Kathleen F. Lambert

Mercury Contamination in Forest and Freshwater Ecosystems in the Northeastern United States

ABSTRACT Eastern North America receives elevated atmospheric mercury deposition from a combination of local, regional, and global sources. Anthropogenic emissions originate largely from electric utilities, incinerators, and industrial processes. The mercury species in these emissions have variable atmospheric residence times, which influence their atmospheric transport and deposition patterns. Forested regions with a prevalence of wetlands and of unproductive surface waters promote high concentrations of mercury in freshwater biota and thus are particularly sensitive to mercury deposition. Through fish consumption, humans and wildlife are exposed to methylmercury, which markedly bioaccumulates up the freshwater food chain. Average mercury concentrations in yellow perch fillets exceed the Environmental Protection Agencys human health criterion across the region, and mercury concentrations are high enough in piscivorous wildlife to cause adverse behavioral, physiological, and reproductive effects. Initiatives are under way to decrease mercury emissions from electric utilities in the United States by roughly 70%.

Nitrogen Pollution in the Northeastern United States: Sources, Effects, and Management Options

Abstract The northeastern United States receives elevated inputs of anthropogenic nitrogen (N) largely from net imports of food and atmospheric deposition, with lesser inputs from fertilizer, net feed imports, and N fixation associated with leguminous crops. Ecological consequences of elevated N inputs to the Northeast include tropospheric ozone formation, ozone damage to plants, the alteration of forest N cycles, acidification of surface waters, and eutrophication in coastal waters. We used two models, PnET-BGC and WATERSN, to evaluate management strategies for reducing N inputs to forests and estuaries, respectively. Calculations with PnET-BGC suggest that aggressive reductions in N emissions alone will not result in marked improvements in the acid–base status of forest streams. WATERSN calculations showed that management scenarios targeting removal of N by wastewater treatment produce larger reductions in estuarine N loading than scenarios involving reductions in agricultural inputs or atmospheric emissions. Because N pollution involves multiple sources, management strategies targeting all major pollution sources will result in the greatest ecological benefits.

Biological Mercury Hotspots in the Northeastern United States and Southeastern Canada

ABSTRACT Biological mercury (Hg) hotspots were identified in the northeastern United States and southeastern Canada using a data set of biotic Hg concentrations. Eight layers representing three major taxa and more than 7300 observations were used to locate five biological Hg hotspots and nine areas of concern. The yellow perch and common loon were chosen as indicator species for the human and ecological effects of Hg, respectively. Biological Hg hotspots receive elevated atmospheric Hg deposition, have high landscape sensitivity, and/or experience large reservoir fluctuations. In the Merrimack River watershed, local Hg emissions are linked to elevated local deposition and high Hg concentrations in biota. Time series data for this region suggest that reductions in Hg emissions from local sources can lead to rapid reductions of Hg in biota. An enhanced Hg monitoring network is needed to further document areas of high deposition, biological hotspots, and the response to emissions reductions and other mitigation strategies.

Functional Activity of the Fanconi Anemia Protein FAA Requires FAC Binding and Nuclear Localization

ABSTRACT Fanconi anemia (FA) is an autosomal recessive disease characterized by genomic instability, cancer susceptibility, and cellular hypersensitivity to DNA-cross-linking agents. Eight complementation groups of FA (FA-A through FA-H) have been identified. Two FA genes, corresponding to complementation groups FA-A and FA-C, have been cloned, but the functions of the encoded FAA and FAC proteins remain unknown. We have recently demonstrated that FAA and FAC interact to form a nuclear complex. In this study, we have analyzed a series of mutant forms of the FAA protein with respect to functional activity, FAC binding, and nuclear localization. Mutation or deletion of the amino-terminal nuclear localization signal (NLS) of FAA results in loss of functional activity, loss of FAC binding, and cytoplasmic retention of FAA. Replacement of the NLS sequence with a heterologous NLS sequence, derived from the simian virus 40 T antigen, results in nuclear localization but does not rescue functional activity or FAC binding. Nuclear localization of the FAA protein is therefore necessary but not sufficient for FAA function. Mutant forms of FAA which fail to bind to FAC also fail to promote the nuclear accumulation of FAC. In addition, wild-type FAC promotes the accumulation of wild-type FAA in the nucleus. Our results suggest that FAA and FAC perform a concerted function in the cell nucleus, required for the maintenance of chromosomal stability.

Meeting report: Methylmercury in marine ecosystems--from sources to seafood consumers.

Mercury and other contaminants in coastal and open-ocean ecosystems are an issue of great concern globally and in the United States, where consumption of marine fish and shellfish is a major route of human exposure to methylmercury (MeHg). A recent National Institute of Environmental Health Sciences–Superfund Basic Research Program workshop titled “Fate and Bioavailability of Mercury in Aquatic Ecosystems and Effects on Human Exposure,” convened by the Dartmouth Toxic Metals Research Program on 15–16 November 2006 in Durham, New Hampshire, brought together human health experts, marine scientists, and ecotoxicologists to encourage cross-disciplinary discussion between ecosystem and human health scientists and to articulate research and monitoring priorities to better understand how marine food webs have become contaminated with MeHg. Although human health effects of Hg contamination were a major theme, the workshop also explored effects on marine biota. The workgroup focused on three major topics: a) the biogeochemical cycling of Hg in marine ecosystems, b) the trophic transfer and bioaccumulation of MeHg in marine food webs, and c) human exposure to Hg from marine fish and shellfish consumption. The group concluded that current understanding of Hg in marine ecosystems across a range of habitats, chemical conditions, and ocean basins is severely data limited. An integrated research and monitoring program is needed to link the processes and mechanisms of MeHg production, bioaccumulation, and transfer with MeHg exposure in humans.

