Discipline: Ecology Environmental and Earth Sciences
Subcategory: Climate Change
Room: Private Dining
Aaliyah Hameed - Louisiana State University
Coastal terrestrial-aquatic interfaces (TAIs) are spatiotemporally dynamic environments that play a major role in controlling our planet’s biogeochemical cycles but remain poorly understood. The Pacific Northwest National Laboratory’s Coastal Observations, Mechanisms, and Predictions Across Systems and Scales (COMPASS) project is a 2-year long pilot study that monitored interactions between water, soils, and plants across salt and freshwater interfaces to better understand their impact on coastal carbon, nutrients, and redox-associated cycles. Soil samples were taken at 4 locations across the TAI (sediment, wetlands, transition, and uplands) at 52 Great Lakes and Mid-Atlantic sites, 14 near the Great Lakes and 38 in the Mid-Atlantic, with 22 at Chesapeake Bay and 18 at Delaware Bay. Through our research efforts, we sought to answer questions surrounding the function and structure of TAIs and their influence on the evolution of coastal environments. We aim to reveal how these mechanisms interact across different geographical regions to improve predictive modelling for a variety of TAIs. Gravimetric water content (GWC), loss on ignition (LOI), and bulk density (BD) analyses were performed to quantify soil saturation, organic carbon content, and density, respectively. GWC measured the difference between field moist and oven dried soil while LOI measured the difference between oven dried and combusted soil, both GWC and LOI were measured in percentages and weights were taken via analytical balance to a 0.01g precision. Bulk density was measured using HYPROP rings on a field scale of 0.1g precision, making sure to subtract the ring’s weight from the total and account for gaps that may have occurred due to improper filling of the ring to avoid irregularities in volume. It was found that the relationship between soil saturation (GWC) and organic carbon (LOI) was positively correlated and shifted across the TAI meaning that increased organic carbon content results in an increased capacity for water retention. The data follows that of an inundation gradient, where sediments tend to stay saturated longer due to their proximity to water and upland soils dry out. Plotting BD against GWC/LOI produced negative exponential curves that portrayed clear relationships between a soil’s density and its ability to store organic matter and water, likely due to pore size. These relationships are key for parameterizing physicochemical relationships for coastal TAIs in Earth system models and will allow us to make generalized predictions about coastal interfaces even when they seem to be vastly different. These numbers and relationships will be used in the future for data-modeling integration and predictive studies on environmental change thresholds as we face a new era of climate change. References: A.D. Keiser, J.D. Knoepp, and M.A. Bradford, Ecosystems 19, 50 (2015). Natural Resources Conservation Service, Inherent Factors Affecting Available Water Capacity (2019).
Funder Acknowledgement(s): A special thanks to Nicholas Ward and Peter Regier for serving as my mentors. Thank you to the U.S. Department of Energy Office of Science for this amazing opportunity. And thank you to the Workforce Development for Teachers and Scientists program for sponsoring and funding this internship. Lastly, I thank Battelle for overseeing my work at the Pacific Northwest National Laboratory and its dedication to worker safety.
Faculty Advisor: Nicholas Ward, firstname.lastname@example.org
Role: My part of the research included performing all the soil analyses on about 600 different soil and sediment samples. These analyses included gravimetric water content, loss on ignition, and bulk density calculations. I also sorted, uploaded, and analyzed all the data for these analyses and built several graphs using the statistical analysis program known as R. I ran correlation plots, box plots, and scatterplots to analyze the differences and similarities between different sections of the coastal terrestrial-aquatic interfaces and the various soil characteristic we quantified.