Deborah L. Swackhamer

Bio: Deborah L. Swackhamer is an academic researcher from University of Minnesota. The author has contributed to research in topics: Bioaccumulation & Toxaphene. The author has an hindex of 34, co-authored 74 publications receiving 6650 citations. Previous affiliations of Deborah L. Swackhamer include United States Fish and Wildlife Service & University of Wisconsin-Madison.

Forecasting agriculturally driven global environmental change

Abstract: During the next 50 years, which is likely to be the final period of rapid agricultural expansion, demand for food by a wealthier and 50% larger global population will be a major driver of global environmental change. Should past dependences of the global environmental impacts of agriculture on human population and consumption continue, 10(9) hectares of natural ecosystems would be converted to agriculture by 2050. This would be accompanied by 2.4- to 2.7-fold increases in nitrogen- and phosphorus-driven eutrophication of terrestrial, freshwater, and near-shore marine ecosystems, and comparable increases in pesticide use. This eutrophication and habitat destruction would cause unprecedented ecosystem simplification, loss of ecosystem services, and species extinctions. Significant scientific advances and regulatory, technological, and policy changes are needed to control the environmental impacts of agricultural expansion.

Bioaccumulation of PCBs by algae: Kinetics versus equilibrium

Abstract: The objectives of this study were to test the hypothesis that bioaccumulation of hydrophobic organic compounds (HOCs) by phytoplankton is correlated to the compound's octanol/water partition coefficient (Kow) in a predictive relationship in laboratory experiments, and to confirm these findings with field observations. In laboratory experiments we measured the uptake of 40 representative polychlorinated biphenyl (PCB) congeners over time under conditions that inhibited and allowed phytoplankton growth. Results indicated that the bioaccumulation process is consistent with partitioning from water into cell lipids but is slower than previously thought. The uptake of PCBs was slow relative to growth of phytoplankton, preventing the chemical from reaching thermodynamic equilibrium in algal cells under conditions promoting growth (nonwinter). Thus under non-winter field conditions, many PCB congeners never reach equilibrium concentrations. Food-chain models that assume equilibrium between HOCs and the primary trophic level could be inaccurate and may need to use a kinetic framework.

Atmospheric Loading of Polycyclic Aromatic Hydrocarbons to Lake Michigan as Recorded in the Sediments

Abstract: Five sediment cores from a north−south transect of Lake Michigan were collected using box cores deployed from the RV Lake Guardian and from a submersible (Johnson Sea Link II, RV Seward Johnson). The sediments, analyzed for PAHs (n = 28) and 210Pb to obtain accumulation rates and inventories of PAHs, were used to determine the role of the atmosphere in contaminant loading to Lake Michigan. The accumulation of PAHs in the sediments increased dramatically around 1900, reached a plateau around 1930−1975, and decreased slightly in recent time. Surface sediment accumulation rates and inventories for ∑PAHs (n = 17 parent), corrected for sediment focusing with 210Pb, equaled 50−70 ng cm-2 yr-1 and 5000−7000 ng cm-2, respectively. The relative abundances of individual PAH compounds from Lake Michigan sediments, PM-10 aerosol of Chicago, and a coke oven signature are statistically similar establishing a linkage between combustion sources in the south, atmospheric deposition, and sediment accumulation. Further supp...

Partitioning and bioaccumulation of PBDEs and PCBs in Lake Michigan.

Abstract: Water from Lake Michigan and fish from all five Great Lakes have been sampled and analyzed for a suite of six polybrominated diphenyl ether (PBDE) congeners and 110 polychlorinated biphenyl congeners (PCBs). The Lake Michigan dissolved phase PBDE congener concentrations (0.2 to 10 pg/L) are similar to dissolved phase PCB congener concentrations (nondetected to 13 pg/L). Partitioning of PBDEs between the particulate and dissolved phases exhibits behavior similar to that of PCBs. Organic-carbon-normalized water−particle partition coefficients (log KOCs) ranged from 6.2 to 6.5. Lake trout are depleted in BDE-99 relative to dissolved phase concentrations, and in contrast to what is expected from the PCB congener patterns. This reflects suspected debromination of BDE-99 in the food web of Lake Michigan. A regression of the log of the bioaccumulation factor (BAF) and the log of the octanol−water partition coefficent (KOW) indicated a positive relationship for both PCB congeners and PBDE congeners. BDE-99 does n...

