Research Activities

July 2008

• WED Scientist Goes to Germany and Ukraine To Lecture on Ecosystem Services and Participate in NATO Advance Research Workshop
• NHEERL Scientists Meet with EPA Program Offices and NIH Chemical Genomics Center Concerning Stress-Based Toxicity Assays
• NHEERL Division Director Participates in Outcome Measurement Study for CFI
• AED Scientist Detailed to U.S. Department of State To Investigate Marine Monitoring, Assessment, and Conservation
• NHEERL Scientist Presents ORD Research at a Regional Green Building Workshop

• NHEERL AED To Present EMS to Southeastern New England Health & Safety Council - Providence, Rhode Island; June 30, 2008

February 2008

• MED Scientists Help Lead Important Effort To Summarize New Generation of Indicators for Coastal Change in Great Lakes

October 2007

• RTD Scientist Recently Interviewed for Jim Lehrer News Hour on PBS

August 2007

• High-Profile Study, "Elevated PBDE Levels in Pet Cats: Sentinels for Humans?" Highlighted in Environmental Science & Technology
• Proceedings of EPA Workshop on Research and Risk Assessment for Arsenic Appear as Special Issue of Toxicology and Applied Pharmacology August 1

June 2007

• Healthy Men Study Published
• Mild Thyroid Disruption Alters Fetal Neuronal Migration

May 2007

• Scientist To Author First Comprehensive and Up-to-Date Review of PFAAs
• Scientists Win Prestigious Award for Work on Perchlorate Risk Characterization
• Scientist Reports Important Findings on Arsenic Effects on Cardiac Risk
• Scientists Generate Important Androgen Receptor for EPA's Endocrine Disruptor Screening Program
• Branch Chief Receives Bronze Medal from EPA Region 5
• Scientist To Have Work Featured on Cover of Journal of Andrology
• Scientist Supports EPA Office of Water in International Ballast Water Treaty Discussion
• Branch Hosts Workshop on Nutrient Criteria Approaches for Oregon Estuaries
• Scientists To Visit Ukraine To Review Collaborative Estuarine Research
• Scientists Invited To Conduct Salt Marsh Research in South Carolina

July 2008

WED Scientist Goes to Germany and Ukraine To Lecture on Ecosystem Services and Participate in NATO Advance Research Workshop

Dixon Landers, NHEERL Western Ecology Division (WED), traveled to the University of Ljubljana in Slovenia, Kiel, Germany, and Kharhiv, Ukraine, to give invited lectures on ecosystem services and challenges of higher education in training interdisciplinary environmental scientists to provide solutions for the world’s increasingly complex environmental problems. Dr. Landers’ lectures on ecosystem services discussed research associated with ORD’s Ecological Research Program, in particular, the Willamette Ecosystems Services Project, which he leads. In Kiel, he presented a lecture at the international workshop “Ecosystems Services―Solution for problems or a problem that needs solutions?” Based on his experiences in conducting interdisciplinary research, Dr. Landers lectured at the North Atlantic Treaty Organization (NATO) Advance Research Workshop entitled “Rethinking Higher Education To Meet the New Challenges of Environmental Security.”

NHEERL Scientists Meet with EPA Program Offices and NIH Chemical Genomics Center Concerning Stress-Based Toxicity Assays

Ram Ramabhadran and Steve Simmons of the Cellular and Molecular Branch of NHEERL’s Neurotoxicology Division visited the National Institutes of Health (NIH) Chemical Genomics Center (NCGC), the Office of Water, the Office of Pesticide Programs, and the Office of Pollution Prevention and Toxics on April 28 and 29. They discussed the stress-based toxicity assays they developed with NCGC staff with the goal of porting these assays to the ultra-high-throughput screening format available at NCGC. At the program offices, they presented three seminars titled “Stress Response Pathway Ensemble: A New Paradigm in High-Throughput Toxicity Screening” to apprise the program office staff of NHEERL's new effort in keeping with the recently released National Academy of Sciences report “Toxicity Testing in the 21st Century.”

