Evolution of the magnitude and spatial extent of the weekend ozone effect in California's South Coast Air Basin, 1981-2000

Since the mid-1970s, ozone (O3) levels in portions of California's South Coast Air Basin (SoCAB) on weekends have been as high as or higher than levels on weekdays, even though emissions of O3 precursors are lower on weekends. Analysis of the ambient data indicates that the intensity and spatial extent of the weekend O3 effect are correlated with-day-of-week variations in the extent of O3 inhibition caused by titration with nitric oxide (NO), reaction of hydroxyl radical (OH) with nitrogen dioxide (NO2), and rates of O3 accumulation. Lower NO mixing ratios and higher NO2/oxides of nitrogen (NOx) ratios on weekend mornings allow O3 to begin accumulating approximately an hour earlier on weekends. The weekday/weekend differences in the duration of O3 accumulation remained relatively constant from 1981 to 2000. In contrast, the rate of O3 accumulation decreased by one-third to one-half over the same period; the largest reductions occurred in the central basin on weekdays. Trends in mixing ratios of O3 precursors show a transition to lower volatile organic compound (VOC)/NOx ratios caused by greater reductions in VOC emissions. Reductions in VOC/NOx ratios were greater on weekdays, resulting in higher VOC/NOx ratios on weekends relative to weekdays. Trends in VOC/NOx ratios parallel the downward trend in peak O3 levels, a shift in the location of peak O3 from the central to the eastern portion of the basin, and an increase in the magnitude and spatial extent of the weekend O3 effect.     

Linking life history to landscape for threatened species conservation in a multiuse region

Landscape-scale conservation that considers metapopulation dynamics will be essential for preventing declines of species facing multiple threats to their survival. Toward this end, we developed a novel approach that combines occurrence records, spatial–environmental data, and genetic information to model habitat, connectivity, and patterns of genetic structure and link spatial attributes to underlying ecological mechanisms. Using the threatened northern quoll (Dasyurus hallucatus) as a case study, we applied this approach to address the need for conservation decision-making tools that promote resilient metapopulations of this threatened species in the Pilbara, Western Australia, a multiuse landscape that is a hotspot for biodiversity and mining. Habitat and connectivity were predicted by different landscape characteristics. Whereas habitat suitability was overwhelmingly driven by terrain ruggedness, dispersal was facilitated by proximity to watercourses. Although there is limited evidence for major physical barriers in the Pilbara, areas with high silt and clay content (i.e., alluvial and hardpan plains) showed high resistance to dispersal. Climate subtlety shaped distributions and patterns of genetic turnover, suggesting the potential for local adaptation. By understanding these spatial–environmental associations and linking them to life-history and metapopulation dynamics, we highlight opportunities to provide targeted species management. To support this, we have created habitat, connectivity, and genetic uniqueness maps for conservation decision-making in the region. These tools have the potential to provide a more holistic approach to conservation in multiuse landscapes globally.     

Grassland root communities: species distributions and how they are linked to aboveground abundance

There is little comprehensive information on the distribution of root systems among coexisting species, despite the expected importance of those distributions in determining the composition and diversity of plant communities. This gap in knowledge is particularly acute for grasslands, which possess large numbers of species with morphologically indistinguishable roots. In this study we adapted a molecular method, fluorescent fragment length polymorphism, to identify root fragments and determine species root distributions in two grasslands in Yellowstone National Park (YNP). Aboveground biomass was measured, and soil cores (2 cm in diameter) were collected to depths of 40 cm and 90 cm in an upland, dry grassland and a mesic, slope-bottom grassland, respectively, at peak foliar expansion. Cores were subdivided, and species that occurred in each 10-cm interval were identified. The results indicated that the average number of species in 10-cm intervals (31 cm3) throughout the sampled soil profile was 3.9 and 2.8 species at a dry grassland and a mesic grassland, respectively. By contrast, there was an average of 6.7 and 14.1 species per 0.5 m2, determined by the presence of shoot material, at dry and mesic sites, respectively. There was no relationship between soil depth and number of species per 10-cm interval in either grassland, despite the exponential decline of root biomass with soil depth at both sites. There also was no relationship between root frequency (i.e., the percentage of samples in which a species occurred) and soil depth for the vast majority of species at both sites. The preponderance of species were distributed throughout the soil profile at both sites. Assembly analyses indicated that species root occurrences were randomly assorted in all soil intervals at both sites, with the exception that Festuca idahoensis segregated from Artemisia tridentata and Pseudoroegnaria spicata in 10-20 cm soil at the dry grassland. Root frequency throughout the entire sampled soil profile was positively associated with shoot biomass among species. Together these results indicated the importance of large, well-proliferated root systems in establishing aboveground dominance. The findings suggest that spatial belowground segregation of species probably plays a minor role in fostering resource partitioning and species coexistence in these YNP grasslands.     

