2024 Abstracts

Biogeochemical Controls Vary Across the Upland to Wetland Gradient of Two U.S. Coastal Regions: Results from the EXCHANGE Consortium


Allison N. Myers-Pigg1,2* (allison.myers-pigg@pnnl.gov), Stephanie C. Pennington1, Allison M. Lewis3, Donnie J. Day2, Matthew L. Kirwan4, Avni Malhotra1, Teri O’Meara5, Peter Regier1, Kaizad F. Patel1, Nicholas D. Ward1,6, Vanessa Bailey1, EXCHANGE Consortium


1Pacific Northwest National Laboratory, Richland, WA; 2The University of Toledo, Toledo, OH; 3Lawrence Berkeley National Laboratory, Berkeley, CA; 4Virginia Institute of Marine Science, Gloucester Point, VA; 5Oak Ridge National Laboratory, Oak Ridge, TN; 6Department of Oceanography, The University of Washington, Seattle, WA



The Exploration of Coastal Hydrobiogeochemistry Across a Network of Gradients and Experiments (EXCHANGE) Consortium, a component of the Coastal Observations, Mechanisms, and Predictions Across Systems and Scales-Field, Measurements, and Experiments (COMPASS-FME) project, synthesizes knowledge related to hydrologically and biogeochemically dynamic coastal terrestrial-aquatic interfaces (TAIs), with the aim to quantify coastal ecosystem heterogeneity across transect and regional scales. The consortium, comprising diverse researchers based around the U.S. Great Lakes and Mid-Atlantic regions, fosters interdisciplinary and synergistic collaborations. During the commencing campaign, EXCHANGE Campaign 1 (EC1), open-access datasets were generated, encompassing geochemical, physicochemical, and organic matter characterizations with interoperable metadata. These resources empower the community to pose new questions and gain insights by contextualizing information across diverse sites and regions. Notably, EC1 data revealed significant spatial variability in soil carbon content, with region, transect location, and soil pH serving as key predictors of soil carbon. Contrary to the hypothesis, transition zones did not exhibit the anticipated highest variability in soil carbon content. The drivers of greenhouse gas production from soils and sediments incubated in seawater were contingent on the originating transect location from across the TAI, suggesting potential biogeochemical feedbacks as inundation regimes shift inland.

In the ongoing EXCHANGE Campaign 2 (EC2), researchers explore how prolonged flooding affects the turnover of soil microbial carbon pools, specifically examining whether carbon starvation or terminal electron availability drives these events. Additionally, to assess how local drivers influence upland-to-wetland conversion, researchers investigate the relationship between soil and water characteristics, elevation, and rates of land conversion inferred from remote sensing data. The outcomes of the EXCHANGE project are integral to validating input parameters for biogeochemical models, contributing to a predictive understanding of coastal biogeochemical function.