Selenium speciation in wheat grain varies in the presence of nitrogen and sulphur fertilisers

This study investigated whether selenium species in wheat grains could be altered by exposure to different combinations of nitrogen (N) and sulphur (S) fertilisers in an agronomic biofortification experiment. Four Australian wheat cultivars (Mace, Janz, Emu Rock and Magenta) were grown in a glasshouse experiment and exposed to 3 mg Se kg^?1 soil as selenate (Se^VI). Plants were also exposed to 60 mg N kg^?1 soil as urea and 20 mg S kg^?1 soil as gypsum in a factorial design (N + S + Se; N + Se; S + Se; Se only). Plants were grown to maturity with grain analysed for total Se concentrations via ICP-MS and Se species determined via HPLC-ICP-MS. Grain Se concentrations ranged from 22 to 70 µg Se g^?1 grain (dry mass). Selenomethionine (SeMet), Se-methylselenocystine (MeSeCys), selenohomolanthionine (SeHLan), plus a large concentration of uncharacterised Se species were found in the extracts from grains. SeMet was the major Se species identified accounting for between 9 and 24 µg Se g^?1 grain. Exposure to different N and S fertiliser combinations altered the SeMet content of Mace, Janz and Emu Rock grain, but not that of Magenta. MeSeCys and SeHLan were found in far lower concentrations (<4 µg Se g^?1 grain). A large component of the total grain Se was uncharacterisable (>30 % of total grain Se) in all samples. When N fertiliser was applied (with or without S), the proportion of uncharacterisable Se increased between 60 and 70 % of the total grain Se. The data presented here indicate that it is possible to alter the content of individual Se species in wheat grains via biofortification combined with manipulation of N and S fertiliser regimes. This has potential significance in alleviating or combating both Se deficiency and Se toxicity effects in humans.     

Estimating source coefficients for phosphorus site indices

Phosphorus release to runoff varies widely for different land-applied organic P sources even when spread at equivalent total P rates. To address this variability, some P site indices include tabulated P source coefficients (PSCs) for differential weighting of applied P materials based on their runoff enrichment potential. Because runoff P can vary widely even within source categories depending on composition, storage, and treatment differences, this study explored a method for estimating PSCs based on the water-extractable P (WEP) content of the applied amendment. Using seven published rainfall-runoff studies that followed National Phosphorus Research Project protocols, runoff dissolved P (RDP) was correlated (r(2) = 0.80) with WEP for multiple surface-applied manures and biosolids. Assuming amendments with WEP >/= 10 g kg(-1) behave as highly soluble P sources and have a maximum PSC of 1.0, an empirical equation was developed for computing source-specific PSCs from laboratory-determined WEP values [PSC = 0.102 x WEP(0.99)]. For two independent runoff experiments, correlations between RDP loss and P source loading rate were improved when loading rates were multiplied by the computed (r(2) = 0.73-0.86) versus generic (r(2) = 0.45-0.48) PSCs. Source-specific PSCs should enhance the ability of assessment tools to identify vulnerable sites and P loss management alternatives, although the exact inclusion process depends on index scaling and conceptual framework.     

Taking Environmental Action: The Role of Local Composition, Context, and Collective

This article explores individual and community action taken in response to perceived environmental risks by investigating the determinants of environmental action across a range of action types. A conceptual framework is first presented, which provides a foundation for investigating the role of local compositional (i.e., individual characteristics), contextual (i.e., neighborhood environment), and collective (i.e., social networks) factors in environmental action. To test the utility of the conceptual framework, a quantitative survey was administered to a random sample of households (n = 512) in Hamilton, Canada. The results suggest that the predictors of environmental action vary by action type (i.e., personal change, individual civic action, and cooperative civic action), and that factors related to perceived environmental exposure and social capital generally play a stronger, more consistent role in civic environmental action than sociodemographic or neighborhood factors. The results underscore the role of social connection in responses to perceived environmental risks.     

Effects of Traffic Management and Transport Mode on the Exposure of Schoolchildren to Carbon Monoxide

The exposure to CO of schoolchildren was assessed in the town of Northampton, UK, both by direct measurement and by GIS-based activity modelling. Personal measurement of CO showed that exposures when travelling by car were significantly greater than those when walking, although journey times by car were shorter. However, journey exposures had little effect on maximum 8h mean CO exposures. CO concentration fields in the study area were modelled from current traffic flows, and those expected under different traffic management scenarios. These fields were then used, in combination with children's home and school location, and their activity profiles, to simulate frequency distributions of exposure for different transport modes and traffic management scenarios. The results show a large variability in the effect of traffic management interventions, depending on the child's home and school location.     

