How “Natural” are inland wetlands? an example from the trail wood audubon sanctuary in Connecticut,USA

We examined the geology of a small inland wetland in Hampton, Connecticut to determine its postglacial history and to assess the severity of human impact at this remote wooded site. Using stratigraphic evidence, we dernonstrate that the present wetland was created when sediment pollution from a 19th-century railroad filled a preexisting artificial reservoir, and that the prehistoric wetland was a narrow drainage swale along Hampton Brook. This same, severely impacted wetland was interpreted by the Pulitzer Prize-winning naturalist Edwin Way Teale as a beautiful wilderness area of particular interest. These conflicting perceptions indicate that artificial wetlands can be naturally mitigated in less than a century of healing, even in the absence of deliberate management. We also point out that the “wilderness” value of the Teale wetland was in the eye of the beholder and that unseen human impacts may have improved the aesthetic experience.     

Communication at inactive hazardous waste sites

The remediation of inactive hazardous waste sites frequently involves a protracted negotiation with the respective state or federal agency and the entity responsible for creating the site and paying the costs. At orphaned sites, decisions are made almost exclusively by agency staff. Most of remedial decisions are made with little input or participation by the interested public. The public usually receives information in a highly technical and difficult-to-understand format after decisions are made. This ineffective form of communication can lead to mistrust and delays or changes in the remediation process. Effective public participation requires multidirectional modes of communication that provide for active and full involvement by all interested parties. At the present time, most agencies pay minimal attention to the needs of the interested public, often leaving area residents suspicious and dissatisfied with the overall program. There is an opportunity to significantly improve the public participation component of the federal Super-fund program through reauthorization. Subtle changes in the program can result in a significant increase of the public's sense of participation and overall satisfaction.     

Antimony impurity in lead arsenate insecticide enhances the antimony content of old orchard soils

Lead arsenate was a commonly used insecticide during the first half of the 20th century, particularly in deciduous tree fruit orchards. Antimony is cotransported with As during the ore refining process and could occur as an impurity in commercial lead arsenate products. The total concentrations of As and Sb in eight soil samples collected from eight orchards located throughout central Washington State were analyzed by neutron activation analysis. Total soil Sb concentrations ranged between 0.4 and 1.5 mg kg(-1), while total soil As concentration ranged from 1 to 170 mg kg(-1). Total soil Sb and As concentrations were positively related. Total Pb and As concentrations in four of the soils were substantially higher than natural background, while the Sb to As concentration ratios in these soils were consistent with values measured in three lead arsenate insecticide products. These results confirm that Sb impurity is present in lead arsenate insecticide and has contributed to Sb enrichment of soils on which lead arsenate-treated plants were grown. Although higher than in uncontaminated soils from the same region, the Sb concentrations in the affected soils fall within the normal range observed worldwide and are substantially lower than values associated with impaired human or environmental health.     

Psychological contracts and OCB: The effect of unfulfilled obligations on civic virtue behavior

This study examines the relationship between violation of an employee's psychological contract and civic virtue behavior. A psychological contract is a set of beliefs regarding mutual obligations between employee and employer. One hundred twenty-six MBA alumni were surveyed at the time of hire (T1), and after 18 months (T2) and 30 months (T3) on the job. When employees felt that their employers had failed to fulfil employment obligations at T2, they were less likely to engage in civic virtue behavior at T3. There was evidence that this relationship was partly mediated by trust. These findings have implications for research on OCB and for managers seeking to maintain employee citizenship behavior.     

INFLUENCE OF HERBIVORY ON REGROWTH OF RIPARIAN SHRUBS FOLLOWING A WILDLAND FIRE1

Streamside vegetation frequently regenerates faster than upland vegetation following wildland fire and contributes to the recovery of riparian and stream ecosystems. Limited data are available, however, on the post‐fire growth of riparian species and the influence of herbivory on regeneration. To determine post‐fire regrowth of riparian vegetation, height, crown area, crown volume, and browse levels were measured for key riparian shrub species in streamside burned and unburned plots along second‐order streams in western Wyoming. Shrubs in the burned plots were subject to high levels of browse ‐ up to 84 percent of the leaders were browsed ‐ by native ungulates in 2002, the second post‐fire year (September 2001 to September 2002). In summer 2003, the burned watershed was also grazed by livestock, resulting in increased browse levels and decreased shrub heights for several species. In the third post‐fire year, September 2002 to September 2003, four of the six most common species showed no increase in crown area or crown volume, indicating that the combination of native ungulate and cattle browsing suppressed their growth. Potential impacts of grazing on post‐fire recovery of stream and riparian ecosystems are discussed.     

