43. Reactive-Solute-Transport Models for Simulation of Nutrient Flux to the Marine Shore and Through the Subterranean Estuary in Shallow Coastal Aquifers

The degradation of the environmental health of the Nation’s coastal waters is a growing concern. The discharge of nutrients and other contaminants to these waters has resulted in contamination by toxic chemicals and widespread eutrophication of coastal waters, with the attendant damage to natural habitats and fisheries and promotion of harmful algal blooms. In many areas, such as the glaciated Northeast (for example, Cape Cod, coastal Rhode Island and Connecticut, and Long Island, N.Y.), direct groundwater discharge from coastal aquifers is a major part of the inflow to coastal embayments along the shore. Communities in these areas are facing enormous costs to manage their wastewaters, which often are discharged to the aquifers, in order to forestall the harmful eutrophication.

Resource managers at Federal, State, and local levels need tools and approaches to evaluate, design, implement, and assess methods to ameliorate coastal eutrophication. Groundwater flow and transport models have been developed for many areas of concern. A wide variety of strategies for measuring and investigating direct groundwater discharge have been developed and tested. Hydrodynamic and ecological-response models are being developed and applied for many coastal water bodies. At present, flow in the aquifer is well modeled in some locations (for example Cape Cod), but flow simulations in the subterranean estuary, and transient reactive-solute transport in both the aquifer and the subterranean estuary are lacking. Attenuation of nitrogen loads in the subsurface has not been simulated with full chemistry and 3-D flow including density effects of mixing freshwater and saltwater. Unknown, then, is whether some disposal locations on land or forms of nitrogen disposal would result in partial or complete attenuation of the nitrogen load before discharge into coastal waters.

Under this Research Opportunity, applicants are invited to focus on developing transient, 3-D, nutrient-transport simulations for shallow coastal aquifers and the subterranean estuary. These should incorporate chemistry, density, and tidal effects in areas where upgradient flow models already exist, such as Cape Cod, coastal Rhode Island, and Long Island, N.Y. The area(s) chosen should include typical northeast nearshore environments—high or low tidal range, fringing or filled saltmarsh embayments, lacustrine or sand-and-gravel deposits—and be locations of substantial nutrient discharge.

A successful proposal will briefly describe the coastal study area and site access and discuss previous work on which this research might build. The research advisors already have a wealth of data at multiple sites that will be offered to the successful candidate. Addition hydrologic and geologic data needed as inputs, for calibration, and for verification of the models should be described as well as the means for data collection, whether from existing literature or from collection in the field. The software intended for use in the simulations should be discussed. If appropriate, possibilities for interdisciplinary collaboration with hydrologists, geomorphologists, hydrodynamicists and biogeochemists should be discussed.

Proposed Duty Station: Woods Hole, MA

Areas of Ph.D.: Civil engineering, hydrology, biogeochemistry, or related disciplines (candidates holding a Ph.D. in other disciplines but with knowledge and skills relevant to the Research Opportunity may be considered).

Qualifications: Applicants must meet one of the following qualifications: Research Geologist, Research Hydrologist, Research Chemist, Research Engineer
(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)

Research Advisors :John Colman, (508) 490-5027, jacolman@usgs.gov; Kevin Kroeger, (508) 457-2270, kkroeger@usgs.gov; Charles Harvey, (617) 258-0392, (Massachusetts Institute of Technology), charvey@MIT.edu

Human Resources Office Contact:Claire Matthews, (703) 648-5786, cmatthews@usgs.gov

Summary of Opportunities