Evaluating Restored Wetland Biogeochemical Cycling Following Thin-layer Sediment Introduction

Description

A. Short Description of Funding Opportunity This research project focuses on quantifying changes in wetland biogeochemical cycles in areas enhanced using dredged materials or other sources of sediment that contain a larger fraction of mineral contents than most coastal wetland soils. The project will focus on systems within the southeast United States and the Gulf Coast (e.g., FL, AL), but may also include sample collections in the mid-Atlantic region. Specialized approaches will be required to collect and analyze soil biogeochemical parameters within coastal wetlands to accomplish the project objectives. B. Background Wetlands provide a number of ecological functions that benefit society, including the reduction of storm surges and increased flood risk reduction for adjacent communities. Recent interest has focused on the need to enhance wetland biogeochemical cycling following wetland restoration project implementation, resulting in the evolution and expansion of the use of Engineering With Nature and Natural and Nature-Based Features techniques in a restoration context. In particular, the application of thin layer placement of dredged sediments into wetlands to increase elevations and enhance ecosystem functions is of increasing interest. Importantly, wetland biogeochemical cycles can undergo a number of biotic and abiotic transformations that have implications for decomposition rates, nutrient turnover, and fate of organic materials in the wetland soil system. Few studies have investigated short to mid-term (~10 year) changes in biogeochemical cycles following restoration, especially with regards to emerging approaches such as thin layer placement. The paucity of studies represents a knowledge gap that must be addressed to improve the management of wetlands within a climate change resiliency and sustainability context. Additionally, improved information is required to guide the design and implementation of wetland restoration projects to maximize ecosystem functions across a variety of wetland types (i.e., floodplains, marshes, mangroves). C. Program Description/Objective The purpose of the work is to 1) document changes in restored wetland biogeochemical cycles following thin layer applications, 2) compare and contrast these cycles between restored and unrestored (i.e., reference) ecosystems, and 3) use study results to inform future project design and implementation to maximize biogeochemical cycling benefits (i.e., carbon sequestration, nutrient cycling, water quality improvement). Objectives: The objectives of the project for the initial year are as follows: 1. Develop technical team and identify study sites. 2. Develop a sample design to sample previously restored wetlands that received thin layer placement treatments. 3. For each study site, collect and analyze samples from paired natural and restored locations (minimum triplicate samples). 4. Generate peer-reviewed journal article with ERDC researchers to describe mid-range project outcomes and inform future design criteria. 5. Develop and present public seminars based on study findings. The objectives for Optional Year 1 and 2 are as follows: 1. Refine the established methodology to increase operational efficiencies. 2. Expand the study to other regions or apply the approach to previously unresearched ecosystems including mangroves, which have not previously received thin layer placement treatments. 3. Generate a peer-reviewed journal articles or public reports in conjunction with ERDC researchers integrating all study conclusions. 4. Develop and present public seminars based on study findings. Successful applicants should have expert knowledge of: 1) biogeochemical cycling dynamics within wetland systems; 2) field data collection capabilities; 3) capacity to perform a number of standard and novel soil physicochemical and microbially mediated analytical procedures linked with ecosystem functions; and 4) experience developing novel approaches to wetland soil characterization, especially with regards to wetland soil biogeochemistry, nutrient cycling, and carbon quality. Areas of expertise that may be required in combination to perform this study include: 1) Capacity to collect and process soil cores within a variety of coastal setting including both organic and mineral dominated substrates. 2) Advanced laboratory capabilities to measure soil biological, chemical, and physical parameters related to ecosystem functions. 3) Experience working with soils and sediments in a wide array of natural and constructed/restored wetland settings. 4) Experience working with thin layer sediment restoration projects in the past.

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