The short-term effects of salinization on anaerobic nutrient cycling and microbial community structure in sediment from a freshwater wetland

Baldwin, Darren S.; Rees, Gavin N.; Mitchell, Alison; Watson, Garth; Williams, Janice Lake

doi:10.1672/0277-5212(2006)26[455:tseoso]2.0.co;2

Cited by 153 publications

(113 citation statements)

References 29 publications

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“…Many studies have observed increased P release from salinized soils (Portnoy and Giblin 1997b, Lamers et al 2001, 2002, Weston et al 2006, while others have observed increased P sorption (Jun et al 2013), or no change in P (Lamers et al 2002). Overall, increased ionic strength decreases the activity coefficient of PO 4 3À , increasing the solubility of mineral-bound P. However, increased concentrations of ions that bind PO 4 3À (e.g., Fe and Ca 2þ ) can precipitate displaced PO 4 3À (Baldwin et al 2006. Sulfate may also displace PO 4 3À from soil exchange sites Edmonds 1997, Bruland andDeMent 2009), but this seems unlikely as PO 4 3À has a higher affinity for exchange sites at circumneutral pH (Schachtschabel and Scheffer 1976).…”

Section: Ionic Changes In Salinizing Wetlandsmentioning

confidence: 98%

“…In field studies, SO 4 2À concentrations as low as 10 mg/L have been shown to inhibit methanogenesis, while a meta-analysis along natural salinity gradients identified 4 mM SO 4 2À (386 mg/L or the equivalent of 5 psu seawater) as a threshold between low porewater CH 4 concentrations (,25 lM CH 4 ) and higher levels (up to .500 lM CH 4 ; Poffenbarger et al 2011). Nevertheless, Na þ and Cl À alone can significantly inhibit methanogenesis in inland systems (Pattnaik et al 2000, Mishra et al 2003, Baldwin et al 2006). These results suggest that methanogen populations along salinity gradients may adapt or migrate in response to salinity exposure, while those experiencing a novel exposure are more sensitive (further considered in Microbial assemblages below).…”

Section: Biogeochemical Cyclingmentioning

confidence: 99%

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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: Ionic Changes In Salinizing Wetlandsmentioning

confidence: 98%

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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“…Many nominally freshwater ecosystems are undergoing salinisation through inappropriate land use practises, which in turn may affect biogeochemical cycling in affected ecosystems. [135] Concentration v. flux; measuring rates of transformation Many of the studies on organic P in aquatic environments are phenomenological. Dynamics and transformations are not directly measured but may be inferred.…”

Section: Expansion Of the Types Of Ecosystems Studiedmentioning

confidence: 99%

Organic phosphorus in the aquatic environment

Baldwin¹

2013

Environ. Chem.

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103

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Environmental context. Organic phosphorus can be one of the major fractions of phosphorus in many aquatic ecosystems. This paper discusses the distribution, cycling and ecological significance of five major classes of organic P in the aquatic environment and discusses several principles to guide organic P research into the future.Abstract. Organic phosphorus can be one of the major fractions of phosphorus in many aquatic ecosystems. Unfortunately, in many studies the 'organic' P fraction is operationally defined. However, there are an increasing number of studies where the organic P species have been structurally characterised -in part because of the adoption of 31 P NMR spectroscopic techniques. There are five classes of organic P species that have been specifically identified in the aquatic environment -nucleic acids, other nucleotides, inositol phosphates, phospholipids and phosphonates. This paper explores the identification, quantification, biogeochemical cycling and ecological significance of these organic P compounds. Based on this analysis, the paper then identifies a number of principles which could guide the research of organic P into the future. There is an ongoing need to develop methods for quickly and accurately identifying and quantifying organic P species in the environment. The types of ecosystems in which organic P dynamics are studied needs to be expanded; flowing waters, floodplains and small wetlands are currently all under-represented in the literature. While enzymatic hydrolysis is an important transformation pathway for the breakdown of organic P, more effort needs to be directed towards studying other potential transformation pathways. Similarly effort should be directed to estimating the rates of transformations, not simply reporting on the concentrations. And finally, further work is needed in elucidating other roles of organic P in the environment other than simply a source of P to aquatic organisms.

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“…These processes can be influenced by changes in environmental conditions such as temperature, soil moisture, oxygen (O 2 ) availability, nutrient supply, and salinity (e.g., Updegraff et al, 1998;Sundareshwar et al, 2003;Baldwin et al, 2006;Bridgham et al, 2008). Environmental changes can have direct effects on biogeochemical transformations (e.g., the presence of O 2 inhibits methanogenesis; Segers, 1998) or the effects can be indirect and driven by interactions among ecosystem components (e.g., nutrient additions increase plant productivity and subsequent O 2 transport to subsurface soil, thereby enhancing methane (CH 4 ) oxidation; Keller et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Tidal freshwater marshes and swamps occur at the landward end of estuaries, where the influence of astronomical tides is felt but river discharge is sufficient to maintain freshwater conditions (Barendregt and Swarth, 2013). With storm surges, droughts, and accelerating rates of sea level rise, there is increasing oceanic influence in the tidal freshwater zone that manifests as transient to sustained increases in salinity (hereafter, "saltwater intrusion").…”

Section: Introductionmentioning

confidence: 99%

Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon

2013

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Abstract. Environmental perturbations in wetlands affect the integrated plant-microbial-soil system, causing biogeochemical responses that can manifest at local to global scales. The objective of this study was to determine how saltwater intrusion affects carbon mineralization and greenhouse gas production in coastal wetlands. Working with tidal freshwater marsh soils that had experienced ∼ 3.5 yr of in situ saltwater additions, we quantified changes in soil properties, measured extracellular enzyme activity associated with organic matter breakdown, and determined potential rates of anaerobic carbon dioxide (CO 2 ) and methane (CH 4 ) production. Soils from the field plots treated with brackish water had lower carbon content and higher C : N ratios than soils from freshwater plots, indicating that saltwater intrusion reduced carbon availability and increased organic matter recalcitrance. This was reflected in reduced activities of enzymes associated with the hydrolysis of cellulose and the oxidation of lignin, leading to reduced rates of soil CO 2 and CH 4 production. The effects of long-term saltwater additions contrasted with the effects of short-term exposure to brackish water during three-day laboratory incubations, which increased rates of CO 2 production but lowered rates of CH 4 production. Collectively, our data suggest that the long-term effect of saltwater intrusion on soil CO 2 production is indirect, mediated through the effects of elevated salinity on the quantity and quality of autochthonous organic matter inputs to the soil. In contrast, salinity, organic matter content, and enzyme activities directly influence CH 4 production. Our analyses demonstrate that saltwater intrusion into tidal freshwater marshes affects the entire process of carbon mineralization, from the availability of organic carbon through its terminal metabolism to CO 2 and/or CH 4 , and illustrate that long-term shifts in biogeochemical functioning are not necessarily consistent with short-term disturbance-type responses.

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The short-term effects of salinization on anaerobic nutrient cycling and microbial community structure in sediment from a freshwater wetland

Cited by 153 publications

References 29 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

Organic phosphorus in the aquatic environment

Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon

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