Estimating the value of foresight: aggregate analysis of natural hazard mitigation benefits and costs

Hazard mitigation planners claim that foresighted present actions and investments produce significant future benefits. However, they have difficulty in supporting their claims, since previously their evidence typically was derived from individual case studies. Constituents and decision makers are often sceptical, believing that individual cases are either inapplicable to their situation or non-randomly selected to support a particular view. Planners need objective evidence based on a large body of experience to support the case for mitigation. Such is the unique contribution of a recent U.S. study that found that each dollar spent in three federal natural hazard mitigation grant programs (the Hazard Mitigation Grant Program, Project Impact, and the Flood Mitigation Assistance Program) saves society an average of $4 in future avoided losses. Complementing the aggregate benefit-cost analysis with community-based evaluations, the study yielded insights on how planners can improve long-term community resilience in the face of extreme events. Valuable lessons for mitigation planners and policy makers emerged: the need to consider a wide variety of losses, the importance of mixing qualitative with quantitative analysis, the value of averaging results over a large number of projects, and the need to more explicitly address social issues and data collection in order to reduce vulnerability and enhance resilience to cope with twenty-first century hazards.     

Environmental accounting of natural capital and ecosystem services for the US National Forest System

The National Forests of the United States encompass 192.7?million acres (78?million hectares) of land, which is nearly five percent of the total land area of the nation. These lands are managed by the US Forest Service (USFS) for multiple uses, including extraction of timber, production of fossil fuels and minerals, public recreation, and the preservation of biodiversity, clean air, water, and soils. The USFS is interested in valuing the natural capital within, and the ecosystem services provided by, their lands. This is in part to justify expenditures in a time of limited resources. We used emergy and an environmental accounting approach, to quantify the ecosystem services, the exported environmental goods and information provided by National Forest System (NFS) lands, and the natural capital residing on those lands. Environmental accounting using emergy provides a method to value these flows of services and storages of capital using a common biophysical unit, the solar emjoule and its monetary equivalent the emdollar. We compare emdollar values to economic values gleaned from the literature. In 2005, the ecosystem services provided by USFS lands were equivalent to 197?billion emdollars, and the value of NFS natural capital was 24.3?trillion emdollars. Our evaluation suggests that the Federal Government budget allocation for the NFS ($5.55E+09 in 2005) was well spent, protecting 24.3?trillion emdollars in natural capital and insuring annual ecosystem services totaling 197?billion emdollars. Monetary values for some natural capital and ecosystem services are similar to emergy-derived values (resources like fish, wildlife, water, and firewood extracted from forests), and others are widely different (biodiversity, fossil, and mineral resources). There is large uncertainty associated with computing the environment’s contributions to society whether using emergy or accepted economic techniques; yet, the magnitude of these emergy-derived estimates suggests that even with the uncertainty, the values are significant and monetary expenditures for the Forest Service are justified.     

Trapping phosphorus in runoff with a phosphorus removal structure

Reduction of phosphorus (P) inputs to surface waters may decrease eutrophication. Some researchers have proposed filtering dissolved P in runoff with P-sorptive byproducts in structures placed in hydrologically active areas with high soil P concentrations. The objectives of this study were to construct and monitor a P removal structure in a suburban watershed and test the ability of empirically developed flow-through equations to predict structure performance. Steel slag was used as the P sorption material in the P removal structure. Water samples were collected before and after the structure using automatic samples and analyzed for total dissolved P. During the first 5 mo of structure operation, 25% of all dissolved P was removed from rainfall and irrigation events. Phosphorus was removed more efficiently during low flow rate irrigation events with a high retention time than during high flow rate rainfall events with a low retention time. The six largest flow events occurred during storm flow and accounted for 75% of the P entering the structure and 54% of the P removed by the structure. Flow-through equations developed for predicting structure performance produced reasonable estimates of structure "lifetime" (16.8 mo). However, the equations overpredicted cumulative P removal. This was likely due to differences in pH, total Ca and Fe, and alkalinity between the slag used in the structure and the slag used for model development. This suggests the need for an overall model that can predict structure performance based on individual material properties.     

Crop uptake of heavy metals in response to the environment and agronomic practices on land near mine tailings in the Zambian Copperbelt Province

Environmental Geochemistry and Health - A field experiment was undertaken on farmers’ fields adjacent to a large mine tailings dam in the Zambian mining town of Kitwe. Experimental plots were...