Impact of sulfate pollution on anaerobic biogeochemical cycles in a wetland sediment
Highlights
► Sulfate addition impacts the anaerobic cycling of C, Fe and Mn. ► Addition of sulfate at low levels inhibits methanogenesis. ► Sulfate additions didn’t substantially affect the cycling of N.
Introduction
The impact of sulfate pollution is increasingly being seen as an issue in the management of inland aquatic ecosystems (Baldwin and Fraser, 2009). Evidence suggests that human practises have increased the amount of sulfate entering inland aquatic ecosystems (Jansen and Roelofs, 1996, Lamers et al., 1998, Lamers et al., 2001). For example, Jansen and Roelofs (1996) report a six-fold increase in sulfate levels in groundwater from southern and eastern parts of the Netherlands between 1966 and 1991. The main sources of sulfur in that study were believed to be both aerial deposition (derived from sulfur from coal-fired electricity generating power plants) and leakage from agricultural systems. Sulfur is regularly applied to agricultural systems as a fertilizer or soil ameliorant (e.g. Jamal et al., 2010) and is known to leach into aquatic ecosystems (e.g. Szynkiewicz et al., 2011).
Rising saline groundwater may be another source of sulfur to inland ecosystems (Hicks et al., 2003). The salt in groundwater is often originally marine-derived (Herczeg et al., 2001) and therefore has a relatively high concentration of sulfate (Hicks et al., 2003). Poor drainage and inappropriate irrigation practises, has caused an estimated 10% of the worlds irrigated land area to be adversely affected by water-logging and salinization (UNESCO, 2003). Thus, unsuitable land use practises have inadvertently provided another source of sulfur to freshwater systems worldwide.
Probably the most dramatic impact of increased sulfate in inland aquatic ecosystems has been the development of high levels of reduced sulfur in the sediments of inland waterways (e.g. Hall et al., 2006). Sulfidic sediments (also referred to as acid sulfate soils) form when sulfate reducing bacteria use the sulfate ion as the terminal electron acceptor for anaerobic respiration. The respiratory end product of this reaction is hydrogen sulfide. The sulfide then reacts with iron (and other metals) to form mineral sulfides such as makinawite and pyrite. Oxidation of sulfidic sediments (e.g. through partial drawdown of a waterbody) can have adverse environmental effects including acidification, deoxygenation and mobilization of heavy metals (Baldwin and Fraser, 2009 and references therein).
Increasing the concentration of sulfate in a waterbody also has the potential to disrupt sediment biogeochemical processes and hence ecological condition. For example, sulfate reduction has been implicated in the methylation of mercury in wetland sediments (Gilmour et al., 1992). Increasing sulfate concentrations has also been implicated in the eutrophication of inland waterways through mobilization of phosphorus (e.g. Boström et al., 1988, Caraco et al., 1989, Mitchell and Baldwin, 1998, Lamers et al., 1998, van der Welle et al., 2008). Sulfide is a strong enough reducing agent to facilitate the reduction of solid ferric minerals to dissolved ferrous ions with concurrent P release (Boström et al., 1988). This reaction is favored by the insolubility of one of the reaction products, iron sulfide. It has also been suggested that S2− can also displace P from insoluble Fe2+ phases (Roden and Edmonds, 1997); again the reaction being favored by the insolubility of the reaction product – FeS. Sulfate pollution may also have the potential to affect other biogeochemical processes. In this study we use sediment slurry experiments to explore how increasing sulfate concentrations alone, or with additional bioavailable carbon affects the dynamics of S (sulfate, and dissolved and particulate sulfide the later measured as acid volatile sulfide; AVS), C (carbon dioxide, bicarbonate, methane and the short chain volatile fatty acids formate, acetate, butyrate and propionate), N (dinitrogen, ammonium, nitrate and nitrite) and redox active metals (Fe(II) and Mn(II)) in the sediments of a wetland that has not previously been exposed to high levels of sulfate.
