College of Agriculture & Natural Resources
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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item DISTRIBUTION AND VARIABILITY OF CARBON STOCKS IN MID-ATLANTIC TIDAL MARSH SOILS(2022) Kim, Jordan; Rabenhorst, Martin C; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Tidal marsh wetlands have the capacity to store disproportionately large quantities of Cdespite their small areal extent. Good estimations of this “blue C” are now more critical than ever due to implications for the global C cycle and climate change, especially since C storage in tidal marshes has historically been understudied. In this study, we set out to measure, more accurately estimate, and conceptually model the C stocks in representative tidal marshes of the Mid-Atlantic region. We found that C storage differs significantly in marshes formed among various pedogeomorphic settings due to differences in pedogenic processes and soil morphology. Further, we have demonstrated that the mean C densities of particular soil materials can be used in conjunction with soil morphological descriptions to reliably estimate the C stocks in the absence of laboratory data. Finally, we augmented existing concepts of tidal marshes in the region by incorporating newly gained understandings of the spatial changes in morphology and C stocks across marshes within different pedogeomorphic settings.Item SUBAQUEOUS SOILS OF CHESAPEAKE BAY: DISTRIBUTION, GENESIS, AND THE PEDOLOGICAL IMPACTS OF SEA-LEVEL ALTERNATIONS(2020) Wessel, Barret Morgan; Rabenhorst, Martin C; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Soils and sediments make up a substantial portion of the resource base that supports human societies and other life on Earth, yet in the subaqueous environment our understanding of these materials pales in comparison to our understanding and management of upland soils. We must develop an understanding of how subaqueous soils/sediments are distributed, how they form and change over time, and how they will be impacted by rising sea-levels as a result of climate change if we are to wisely manage these resources. The goal of this study is to improve this understanding in Chesapeake Bay subestuaries. The Rhode River subestuary was first surveyed to identify rates of bathymetric change in these settings and to characterize the common material types found in these settings. Bathymetric change was evaluated using hydrographic surveys dating back to 1846, and though the river bottom does change slowly, it has been more or less stable during the years evaluated. Several types of morphologically distinct materials make up the soil profiles in Rhode River. Materials highest in organic matter are easy to identify in the field, and commonly become ultra-acidic if disturbed. Also present were submerged upland soils, colored and structured like soils in the surrounding landscape. To better understand the impacts of submergence on these materials, a sampling campaign was conducted on shallow marine sediments, reclaimed land, and restored aquatic environments under both seawater and freshwater. This demonstrated that shallow marine sediments develop upland soil features and biogeochemical characteristics within 150 years of drainage, and that these characteristics do indeed persist in the subsoil two years after submergence. Topsoil changes more radically, releasing anomalous amounts of Fe while accumulating anomalous amounts of reduced S minerals, a process exacerbated by seawater flooding. Using these results, a soil-landscape conceptual model was developed and used to predict subaqueous soil distribution in the West River subestuary. These predictions were evaluated with a sampling campaign, and found to be significant. This model can now be used in other subestuaries to quickly and efficiently survey subaqueous soils, supporting the development of future land-use interpretations in these environments.Item Pedogenesis, Inventory, and Utilization of Subaqueous Soils in Chincoteague Bay, Maryland(2007-11-28) Balduff, Danielle Marie; Rabenhorst, Martin C.; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Chincoteague Bay is the largest (19,000 ha) of Maryland's inland coastal bays bounded by Assateague Island to the east and the Maryland mainland to the west. It is connected to the Atlantic Ocean by the Ocean City inlet to the north and the Chincoteague inlet to the south. Water depth ranges mostly from 1.0 to 2.5 meters mean sea level (MSL). The objectives of this study were to identify the subaqueous landforms, evaluate the suitability of existing subaqueous soil-landscape models, develop a soils map, and demonstrate the usefulness of subaqueous soils information. Bathymetric data collected by the Maryland Geological Survey in 2003 were used to generate a digital elevation model (DEM) of Chincoteague Bay. The DEM was used, in conjunction with false color infrared photography to identify subaqueous landforms based on water depth, slope, landscape shape, depositional environment, and geographical setting (proximity to other landforms). The eight such landforms identified were barrier cove, lagoon bottom, mainland cove, paleo-flood tidal delta, shoal, storm-surge washover fan flat, storm-surge washover fan slope, and submerged headland. Previously established soil-landscape models were evaluated and utilized to create a soils map of the area. Soil profile descriptions were collected at 163 locations throughout Chincoteague Bay. Pedons representative of major landforms were characterized for a variety of chemical, physical and mineralogical properties. Initially classification using Soil Taxonomy (Soil Survey Staff, 2006) identified the major soils as Typic Sulfaquents, Haplic Sulfaquents, Sulfic Hydraquents, and Thapto-Histic Sulfaquents. Using a proposed modification to Soil Taxonomy designed to better accommodate subaqueous soils with the new suborder of Wassents, soils of Chincoteague Bay were primarily classified as Fluvic Sulfiwassents, Haplic Sulfiwassents, Thapto-Histic Sulfiwassents, Sulfic Hydrowassents, and Sulfic Psammowassents. To illustrate the application of subaqueous soils information, the suitability of soils for submerged aquatic vegetation (SAV) habitat was assessed, based upon past and current growth patterns in Chincoteague Bay and sediment properties known to affect SAV establishment and growth. The refined soil-landscape models and extensive soil characterization obtained in this study have advanced our understanding of subaqueous soils in coastal lagoon systems, and should prove valuable to coastal specialists managing these critical resources.