Observations on the methane oxidation capacity of landfill soils

The objective of this study was to determine the role of CH₄ loading to a landfill cover in the control of CH₄ oxidation rate (g CH₄ m⁻² d⁻¹) and CH₄ oxidation efficiency (% CH₄ oxidation) in a field setting. Specifically, we wanted to assess how much CH₄ a cover soil could handle. To achieve this objective we conducted synoptic measurements of landfill CH₄ emission and CH₄ oxidation in a single season at two Southeastern USA landfills. We hypothesized that percent oxidation would be greatest at sites of low CH₄ emission and would decrease as CH₄ emission rates increased. The trends in the experimental results were then compared to the predictions of two differing numerical models designed to simulate gas transport in landfill covers, one by modeling transport by diffusion only and the second allowing both advection and diffusion. In both field measurements and in modeling, we found that percent oxidation is a decreasing exponential function of the total CH₄ flux rate (CH₄ loading) into the cover. When CH₄ is supplied, a cover’s rate of CH₄ uptake (g CH₄ m⁻² d⁻²) is linear to a point, after which the system becomes saturated. Both field data and modeling results indicate that percent oxidation should not be considered as a constant value. Percent oxidation is a changing quantity and is a function of cover type, climatic conditions and CH₄ loading to the bottom of the cover. The data indicate that an effective way to increase the % oxidation of a landfill cover is to limit the amount of CH₄ delivered to it.     

Qualitative analysis of volatile organic compounds on biochar

Qualitative identification of sorbed volatile organic compounds (VOCs) on biochar was conducted by headspace thermal desorption coupled to capillary gas chromatographic-mass spectrometry. VOCs may have a mechanistic role influencing plant and microbial responses to biochar amendments, since VOCs can directly inhibit/stimulate microbial and plant processes. Over 70 biochars encompassing a variety of parent feedstocks and manufacturing processes were evaluated and were observed to possess diverse sorbed VOC composition. There were over 140 individual chemical compounds thermally desorbed from some biochars, with hydrothermal carbonization (HTC) and fast pyrolysis biochars typically possessing the greatest number of sorbed volatiles. In contrast, gasification, thermal or chemical processed biochars, soil kiln mound, and open pit biochars possessed low to non-detectable levels of VOCs. Slow pyrolysis biochars were highly variable in terms of their sorbed VOC content. There were no clear feedstock dependencies to the sorbed VOC composition, suggesting a stronger linkage with biochar production conditions coupled to post-production handling and processing. Lower pyrolytic temperatures (?350 °C) produced biochars with sorbed VOCs consisting of short carbon chain aldehydes, furans and ketones; elevated temperature biochars (>350 °C) typically were dominated by sorbed aromatic compounds and longer carbon chain hydrocarbons. The presence of oxygen during pyrolysis also reduced sorbed VOCs. These compositional results suggest that sorbed VOCs are highly variable and that their chemical dissimilarity could play a role in the wide variety of plant and soil microbial responses to biochar soil amendment noted in the literature. This variability in VOC composition may argue for VOC characterization before land application to predict possible agroecosystem effects.     

Using a diagnostic tool to evaluate the longevity of urban community sanitation systems: A case study from Indonesia

Improving access to water and sanitation does not necessarily guarantee longevity of those systems transferred. Lessons from past interventions suggest that success depends on acceptance of the technology from the recipients and sustained use after donor assistance ends. A qualitative evaluation of urban community sanitation systems in Indonesia is conducted by use of a diagnostic tool, called RECAP, focusing on technology performance and experience. By means of surveys and qualitative interviews, the perceptions of involved stakeholders (local government, implementing agency and users) are evaluated. Conclusions suggest bridging the gap between governments and users in relation to maintenance and monitoring would improve the quality and longevity of interventions.     

Predicting how defaunation-induced changes in seed predation and dispersal will affect tropical tree populations

The loss of large animals due to overhunting and habitat loss potentially affects tropical tree populations and carbon cycling. Trees reliant on large-bodied seed dispersers are thought to be particularly negatively affected by defaunation. But besides seed dispersal, defaunation can also increase or decrease seed predation. It remains unclear how these different defaunation effects on early life stages ultimately affect tree population dynamics. We reviewed the literature on how tropical animal loss affects different plant life stages, and we conducted a meta-analysis of how defaunation affects seed predation. We used this information to parameterize models that altered matrix projection models from a suite of tree species to simulate defaunation-caused changes in seed dispersal and predation. We assessed how applying these defaunation effects affected population growth rates. On average, population-level effects of defaunation were negligible, suggesting that defaunation may not cause the massive reductions in forest carbon storage that have been predicted. In contrast to previous hypotheses, we did not detect an effect of seed size on changes in seed predation rates. The change in seed predation did not differ significantly between exclosure experiments and observational studies, although the results of observational studies were far more variable. Although defaunation surely affects certain tree taxa, species that benefit or are harmed by it and net changes in forest carbon storage cannot currently be predicted based on available data. Further research on how factors such as seed predation vary across tree species and defaunation scenarios is necessary for understanding cascading changes in species composition and diversity.     

