ) that build up in surface sediments during hypoxia oxidize seasonally when systems re-oxygenate [20]. These oxidation reactions produce strong acids that titrate alkalinity and lower pH [15].…”

Section: Ecosystem Occurrence Of Low Oxygen and Acidificationmentioning

confidence: 99%

Hypoxia and acidification in ocean ecosystems: coupled dynamics and effects on marine life

2016

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There is increasing recognition that low dissolved oxygen (DO) and low pH conditions co-occur in many coastal and open ocean environments. Within temperate ecosystems, these conditions not only develop seasonally as temperatures rise and metabolic rates accelerate, but can also display strong diurnal variability, especially in shallow systems where photosynthetic rates ameliorate hypoxia and acidification by day. Despite the widespread, global co-occurrence of low pH and low DO and the likelihood that these conditions may negatively impact marine life, very few studies have actually assessed the extent to which the combination of both stressors elicits additive, synergistic or antagonistic effects in marine organisms. We review the evidence from published factorial experiments that used static and/or fluctuating pH and DO levels to examine different traits (e.g. survival, growth, metabolism), life stages and species across a broad taxonomic spectrum. Additive negative effects of combined low pH and low DO appear to be most common; however, synergistic negative effects have also been observed. Neither the occurrence nor the strength of these synergistic impacts is currently predictable, and therefore, the true threat of concurrent acidification and hypoxia to marine food webs and fisheries is still not fully understood. Addressing this knowledge gap will require an expansion of multi-stressor approaches in experimental and field studies, and the development of a predictive framework. In consideration of marine policy, we note that DO criteria in coastal waters have been developed without consideration of concurrent pH levels. Given the persistence of concurrent low pH-low DO conditions in estuaries and the increased mortality experienced by fish and bivalves under concurrent acidification and hypoxia compared with hypoxia alone, we conclude that such DO criteria may leave coastal fisheries more vulnerable to population reductions than previously anticipated.

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The effect of biogeochemical processes on pH

Cited by 235 publications

References 49 publications

pH modelling in aquatic systems with time-variable acid-base dissociation constants applied to the turbid, tidal Scheldt estuary

pH modelling in aquatic systems with time-variable acid-base dissociation constants applied to the turbid, tidal Scheldt estuary

Calcite-accumulating large sulfur bacteria of the genus Achromatium in Sippewissett Salt Marsh

Hypoxia and acidification in ocean ecosystems: coupled dynamics and effects on marine life

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