Partitioning of cadmium,copper, lead and zinc amongst above-ground parts of seed and grain crops grown in selected locations in the USA

The distribution of Cd, Cu, Pb and Zn in above-ground parts of corn, small grains and pulse crops was investigated. Sampled parts included grain or seed, leaves, stems, silk and husks of corn-ears, rachilla and chaff of small grains and pods of bean plants. The distribution of these elements was variable and reflected, primarily, their relative mobility between plant parts including transfer into the grain. Generally, Zn and Cu were preferentially transferred into the seed or grain, while Cd and Pb were selectively excluded from these organs. For example, the distribution pattern in ears of corn was: for Cd, husks > silk > grain; for Zn, silk > grain > husks. The selective transfer of Zn and Cu into seed or grain, in contrast to the restricted movement of Cd and Pb into these organs, may be the result of selective absorption of Zn and Cu over Cd and Pb by vascular transfer cells within the plant's reproductive tissues. The effect of soil type on Cd, Cu, Pb and Zn levels in cereal grain or pulse seed was small compared to the differences found in the concentrations of these elements between different plant organs. Thus, grain and seed crops serve as natural barriers to the movement of the potentially toxic heavy metals, Cd and Pb, into the animal/human food chain, minimising their transfer from soils while conserving Zn and Cu levels in edible portions of these crops.Soil Scientist, USDA, Soil Conservation Service, Retired.     

An experimental examination of implicit stress theory

Implicit theories lead individuals to make assumptions about one trait based on their knowledge of another trait. This study experimentally examined Implicit Stress Theory under conditions of high and low performance information. The objective was to test for evidence of Implicit Stress Theory in ratings of effectiveness, commitment, and burnout. Results indicated moderate support for Implicit Stress Theory such that raters evaluated employee burnout and commitment as higher when the employee was perceived to be working under stressful conditions. Interestingly, the data suggested stronger support (based on the proportion of variance explained) for an Implicit Performance Theory such that information regarding good performance was associated with higher levels of commitment and less burnout than poor performance.     

Type of disturbance and ecological history determine structural stability.

This study aims to reveal whether complexity, namely, community and trophic structure, of chronically stressed soil systems is at increased risk or remains stable when confronted with a subsequent disturbance. Therefore, we focused on a grassland with a history of four centuries of patchy contamination. Nematodes were used as model organisms because they are an abundant and trophically diverse group and representative of the soil food web and ecosystem complexity. In a field survey, a relationship between contaminants and community structures was established. Following, two groups of soil mesocosms from the field that differed in contamination level were exposed to different disturbance regimes, namely, to the contaminant zinc and a heat shock. The zinc treatment revealed that community structure is stable, irrespective of soil contamination levels. This implies that centuries of exposure to contamination led to adaptation of the soil nematode community irrespective of the patchy distribution of contaminants. In contrast, the heat shock had adverse effects on species richness in the highly contaminated soils only. The total nematode biomass was lower in the highly contaminated field samples; however, the biomass was not affected by zinc and heat treatments of the mesocosms. This means that density compensation occurred rapidly, i.e., tolerant species quickly replaced sensitive species. Our results support the hypothesis that the history of contamination and the type of disturbance determine the response of communities. Despite that ecosystems may be exposed for centuries to contamination and communities show adaptation, biodiversity in highly contaminated sites is at increased risk when exposed to a different disturbance regime. We discuss how the loss of higher trophic levels from the entire system, such as represented by carnivorous nematodes after the heat shock, accompanied by local biodiversity loss at highly contaminated sites, may result in detrimental effects on ecosystem functions.     

Precaution and the Methodological Status of Scientific (Un)certainty

An effective application of thePrecautionary Principle (PP) hinges on thestipulation that, ``a lack of scientificcertainty shall not be used as a reason forpostponing measures.' The practicalconsequences of this expression are presentlynot clear enough in most contexts of use toenable constructive communication and thereforethe PP is not sufficiently operational now. Apragmatic and fundamental methodology forunderstanding scientific (un)certainty indifferent practical contexts needs to be put inplace to create a communicative basis foreffective precaution. Lack of clarity aboutproblem definition and problem ownershipcreates artificial controversies that willobstruct a precautionary approach. Given thefact that different practical contexts ofscientific (un)certainty exist, it may seemfrom one context as if no precaution iswarranted whereas concerns from anotherrelevant context may suggest otherwise.Therefore, an integrative methodologicalframework for communicating about scientific(un)certainty is sorely needed in internationalpolicy-making. By putting a focus on therelevance of specified research questions forthe objective of taking precaution, acommunicative methodology may be adopted thatis dedicated to the design properties of asustainable future. Precaution cannot beoperationalized without a methodological basisthat allows for effective transparency andevades the stalemates of artificialcontroversy. Existing debate methodologies haveso far not managed to accommodate thesepressing demands.     

Bombs and Butterflies: A Case Study of the Challenges of Post Cold War Environmental Planning and Management for the US Nuclear Weapons Sites

When the cold war ended, the United States stopped developing,testing and building nuclear weapons at nearly all of its former nuclear weapon sites. The Department of Energy (DoE) began a massive environmental remediation programme, which includes engaging surrounding communities in a future land use planning process. Using the Savannah River site as an example, we show that this process faces large obstacles, especially a legacy of mistrust of the DoE and organizational limitations at the federal and local government scales. These hinder open dialogue about future land use. The authors suggest three planning principles for future land use planning and organizational issues that must be addressed before these can be fruitfully explored.     

The Effects of Changing Land Cover on Streamflow Simulation in Puerto Rico

This study quantitatively explores whether land cover changes have a substantive impact on simulated streamflow within the tropical island setting of Puerto Rico. The Precipitation Runoff Modeling System (PRMS) was used to compare streamflow simulations based on five static parameterizations of land cover with those based on dynamically varying parameters derived from four land cover scenes for the period 1953‐2012. The PRMS simulations based on static land cover illustrated consistent differences in simulated streamflow across the island. It was determined that the scale of the analysis makes a difference: large regions with localized areas that have undergone dramatic land cover change may show negligible difference in total streamflow, but streamflow simulations using dynamic land cover parameters for a highly altered subwatershed clearly demonstrate the effects of changing land cover on simulated streamflow. Incorporating dynamic parameterization in these highly altered watersheds can reduce the predictive uncertainty in simulations of streamflow using PRMS. Hydrologic models that do not consider the projected changes in land cover may be inadequate for water resource management planning for future conditions.