Protected area planning to conserve biodiversity in an uncertain future

Protected areas are a key instrument for conservation. Despite this, they are vulnerable to risks associated with weak governance, land-use intensification, and climate change. We used a novel hierarchical optimization approach to identify priority areas for expanding the global protected area system that explicitly accounted for such risks while maximizing protection of all known terrestrial vertebrate species. To incorporate risk categories, we built on the minimum set problem, where the objective is to reach species distribution protection targets while accounting for 1 constraint, such as land cost or area. We expanded this approach to include multiple objectives accounting for risk in the problem formulation by treating each risk layer as a separate objective in the problem formulation. Reducing exposure to these risks required expanding the area of the global protected area system by 1.6% while still meeting conservation targets. Incorporating risks from weak governance drove the greatest changes in spatial priorities for protection, and incorporating risks from climate change required the largest increase (2.52%) in global protected area. Conserving wide-ranging species required countries with relatively strong governance to protect more land when they bordered nations with comparatively weak governance. Our results underscore the need for cross-jurisdictional coordination and demonstrate how risk can be efficiently incorporated into conservation planning. Planeación de las áreas protegidas para conservar la biodiversidad en un futuro incierto     

Pyrrhic victories: the cost to the board of ousting the CEO

Going against anecdotal evidence and common perception, the findings presented here show that boards who take action against their CEOs do so only at great cost to themselves, winning only a pyrrhic victory. Indeed, the findings presented show three distinct levels of board turnover. Normal attrition in periods of continuity produced a turnover of 10.99 per cent over two years; routine retirement exists (22.35 per cent) produced a similar turnover level to forced exits which did not imply a failure of the board to perform its monitoring function (25.36 per cent). However, forced CEO exits which implied a failure in the board's monitoring and advising roles caused a dramatically higher level of subsequent board turnover (40.55 per cent). These findings demonstrate that is not only the CEO that is forced to sacrifice his or her job when a company is in distress, but that the board is also accountable for its failure to perform its monitoring and advising duties adequately. Copyright © 1999 John Wiley & Sons, Ltd.     

Perceptions and Behaviors of Indigenous Populations Regarding Illegal Use of Protected Area Resources in East Africa’s Mountain Gorilla Landscape

Illegal activities and use of park resources are the main challenges facing mountain gorilla (Gorilla beringei beringei) conservation and the protection of their habitats in the East Africa’s Greater Virunga Transboundary Landscape (GVTL). Indigenous residents around GVTL are considered the primary illegal users of park resources. Despite this, there is limited understanding of the current and past perceptions of indigenous residents living in communities adjacent to two GVTL parks; Volcanoes National Park in Rwanda and Mgahinga Gorilla National Park in Uganda. Equally, there is also limited understanding regarding the actual incidences of illegal activities inside both parks. This paper addresses these gaps. Perception data were collected from indigenous residents living adjacent to both parks. Further, Ranger-based Monitoring (RbM) data from both parks were analyzed to determine actual numbers and types of illegal activities over the 9-year period. Interestingly, findings indicated that residents perceived the prevalence of illegal activities to be decreasing across GVTL. To the contrary, RbM findings indicated that the number of actual illegal activities was increasing significantly, particularly in Volcanoes National Park. The discrepancy found between the two perspectives provides for a discussion of the social biases potentially present in these data, and their implications for management. Results also illuminated the subsistence-related nature of most illegal behaviors and suggest that to reduce illegal activities and local dependency on park resources, park management must work with communities and support them in tapping into alternative livelihoods and finding ways to address community household subsistence needs.     

Institutions for Interstate Water Resources Management1

Abstract:  This paper evaluates alternative approaches to management of interstate water resources in the United States (U.S.), including interstate compacts, interstate associations, federal‐state partnerships, and federal‐interstate compacts. These governance structures provide alternatives to traditional federalism or U.S. Supreme Court litigation for addressing problems that transcend political boundaries and functional responsibilities. Interstate compacts can provide a forum for ongoing collaboration and are popular mechanisms for allocating water rights among the states. Federal‐interstate compacts, such as the Delaware River Basin Compact and federal‐state partnerships, such as the National Estuary Program, are also effective and complementary approaches to managing water resources. However, all of these approaches can only make modest improvements in managing water resources given the complicated and fragmented nature of our federalist system of government.     

Predicting estuarine sediment metal concentrations and inferred ecological conditions: an information theoretic approach

Empirically derived relationships associating sediment metal concentrations with degraded ecological conditions provide important information to assess estuarine condition. Resources limit the number, magnitude, and frequency of monitoring activities to acquire these data. Models that use available information and simple statistical relationships to predict sediment metal concentrations could provide an important tool for environmental assessment. We developed 45 predictive models for the total concentrations of copper, lead, mercury, and cadmium in estuarine sediments along the Southern New England and Mid-Atlantic regions of the United States. Using information theoretic model-averaging approaches, we found total developed land and percent silt/clay of estuarine sediment were the most important variables for predicting the presence of all four metals. Estuary area, river flow, tidal range, and total agricultural land varied in their importance. The model-averaged predictions explained 78.4, 70.5, 56.4, and 50.3% of the variation for copper, lead, mercury, and cadmium, respectively. Overall prediction accuracies of selected sediment benchmark values (i.e., effects ranges) were 83.9, 84.8, 78.6, and 92.0% for copper, lead, mercury, and cadmium, respectively. Our results further support the generally accepted conclusion that sediment metal concentrations are best described by the physical characteristics of the estuarine sediment and the total amount of urban land in the contributing watershed. We demonstrated that broad-scale predictive models built from existing monitoring data with information theoretic model-averaging approaches provide valuable predictions of estuarine sediment metal concentrations and show promise for future environmental modeling efforts in other regions.     

A critical review of the theory and application of social learning in participatory natural resource management processes

Social learning is increasingly cited as an essential component of sustainable natural resource management and the promotion of desirable behavioural change. This paper attempts to contribute to the current debate about social learning and public participation by reviewing the many perspectives on social learning and associated claims and benefits. Based on this analysis the paper identifies conceptual and practical weaknesses of the concept of social learning and their implications for the design of participatory processes in natural resource management.