Effects of Landscape Composition and Wetland Fragmentation on Frog and Toad Abundance and Species Richness in Iowa and Wisconsin, U.S.A.

Abstract: Management of amphibian populations to reverse recent declines will require defining high-quality habitat for individual species or groups of species, followed by efforts to retain or restore these habitats on the landscape. We examined landscape-level habitat relationships for frogs and toads by measuring associations between relative abundance and species richness based on survey data derived from anuran calls and features of land-cover maps for Iowa and Wisconsin. The most consistent result across all anuran guilds was a negative association with the presence of urban land. Upland and wetland forests and emergent wetlands tended to be positively associated with anurans. Landscape metrics that represent edges and patch diversity also had generally positive associations, indicating that anurans benefit from a complex of habitats that include wetlands. In Iowa the most significant associations with relative abundance were the length of the edge between wetland and forest ( positive) and the presence of urban land (negative). In Wisconsin the two most significant associations with relative abundance were forest area and agricultural area ( both positive). Anurans had positive associations with agriculture in Wisconsin but not in Iowa. Remnant forest patches in agricultural landscapes may be providing refuges for some anuran species. Differences in anuran associations with deep water and permanent wetlands between the two states suggest opportunities for management action. Large-scale maps can contribute to predictive models of amphibian habitat use, but water quality and vegetation information collected from individual wetlands will likely be needed to strengthen those predictions. Landscape habitat analyses provide a framework for future experimental and intensive research on specific factors affecting the health of anurans.     

Food contamination as a pathway for lead exposure in children during the 2010–2013 lead poisoning epidemic in Zamfara, Nigeria

In 2010, an estimated 400 to 500 children died of acute lead poisoning associated with artisanal gold mining in Zamfara, Nigeria. Processing of gold ores containing up to 10% lead within residential compounds put residents, especially children, at the highest risk. Principal routes of exposure were incidental ingestion and inhalation of contaminated soil and dusts. Several Nigerian and international health organizations collaborated to reduce lead exposures through environmental remediation and medical treatment. The contribution of contaminated food to total lead exposure was assessed during the environmental health response. Objectives of this investigation were to assess the influence of cultural/dietary habits on lead exposure pathways and estimate the contribution of contaminated food to children's blood lead levels(BLLs). A survey of village dietary practices and staple food lead content was conducted to determine dietary composition, caloric intakes, and lead intake. Potential blood lead increments were estimated using bio-kinetic modeling techniques. Most dietary lead exposure was associated with contamination of staple cereal grains and legumes during post-harvest processing and preparation in contaminated homes. Average post-harvest and processed cereal grain lead levels were 0.32 mg/kg and 0.85 mg/kg dry weight, respectively. Age-specific food lead intake ranged from 7 to 78 μg/day. Lead ingestion and absorption were likely aggravated by the dusty environment, fasting between meals, and nutritional deficiencies. Contamination of staple cereal grains by highly bioavailable pulverized ores could account for as much as 11%–34% of children's BLLs during the epidemic, and were a continuing source after residential soil remediation until stored grain inventories were exhausted.     

