Increasing population density and changing agricultural practices in coastal areas have led to releases of nutrients (and other contaminants) into the coastal environment from fertilizer use, industrial practices, and wastewater discharge. These increased nutrient releases have led to eutrophication in many coastal waters, which is a widespread concern. Yet, the role that groundwater-derived nutrients has played in coastal eutrophication is not well understood in many areas. The ecological and economic impacts of eutrophication have been substantial in many coastal regions, which demands a better understanding of the contribution of groundwater-derived nutrient fluxes. Management of wastewater treatment practices in coastal regions critically depends on accurate estimates of the flux and quality of ground water in the coastal zone. In addition, informed resource management requires an improved understanding of the geological framework of coastal aquifers, the pathways by which ground water travels to the coastal zone, the specific locations and dimensions of submarine discharge zones, and the geochemical transformations that take place prior to discharge.
Basic science questions related to how fluid flux across ocean margins and fluid recirculation through ocean margin sediments affects elemental cycling at all scales are also scientific priorities of this research effort. Experiments that address more applied aspects of nutrient delivery can also yield information that is valuable for developing a more general understanding of land-ocean aquifer interactions.
While previously, the focus of the Coastal Aquifer Project was to examine geologic control on coastal aquifers and groundwater discharge, today it is apparent that knowledge of land–sea exchange must also encompass interplay among ecosystems science including ecosystems health and climate change-related processes, as well as natural geohazards.
10/1/2004 - 9/30/2018
The ultimate objective for this project is to be able to make accurate generalizations and predictions regarding rates and ecological consequences of SGD under differing hydrogeologic, geographical and climatological regimes. This collective work will thus permit a first-order national assessment of coastal submarine groundwater discharge impact. Current research goals include:
Our research depends critically upon techniques that have been refined over the years of the Coastal Aquifer Project. These techniques include qualitative mapping tools (e.g., radon-mapping, continuous resistivity profiling, shallow seismic, salinity mapping, etc) as well as quantitative passive and active techniques (e.g., radon times series, radium-quartet isotope models, seepage meters, well transects, and modeling).
The general long-term approach—developing a regional perspective of submarine ground-water discharge—is carried out with local studies at sites that are typologically representative of more general geological conditions and processes. In addition, consideration is given to mission and regional priorities of USGS (including WRD and BRD) and DOI, including management priorities of sister DOI bureaus and other federal agencies. To date, research has benefitted resource managers at Assateague Island, Cape Cod, and Fire Island National Seashores, as well as NSF-funded research partners.