NHEERL Division Director Participates in Outcome Measurement Study for CFI

The Canada Foundation for Innovation (CFI) is planning a series of outcome measurement study (OMS) visits to universities between now and 2010. The purpose of the OMS is to assess the degree to which CFI[‘s investment in research infrastructure has been a critical contributing factor in the realization of certain outcomes. It involves visits to CFI-funded institutions and focuses on identified thematic areas in which major investments have been made. William H. Benson (Director, NHEERL's Gulf Ecology Division) serves as a member of the OMS committee in the thematic area of Ocean and Environment, Science, and Technology. The 2-day, mid-May meeting was held at the University of Victoria. The Outcome Measurement Committee consists of a chair, three international scientific experts who can identify transformative research findings and innovation, a user expert, observing representatives from the provincial government, other funders, and CFI evaluation staff. The review team collected information from a range of indicators designed to capture the impacts of the CFI infrastructure on theimpact on university strategic research planning, research capacity, highly qualified personnel, research productivity, and innovation.

AED Scientist Detailed to U.S. Department of State To Investigate Marine Monitoring, Assessment, and Conservation

Stephen Hale, a Research Ecologist in NHEERL’s Atlantic Ecology Division (AED), was selected by the Embassy Science Fellows Program for an 8-week detail to the U.S. Department of State’s embassy in Lisbon, Portugal, from April 7 to May 30. The Portuguese government is interested in science and technology cooperation in marine environmental monitoring and conservation. This visit fostered areas of cooperation between Portugal and the United States on ecological indicators in support of the European Union Water Framework Directive and the U.S. Clean Water Act. Contacts with Portuguese government and academic researchers will further the development of techniques for intercalibrating marine benthic indices from different biogeographic areas; this will be useful for national aquatic resource surveys conducted in both Portugal and the United States.

NHEERL Scientist Presents ORD Research at a Regional Green Building Workshop

Marc Russell of NHEERL’s Gulf Ecology Division spoke at a Green Workshop organized by the West Florida Regional Planning Council on June 20. The overall premise of the workshop was to discuss green building design, green infrastructure, native landscaping, sustainability, walkable communities, etc. Speakers included a Green Infrastructure Representative from EPA Region 4 and representatives from the Northern Gulf Chapter of the U.S. Green Building Council and the Florida Department of Environmental Protection’s Sustainable Initiative Program. Dr. Russell’s talk was entitled “Ecological Services―Tampa Bay Demonstration Project.” This project, part of EPA’s Ecological Research Program, is a challenging mix of ecological, economic, and social sciences at multiple scales.

The presentation covered ecological services in urban environments: problems, some proposed solutions, and an approach for determining the production of ecological services from urban-influenced ecosystems in the Tampa region. The talk also suggested how this research is applicable to many regions around the Gulf of Mexico. There was a focus on the effects of placing people on the landscape in a more sustainable manner.

June 2008

NHEERL AED To Present EMS to Southeastern New England Health & Safety Council - Providence, Rhode Island; June 30, 2008

In response to previous Executive Orders (EOs) and the most recent EO13423, Strengthening Federal Environmental, Energy, and Transportation Management (January 24, 2007), NHEERL’s Atlantic Ecology Division (AED) has implemented a practical, facility-level environmental management system (EMS) with the general goal of lessening the facility’s environmental footprint. EO13423 requires proactive communication of our approach to EMS to external groups. To begin meeting this requirement, members of AED’s EMS Team made a presentation entitled “Environmental Management Systems: Federal Requirements and U.S. Environmental Protection Agency (Atlantic Ecology Division) Implementation” to the Southeastern New England Health & Safety Council in Providence, RI, on June 30. Additionally, AED’s EMS Team will be initiating interaction with other area groups and stakeholders (including homeowners’ and fishermen’s associations) to enhance communication of the program.

MED Scientists Help Lead Important Effort To Summarize New Generation of Indicators for Coastal Change in Great Lakes

A special edition of the Journal of Great Lakes Research (JGLR) summarizes a new generation of indicators for coastal change in the Great Lakes. These environmental indicators are benchmarks for the current conditions of the lakes’ coastal region and provide measurable endpoints to assess the success of future management, conservation, protection, and restoration of this important freshwater resource. The new indicators are especially timely because of increasing recognition of human pressures in the coastal zone that affect ecosystem quality and the related services people expect from coastal ecosystems. The need to track coastal conditions recently has become a special emphasis of the International Joint Commission and is a major discussion area as revisions to the U.S.-Canada Great Lakes Water Quality Agreement are being considered.

