Optimizing the removal of small fish passage barriers

Removing small artificial barriers that hinder upstream migrations of fish is a major problem in riparian habitat restoration. Because of budgetary limitations, it is necessary to prioritize barrier removal and repair decisions. These have usually been based on scoring and ranking procedures, which, although simple to use, can be very inefficient in terms of increasing the amount of accessible instream habitat. We develop a novel decision-making approach, based on integer programming techniques, which optimizes repair and removal decisions. Results show based on real datasets of barrier culverts located in Washington State that scoring and ranking is over 25% below the optimum on average and a full 100% below in the worst case, producing no net habitat gain whatsoever. This is compared to a dynamic programming method that was able to find optimal solutions in less than a second, even for problems with up to several hundred variables, and a heuristic method, which found solutions with less than a 1% average optimality gap in even less time.     

Soil criteria to protect terrestrial wildlife and open-range livestock from metal toxicity at mining sites

Thousands of hard rock mines exist in the western USA and in other parts of the world as a result of historic and current gold, silver, lead, and mercury mining. Many of these sites in the USA are on public lands. Typical mine waste associated with these sites are tailings and waste rock dumps that may be used by wildlife and open-range livestock. This report provides wildlife screening criteria levels for metals in soil and mine waste to evaluate risk and to determine the need for site-specific risk assessment, remediation, or a change in management practices. The screening levels are calculated from toxicity reference values based on maximum tolerable levels of metals in feed, on soil and plant ingestion rates, and on soil to plant uptake factors for a variety of receptors. The metals chosen for this report are common toxic metals found at mining sites: arsenic, cadmium, copper, lead, mercury, and zinc. The resulting soil screening values are well above those developed by the US Environmental Protection Agency. The difference in values was mainly a result of using toxicity reference values that were more specific to the receptors addressed rather than the most sensitive receptor.     

The Dynamics of Justification in Policy Reform: Insights from Water Policy Debates in Ireland

Policy reform can be complex and fraught with contending arguments. Although much research has been conducted into the politics of coalition formation, less attention has been devoted to legitimating logics in policy reform. Drawing on the work of Boltanski and Thévenot, this exploratory study addresses this deficit by examining the influence of justifications deployed in policy debates. The paper analyses the role of shifting reasoning in contentious debates concerning attempts to reform water policy, including the introduction of domestic water charges in Ireland. Employing data from parliamentary deliberations, the paper traces the changing forms of justification used by those favouring and opposing the reforms. This examination suggests the importance of aligning an argument’s content with the shifting context into which it is introduced. The paper highlights the benefits of an investigative approach concerning policy justification for understanding policy reform dynamics at the intersection of politics and environmental communication.     

Absorption of Gaseous Air Pollutants By a Standardized Plant Canopy

Concentration profiles for hydrogen fluoride(HF), sulfur dioxide(SO₂), ozone (O₃), nitrogen dioxide(NO₂), and nitric oxide(NO) generated in a standardized alfalfa canopy are presented. Wind, light, temperature, and carbon dioxide(CO₂) profiles, canopy pollutant uptake rates, and canopy structural data are also given. Canopy pollutant concentration profile characteristics were studied to evaluate the relative potentials for major air pollutants to penetrate into canopies. The study was conducted in an environmental growth chamber equipped to control automatically environmental conditions and monitor continuously gas exchange rates. HF, SO₂, and NO₂ profiles suggested that these gases were removed efficiently by the upper portion of the canopy as well as by the immediate subsurface vegetation. The steady state HF profile showed the greatest displacement within the canopy. The NO profile was displaced the least. The uptake rate of NO by plants was apparently too slow in comparison with gas transport and mixing within the canopy to affect the internal profile substantially. O₃ appeared to be readily deposited on the surface tissues, but the deeper tissues in the canopy had less effect on the concentration profile. Data are also presented to show the relationship between NO₂ concentration within the canopy and changes in the air concentration above the vegetation. The results indicated that gas transport between the atmosphere and canopy interior was rapid. The data presented should be of current interest to agriculturists, researchers, administrators, and environmental planners concerned with effects of air pollutants on plants and on the fate of pollutants in the microenvironment.     

Transport of fecal bacteria by boots and vehicle tires in a rural Alaskan community

People living without piped water and sewer can be at increased risk for diseases transmitted via the fecal-oral route. One rural Alaskan community that relies on hauling water into homes and sewage from homes was studied to determine the pathways of fecal contamination of drinking water and the human environment so that barriers can be established to protect health. Samples were tested for the fecal indicator, Escherichia coli, and the less specific indicator group, total coliforms. Shoes transported fecal contamination from outside to floor material inside buildings. Contamination in puddles on the road, in conjunction with contamination found on all-terrain vehicle (ATV) tires, supports vehicle traffic as a mechanism for transporting contamination from the dumpsite or other source areas to the rest of the community. The abundance of fecal bacteria transported around the community on shoes and ATV tires suggests that centralized measures for waste disposal as well as shoe removal in buildings could improve sanitation and health in the community.     

