T. C. Sheahan’s research while affiliated with Northeastern University and other places

Climate change has led to the need for innovation in resilient infrastructure and the social policies which will support those. This requires greater interdisciplinary interactions and knowledge building among emerging professionals. This paper presents a case study of a pilot short course intended to immerse graduate students in the design of resilient infrastructure using place-based and interdisciplinary active team learning. This course helps graduate students bridge the gap between research and practice on the social science and engineering of resilient infrastructure for coastal adaptation. The intellectual framework for the course (the Adaptive Gradients Framework) provides a holistic evaluation of adaptation design proposals and was used to recognize the complexity of social, ecological and engineering aspects and varied social benefits. The course provides a model to move outside rigid boundaries of institutions and disciplines to begin to build, in both students and instructors, the ability to work more effectively on complex social-ecological-engineering problems. Finally, this paper presents a summary of lessons learned from this pilot short course.

Current and future climate-related coastal impacts such as catastrophic and repetitive flooding, hurricane intensity, and sea level rise necessitate a new approach to developing and managing coastal infrastructure. Traditional “hard” or “grey” engineering solutions are proving both expensive and inflexible in the face of a rapidly changing coastal environment. Hybrid solutions that incorporate natural, nature-based, structural, and non-structural features may better achieve a broad set of goals such as ecological enhancement, long-term adaptation, and social benefits, but broad consideration and uptake of these approaches has been slow. One barrier to the widespread implementation of hybrid solutions is the lack of a relatively quick but holistic evaluation framework that places these broader environmental and societal goals on equal footing with the more traditional goal of exposure reduction. To respond to this need, the Adaptive Gradients Framework was developed and pilot-tested as a qualitative, flexible, and collaborative process guide for organizations to understand, evaluate, and potentially select more diverse kinds of infrastructural responses. These responses would ideally include natural, nature-based, and regulatory/cultural approaches, as well as hybrid designs combining multiple approaches. It enables rapid expert review of project designs based on eight metrics called “gradients”, which include exposure reduction, cost efficiency, institutional capacity, ecological enhancement, adaptation over time, greenhouse gas reduction, participatory process, and social benefits. The framework was conceptualized and developed in three phases: relevant factors and barriers were collected from practitioners and experts by survey; these factors were ranked by importance and used to develop the initial framework; several case studies were iteratively evaluated using this technique; and the framework was finalized for implementation. The article presents the framework and a pilot test of its application, along with resources that would enable wider application of the framework by practitioners and theorists.

Understanding the interaction of environmental contamination and its impact on human health stretches the disciplinary demands required for effective research. Team science is required to understand the origin of contaminants, their pathways to human, their health effects, and for development of effective mitigation. We describe a team science model applied to the study of preterm birth in a region of karst hydrogeology, the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT). This research program uses an innovative, holistic, source-to-outcome transdisciplinary approach that integrates epidemiological, toxicological, analytical, fate-transport, and remediation studies, along with a unified sampling infrastructure, a centralized, indexed data repository and a data management system. PROTECT is contributing new knowledge about the risk that contaminants may pose in pregnancy resulting in preterm birth, how these contaminants reach karst aquifers, and what are the biological mechanisms by which environmental contaminants may promote preterm birth. PROTECT also is developing novel remediation approaches that will target removal of contaminants linked to preterm births from ground water. These integrated efforts offer unique opportunities to address a serious public health problem and its solution would result in a healthier population and a healthier environment.

This paper describes the development and multistep validation of a one-dimensional, large strain consolidation coupled contaminant transport model with nonlinear and nonequilibrium sorption kinetics. The RCM-XPORT2K model uses the CS2 large strain consolidation approach for modeling the deforming saturated porous medium consolidating under a surcharge stress, coupled with reactive advective/dispersive solute transport through the medium, capped with a thin-layered reactive sequestering geocomposite known as a reactive core mat (RCM). In addition to assumptions made in previously developed, one-dimensional consolidation coupled contaminant transport model RCM-XPORT2, the RCM-XPORT2K model accounts for sediment- and sorbent-specific sorption kinetics to model nonlinear, and nonequilibrium sorption behavior. Validation of the model is presented by simulating: (1) sorption kinetics tests performed on sediment sampled from Neponset River, Milton, Massachusetts, USA and a commercial product, CETCO Organoclay PM-199; (2) solute transport from the large strain consolidation coupled contaminant transport tests with Br⁻ and Cl⁻ using a high water content inert silt sample (New York Silt); and (3) the naphthalene transport and breakthrough times observed in upflow column tests with Neponset River sediment with various overlying cap layers.