Section snippets
Sampling
Sediment samples were taken from Norman’s Lagoon – a small, permanent oxbow lake (approximately 2 km2) located on the River Murray floodplain near Albury, New South Wales, Australia (36°15′S, 146°55′E). The climate is Mediterranean with cool, wet winters and hot, dry summers. The water and sediment chemistry of the wetland have been described in detail elsewhere (Gribben et al., 2003, Mitchell, 2002). Briefly, the surficial sediments of the billabong are flocculent with approximately 80% water
Sulfur dynamics
The initial concentrations of sulfate in both experiments are presented in Table 1. In the sulfate addition experiment sulfate was consumed in all treatments (Table 1); the loss of sulfate approximately following a first order decline for all treatments with added sulfate (Table 1). The total amount of sulfate consumed during the course of the experiment varied linearly with the initial concentration of sulfate added (r2 = 0.98; slope = 0.39; see also Fig. 1). Addition of carbon as either
Sulfur dynamics
Sulfate consumption followed first-order kinetics, with no apparent lag phase. This contrast with the results of Whitworth and Baldwin (2011) who found that sulfate loss from solution for dry wetland sediments proceeded after a lag phase of about 40 days. They attributed this lag phase to the slow initial mineralization of C in the sediments and the requirement to grow microbial biomass. The lack of a lag phase in the current study suggests that in already wetted and anaerobic sediments, carbon
Conclusions
The purpose of this study was to see how the addition of sulfate affects the biogeochemistry of wetland sediments. Clearly the addition of sulfate promotes sulfate reduction and the build-up of reduced sulfur in sediments; which in turn can lead to acidification, deoxygenation and heavy metal mobilization if these reserves are disturbed. What this study shows is that the rates of accumulation of reduced sulfur compounds can be quite rapid. Therefore, even short-term exposure to elevated levels
Acknowledgments
This project was supported by the National Water Commission through its Raising National Water Standards Program. This Australian Government program supports the implementation of the National Water Initiative by funding projects that are improving Australia’s national capacity to measure, monitor and manage its water resources. Additional funding was also received from the NSW Murray Wetlands Working Group and the Murray-Darling Freshwater Research Centre. The funding bodies did not play an
References (39)
- et al.
Rehabilitation options for inland waterways impacted by sulfidic sediments – a synthesis
Journal of Environmental Management
(2009) - et al.
Sulfide-induced dissimilatory nitrate reduction to ammonia in anaerobic freshwater sediments
FEMS Microbiology Ecology
(1996) - et al.
Sedimentary iron geochemistry in acidic waterways associated with coastal lowland acid sulfate soils
Geochimica et Cosmochimica Acta
(2006) - et al.
Distribution of inland wetlands with sulfidic sediments in the Murray-Darling Basin, Australia
Science of the Total Environment
(2006) - et al.
Spectrophotometric determination of manganese utilizing metal ion substitution in the cadmium-α,β,γ,δ-tetrakis (4-carboxyphenol) porphrine complex
Analytica Chimica Acta
(1982) - et al.
Restoration of Cirsio-Molinietum wet meadows by sod cutting
Ecological Engineering
(1996) - et al.
Sulfide and sulfate inhibition of methanogenesis
Water Research
(1987) - et al.
N2O accumulation in estuarine and coastal sediments: the influence of H2S on dissimilatory nitrate reduction
Estuarine Coastal and Shelf Science
(2006) - et al.
Anthopogenic sulfate loads in the Rio Grande, New Mexico (USA)
Chemical Geology
(2011) - et al.
Multi-level effects of sulfur-iron interactions in freshwater wetlands in the Netherlands
Science of the Total Environment
(2008)
Standard Methods for the Examination of Water and Wastewater
Dissimilatory nitrate reduction to ammonia (DNRA) as a nitrogen link, versus denitrification as a sink in a shallow estuary (Laguna Madre/Baffin Bay, Texas)
Marine Ecology Progress Series
The effects of exposure to air and subsequent drying on the phosphate adsorption characteristics of sediments from a eutrophic reservoir
Limnology and Oceanography
The short-term effects of salinization on anaerobic nutrient cycling and microbial community structure in sediment from a freshwater wetland
Wetlands
Organic matter degradation and nutrient regeneration in Australian freshwater 2. Spatial and temporal variation and relationship with environmental conditions
Archive für Hydrobiologie
Exchange of phosphorus across the sediment-water interface
Hydrobiologia
Evidence for sulfate-controlled phosphorus release from sediments from aquatic systems
Nature
Spectrophotometric determination of hydrogen sulfide in natural waters
Limnology and Oceanography
Sulfate stimulation of mercury methylation in fresh-water sediments
Environmental Science and Technology
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