Occurrence and bioaccumulation of organochlorine compounds in fishes from Siskiwit Lake, Isle Royale, Lake Superior.

Abstract: A wide range of chlorinated organic compounds was measured in different size classes of lake trout (Salvelinus namaycush namaycush) and whitefish (Coregonus culpeaformis neohantoniensus) from Siskiwit Lake, a remote lake on Isle Royale in Lake Superior. Our results confirm the long-range transport of several chlorinated pesticides and polychlorinated biphenyls (PCBs) and, in addition, indicate that technical chlordane constituents, octachlorostyrene, pentachloroanisole, and decachlorodiphenyl ether also are transported to remote locations. Chemical concentrations as a function of fish age (size) were not similar between species and were not consistent among compounds. Differences in bioaccumulation with age between species for a given compound indicated that physical-chemical properties alone do not determine bioaccumulation in a species; fish characteristics are also important. The relationship of the bioconcentration factor (BCF) and the octanol-water partition coefficient (K{sub OW}) was examined. The correlation was weak for pesticides and poor for PCB congeners when compared to published relationships based on laboratory data.

Global Consequences of Land Use

Abstract: Land use has generally been considered a local environmental issue, but it is becoming a force of global importance. Worldwide changes to forests, farmlands, waterways, and air are being driven by the need to provide food, fiber, water, and shelter to more than six billion people. Global croplands, pastures, plantations, and urban areas have expanded in recent decades, accompanied by large increases in energy, water, and fertilizer consumption, along with considerable losses of biodiversity. Such changes in land use have enabled humans to appropriate an increasing share of the planet’s resources, but they also potentially undermine the capacity of ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate and air quality, and ameliorate infectious diseases. We face the challenge of managing trade-offs between immediate human needs and maintaining the capacity of the biosphere to provide goods and services in the long term.

Food Security: The Challenge of Feeding 9 Billion People

Abstract: Continuing population and consumption growth will mean that the global demand for food will increase for at least another 40 years. Growing competition for land, water, and energy, in addition to the overexploitation of fisheries, will affect our ability to produce food, as will the urgent requirement to reduce the impact of the food system on the environment. The effects of climate change are a further threat. But the world can produce more food and can ensure that it is used more efficiently and equitably. A multifaceted and linked global strategy is needed to ensure sustainable and equitable food security, different components of which are explored here.

Agricultural sustainability and intensive production practices

Abstract: A doubling in global food demand projected for the next 50 years poses huge challenges for the sustainability both of food production and of terrestrial and aquatic ecosystems and the services they provide to society. Agriculturalists are the principal managers of global useable lands and will shape, perhaps irreversibly, the surface of the Earth in the coming decades. New incentives and policies for ensuring the sustainability of agriculture and ecosystem services will be crucial if we are to meet the demands of improving yields without compromising environmental integrity or public health.

Catastrophic shifts in ecosystems.

Abstract: All ecosystems are exposed to gradual changes in climate, nutrient loading, habitat fragmentation or biotic exploitation. Nature is usually assumed to respond to gradual change in a smooth way. However, studies on lakes, coral reefs, oceans, forests and arid lands have shown that smooth change can be interrupted by sudden drastic switches to a contrasting state. Although diverse events can trigger such shifts, recent studies show that a loss of resilience usually paves the way for a switch to an alternative state. This suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.

Solutions for a cultivated planet

Abstract: Increasing population and consumption are placing unprecedented demands on agriculture and natural resources. Today, approximately a billion people are chronically malnourished while our agricultural systems are concurrently degrading land, water, biodiversity and climate on a global scale. To meet the world's future food security and sustainability needs, food production must grow substantially while, at the same time, agriculture's environmental footprint must shrink dramatically. Here we analyse solutions to this dilemma, showing that tremendous progress could be made by halting agricultural expansion, closing 'yield gaps' on underperforming lands, increasing cropping efficiency, shifting diets and reducing waste. Together, these strategies could double food production while greatly reducing the environmental impacts of agriculture.