Comparison of Soil Physical, Chemical, and Microbial Activity Properties in Wetlands Created Using Traditional and Novel Ecological Engineering Approaches.

Many waterways undergo periodic dredging to maintain navigation channels. Dredged materials are available to build wetlands, providing an opportunity to examine microbial activities and wetland soil function in created environments. Dredged material from the Atchafalaya River, Louisiana was utilized to create a wetland exhibiting characteristics of naturally occurring riverine wetlands within the region. This construction technique adheres to Engineering With Nature (EWN) concepts which utilize natural processes to maximize benefits for navigation, while improving environmental outcomes. We examined soil physical, nutrient and biogeochemical properties at the EWN wetland and compared those parameters to those observed at a traditional dredge material placement wetland (TDMP). Soil carbon and nitrogen at EWN continue to accumulate over time, however TDMP displayed a significantly higher degree of soil formation as indicated by lower bulk density, and higher soil organic matter, carbon, nitrogen, and extractable nitrate. Despite the observed differences between created wetland habitats, rates of potential nitrate removal and microbial biomass nitrogen did not differ between wetlands, suggesting that nutrient cycling and nitrate removal capacities remained equivalent between study sites. Findings indicate that novel wetland creation techniques utilizing natural riverine processes perform wetland soil microbial functions at similar rates to traditional ecological engineering approaches.