Science and Society: The Role of Long-Term Studies in Environmental Stewardship

Long-term research should play a crucial role in addressing grand challenges in environmental stewardship. We examine the efforts of five Long Term Ecological Research Network sites to enhance policy, management, and conservation decisions for forest ecosystems. In these case studies, we explore the approaches used to inform policy on atmospheric deposition, public land management, land conservation, and urban forestry, including decisionmaker engagement and integration of local knowledge, application of models to analyze the potential consequences of policy and management decisions, and adaptive management to generate new knowledge and incorporate it into decisionmaking. Efforts to enhance the role of long-term research in informing major environmental challenges would benefit from the development of metrics to evaluate impact; stronger partnerships among research sites, professional societies, decisionmakers, and journalists; and greater investment in efforts to develop, test, and expand practice-based experiments at the interface of science and society.

Integrating mercury science and policy in the marine context: challenges and opportunities.

Mercury is a global pollutant and presents policy challenges at local, regional, and global scales. Mercury poses risks to the health of people, fish, and wildlife exposed to elevated levels of mercury, most commonly from the consumption of methylmercury in marine and estuarine fish. The patchwork of current mercury abatement efforts limits the effectiveness of national and multi-national policies. This paper provides an overview of the major policy challenges and opportunities related to mercury in coastal and marine environments, and highlights science and policy linkages of the past several decades. The U.S. policy examples explored here point to the need for a full life cycle approach to mercury policy with a focus on source reduction and increased attention to: (1) the transboundary movement of mercury in air, water, and biota; (2) the coordination of policy efforts across multiple environmental media; (3) the cross-cutting issues related to pollutant interactions, mitigation of legacy sources, and adaptation to elevated mercury via improved communication efforts; and (4) the integration of recent research on human and ecological health effects into benefits analyses for regulatory purposes. Stronger science and policy integration will benefit national and international efforts to prevent, control, and minimize exposure to methylmercury.

Marine mercury fate: from sources to seafood consumers.

Mercury in the biosphere has markedly increased over the past century leading governments around the world to consider policies that would reduce sources to limit human exposure to this global contaminant. The nine articles in this issue provide a synthesis of the science on the sources, fate, and human exposure to mercury (Hg) in marine systems. These papers along with two papers recently published in Environmental Health Perspectives are the products of two workshops convened by the Coastal and Marine Mercury Ecosystem Research Collaborative (C-MERC) sponsored by the Dartmouth Superfund Research Program. In September 2010 and July 2011 we brought together scientists and policy stakeholders to compile and distill information on the inputs, cycling and uptake of Hg in marine ecosystems and the links to fish, wildlife and human exposure to methylmercury (MeHg), the most bioaccumulative form of this global contaminant. The goal of this C-MERC effort was to provide a summary of the current science relevant to public policies being considered at the regional, national and global levels, such as the effort of the United Nations Environment Program to establish the first International Mercury Treaty. Seven papers in this special issue review the pathways and transformations of Hg and MeHg from sources to seafood consumers in specific marine ecosystems. These include: the Gulf of Maine (Sunderland et al., in this issue); the Gulf of Mexico (Harris et al., in this issue-a,b); San Francisco Bay (Davis et al., in this issue); the Arctic Ocean (Kirk et al., in this issue); Tropical Oceans (Costa et al., in this issue); and the global oceans (Mason et al. in this issue). The paper by Driscoll et al. (2007) presents a conceptual model of interactions between Hg cycling and nutrient loading in marine ecosystems and the paper by Lambert et al. (in this issue) provides a review of Hg science on marine ecosystems and implications for policy. The C-MERC papers published in Environmental Health Perspectives focused on human health effects of low level methylmercury (MeHg) exposure (Karagas et al., 2012) and on the complexities of providing clear, unified fish consumption advice (Oken et al., 2012). Coal burning and energy production along with mining and industrial activities have led to increased mercury in the environment (Mason et al., 1994; Driscoll et al., 2007; Selin et al., 2008). Mercury is ranked third on the Agency for Toxic Substances and Disease Registry’s priority list of contaminants that pose significant human health threats to the US population (ATSDR, 2007). More than 90% of Hg exposure in the US comes from consumption of estuarine and marine fish contaminated by MeHg, the most bioavailable form (Sunderland, 2007; Chen et al., 2008). This exposure is the result of consuming higher trophic level fish, which generally have higher MeHg concentrations, in combination with more frequently eaten lower trophic level species (e.g., pollock, crabs, shrimp).

NITROGEN POLLUTION: Sources and Consequences in the U.S. Northeast

Abstract In the past century, human activity has doubled the global rate at which reactive nitrogen is produced, greatly increasing nitrogen pollution in the environment. This article investigates this phenomenon in the northeastern United States, describing the regions largest sources of nitrogen pollution, the problems it causes, and the policy options that could reduce its production and diminish its effects.

THE IMPORTANCE OF LONG-TERM DATA IN ADDRESSING REGIONAL ENVIRONMENTAL ISSUES

Long-term data have been used to evaluate complex, environ- mental problems, such as the anthropogenic acidification of regional landscapes by acid rain, and to quantify changes in ecosystem function associated with large-scale land use, such as forest harvesting and development. In this paper, we discuss the importance of long-term monitoring in addressing regional environmental issues by examining two examples of anthropogenic stress-acid rain and forest harvesting. We also suggest that a watershed-ecosystem ap- proach is useful for understanding, and for managing, the potential synergistic effects of chemical and vegetational changes in forest ecosystems in the north- eastern U.S.