Biogeochemical recovery of oligohaline wetland soils experiencing a salinity pulse

Document Type

Article

Publication Date

11-1-2013

Abstract

Oligohaline wetlands exist at a dynamic interface along a river-to-estuary gradient where salinity changes frequently due to fluctuating tidal cycles and weather events. Large storms can cause short-term saltwater intrusion into these low-lying coastal areas, exposing oligohaline wetland plants and soils to above-normal salinities and severe stress on wetland organisms. The objective of this study was to determine how oligohaline wetland soils respond to a single pulse saltwater intrusion, similar to what may occur during hurricane- associatedstorm surge. Soil response variables were measured in intrusion-Impacted and Reference soils before, during, and after a 6-wk saltwater intrusion event to determine potential impacts on microbial biomass and activity and associated nutrient dynamics. We observed no significant change in basal CO2 or CH4production in oligohaline soils (interstitial salinity = 1.3 ± 0.1 practical salinity units [psu]; mean ± 1 SD) exposed to 20 psu saltwater, while substrate-induced methanogenesis was negatively correlated with salinity. Microbial biomass C (MBC) responded positively to saltwater intrusion by doubling in concentration at the 0- to 5-cm depth interval. Saltwater intrusion had no impact on porewater nutrient concentrations; however, extractable NH4 + decreased as salinity increased. Although some significant changes in microbial activity, abundance, and nutrient availability occurred due to saltwater intrusion, these impacts were generally transient, with post-intrusion conditions resembling pre-intrusion conditions. These results suggest that short-term and transient saltwaterintrusion may have little longer-term effect on wetland soil biogeochemistry. However, compounding effects of frequent saltwater intrusion pulses due to strong, regularly occurring storm events could cause longer-lasting shifts in biogeochemical functioning of these wetlands. © Soil Science Society of America. All rights reserved.

Publication Source (Journal or Book title)

Soil Science Society of America Journal

First Page

2205

Last Page

2215

This document is currently not available here.

Share

COinS