Energy Consumption Reduction Using Two-Stage Venturi Scrubbers

Performance of a three-component monostatic Doppler sodar was compared with performance of collocated meteorological tower instruments and evaluated for electric utility applications. The sensors were components of an air pollution monitoring network that was upgraded to assess the impact of coal conversion on ambient air quality at Northeast Utilities' Mt. Tom Generating Station situated in rugged terrain in the Connecticut River valley of western Massachusetts. To determine how well sodar and tower measurements agree, and how reliable sodar is for this type of application, meteorological data and system performance statistics obtained from August 1982 through July 1983 were examined. A statistical comparison of wind speed and direction measurements at 50 m indicated good agreement between the two monitoring techniques. High correlations also were observed for data collected during various weather conditions. System reliability was demonstrated by data recovery rates and sodar vertical range capabilities. Monthly data recovery rates exceeded 90 percent and occasionally approached 98 percent after initial break-in problems were resolved. Sodar range was 100 m more than 95 percent of the time and 200 m more than 50 percent of the time. Under optimum conditions, the vertical range extended beyond 200 m.     

New Source Performance Standards For Coal-Fired Power Plants

To preserve and improve environmental quality in a prosperous industrialized nation like the United States, we must use efficient control technology to reduce the pollution which would otherwise accompany our growth. The need for control is especially great in our use of energy. In the near term our country must depend increasingly on coal to meet our energy needs. In his 1977 energy message President Carter declared that it would be this Administration’s policy to require the use of best available control technology for all new coal burning plants. EPA is implementing this policy by adopting a rule that will require such controls on new coal-fired power plants.     

Estimating population impacts via dynamic occupancy analysis of Before-After Control-Impact studies

Estimating environmental impacts on populations is one of the main goals of wildlife monitoring programs, which are often conducted in conjunction with management actions or following natural disturbances. In this study we investigate the statistical power of dynamic occupancy models to detect changes in local survival and colonization from detection-nondetection data, while accounting for imperfect detection probability, in a Before-After Control-Impact (BACI) framework. We simulated impacts on local survival and/or detection probabilities, and asked questions related to: (1) costs and benefits of different analysis models, (2) confounding changes in detection with changes in local survival, (3) sampling design trade-offs, and (4) species with low vs. high rates of turnover. Estimating seasonal effects on local survival and colonization, as opposed to estimating Before-After effects, had little effect on the power to detect changes in local survival. Estimating a parameter that accounted for pretreatment differences in local survival between Control and Impact sites decreased power by 50%, but it was critical to include when such differences existed. When the experimental treatment had a negative impact on species detectability but analysis assumed constant detection, the Type I error rates were dramatically inflated (0.20 0.33). In general, there was low power (< 0.5) to detect a 50% decrease in local survival for all combinations of sites (N = 50 vs. 100), seasons sampled (8 vs. 12), and visits per site per season (4 vs. 6). Unbalanced designs performed worse than balanced designs, with the exception of the case of treatments being implemented in different seasons at different sites. Adding more control sites improved the ability to detect changes in local survival. Surveying more seasons after impact resulted in modest power gains, but at least three seasons before impact were required to successfully implement BACI occupancy studies. Turnover rates had a low impact on power. Occupancy studies conducted in a BACI design offer the opportunity to detect environmental impacts on wildlife populations without the costs of intensive studies. However, given the low power to detect small changes (20%) in local survival, these studies should be used when researchers are confident that major treatment impacts will occur or very large sample sizes are obtainable.     

Active density-dependent habitat selection in a controlled population of small mammals

Density-dependent habitat selection has numerous and far-reaching implications to population dynamics and evolutionary processes. Although several studies suggest that organisms choose and occupy high-quality habitats over poorer ones, definitive experiments demonstrating active selection, by the same individuals at the appropriate population scale, are lacking. We conducted a reciprocal food supplementation experiment to assess whether voles would first occupy a habitat receiving extra food, then change their preference to track food supplements moved to another habitat. Meadow voles, as predicted, were more abundant in food-supplemented habitat than in others. Density declined when food supplements ceased because the voles moved to the new habitat receiving extra food. Although males and females appeared to follow different strategies, meadow-vole densities reflected habitat quality because voles actively selected the best habitat available. It is thus clear that behavioral decisions on habitat use can motivate patterns of abundance, frequency, and gene flow that have widespread effects on subsequent evolution.