NHEERL’s Mid-continent Ecology Division (MED) has collaborated with the STAR-funded Great Lakes Environmental Indicators Project through a U.S. Environmental Protection Agency cooperative agreement with the Natural Resources Research Institute at the University of Minnesota Duluth. The JGLRspecial issue includes 22 papers on the development of coastal indicators that make a link between landscape disturbance metrics and the condition of coastal receiving waters and biota. MED scientists are lead authors of two of the papers, and nine others are contributing co-authors to the special issue, which will be available in March 2008.

October 2007

RTD Scientist Recently Interviewed for Jim Lehrer News Hour on PBS

L. Earl Gray, NHEERL's Reproductive Toxicology Division (RTD), was interviewed on October 23 for the Jim Lehrer News Hour on PBS. A renowned expert in the field of endocrine disruptors and reproductive development, Dr. Gray was asked about the controversy surrounding bisphenol A (BPA), a compound used in the manufacture of a wide variety of consumer products, from plastic water bottles to dental sealants. BPA has been the topic of studies linking chemical exposures and reproductive disorders. Dr. Gray recently served on a National Toxicology Program Expert Panel reviewing these studies. The report of this panel differed from that of another workshop held in Chapel Hill, NC, a fact that drew media attention.

August 2007

High-Profile Study, "Elevated PBDE Levels in Pet Cats: Sentinels for Humans?" Highlighted in Environmental Science & Technology

A study by NHEERL scientists Jan Dye and Linda Birnbaum, along with colleagues from Indiana University and the University of Georgia, is highlighted in this month's issue of Environmental Science & Technology. Their investigation included data on polybrominated diphenyl ether (PBDE) levels measured in pet cats (serum acquired from veterinary teaching hospitals) as sentinels and the potential linkage of PBDE exposure to development of feline hyperthyroidism, an increasingly common endocrine disease of pet cats. The study is to be available online in mid-August and in print soon after.

Manuscript: J. A. Dye, M. Venier, L. Zhu, C. R. Ward, R. A. Hites, and L. S. Birnbaum. Elevated PBDE Levels in Pet Cats: Sentinels for Humans? Environmental Science and Technology (in press).

Proceedings of EPA Workshop on Research and Risk Assessment for Arsenic Appear as Special Issue of Toxicology and Applied Pharmacology August 1

David J. Thomas of NHEERL's Experimental Toxicology Division (ETD) served as co-editor of this special issue and was one of the organizers of the workshop, along with Rebecca Calderon and Edward Hudgens of NHEERL's Human Studies Division. The 21 manuscripts in this special issue were prepared by participants in a workshop held at the National Conservation Training Center in Shepherdstown, WV, from May 31 to June 2, 2006. About 50 individuals from EPA, other Federal agencies, academia, and the private sector participated in this workshop. Manuscripts prepared by speakers from the workshop presented new research on the adverse health effects of arsenic exposure in human populations, on recent developments with animal models potentially useful for understanding the biological basis for these adverse effects, and on the relation between the metabolism of arsenic and its modes of action as a toxicant and carcinogen. You may view an electronic version of the special issue. The following EPA authors contributed manuscripts published in the special issue:

• NHEERL, Experimental Toxicology Division Blakely M. Adair, Hisham A. El-Masri, Michael F. Hughes, Elaina M. Kenyon, and David J. Thomas;
• NHEERL, Human Studies Division Rebecca L. Calderon, John P. Creason, Edward E. Hudgens, Danelle Lobdell, Pauline Mendola, and Judy L. Mumford;
• NHEERL, Experimental Carcinogenesis Division Kirk T. Kitchin, A.D. Kligerman, A.H. Tennant, and Douglas C. Wolf;
• National Center for Environmental Assessment Reeder Sams II;
• Office of Water Santhini Ramasamy and Ed Ohanian; and
• Office of Pesticide Programs Jonathan Chen and Anna Lowit.

June 2007

Healthy Men Study Published

NHEERL Reproductive Toxicology Division Acting Director Sally Perreault Darney is one of the lead authors on a paper reporting results from the Healthy Men Study, a collaborative effort between NHEERL scientists and epidemiologists from the University of North Carolina. The study evaluated whether disinfection by-products (DBPs) in drinking water may harm the human male reproductive system. In this study, men were recruited from several localities based on drinking water DBP levels. Semen samples from exposed individuals were evaluated for sperm characteristics such as concentration, morphology, and DNA and chromatin integrity, factors associated with male-mediated adverse pregnancy outcomes. Results from this study indicate that DBPs resulting from disinfection by chloramination and present in municipal water supplies at moderate levels (within but approaching the current maximum contaminant levels) are not associated with abnormal decrements in semen quality. This research provides the Office of Water with information that adds to the weight of evidence that current rules specifying the levels of DBPs that may be present in drinking water are protective of male reproductive health. Such information will be useful to the Office of Water in its next 2-year review of the Stage 2 Disinfection By-product Rules.

