Limitation of African Wild Dogs by Competition with Larger Carnivores

African wild dogs ( Lycaon pictus ) are endangered largely because their population-density is low under all conditions. Interspecific competition with larger carnivores may be a factor limiting wild dog density. The density of wild dogs on a 2600-km² area of the Selous Game Reserve (Tanzania) was 0.04 adults/km². Spotted hyaena ( Crocuta crocuta ) density for the same area was estimated by audio playbacks as 0.32 hyaenas/km². Lion ( Panthera leo ) density, determined from the ratio of hyaenas to lions, was 0.11 lions/km². Across six ecosystems including Selous, there were strong negative correlations between wild dog and hyaena densities (r = −0.92; p = 0.01) and between wild dog and lion densities (r = −0.91; p = 0.03). Hyaenas out-numbered wild dogs by ratios ranging from 8:1 to 122:1. Ratios of lions to wild dogs ranged from 3:1 to 21:1. The diets of hyaenas and wild dogs overlap extensively; those of wild dogs and lions show less overlap. Where hyaenas are common and visibility is good, interference competition from hyaenas at wild dog kills is common and reduces wild dogs' feeding time. Where hyaena density is lower and visibility is poor, interference competition at wild dog kills is rare. Wild dogs are commonly killed by lions and occasionally by hyaenas. These data suggest that competition with spotted hyaenas may limit or exclude wild dogs when hyaena density is high. Competition with lions appears less intense, but direct predation by lions on wild dogs is important. Competition and predation by larger carnivores may be of broad importance to the conservation of wild dogs and other medium-sized carnivores.     

Selective extraction of persistent organic pollutants from environmental matrices

An attempt is made to determine the bioavailability of persistent organic pollutants (POP's) in environmental matrices. The approach is based on the use of the Hildebrand Solubility Parameter, and its individual parameters of hydrogen bonding, dispersion and polarity to select weak and strong solvents to extract POP's from soil matrices. The approach has been applied to both spiked soils and certified reference materials. Initial results indicate that it is possible to fractionate POP's from soil matrices based on their ability to be extracted from soil by particular solvents.     

Representational success: A new paradigm for achieving species protection by reserve site selection

Models for designing habitat reserve networks have focused on minimizing the number of sites necessary to cover each species one or more times. A solution to this problem is usually one from among a large number of alternative optimal configurations of sites. This paper develops an iterative method for building reserve networks that produces an optimal solution to the species set covering problem (SSCP) and also maximizes the number of species covered two or more times, three or more times, and so on, conditional on the solution to the previous iteration. We refer to this as representational success. Thus, a pareto optimal species set covering is achieved that is preferable to an arbitrary optimal solution to the SSCP.     

Cadmium concentrations in human kidney in the UK: 1978-1993

Almost 2700 samples of human renal cortex have been collected from throughout the UK over a 16 year period from 1978 to 1993. The mean Cd concentration was 19 micrograms g-1 and the median 16 micrograms g-1. Smokers were, on average, about 5 micrograms g-1 higher than non-smokers. Cd increased from low concentration in the young to a maximum of 23 micrograms g-1 in middle age followed by a decrease in old age. Subjects who had died of renal disease had lower Cd concentrations. Geographical variations in the UK are small and the concentrations appear to be static over the 16 year period. Some 3.9% of the population had Cd concentrations > 50 micrograms g-1, the critical level at which beta 2-microglobulin appears in urine.     

Improvement of the Bag-Mediated Filtration System for Sampling Wastewater and Wastewater-Impacted Waters

Environmental surveillance of poliovirus (PV) plays an important role in the global program for eradication of wild PV. The bag-mediated filtration system (BMFS) was first developed in 2014 and enhances PV surveillance when compared to the two-phase grab method currently recommended by the World Health Organization (WHO). In this study, the BMFS design was improved and tested for its usability in wastewater and wastewater-impacted surface waters in Nairobi, Kenya. Modifications made to the BMFS included the size, color, and shape of the collection bags, the filter housing used, and the device used to elute the samples from the filters. The modified BMFS concentrated 3–10 L down to 10 mL, which resulted in an effective volume assayed (900–3000 mL) that was 6–20 times greater than the effective volume assayed for samples processed by the WHO algorithm (150 mL). The system developed allows for sampling and in-field virus concentration, followed by transportation of the filter for further analysis with simpler logistics than the current methods. This may ultimately reduce the likelihood of false-negative samples by increasing the effective volume assayed compared to samples processed by the WHO algorithm, making the BMFS a valuable sampling system for wastewater and wastewater-impacted surface waters.     

Mercury bioaccumulation in aquatic biota along a salinity gradient in the Saint John River estuary

Although estuaries are critical habitats for many aquatic species, the spatial trends of toxic methylmercury(MeHg) in biota from fresh to marine waters are poorly understood. Our objective was to determine if MeHg concentrations in biota changed along a salinity gradient in an estuary. Fourspine Stickleback(Apeltes quadracus), invertebrates(snails,amphipods, and chironomids), sediments, and water were collected from ten sites along the Saint John River estuary, New Brunswick, Canada in 2015 and 2016, with salinities ranging from 0.06 to 6.96. Total mercury(proxy for MeHg) was measured in whole fish and MeHg was measured in a subset of fish, pooled invertebrates, sediments, and water. Stable sulfur(δ~(34)S), carbon(δ~(13) C), and nitrogen(δ~(15)N) isotope values were measured to assess energy sources(S, C) and relative trophic level(N). There were increases in biotic δ~(13)C and δ~(34)S from fresh to more saline sites and these measures were correlated with salinity.Though aqueous MeHg was higher at the freshwater than more saline sites, only chironomid MeHg increased significantly with salinity. In the Saint John River estuary, there was little evidence that MeHg and its associated risks increased along a salinity gradient.     