Mercury: An agent of poverty in Ghana's small-scale gold-mining sector?

There is consensus worldwide that the artisanal and small-scale mining (ASM) sector is comprised of individuals who are trapped in a vicious cycle of poverty, lacking the necessary financial and technological means to improve their standards of living. Minimal work, however, has been undertaken to identify the very factors behind miners’ plight, which inevitably vary from country to country. This paper uses a case study of Ghana to argue that an increased dependence upon mercury for amalgamation in artisanal gold-mining communities is one such—albeit overlooked—“agent of poverty”. There is mounting empirical evidence which suggests that dealings with the monoponistic middlemen who supply mercury, purchases of costly medicines to remedy ailments caused by mercury poisoning, and a lack of appropriate safeguards and alternatives to amalgamation, are preventing gold miners from improving their practices and livelihoods. The solution to the problem lies in breaking this cycle of dependency, which can be achieved by providing miners with robust support services, mercury-free technologies and education.     

Interaction between sorption and biodegradation processes in the contaminant transport

The main goal of this work is to examine in detail the equilibrium and non-equilibrium sorption in a multiple species contaminant transport system undergoing multiplicative Monod biodegradation kinetics, which characterizes a scenario of subsurface contamination by organic contaminants. Mathematically, the problem is given by a nonlinear advection-diffusion-reaction partial differential system coupled by the reaction terms, associated with the biodegradation process. A new operator splitting approach is proposed for treating in a sequential fashion the convective-diffusive and reactive terms. A predictor-multicorrector algorithm with Newton–Raphson and stabilized finite element (streamline-upwind Petrov-Galerkin, SUPG) methods is used in the time and spatial discretizations, respectively. Numerical results illustrate the good applicability of the present approach, corroborating the well-known observation nonlinear physical and biological processes should be inserted in the model that to better predict the contamination scenarios.     

An implicit wetting–drying algorithm for the discontinuous Galerkin method: application to the Tonle Sap,Mekong River Basin

Environmental Fluid Mechanics - The accurate simulation of wetting–drying processes in floodplains and coastal zones is a challenge for hydrodynamic modelling, especially for long time...     

Biomarker responses of <Emphasis Type="Italic">Peromyscus leucopus</Emphasis> exposed to lead and cadmium in the Southeast Missouri Lead Mining District

Biomarker responses and histopathological lesions have been documented in laboratory mammals exposed to elevated concentrations of lead and cadmium. The exposure of white-footed mice (Peromyscus leucopus) to these metals and the potential associated toxic effects were examined at three contaminated sites in the Southeast Missouri Lead Mining District and at a reference site in MO, USA. Mice from the contaminated sites showed evidence of oxidative stress and reduced activity of red blood cell δ-aminolevulinic acid dehydratase (ALAD). Histological examinations of the liver and kidney, cytologic examination of blood smears, and biomarkers of lipid peroxidation and DNA damage failed to show indications of toxic effects from lead. The biomagnification factor of cadmium (hepatic concentration/soil concentration) at a site with a strongly acid soil was 44 times the average of the biomagnification factors at two sites with slightly alkaline soils. The elevated concentrations of cadmium in the mice did not cause observable toxicity, but were associated with about a 50% decrease in expected tissue lead concentrations and greater ALAD activity compared to the activity at the reference site. Lead was associated with a decrease in concentrations of hepatic glutathione and thiols, whereas cadmium was associated with an increase. In addition, to support risk assessment efforts, we developed linear regression models relating both tissue lead dosages (based on a previously published a laboratory study) and tissue lead concentrations in Peromyscus to soil lead concentrations.