Reference: Luben, T.H., Olshan, A.F., Herring, A.H., Jeffay, S., Strader, L., Buus, R.M., Chan, R.L., Savitz, D.A., Singler, P.C., Weinbery, H.S., and Perreault, S.D. (2007). The Healthy Men Study: An Evaluation of Exposure to Disinfection By-products in Tap Water and Sperm Quality. Environmental Health Perspectives, in press. Available online: http://www.ehponline.org/docs/2007/10120/abstract.html .

Mild Thyroid Disruption Alters Fetal Neuronal Migration

Stunted growth and mental deficiencies follow severe disruption of thyroid hormone supply to the developing fetal brain; however, relatively little is known about how low-level thyroid disruption may alter brain development. NHEERL scientist, Mary Gilbert, has discovered a previously overlooked cluster of dislocated brain neurons following experimental mild hypothyroidism in developing laboratory rats. This work, in collaboration with Jeffrey Goodman of Helen Hayes Hospital, New York, entitled "Modest Thyroid Hormone Insufficiency During Development Induces a Cellular Malformation in the Corpus Callosum: A Model of Cortical Dysplasia" was published in the May issue of Endocrinology, the official journal of the Endocrine Society. The article was further featured in News and Views section of that issue of the journal and was accompanied by an invited critique by a leading endocrinologist. The malformation, called a heterotopia, lies within the corpus callosum, which is the primary fiber network that interconnects the two cerebral hemispheres. Not only has this brain abnormality remained undetected until now, alarmingly, it appears in the brains of rodents experiencing only modest degrees of hormone insufficiency. This finding demonstrates that subtle transient reductions of maternal thyroid hormone reliably produce dramatic structural alterations in brain development. The dose-dependent characteristics of these alterations are consistent with the concern that early subclinical thyroid hormone insufficiency can contribute to a number of neurological disorders of childhood origin. Dr. Gilbert's discovery underscores the importance of ORD's research program on endocrine disruptors, as well as work on how chemical mixtures disrupt thyroid function under the ORD Human Health Research Program. Characterization of the signaling pathways under thyroid hormone control that lead to generation of this malformation may provide sensitive and predictive biomarkers of subtle perturbations of the thyroid axis and improve the ability to identify and characterize risk of xenobiotics with potential thyroid action.

May 2007

Scientist To Author First Comprehensive and Up-to-Date Review of PFAAs

Christopher Lau of NHEERL's Reproductive Toxicology Division is first author on a paper that is the first comprehensive and up-to-date review of the perfluoroalkyl acids (PFAAs), of which the two most well known are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Online this week on the Toxicological Sciences Web site, the paper is a collaborative effort wherein Dr. Lau provides his well-known expertise on the toxicology of PFAAs, and members of the Risk Assessment Division of the Office of Pollution Prevention and Toxics (OPPT) provide their expertise in biomonitoring, as well as efforts in the tabulation of vast amounts of biomonitoring and exposure data. Members of OPPT contributing to the paper include Drs. Anitole, Hodes, Lai, Pfahles-Hutchens, and Seed. PFAAs are a family of chemicals that have been identified in humans and wildlife worldwide. Recent research has led to progress in the understanding of the toxicology of these compounds with respect to developmental toxicity, immunotoxicity, and hepatotoxicity, as well as potential modes of action. This paper provides an overview of the recent advances in the toxicology and mode of action for PFAAs and of the monitoring data now available for the environment, wildlife, and humans. A review such as this is an invaluable resource on PFAAs for researchers in the Agency and worldwide and will serve to aid in the development of new areas of research that will further the understanding of this important group of chemicals.

