Research Areas

Research in Dr. Reible's group is focused on the in-situ assessment and management of contaminated sediments and the sustainable development of water resources for both municipal and industrial uses. Research in contaminated sediments includes research into the fate and transport processes influencing contaminants in sediments, passive sampling for the assessment of sediment risks and remedy performance and the technologies of contaminated sediment management. Research in the sustainable development of water resources includes research into the exploitation and treatment of poor quality waters including brackish and produced water.
Dr. Reible's group is also undertaking research into the education of environmental engineers, exploring ways for engineers to better understand the broader consequences and implications of their work.

Enhancing Resilience in Water Infrastructure

Government and commercial services can be significantly disrupted by the loss of primary utilities such as water or electricity as results of human or natural events leading to equipment, communication or process failures. Particularly at risk are small communities that lack the resources to adequately plan and prepare for such events. This research area is designed to address resiliency in water infrastructure by (1) Analysis of potential impacts of infrastructure failure, (2) Identify planning responses to build greater resiliency, (3) Education and workforce development to build capacity, particularly in rural and agricultural small communities, (4) Identify and develop alternative water sources such as brackish groundwater, and (5) Identify and develop alternative water treatment technologies that can more efficiently provide high quality waters from poor quality sources.

Passive Sampling of Sediment Contaminants

This research is focused on in situ and ex situ sediment porewater sampling via passive means. The primary focus is on the use of diffusion gradient in thin film devices and dialysis samplers to monitor mercury in porewater and biogeochemical processes and the use of polymer sorbents, polydimethylsiloxane (PDMS), polyethylene (PE), and polyoxymethylene (POM) to monitor hydrophobic organic compounds. Work underway is designed to better understand what these tools measure and how they can be practically implemented and interpreted.

Assessment and Management of Stormwater Impacts on Sediment Recontamination

This work seeks to characterize the role of urban stormwater in contamination of sediments and remediated sites. The research focuses on the development and application of techniques to assess the magnitude and characteristics of episodic distributed sources (i.e. stormwater), and the effects of these sources on sediments and benthos. The work considers baseline conditions, loads of stormwater contaminants, relationship to other potential sources of sediment contamination and the potential for recontamination following remediation. The bulk chemical contamination is being integrated with site-specific bioavailability, the potential for bioaccumulation, and identification of key stressors and ecological risk of stormwater and stormwater -related sediment contaminants. This is providing the foundation for a decision making framework for identifying stormwater sources and their consequences, designing effective source controls and identifying the remedial goals realistically achievable without such controls.

Gas and NAPL mobility in sediments

Many current sites exhibit significant entrapped gas or nonaqueous phase liquids (NAPLs) whose mobilization may compromise the success of in situ-capping or treatment efforts. Research is underway to develop an improved experimental procedure to assess the response (mobilization) of this gas or NAPL to the disturbance and loading associated with sediment capping and resulting consolidation processes. This research is focused on developing a variant of traditional triaxial cell consolidation testing using undisturbed cores and realistic loadings combined with simultaneous measurement of consolidation and phase and contaminant mobilization. This research is coupled with complementary research into active capping technologies that can mitigate gas or NAPL mobilization including evaluation of the filtering effects of conventional sand caps and the effectiveness and appropriate design of organoclay amended caps

Biogeochemical response to capping

Capping contaminanted sediments inherently results in significant modifications of the biogeochemical environment of the sediment contaminants. These modifications may be positive, e.g. development of strong anaerobic conditions which limits mobility of some metals and may eliminate mercury methylation, or negative, e.g. the reduction in biodegradation of many hydrophobic organic compounds under strongly anaerobic conditions. The evaluation of the dynamics of these biogeochemical changes and their influence on contaminant mobility and fate is the subject of this area of Dr. Reible's research. This research considers both changes in the sediment underlying a cap and the changes in the cap itself. An important product of this research is expected to be a better understanding of the biogeochemical environment within the cap and the effectiveness of a cap in the promotion biodegradation processes. This research is focused on evaluating these processes under both generic conditions and at specific sites where the fate processes within a sediment cap are an important design constraint.

Bioavailability of sediment contaminants

It is increasingly recognized that bulk sediment concentrations provide a limited indication of the potential toxic effects of the sediment. Bioavailability research conducted in Dr. Reible's research laboratory is focused on the development of better tools for the in-situ assessment of bioavailability and the practical implications of common management approaches, e.g. capping, on bioavailability. Solid phase microextraction fibers are a useful analytical tool in the laboratory for assessment of porewater concentrations, often a good indicator of bioavailability. The development of practical approaches to using this tool in the field is underway and includes the demonstration of the relationship to organism uptake and effects measured simultaneously. Part of this research is directed toward assessing the effectiveness of commonly used “backfill” approaches to the management of dredging residuals at contaminated sediment sites. Although effective at reducing bulk sediment concentration, reductions in bioavailability associated with this approach are unproven.

Active Capping of Contaminated Sediments

Dr. Reible's research is also directed toward continuing the development of new approaches to combining capping and treatment of sediments. Some of these approaches are directed toward control of specific contaminants, such as organoclays to manage NAPLs as described above, but other aspects of this research are directed toward general improvement in the options available for simultaneous containment and treatment of sediment contaminants. Part of this research is directed toward continuing monitoring of the efficacy of the caps placed during the Anacostia River Active Capping Demonstration led by Dr. Reible. Other components of this research are directed toward the laboratory evaluation of new potential capping materials and procedures, including the use of combination caps for simultaneous metal and organic contaminant sequestration with erosion control. Specific materials under consideration, either alone or in combination, include phosphate minerals, activated carbon, organoclays, zero-valent iron and a variety of biopolymers.

Developing Reflective Engineers with Artful Methods (DREAM)

This work explores the hypothesis that artful training methods (i.e., those that explicitly incorporate the arts and humanities) in education can improve engineering students' understandings of ethical and socioeconomic challenges through reflective thinking. Through mixed-methods research, we are exploring various training methods and pedagogies that can help students to (a) become more cognizant of the risks, uncertainties, and other implications of their engineering solutions, (b) act with ethical and professional responsibility, and (c) make informed judgments that consider the impact of engineering solutions. Methods we are exploring for increasing reflection include:
(1) Developing oneself through writing autobiographical accounts.
(2) Developing phronesis through reflections on current problems.
(3) Developing observational skills through Visual Thinking Strategies (VTS).
(4) Developing awareness for environmental justice through exposure to and participation in various forms of art (e.g., through museum visits, photography exercises, reading poetry and fiction, etc.).