Porewater chemistry of Louisiana marshes with contrasting salinities and its implications for coastal acidification

Estuarine, Coastal and Shelf Science
By: , and 

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Abstract

Dissolved inorganic carbon (DIC) and total alkalinity (TA) are fundamental components of carbonate systems that control pH and buffering capacity of the receiving water body. Three coastal marshes with contrasting salinities in Barataria Basin, Louisiana, USA, were sampled to understand seasonal changes in porewater carbonate chemistry and its impact on surrounding water bodies. Each marsh was sampled five times between December 2018 and October 2019. Porewater DIC and TA increased with depth irrespective of marsh type and ranged from 4.47 to 31.61 mmol/kg and from 1.78 to 28.56 mmol/kg, respectively. The salt marsh had higher porewater DIC and TA compared to the lower salinity intermediate and brackish marshes, probably due to sulfate reduction in the salt marsh. However, it is likely that denitrification is the dominant anaerobic process in these marshes because of low porewater TA/DIC ratios in all three marshes. Porewater TA and DIC concentrations were generally higher during warmer months than colder months. However, the marsh flooding regime had a profound influence on TA and DIC concentrations by changing the redox potential of the marsh soil. Porewater TA/DIC ratios in all three marshes were generally less than 1, while surface water TA/DIC ratios were around 1, suggesting that export of DIC and TA from coastal marshes have the potential to contribute to coastal acidification.

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Publication type Article
Publication Subtype Journal Article
Title Porewater chemistry of Louisiana marshes with contrasting salinities and its implications for coastal acidification
Series title Estuarine, Coastal and Shelf Science
DOI 10.1016/j.ecss.2022.107801
Volume 268
Year Published 2022
Language English
Publisher Elsevier
Contributing office(s) Lower Mississippi-Gulf Water Science Center
Description 107801, 12 p.
Country United States
State Louisiana
Other Geospatial Barataria Bay
Additional publication details