Scientists Win Prestigious Award for Work on Perchlorate Risk Characterization

Annie Jarabek, team leader, William Boyes, Kevin Crofton, Andrew Geller, Mary Gilbert, Ralph Smialowicz, and Doug Wolf, all of NHEERL, have been recognized with an EPA National Honor Award Gold Medal for their efforts as part of the Perchlorate Risk Characterization Team. NHEERL provided the Agency with expertise in data analysis and interpretation and on the thyroid system and with assistance in writing the EPA risk characterization. NHEERL scientists supported EPA efforts through two external peer reviews and a National Research Council review. This was truly a team effort, combining the talents of NHEERL scientists with those of theirs partners in NCEA, NERL, Region 9, NIEHS, and NIOSH). Formal presentation of the award will be on June 13 at the Warner Theater in Washington, DC.

Scientist Reports Important Findings on Arsenic Effects on Cardiac Risk

Judy Mumford, a researcher in NHEERL's Human Studies Division (HSD), has published a peer-reviewed paper in the May issue of Environmental Health Perspectives (EHP) showing that arsenic upsets heartbeat, and that ECGs may give early warning for arsenic-associated cardiac disease. The title of the paper is "Chronic Arsenic Exposure and Cardiac Repolarization Abnormalities with QT Interval Prolongation in a Population-Based Study,'' and it was authored by J. Mumford, K. Wu, Y. Xia, R. Kwok, Z. Yang, J. Foster, and W.E. Sanders, Jr. The article has been cited by safedrinkingwater.com and reviewed by the National Institute of Environmental Health Sciences' EHP News.

Scientists Generate Important Androgen Receptor for EPA's Endocrine Disruptor Screening Program

NHEERL Reproductive Toxicology Division (RTD) scientist Phillip Hartig, in collaboration with Vickie Wilson and co-workers at RTD, has generated a recombinant chimpanzee androgen receptor (AR) in response to a specific request from EPA's Endocrine Disruptor Screening Program (EDSP) managed by OSCP. This recombinant receptor is being used to address the need for an alternative mammalian AR binding assay for use in EPA's endocrine disruptor screening battery. Further, the joint European Centre for the Validation of Alternative Methods/EPA committee is planning to use Dr. Hartig's receptor in the interlaboratory assay validation exercise currently ongoing for in vitro assays. To develop the alternative, AR cell-free binding assay, Dr. Hartig first had the chimp AR gene synthesized, so that it could be transferred into cells. These cells then produced the chimp AR, and this AR was used first in standard binding and transcriptional activation assays. The cell-free binding assay is being optimized in which the AR is extracted from the cells and used in the new assay. Importantly, this cell-free binding assay is expected to replace the rat AR binding assay currently in the EDSP battery and, thereby, reduce the use of animals when screening for endocrine disruptors. After validation, the assay from Dr. Hartig's laboratory will be made available to labs worldwide to use for screening chemicals for androgenic and antiandrogenic activities. This research team is using a similar approach to evaluate both androgen and estrogen receptors from all four vertebrate classes for potential use in the evaluation of the impact of endocrine-disrupting chemicals on wildlife.

Branch Chief Receives Bronze Medal from EPA Region 5

Mace G. Barron, a branch chief at NHEERL's Gulf Ecology Division (GED), received a bronze medal as a member of the AK Steel Case Team. He was the lead ecological risk assessor and an expert witness supporting the U.S. Department of Justice and EPA Region 5 at a polychlorinated-biphenyl-contaminated steel facility in Ohio from 2004 to 2006. The award was given "for sustained efforts in developing, litigating, negotiating, and settling a multimedia case against AK Steel that will result in significant environmental improvement in and around Middletown, Ohio."

Scientist To Have Work Featured on Cover of Journal of Andrology

NHEERL Reproductive Toxicology Division (RTD) principal investigator Gary Klinefelter will have his work featured on the cover of the Journal of Andrology, the publication of the Society of Andrology. Entitled "Chronic Exposure to Low Levels of Dibromoacetic Acid, a Water Disinfection By-Product, Adversely Affects Reproductive Function in Male Rabbits," the paper is available online prior to publication at http://www.andrologyjournal.org/cgi/rapidpdf/jandrol.107.002550v1 and is to be published in volume 28, issue 4, 2007. In this paper, treatment of rabbits with one of the important disinfection byproducts, dibromoacetic acid (DBA), resulted in reductions in both the concentration of SP22, a sperm membrane fertility protein, and the conception rate following artificial insemination. Histologic lesions in the testes also were increased. Dr. Klinefelter's laboratory was the first to recognize SP22 as a sperm marker for which measured levels could be correlated with fertility in laboratory animals. This paper represents ongoing work in Dr. Klinefelter's laboratory studying effects of drinking water disinfection by-products on male reproductive function. Investigating the reproductive effects of drinking water disinfection by-products is a high-priority research area in RTD and is responsive to the needs of the Office of Water.

