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| Titel |
Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon |
| VerfasserIn |
S. C. Neubauer, R. B. Franklin, D. J. Berrier |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 12 ; Nr. 10, no. 12 (2013-12-11), S.8171-8183 |
| Datensatznummer |
250085473
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| Publikation (Nr.) |
 copernicus.org/bg-10-8171-2013.pdf |
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| Zusammenfassung |
| 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 (CO2) and
methane (CH4) 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 CO2 and
CH4 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 CO2 production but
lowered rates of CH4 production. Collectively, our data suggest that
the long-term effect of saltwater intrusion on soil CO2 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
CH4 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 CO2 and/or CH4, and illustrate that long-term shifts
in biogeochemical functioning are not necessarily consistent with short-term
disturbance-type responses. |
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