Characterisation of major component leaching and buffering capacity of RDF incineration and gasification bottom ash in relation to reuse or disposal scenarios

Thermal treatment of refuse derived fuel (RDF) in waste-to-energy (WtE) plants is considered a promising solution to reduce waste volumes for disposal, while improving material and energy recovery from waste. Incineration is commonly applied for the energetic valorisation of RDF, although RDF gasification has also gained acceptance in recent years. In this study we focused on the environmental properties of bottom ash (BA) from an RDF incineration (RDF-I, operating temperature 850-1000 °C) and a RDF gasification plant (RDF-G, operating temperature 1200-1400 °C), by evaluating the total composition, mineralogy, buffering capacity, leaching behaviour (both at the material’s own pH and as a function of pH) of both types of slag. In addition, buffering capacity results and pH-dependence leaching concentrations of major components obtained for both types of BA were analysed by geochemical modelling. Experimental results showed that the total content of major components for the two types of BA was fairly similar and possibly related to the characteristics of the RDF feedstock. However, significant differences in the contents of trace metals and salts were observed for the two BA samples as a result of the different operating conditions (i.e. temperature) adopted by the two RDF thermal treatment plants. Mineralogy analysis showed in fact that the RDF-I slag consisted of an assemblage of several crystalline phases while the RDF-G slag was mainly made up by amorphous glassy phases. The leached concentrations of major components (e.g. Ca, Si) at the natural pH of each type of slag did not reflect their total contents as a result of the partial solubility of the minerals in which these components were chemically bound. In addition, comparison of total contents with leached concentrations of minor elements (e.g. Pb, Cu) showed no obvious relationship for the two types of BA. According to the compliance leaching test results, the RDF-G BA would meet the limits of the Italian legislation for reuse and the European acceptance criteria for inert waste landfilling. RDF-I BA instead would meet the European acceptance criteria for non hazardous waste landfilling. A new geochemical modelling approach was followed in order to predict the leaching behaviour of major components and the pH buffering capacity of the two types of slags on the basis of independent mineralogical information obtained by XRD analysis and the bulk composition of the slag. It was found that the combined use of data regarding the mineralogical characterization and the buffering capacity of the slag material can provide an independent estimate of both the identity and the amount of minerals that contribute to the leaching process. This new modelling approach suggests that only a limited amount of the mineral phases that control the pH, buffering capacity and major component leaching from the solid samples is available for leaching, at least on the time scale of the applied standard leaching tests. As such, the presented approach can contribute to gain insights for the identification of the types and amounts of minerals that control the leaching properties and pH buffering capacity of solid residues such as RDF incineration and gasification bottom ash.     

Determining the community structure of the coral Seriatopora hystrix from hydrodynamic and genetic networks

The exchange of genetic information between coral reefs through the transport of larvae can be described in terms of networks that capture the linkages between distant populations. A key question arising from these networks is the determination of the highly connected modules (communities). Communities can be defined using genetic similarity or distance statistics between multiple samples but due to limited specimen sampling capacity the boundaries of the communities for the known coral reefs in the seascape remain unresolved. In this study we use the microsatellite composition of individual corals to compare sample populations using a genetic dissimilarity measure (F_ST) which is then used to create a complex network. This network involved sampling 1025 colonies from 22 collection sites and examining 10 microsatellites loci. The links between each sampling site were given a strength that was created from the pair wise F_ST values. The result is an undirected weighted network describing the genetic dissimilarity between each sampled population. From this network we then determined the community structure using a leading eigenvector algorithm within graph theory. However, given the relatively limited sampling conducted, the representation of the regional genetic structure was incomplete. To assist with defining the boundaries of the genetically based communities we also integrated the communities derived from a hydrodynamic and distance based networks. The hydrodynamic network, though more comprehensive, was of smaller spatial extent than our genetic sampling. A Bayesian Belief network was developed to integrate the overlapping communities. The results indicate the genetic population structure of the Great Barrier Reef and provide guidance on where future genetic sampling should take place to complete the genetic diversity mapping.     

Analytical solution for katabatic flow induced by an isolated cold strip

An analytical model for katabatic flow induced by cold strip of finite width in the cross-slope direction but of infinite extent in the downslope direction is presented. The fluid is assumed to have a constant (eddy) viscosity, and the Coriolis force is neglected. A numerical simulation has been used to verify the model, which is shown to revert to the classical Prandtl model if the strip width goes to infinity. The effects of the strip width and slope angle on the katabatic flow are studied. The buoyancy and downslope velocity reach maximum values at the centre of the strip, and spread outwards in the cross-slope direction. The downslope wind maximum weakens for narrow strips and shallow slopes. In contrast to the Prandtl solution, which shows a counter flow above the wind maximum, our model predicts the counter flow to occur outside the strip. The cross-slope variation in the surface forcing induces cross-slope and slope-normal velocities, which are manifested in vortices at the strip edges. Below the wind maximum, the fluid above the cooling surface descends and moves toward the strip edge where it is detrained from the strip region. Replenishment of fluid into the strip region takes place above the wind maximum.     

Sensitive issues in natural resource management and discursive strategies addressing them

In natural resource management facilitation literature, little attention is paid to sensitive issues in multi-stakeholder interaction and learning. This article aims to fill this gap. It discusses the variety of discursive strategies used by stakeholders to address sensitive issues with regard to fishery management in Benin, in three different settings: individual interviews, homogeneous groups' discussions, and a heterogeneous group meeting. Issues that proved sensitive were discussed openly in the interviews or homogeneous groups' discussions, but not at all, or only indirectly, in the heterogeneous group meeting. With indirect discursive strategies, two out of the seven sensitive issues were put on the discussions' agenda. We conclude that the other issues were too sensitive among others because of historically grown interdependency between interventionists and fishers. We suggest that dealing with sensitive issues is an important dimension of the facilitation of interactive learning processes and provide methodological guidelines to detect and address such issues.     

