Conversion or conservation? Understanding wetland change in northwest Costa Rica.

Wetlands are more threatened than any other ecosystem type, with losses exceeding 50% of their original extent worldwide. Despite the small portion of the Earth's surface that they comprise, wetlands contribute significantly to global ecosystem services. In this study, we tested the hypothesis that the location and rate of change in wetland amount in the Tempisque Basin of northwest Costa Rica is predictable from landscape setting. Our results demonstrate that a strong potential exists for developing predictive models of wetland conversion based on an understanding of wetland location and surrounding trends of land use. We found that topography was the single most important predictor of wetland conversion in this area, entraining other conversion processes, and that spatial patterns of wetland loss could consistently be predicted from landscape-level variables. Areas with highest probabilities of conversion were found in the most accessible, non-protected regions of the landscape. While Palo Verde National Park made a substantial contribution to wetland conservation, our results highlight the dependence of lower-lying protected areas on upland processes, adding a little-addressed dimension of complexity to the dialogue about protected area management. Conservation strategies aimed at reducing wetland loss in tropical habitats will benefit from careful analysis of the dominant land use system(s) at a relatively broad scale, and the subsequent development of management and policy responses that take into account dynamic opportunities and constraints in the landscape.     

PREDICTION OF STREAM TEMPERATURE IN FORESTED WATERSHEDS1

ABSTRACT: Removal of streamside vegetation changes the energy balance of a stream, and hence its temperature. A common approach to mitigating the effects of logging on stream temperature is to require establishment of buffer zones along stream corridors. A simple energy balance model is described for prediction of stream temperature in forested headwater watersheds that allows evaluation of the performance of such measures. The model is designed for application to “worst case” or maximum annual stream temperature, under low flow conditions with maximum annual solar radiation and air temperature. Low flows are estimated via a regional regression equation with independent variables readily accessible from GIS databases. Testing of the energy balance model was performed using field data for mostly forested basins on both the west and east slopes of the Cascade Mountains, and was then evaluated using the regional equations for low flow and observed maximum reach temperatures in three different east slope Cascades catchments. A series of sensitivity analyses showed that increasing the buffer width beyond 30 meters did not significantly decrease stream temperatures, and that other vegetation parameters such as leaf area index, average tree height, and to a lesser extent streamside vegetation buffer width, more strongly affected maximum stream temperatures.     

Risk-mitigating beliefs,risk estimates,and self-reported speeding in a sample of Australian drivers

PROBLEM: Research suggests that people who engage in risk-taking behaviors often hold specific beliefs that can mitigate or reduce their perceptions of risk associated with those behaviors. METHOD: A scale was developed (Speeding Risk Belief Scale (SRBS)) to assess beliefs about speeding-related risk and predict self-reported speeding in a random-digit telephone survey of 800 South Australian drivers between the ages of 16 and 50. RESULTS: The scale was internally consistent, and path analyses showed it to be associated with self-reported speeding, both directly and indirectly through participants' estimates of speeding-related risk. DISCUSSION: Origins of risk-mitigating beliefs and the extent to which they may be causally linked with speeding are discussed, and recommendations are made for future research. IMPACT ON INDUSTRY: This research has strong implications for the conduct of countermeasure campaigns that disseminate information on speeding-related risk.     

Atmospheric benzene depletion by soil microorganisms

Gaseous benzene was rapidly depleted in exposure chambers containing viable soils and plants. When separate components of the system were analyzed, no benzene was detected in soils, plants, or water. Soil microorganisms were shown to be responsible for metabolizing benzene, yielding CO₂ as the main product. The rates were sufficiently rapid to suggest that this reaction forms a major pathway for the elimination of benzene from the environment.This work was sponsored and conducted at the Environmental Protection Agency-Environmental Monitoring Systems Laboratory, Las Vegas, Nevada, U.S.A.     

Water quality parameters controlling the photodegradation of two herbicides in surface waters of the Columbia Basin,Washington

The water quality parameters nitrate-nitrogen, dissolved organic carbon, and suspended solids were correlated with photodegradation rates of the herbicides atrazine and 2,4-D in samples collected from four sites in the Columbia River Basin, Washington, USA. Surface water samples were collected in May, July, and October 2010 and analyzed for the water quality parameters. Photolysis rates for the two herbicides in the surface water samples were then evaluated under a xenon arc lamp. Photolysis rates of atrazine and 2,4-D were similar with rate constants averaging 0.025 h⁻¹ for atrazine and 0.039 h⁻¹ for 2,4-D. Based on multiple regression analysis, nitrate-nitrogen was the primary predictor of photolysis for both atrazine and 2,4-D, with dissolved organic carbon also a predictor for some sites. However, at sites where suspended solids concentrations were elevated, photolysis rates of the two herbicides were controlled by the suspended solids concentration. The results of this research provide a basis for evaluating and predicting herbicide photolysis rates in shallow surface waters.     

Costs,Emissions Reductions,and Vehicle Repair: Evidence from Arizona

ABSTRACT

The Arizona inspection and maintenance (I/M) program provides one of the first opportunities to examine the costs and effectiveness of vehicle emission repair. This paper examines various aspects of emission reductions, fuel economy improvements, and repair costs, drawing data from over 80,000 vehicles that failed the I/M test in Arizona between 1995 and the first half of 1996. We summarize the wealth of data on repair from the Arizona program and highlight its limitations. Because missing or incomplete cost information has been a serious shortcoming for the evaluation of I/M programs, we develop a method for estimating repair costs when they are not reported. We find surprising evidence that almost one quarter of all vehicles that take the I/M test are never observed to pass the test. Using a statistical analysis, we provide some information about the differences between the vehicles that pass and those that do not. Older, more polluting vehicles are much more likely never to pass the I/M test, and their expected repair costs are much higher than those for newer cars.

This paper summarizes the evidence on costs and emission reductions in the Arizona program, comparing costs and emissions reductions between cars and trucks. Finally, we examine the potential for more cost-effective repair, first through an analysis of tightening I/M cut points and then by calculating the cost savings of achieving different emission reduction goals when the most cost-effective repairs are made first.     

Methane and carbon dioxide emission from two pig finishing barns

Agricultural activities are an important source of greenhouse gases. However, comprehensive, long-term, and high-quality measurement data of these gases are lacking. This article presents a field study of CH(4) and CO(2) emission from two 1100-head mechanically ventilated pig (Sus scrofa) finishing barns (B1 and B2) with shallow manure flushing systems and propane space heaters from August 2002 to July 2003 in northern Missouri. Barn 2 was treated with soybean oil sprinkling, misting essential oils, and misting essential oils with water to reduce air pollutant emissions. Only days with CDFB (complete-data-full-barn), defined as >80% of valid data during a day with >80% pigs in the barns, were used. The CH(4) average daily mean (ADM) emission rates were 36.2 +/- 2.0 g/d AU (ADM +/- 95% confidence interval; animal unit = 500 kg live mass) from B1 (CDFB days = 134) and 28.8 +/- 1.8 g/d AU from B2 (CDFB days = 131). The CO(2) ADM emission rates were 17.5 +/- 0.8 kg/d AU from B1 (CDFB days = 146) and 14.2 +/- 0.6 kg/d AU from B2 (CDFB days = 137). The treated barn reduced CH(4) emission by 20% (P < 0.01) and CO(2) emission by 19% (P < 0.01). The CH(4) and CO(2) released from the flushing lagoon effluent were equivalent to 9.8 and 4.1% of the CDFB CH(4) and CO(2) emissions, respectively. The emission data were compared with the literature, and the characteristics of CH(4) and CO(2) concentrations and emissions were discussed.