Scientist Supports EPA Office of Water in International Ballast Water Treaty Discussion

Henry Lee, NHEERL Western Ecology Division (WED), participated in the Ballast Water Working Group (BWWG) of the Marine Environmental Protection Committee of the International Maritime Organization of the United Nations. The meeting was held in London, April 16-20. Dr. Lee's assistance was requested by EPA's Office of Water and the U.S. Coast Guard. His primary role was to provide technical assistance on the section of the treaty that allows a risk assessment approach for voyages between specified ports. This risk assessment approach would be in lieu of the biological-based standard (number of organisms per cubic meter) that is to be applied to all ships constructed after 2009. Dr. Lee has been instrumental in developing the U.S. strategy for ballast water risk assessment and has participated in the last two BWWG meetings in London. One major thrust of the recent meeting was to harmonize the U.S. approach with that proposed by New Zealand and Australia.

Branch Hosts Workshop on Nutrient Criteria Approaches for Oregon Estuaries

Scientists at the Pacific Coastal Ecology Branch (PCEB) of NHEERL's Western Ecology Division (WED) hosted a workshop to discuss a potential approach to establishing water quality criteria for Oregon estuaries. The workshop took place April 19 at the EPA facility in Newport, OR. WED scientists have synthesized the research results of field sampling, trend analyses, and modeling approaches to produce a nutrient criteria case study for the Yaquina Estuary, the coastal system where PCEB is located. The case study presents an approach that could be used by the State for establishing nutrient criteria for this system. This research was conducted in support of the Office of Water, OST water quality criteria program. The workshop participants reviewed the technical approach for establishing nutrient criteria for the Yaquina Estuary, discussed the applicability of the approach to other estuarine systems within Oregon, and discussed issues with design of monitoring programs for compliance. Participants included WED scientists, representatives of the standards and monitoring programs at the Oregon Department of Environmental Quality, EPA Region 10 Headquarters and Field Office staff, South Slough National Estuarine Research Reserve Staff, and academic scientists.

Scientists To Visit Ukraine To Review Collaborative Estuarine Research

The Agency's Office of International Affairs, along with the U.S. Department of State, operates a program to engage former biological and chemical weapons scientists in newly independent states to conduct beneficial environmental research. The Former Bio-Chemical Weapons Scientists Redirect Program funds environmental studies by scientists in Russia, Kazakhstan, Armenia, Ukraine, Georgia, Moldova, and other former Soviet Union countries. Participants collaborate with EPA scientists to develop scientifically sound and relevant projects designed to better understand and manage environmental problems in the host country. NHEERL Atlantic Ecology Division (AED) scientists Robert Burgess and Kay Ho are collaborating in a 3-year project with Ukrainian scientists at several institutes in Kyiv and Sevastopol to better understand the magnitude and causes of environmental impairments in three Ukrainian estuaries: Dnieper, Boh, and Danube. In June, Dr. Burgess and Dr. Ho will spend a week meeting with Ukrainian scientists collaborating on the project to review the first year of sampling and analyses. Data from sediment toxicity testing, benthic community assessments, and chemical analyses of sediments and tissues will be discussed, along with planning the second year's activities.

Scientists Invited To Conduct Salt Marsh Research in South Carolina

Cathleen Wigand and Earl Davey of NHEERL's Atlantic Ecology Division (AED) have been invited to Baruch Marine Field Laboratory, in Georgetown, SC, August 5-15, to conduct research using a combination of computer-aided tomography (CT) and soil respiration measures to assess condition in coastal salt marshes of South Carolina. CT imaging will be used to examine macro-organic matter and belowground structure in cores collected from long-term fertilized plots, control plots, and salt marsh areas with varying accretion rates in North Inlet-Winyah Bay. The CT imaging will allow for an estimate of the plant- tissue-gas and peat-water volumetric fractions of the salt marsh cores. Coupled with these measures of belowground structure in the salt marsh plots, in situ measures of carbon dioxide efflux as an indicator of soil respiration will be determined. The combination of CT imaging and soil respiration measures are a practical and useful approach to monitoring condition and assessing impairment in coastal salt marshes.