Closing the Incentive Gap: The Role of Public and Private Actors in Governing Indonesia's Tuna Fisheries

Indonesia is one of the world's largest tuna producing countries, yet regulatory oversight remains weak and management is poor. Incentive-based approaches are a way to improve state-based resource management, but they often require strong government regulation. In this paper, we use principal–agent theory and the notion of the ‘incentive gap’ to explore how incentives could be brought to bear in Indonesia through a combination of private and public actors. With a shared fish stock like tuna, we argue that a double principal–agent problem emerges, where information, asymmetries between various players complicate management. We focus on the problems of adverse selection and moral hazard in three different tuna fisheries in Indonesia to identify the nature of the incentive gap, and comment on the mix of public and private actors currently engaged in tuna fishery governance towards reducing the gap. The double principal–agent problem is a useful yet underutilized framework to understand the dynamics of shared stocks management. In this first application to a developing country fishery, we conclude that information asymmetries cannot be overcome without the involvement of private actors, who are increasingly becoming important in aligning regional and global objectives with those of fishers themselves.     

Prepared for climate change? A method for the ex-ante assessment of formal responsibilities for climate adaptation in specific sectors

Climate change-related risks encompass an intensification of extreme weather events, such as fluvial and pluvial flooding, droughts, storms, and heat stress. A transparent and comprehensive division of responsibilities is a necessary—but not the only—precondition for being prepared for climate change. In this paper, we present, and preliminarily test, a method for the ex-ante assessment of the division of public and private responsibilities for climate adaptation in terms of comprehensiveness, transparency, legitimacy, and effectiveness. This method proofs particularly suited for the assessment of adaptation responsibilities in combination with a sectoral approach. It helps identifying a number of shortcomings in divisions of responsibilities for climate adaptation. We conclude that this method is useful as a diagnostic tool for identifying the expected climate change preparedness level, and recommend to combine this with ex-post analyses of real-life cases of extreme events in order to assess the actual preparedness for climate change. Besides the scientific purpose of providing a generally applicable assessment method, with this method, we also intend to assist policy-makers in developing and implementing adaptation plans at various levels.     

Sociocultural valuation of ecosystem services to improve protected area management: a multi-method approach applied to Catalonia,Spain

The notion of ecosystem services is considered useful for integrating perceptions and values into decision-making on environment and nature. Sociocultural factors have been suggested to explain perceptions and values assigned to ecosystem services. We examine this by undertaking a sociocultural valuation of ecosystem services provided by the natural park of Sant Llorenç del Munt, located at the edge of the Barcelona Metropolitan Region. Four methods are used, namely a review of the literature on ecosystem services, non-participant observation, semi-structured interviews with stakeholders and a valuation survey among visitors. We assess whether visitors and other stakeholders understand the term ecosystem service, finding that the concept is rather unknown or misunderstood. Among the 28 ecosystem services identified, habitat and cultural services were the most valued. We statistically identify socioeconomic characteristics of visitors that have a main influence on their valuation of ecosystem services. We further assess diverging preferences of all stakeholders that might give rise to conflicting views about policies for protected areas. We draw lessons about the usefulness of the multi-method approach and about the management of protected areas.     

A people‐centred perspective on climate change,environmental stress,and livelihood resilience in Bangladesh

The Ganges–Brahmaputra delta enables Bangladesh to sustain a dense population, but it also exposes people to natural hazards. This article presents findings from the Gibika project, which researches livelihood resilience in seven study sites across Bangladesh. This study aims to understand how people in the study sites build resilience against environmental stresses, such as cyclones, floods, riverbank erosion, and drought, and in what ways their strategies sometimes fail. The article applies a new methodology for studying people’s decision making in risk-prone environments: the personal Livelihood History interviews (N = 28). The findings show how environmental stress, shocks, and disturbances affect people’s livelihood resilience and why adaptation measures can be unsuccessful. Floods, riverbank erosion, and droughts cause damage to agricultural lands, crops, houses, and properties. People manage to adapt by modifying their agricultural practices, switching to alternative livelihoods, or using migration as an adaptive strategy. In the coastal study sites, cyclones are a severe hazard. The study reveals that when a cyclone approaches, people sometimes choose not to evacuate: they put their lives at risk to protect their livelihoods and properties. Future policy and adaptation planning must use lessons learned from people currently facing environmental stress and shocks.     

Digital innovation through partnership between nature conservation organisations and academia: A qualitative impact assessment

Nature conservation organisations increasingly turn to new digital technologies to help deliver conservation objectives. This has led to collaborative forms of working with academia to spearhead digital innovation. Through in-depth interviews with three UK research-council-funded case studies, we show that by working with academics conservation organisations can receive positive and negative impacts, some of which cut across their operations. Positive impacts include new ways of engaging with audiences, improved data workflows, financial benefits, capacity building and the necessary digital infrastructure to help them influence policy. Negative impacts include the time and resources required to learn new skills and sustain new technologies, managing different organisational objectives and shifts in working practices as a result of the new technologies. Most importantly, collaboration with academics was shown to bring the opportunity of a profound change in perspectives on technologies with benefits to the partner organisations and individuals therein.