Developing alternative land-use scenarios to facilitate natural resource management across jurisdictional boundaries

Scenario planning is an effective approach for examining possible futures by exploring the implications and consequences of different policy responses to landscape stressors. We present here a case study that explores plausible futures of urban growth in Southern Nevada, USA that illustrates how scenario analysis can be used to inform region-wide resource management by spatially modeling drivers of change, resource impacts, and potential policy responses. Using a suite of energy, water and biodiversity impact models, we assess the outcomes of the various futures on priority resources, resulting in a clear basis of comparison between alternative policies and their potential outcomes. This case study demonstrates the utility of scenario modeling for natural resource management by exploring crucial policy decisions that might be made in the near-term that could have lasting and sometimes conflicting influences on regional resources over the long term.     

Hydrological,Physical, and Chemical Functions and Connectivity of Non‐Floodplain Wetlands to Downstream Waters: A Review

We reviewed the scientific literature on non‐floodplain wetlands (NFWs), freshwater wetlands typically located distal to riparian and floodplain systems, to determine hydrological, physical, and chemical functioning and stream and river network connectivity. We assayed the literature for source, sink, lag, and transformation functions, as well as factors affecting connectivity. We determined NFWs are important landscape components, hydrologically, physically, and chemically affecting downstream aquatic systems. NFWs are hydrologic and chemical sources for other waters, hydrologically connecting across long distances and contributing compounds such as methylated mercury and dissolved organic matter. NFWs reduced flood peaks and maintained baseflows in stream and river networks through hydrologic lag and sink functions, and sequestered or assimilated substantial nutrient inputs through chemical sink and transformative functions. Landscape‐scale connectivity of NFWs affects water and material fluxes to downstream river networks, substantially modifying the characteristics and function of downstream waters. Many factors determine the effects of NFW hydrological, physical, and chemical functions on downstream systems, and additional research quantifying these factors and impacts is warranted. We conclude NFWs are hydrologically, chemically, and physically interconnected with stream and river networks though this connectivity varies in frequency, duration, magnitude, and timing.     

Modes of governing Canadian waste management: a case study of Metro Vancouver’s energy-from-waste controversy

Managing municipal solid waste is a pressing environmental and political concern for Canadian municipalities who bear the primary responsibility for waste management (WM). In 2015, Metro Vancouver’s (MV’s) plans to expand their capacity to expand their WM capacity with energy-from-waste technology was abandoned, despite shrinking landfill space and persistent public opposition to new landfills. Using Bulkeley et al.’s [(2005). Governing municipal waste: towards a new analytical framework. Journal of Environmental Policy and Planning, 7(1), 1–23. doi:10.1080/15239080500251700] ‘modes of governing framework’, we analyse MV’s failed attempt to expand their energy-from-waste capacity to better understand the challenges associated with governing WM in Canada. We argue that a history of downloading responsibility for WM to municipalities, regional districts, and industry has fragmented WM governance, posing a challenge for developing new waste infrastructure. We find that this localization of responsibility is incompatible with contemporary WM challenges. The scalar mismatch between waste’s material impacts and the scale at which waste is managed has resulted in co-dependence and conflict between putatively independent municipalities, regional districts, and private companies. This inhibits higher-level WM coordination while the autonomy of individual municipalities is simultaneously undermined.     

Cost comparison of syngas production from natural gas conversion and underground coal gasification

Underground coal gasification (UCG) is a promising technology to reduce the cost of producing syngas from coal. Coal is gasified in place, which may make it safer, cleaner and less expensive than using a surface gasifier. UCG provides an efficient approach to mitigate the tension between supplying energy and ensuring sustainable development. However, the coal gasification industry presently is facing competition from the low price of natural gas. The technology needs to be reviewed to assess its competiveness. In this paper, the production cost of syngas from an imaginary commercial-scale UCG plant was broken down and calculated. The produced syngas was assumed to be used as feedstock in liquid fuel production through the Fischer-Tropsch process or methanol synthesis. The syngas had a hydrogen (H₂) to carbon monoxide (CO) ratio of 2. On this basis, its cost was compared with the cost of syngas produced from natural gas. The results indicated that the production cost of syngas from natural gas is mainly determined by the price of natural gas, and varied from $24.46 per thousand cubic meters (TCM) to $90.09/TCM, depending on the assumed price range of natural gas. The cost of producing UCG syngas is affected by the coal seam depth and thickness. Using the Harmon lignite bed in North Dakota, USA, as an example, the cost of producing syngas through UCG was between $37.27/TCM and $39.80/TCM. Therefore, the cost of UCG syngas was within the cost range of syngas produced by natural gas conversion. A sensitivity analysis was conducted to investigate how the cost varies with coal depth and thickness. It was found that by utilizing thicker coal seams, syngas production per cavity can be increased, and the number of new wells drilled per year can be reduced, therefore improving the economics of UCG. Results of this study indicate the competitiveness of UCG regarding to natural gas conversion technologies, and can be used to guide UCG site selection and to optimize the operation strategy.