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Open access publications by faculty, postdocs, and graduate students in the Department of Earth Sciences.
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Browsing Open Access Publications by Subject "climate action"
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Item Hydrologic Control on Arsenic Cycling at the Groundwater–Surface Water Interface of a Tidal Channel(Environmental Science and Technology, 2023-01-10) Yu, Xuan; LeMonte, Joshua J.; Li, Junxia; Stuckey, Jason W.; Sparks, Donald L.; Cargill, John G.; Russoniello, Christopher J.; Michael, Holly A.Historical industrial activities have resulted in soil contamination at sites globally. Many of these sites are located along coastlines, making them vulnerable to hydrologic and biogeochemical alterations due to climate change and sea-level rise. However, the impact of hydrologic dynamics on contaminant mobility in tidal environments has not been well studied. Here, we collected data from pressure transducers in wells, multi-level redox sensors, and porewater samplers at an As-contaminated site adjacent to a freshwater tidal channel. Results indicate that sharp redox gradients exist and that redox conditions vary on tidal to seasonal timescales due to sub-daily water level fluctuations in the channel and seasonal groundwater–surface water interactions. The As and Fe2+ concentrations decreased during seasonal periods of net discharge to the channel. The seasonal changes were greater than tidal variations in both Eh and As concentrations, indicating that impacts of the seasonal mechanism are stronger than those of sub-daily water table fluctuations. A conceptual model describing tidal and seasonal hydro-biogeochemical coupling is presented. These findings have broad implications for understanding the impacts of sea-level rise on the mobility of natural and anthropogenic coastal solutes.Item Saltwater Intrusion Into a Confined Island Aquifer Driven by Erosion, Changing Recharge, Sea-Level Rise, and Coastal Flooding(Water Resources Research, 2024-01-08) Stanic, S.; LeRoux, N. K.; Paldor, A.; Mohammed, A. A.; Michael, H. A.; Kurylyk, B. L.Aquifers on small islands are at risk of salinization due to low elevations and limited adaptive capacity, and present risks will be exacerbated by climate change. Most studies addressing small-island saltwater intrusion (SWI) have focused on homogeneous sandy islands and one or two hydraulic disturbances. We herein investigate SWI dynamics in a layered, confined island aquifer in response to multiple environmental perturbations related to climate change, with two considered in tandem. Our field and modeling work is based on an island aquifer that provides the drinking water supply for an Indigenous community in Atlantic Canada. Observation well data and electrical resistivity profiles were used to calibrate a numerical model (HydroGeoSphere) of coupled groundwater flow and salt transport. The calibrated model was used to simulate the impacts of climate change including sea-level rise (SLR), storm surge overtopping, changing aquifer recharge, and erosion. Simulated aquifer conditions were resilient to surges because the confining layer prevented deeper saltwater leaching. However, reduced recharge and erosion resulted in saltwater wedge migration of 170 and 110 m, respectively when considered individually, and up to 295 m (i.e., into the wellfield) when considered together. Despite the confining conditions, SLR resulted in wedge migration up to 55 m as the confining pressures were not sufficient to resist wedge movement. This is the first study to harness an integrated, surface-subsurface hydrologic model to assess effects of coastal erosion and other hydroclimatic stressors on island aquifers, highlighting that climate change can drive extensive salinization of critical groundwater resources. Key Points - A surface-subsurface numerical model is used to investigate climate change impacts on island groundwater resources used for water supply - The confined aquifer is resilient to storm surges which only salinize the unpumped surficial aquifer before being flushed - Coastal erosion and recharge reductions result in the most saltwater intrusion and can work in tandem to threaten future water supply Plain Language Summary Due to their limited resources and adaptive capacity, small islands are highly vulnerable to climate change impacts, including saltwater intrusion. Freshwater needs on small islands are often sourced from small aquifers that are in delicate balance between conditions in the ocean, atmosphere, and land. In this study, we investigate the movement of saltwater into the freshwater aquifer of a small island that provides drinking water resources for an Indigenous First Nation. We consider climatic changes in the ocean (sea-level rise (SLR), storm surges, and related coastal erosion) and atmosphere (changes to net precipitation) and associated impacts to the island's fresh groundwater resources. We use field data paired with a mathematical model and demonstrate that the pressurized conditions of the layered island aquifer make it more resilient to SLR than unconfined aquifers in sandy islands are. However, the aquifer's freshwater volume is susceptible to coastal erosion and reduced precipitation, particularly when these happen at the same time. Results point to coastal erosion as a potential widespread driver of freshwater loss along eroding portions of the global coastline.