Ambient nitrogen oxides exposure and early childhood respiratory illnesses

Acute respiratory infections are common in children below 5 years and recent studies suggest a possible link with air pollution. In this study, we investigated the association between ambient nitrogen oxides (NO_x) and bronchitis or upper airway inflammation.This longitudinal study was conducted in Teplice and Prachatice districts, Czech Republic. Children were followed from birth to 4.5 years of age. Data were compiled from medical records at delivery and at follow up, and from self-administered questionnaires from the same two time points. Air pollution monitoring data were used to estimate exposure over five different averaging periods ranging from three to 45 days prior to an episode. To quantify the association between exposure and outcome, while accounting for repeated measure correlation we conducted logistic regression analysis using generalized estimating equations.During the first 2 years of life, the adjusted rate ratio for bronchitis associated with interquartile increase in the 30-day average NO_x was 1.31 [95% confidence interval (CI): 1.07, 1.61] and for two to 4.5 year olds, it was 1.23 (95% CI: 1.01, 1.49). The 14-day exposure also had stable association across both age groups: below 2 years it was 1.25 (95% CI: 1.06, 1.47) and for two to 4.5 years it was 1.21 (95% CI: 1.06, 1.39). The association between bronchitis and NO_x increased with child's age in the under 2 years group, which is a relatively novel finding.The results demonstrate an association between NO_x and respiratory infections that are sufficiently severe to come to medical attention. The evidence, if causal, can be of public health concern because acute respiratory illnesses are common in preschool children.     

Effects of a complex archipelago on genetic subdivision of the intertidal limpet Siphonaria kurracheensis

Allozyme variation in the intertidal limpet Siphonaria kurracheensis was examined in 11 populations from the Houtman Abrolhos Islands, Western Australia, and four from the adjacent mainland, to test if the effects of these islands on genetic subdivision should include species with high dispersal. Consistent with extensive planktonic dispersal, genetic subdivision was low, with an average standardized variance in allelic frequencies (F_ST) of 0.010 over 400 km along the mainland, and 0.009 over 70 km in the Abrolhos Islands. Nevertheless, subdivision was statistically significant at the smallest scale examined (about 10 km), showing a pattern of local heterogeneity and large-scale homogeneity, which is common in planktonic dispersers. Among the island populations, heterozygosity was positively correlated with a multivariate index of exposure. The level of heterozygosity at the most exposed island sites is equivalent to that at the (also exposed) mainland sites, whereas it is lower in the most sheltered island sites. Although this indicates that some island populations are less well connected to the major pool of larvae, the overall effect of the archipelago on genetic subdivision is no greater than occurs on the mainland coast. This is contrary to findings in previously studied species with less potential for dispersal, suggesting that the local impediments to dispersal are selective in their effects, and are unlikely to be broadly important for genetic divergence in widely dispersing species.     

A Model for Gaseous Pollutant Sorption by Leaves

A model simulating pollutant exchange with isolated leaves that integrates factors which have been found to be important in regulating pollutant uptake by leaves is presented. The model is patterned after an electrical analogue simulator and was designed to emphasize the effects of pollutant and leaf properties on the process. The article discusses the relative significance of factors affecting gas transfer, sorption of pollutants by leaf surfaces, and pollutant solubility and fate on the uptake process. Data is presented showing uptake of ozone by exposed mesophyll and several epidermal surfaces chosen for their different surface characteristics. The model was used to derive a mathematical expression for the exchange process which was rearranged to define internal (average) pollutant solute concentration in terms of external concentration, leaf and boundary layer diffusion resistance, surface sorption and pollutant solubility. The importance of estimating internal solute concentration is discussed.     

Endosulfan transport: I. Integrative assessment of airborne and waterborne pathways

To reduce endosulfan (C9H6O3Cl6S; 6,7,8,9,10,10-hexachloro-1,5, 5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin 3-oxide) contamination in rivers and waterways, it is important to know the relative significances of airborne transport pathways (including spray drift, vapor transport, and dust transport) and waterborne transport pathways (including overland and stream runoff). This work uses an integrated modeling approach to assess the absolute and relative contributions of these pathways to riverine endosulfan concentrations. The modeling framework involves two parts: a set of simple models for each transport pathway, and a model for the physical and chemical processes acting on endosulfan in river water. An averaging process is used to calculate the effects of transport pathways at the regional scale. The results show that spray drift, vapor transport, and runoff are all significant pathways. Dust transport is found to be insignificant. Spray drift and vapor transport both contribute low-level but nearly continuous inputs to the riverine endosulfan load during spraying season in a large cotton (Gossypium hirsutum L.)-growing area, whereas runoff provides occasional but higher inputs. These findings are supported by broad agreement between model predictions and observed typical riverine endosulfan concentrations in two rivers.