The uptake of PCBs contained in marine sediments by the green macroalga Ulva rigida was investigated in both laboratory and field experiments. Under laboratory conditions, total PCBs (tPCBs) uptake was significantly greater in live vs dead plants. The concentration of tPCB taken up in live plants was greatest in the first 24h (1580μgkg(-1) dry weight), and then increased at a lower rate from day 2 to 14. Dead plants had a significantly lower tPCB concentration after 24h (609μgkg(-1) dry weight) and lower uptake rate through day 14. Lesser chlorinated PCB congeners (below 123) made up the majority of PCBs taken up. Congener composition in both laboratory and field experiments was correlated to congener logKow value and sediment content. Field experiments showed that Ulva plants could concentrate PCBs to 3.9mgkg(-1) in 24h. Thus, U. rigida is capable of removing PCBs in sediments at a rapid rate.

The Sustainable Adaptive Gradients in the Coastal Environment (SAGE) research collaboration network is composed of U.S., Caribbean, and European engineers, geoscientists, ecologists, social scientists, planners, and policy makers. The goal of SAGE is to establish international, cross-disciplinary networks of researchers working on resilient coastal infrastructure (gray, green, and cultural), with a focus on understanding how varying coastal characteristics contribute toward resilient adaptation strategies (funded under National Science Foundation grant ICER-1338767).

This paper describes the results of a benchscale testing program to assess the efficacy of a reactive core mat (RCM) for short term isolation and partial remediation of contaminated, subaqueous sediments. The 1.25 cm thick RCM (with a core reactive material such as organoclay with filtering layers on top and bottom) is placed on the sediment, and approximately 7.5 - 10 cm of overlying soil is placed on the RCM for stability and protection. A set of experiments were conducted to measure the sorption characteristics of the mat core (organoclay) and sediment used in the experiments, and to determine the fate of semi-volatile organic contaminants and non-reactive tracers through the sediment and reactive mat. The experimental study was conducted on naphthalene-spiked Neponset River (Milton, MA) sediment. The results show nonlinear sorption behavior for organoclay, with sorption capacity increasing with increasing naphthalene concentration. Neponset River sediment showed a notably high sorption capacity, likely due to the relatively high organic carbon fraction (14%). The fate and transport experiments demonstrated the short term efficiency of the reactive mat to capture the contamination that is associated with the post-capping period during which the highest consolidation-induced advective flux occurs, driving solid particles, pore fluid and soluble contaminants toward the reactive mat. The goal of the mat placement is to provide a physical filtering and chemically reactive layer to isolate contamination from the overlying water column. An important finding is that because of the high sorption capacity of the Neponset River sediment, the physical filtering capability of the mat is as critical as its chemical reactive capacity.

The effect of a thin sand capping layer (7.5cm) on the bioavailability of hydrophobic organic compounds (HOCs, i.e., PCBs and naphthalene) was studied using oligochaete worms, and the results compared to previously obtained bioavailability tests with a reactive core mat (RCM) cap. The study investigated the difference in HOC concentration in worms exposed to: (a) a grab sample of sediment used as sampled for PCBs and spiked for PAHs; (b) an initially clean mixture of sand and organic matter (biouptake layer) directly overlying the sediment; and (c) the biouptake layer placed on top of the RCM-capped sediment. Benchscale experiments were performed to induce pore fluid flux through the sediment and into the overlying layer(s). Principal component analysis (PCA) was used to assess PCB homolog group concentrations. Results indicate that the thin sand cap alone reduced the average bioavailability of PCBs by a factor of 100 compared to direct exposure, but had no effect on the bioavailability of naphthalene. However, worms exposed to the RCM-protected biouptake layer show virtually the same HOC concentrations as those in the background worm samples, indicating effective isolation by the RCM.

Mentoring is useful in career development for the sciences and professions due to the cultures, skill sets, and experience-based learning in these fields. A framework for mentoring based on observations and data gathered as part of an international research and education project is presented. Students with multiple levels of experience and background were placed with researchers resulting in an effective progressive mentoring structure. The article focuses on students’ and mentors’ experiences. The model is discussed in terms of the Zone of Proximal Development of Vygotsky.