Research

Exploring how hydraulic fracturing (fracking) affects surface water quality in the Marcellus Shale region

Hydraulic fracturing, also known as unconventional oil and gas production or fracking, has proliferated in the Marcellus Shale region (including West Virginia, Pennsylvania, Ohio and New York State) over the past decade. There are many ways that the activities associated with fracking — including drilling and fracturing the well and transporting, storing or disposing of wastewater — could potentially impact water sources, and some instances of fracking-related water pollution have been documented. However, the extent of this pollution and how it relates to particular aspects of the fracking process remain poorly understood. So far, our lab group has collected water samples from streams in Pennsylvania, Maryland, Virginia and West Virginia, and our data suggest that there are some categorical differences between watersheds with and without fracking in terms of water quality. We are now working on analyzing the data we’ve collected, modeling the impact on the Potomac River (DC’s water source) and seeking additional funding to expand the project. The first phase of this project was funded by the DC Water Resources Research Institute and by internal grants.

Understanding the effects of watershed urbanization on hydrology and water quality

Focusing on three streams in Meadowood Special Recreation Management Area (a Bureau of Land Management property in Lorton, VA), we have been investigating how varying levels of urbanization in the watershed affect water chemistry, nutrient loading, and hydrology. Our preliminary results show clear differences between the three streams with high, medium and low levels of urbanization in terms of groundwater inputs and water quality. Currently, we are continuing weekly in-person surface water sampling to assess seasonal and inter-annual variability and adding groundwater sampling. We also plan to install automated samplers to better understand stormflow chemistry. This project is funded by a grant from the Bureau of Land Management.

Using radon to trace gas evasion and biogenic nitrogen gas production in agricultural watersheds

Nitrogen pollution is a major threat to the ecological health of coastal and estuarine ecosystems such as Chesapeake Bay. Much of the nitrogen comes from human activities such as agriculture and wastewater discharges within the watershed. But, surprisingly, scientists still do not know the fate of 75% or more of these net anthropogenic nitrogen inputs (NANI). Our research focuses on testing the hypothesis that the nitrogen undergoes denitrification within the aquifer, transforming it into nitrogen gas which then escapes to the atmosphere once the groundwater emerges into a stream. Working with collaborators Tom Jordan (Smithsonian Environmental Research Center), Tom Fisher (University of Maryland) and Rebecca Fox (Washington College), we developed a radon-based method to measure how much nitrogen escapes from the stream and separate the biogenic and abiogenic components of that nitrogen flux. The project was funded by the National Science Foundation, and we are currently working on writing up the results and seeking funding for the next phase.

Understanding heterogeneity in natural tracers of submarine groundwater discharge

I have been working with Holly Michael, Neil Sturchio, and Carlos Duque Calvache of the University of Delaware to better characterize and understand spatial and temporal heterogeneity in radium and radon, two natural tracers of submarine groundwater discharge (SGD). These tracers provide valuable, spatially-integrated estimates of SGD into coastal waters, but they can vary greatly over small distances in the coastal aquifer. Using a combination of high-resolution sampling and modeling, we hope to use this heterogeneity to gain insight about groundwater flow and groundwater-surface water interactions in the subterranean estuary.

Characterizing urban seepage spring habitats in the Washington, DC area

Washington, DC’s only endangered species is the groundwater-dwelling Hayes Spring amphipod, which lives in Rock Creek Park. In order to understand the ecology of these creatures and their relatives, which inhabit seepage springs throughout the DC area, I have been working with Dave Culver, Dan Fong and their students to characterize water quality in the springs. In particular, we are investigating the residence time of water in the perched aquifers that feed these springs, the size of these aquifers’ recharge areas, and the vulnerability of the springs to pollution. The project’s goals are (1) to improve scientific understanding of an understudied hydrogeologic setting, and (2) to support more effective conservation of Hayes Spring amphipods and other groundwater biota.

Assessing the effectiveness of urban gardens in reducing stormwater pollution

Urban gardens and farms are an integral part of the green infrastructure of Washington, DC and many other cities. This project focuses on quantifying how they compare to other green areas, specifically grass, in terms of their ability to absorb water and retain nutrients and dissolved metals during rainfall events.

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