Drought frequency in the Volta Basin of West Africa

According to various reports, climate change is responsible for the change in rainfall amount and pattern accompanied by the various degrees of extreme events in Sahelian West Africa in recent years. Other reports also suggest that there has been a “recovery” of the rainy season (Nicholson 2005). In this study, temporal characteristics of meteorological droughts in the Volta basin, a semi-arid region in West Africa, are investigated in order to provide a guide for sustainable water resource management. For this purpose, drought intensity, areal extent and recurrence frequency is analysed using the standardised precipitation index (SPI) for a time series between 1961 and 2005 from 52 meteorology stations across the Volta basin. Using this analysis the severity of the historical droughts of 1961, 1970, 1983, 1992 and 2001 that occurred in the region are assessed and their intensity, areal extent and return periods are obtained. The drought intensity is lower than −2.0 over nearly 75% of the region, meaning that a major part of the region was under extreme drought conditions during this year. The drought of 1983/1984 has a probability of occurrence of up to 0.1 from records spanning 44 years. The areal extent of extreme drought conditions is about 90% during this drought period.     

Towards institutional analysis of sustainability science: a quantitative examination of the patterns of research collaboration

This paper examines quantitatively the patterns of collaboration over geographical boundaries in the emerging field of sustainability science by empirically analyzing the bibliometric data of scientific articles. The results indicate that an increasing number of countries are engaged in research on sustainability, with the proportion of articles published through international collaboration rising as well. The number of countries engaged in international collaboration on sustainability research has been increasing, and the diversity of countries engaged in research collaboration beyond national borders is also increasing. The geographical patterns of collaboration on sustainability show that research collaboration tends to be conducted between countries which are geographically located closely, suggesting that communication and information exchange might be limited within the regional clusters. The focused fields of research activities on sustainability are significantly different between countries, as each country has its focused fields of research related to sustainability. The specialization of research activities is also observed in international collaboration. While these patterns of international collaboration within regional clusters focusing on specific fields could be effective in promoting the creation, transmission, and sharing of knowledge on sustainability utilizing the already existing regional networks, they could pose a serious obstacle to collecting, exchanging, and integrating diverse types of knowledge, especially when it is necessary to deal with problems involving large-scale complex interactions with long-term implications, such as climate change. It would be of critical importance to establish inter-regional linkages by devising appropriate institutional arrangements for global research collaboration on sustainability science.     

Sex-specific predation on two lizard species by kestrels

Sex-biased predation is thought to have important implications for sexual selection, sex allocation, and population dynamics (Magnhagen, 1991; Le-Galliard et al., 2005 for an example in lizards). Most studies found that males are subjected to higher predation pressure than females during the reproductive season (Korpimäki, 1985; Lodé et al., 2004; Christe et al., 2006; Costantini et al., 2007). In that period, males are very mobile, emit acoustic signals and exhibit brilliant colourations, which are needed to attract females but may make them more visible to predators. With regard to lizards, a recent study provided the first evidence that males of a lizard species may be preyed on more than females (Costantini et al., 2007). In the present study, we investigated whether there is sex-biased predation on two small lacertid species, the common wall lizard Podarcis muralis (Laurenti, 1768) and the Italian wall lizard Podarcis sicula (Rafinesque-Schmaltz, 1810), by Eurasian kestrels (Falco tinnunculus) during the reproductive season. We also examined whether (1) the rate of predation differed between species and (2) the rate of predation differed across years or among hunting habitats for each species.     

Ethylene: An Urban Air Pollutant

Ethylene is an unusual air pollutant in that it is a plant hormone. Motor vehicle exhaust is a primary source. In the Washington, D. C, area, ethylene concentrations ranged from 700 ppb in the city center to 39 ppb in areas outside the circumferential beltway. Plants grown in these concentrations of ethylene, using controlled environment chambers, exhibited typical symptoms of ethylene toxicity: reduced growth, premature senescence, and reduced flowering and fruit production. When plants were grown in carbon-filtered ambient air, which was also filtered through KMnO₄ to remove ethylene by oxidation, growth, flowering, and fruit production increased. These observations demonstrate that ethylene air pollution is a continual source of stress for plant growth and development in an urban environment.     

Emissions into the Atmosphere Due to the Ceramic Salt Glazing Process

The techniques of Principal Component Analysis (PCA) and subsequent regression analysis were used in an attempt to describe local and upwind chemical and physical factors which affect the variability of SO₄ ^–2 concentrations observed in a rural area of the northeastern U.S. The data used in the analyses included upwind and local O₃ concentrations, temperature, relative humidity and other climatological information, SO₂, and meteorological information associated with backward trajectories. The investigation identified five principal components, three major (eigenvalues >1) and two minor (eigenvalues < one), which accounted for 52% (r = 0.72) of the variability in the SO₄ ^–2 regression model. These components can be described as representing local and upwind photochemistry, droplet growth, SO₂ emissions, and air mass characteristics. The study also indicated that in future studies it will be necessary to a priori select air pollution and meteorological variables for measurement to potentially increase the sensitivity of this type of receptor model.     

Comparison of Predicted and Measured Concentrations for 58 Alternative models of Plume Transport in Complex Terrain

The purpose of this study was to evaluate alternative prediction models for the SO₂ concentrations produced in the vicinity of the Ohio Edison Company Sammis Power Plant. The plant is situated in the northeastern portion of the Ohio River Valley in complex terrain. Comparisons of the 16 highest predicted and measured short-term SO₂ concentrations were conducted for a one year period for 58 alternative models. Several models were found to predict reasonably accurately the 16 highest measured 24-hour SO₂ concentrations. Each of these models requires an upward adjustment in the plume centerline location as the plume is transported downwind in rising terrain. These same models overpredict by substantial margins the 16 highest measured 3-hour SO₂ concentrations. Improvements in emissions inventory data and improvements in the prediction models used are believed necessary to increase prediction accuracy further.     

Ecosystem services and hydroelectricity in Central America: modelling service flows with fuzzy logic and expert knowledge

Because ecosystem services are generally not produced and used in the same place, their assessment should consider the flows of services from ecosystems to users. These flows depend on the characteristics and spatial distribution of ecosystems and users, the spatial relationships between them, and the presence of filters or barriers between ecosystems and users. The objective of this paper is to map the ecosystem services provided to the Costa Rican and Nicaraguan hydroelectric sectors, which are crucial sectors for national sustainable development and depend directly on hydrological ecosystem services. The paper presents an approach for modelling the flows of multiple services from diverse ecosystems to diverse users through different kinds of filters in a landscape. The approach uses expert knowledge and fuzzy numbers to handle uncertainties. The analyses for Costa Rica and Nicaragua show how the approach helps identify priority areas for the conservation and restoration of forests for the services they provide to the hydroelectric sector. As such, it is a useful tool for defining spatially targeted policies for the conservation of ecosystem services and for involving the users of ecosystem services in ecosystem management.