Over five years have elapsed since the coming into force of the much heralded United Nations Convention on Biological Diversity (CBD or Convention) signed during the 'Earth Summit' at Rio de Janeiro in June 1992 (CBD 1992). Despite the warm, even euphoric welcome extended to this treaty by the environmental community, the difficulties of implementing the CBD in the last five years are unmasking and uncovering its flawed environmental foundations. The language of any legal instrument embodies and expresses the considered intentions of its creators, and may contain obligatory provisions that are legally binding. They may also contain hortatory and aspirational commitments that are not legally enforceable. The CBD rejected 'hard' environmental obligations that are legally binding for non-legal exhortations, and highly qualified 'soft' commitments. Whatever their value be as face-saving strategies for reaching agreement on the CBD, such aspirational expressions do not create a stable foundation for tough decisions in the world of realpolitik.

Characteristics, impacts and economic costs and benefits of blast fishing have been little investigated and they were therefore studied in Indonesia, at the scale of individual fishing households and of Indonesian society as a whole. Although illegal and highly destructive to coral reefs, blast fishing provides income and fish to a vast number of coastal fishers who claim that they have no alternative to make a living. Crew members in small-, medium- and large-scale blast fishing operations earned net incomes per month of US$55, 146 and 197 respectively. Boat owners in the same types of operations earned US$55, 393 and 1100 respectively. These incomes were comparable to the highest incomes in the conventional coastal fisheries. At the individual household level, the differences between the three types of operations show clear incentives for scale enlargement. The cost-benefit balance at the society level was calculated with an economic model. This analysis showed a net loss after 20 years of blast fishing of US$306 800 per km2 of coral reef where there is a high potential value of tourism and coastal protection, and US$33 900 per km2 of coral reef where there is a low potential value. The main quantifiable costs are through loss of the coastal protection function, foregone benefits of tourism, and foregone benefits of non-destructive fisheries. The economic costs to society are four times higher than the total net private benefits from blast fishing in areas with high potential value of tourism and coastal protection. This analysis of characteristics, impact and economics of blast fishing should help to raise the political will to ban blast fishing from Indonesian waters. Moreover, it allows for an evaluation of possible management solutions, taking into account their costs and the socio-economic framework that caused coastal fishers to start using explosives.

Today there is much concern about the potential contamination, overuse and development of scenic rivers in more or less pristine environments. The objective of this work was to quantify the spatial and temporal changes in land-use occurring in a watershed draining a nationally protected river. The Buffalo National River of Arkansas was chosen to serve as an example of how Geographic Information System (GIS) technology can rapidly assess the environmental changes that have occurred within a watershed. GIS was used to develop a spatial database of the watershed and to describe differences in land-use data from five sample years during 1965–92. Over this time span, approximately 40 000 ha of forest were lost and converted primarily to pasture. The average rate of loss of forest was 1480 ha/yr. During this same period, the average rate of gain of pasture was 1381 ha/yr. Buffer analyses showed that pasture increased at a higher percentage rate in the buffer zones surrounding the Buffalo River than in the tributaries of the Buffalo River, and a large proportion of the increase was on higher slopes. Land-use changes were dynamic with a greater area converted to pasture than area of pasture converted to forest in the watershed. The cleared forest lands were mostly near older pastures and along streams. The reforested lands tended to occur in the more isolated areas. The Buffalo River Watershed has undergone changes in land-use that may have had impact on the water quality of the region.

The spatial requirements of populations ought to be central to developing conservation strategies and ecological theory, but they are difficult to identify from the published collection of reported population estimates. Transforming population estimates into density and log values may have clouded recognition of the discontinuous relationship that exists between abundance estimates and the areas within which they were made. I used abundance estimates of terrestrial mammalian Carnivora to identify scale domains of abundance. In scale domain A, the study areas were too small to include all the individuals of the population, and abundance estimates increased propor-tionally with study area size. Scale domain B included high variation in abundance estimates, but these estimates no longer increased with increasing size of study area as they did in domain A. I refer to the smallest area in the scale domain B as the 'threshold area' (the minimum area known to support a population of the particular species). The abundance in scale domain B averaged 52 individuals amongst all but three outlier species. Scale domains C and D were also identified, and included much larger study areas and substantially larger abundance estimates.

The threshold area is the first empirically-derived representation of the minimum space used by populations of each species. However, nearly half of all carnivore abundance estimates were made in areas smaller than the threshold area, and only 4% could be used to represent transitions between scale domains B, C and D. The remainder varied within domains B, C and D due to variation in environmental conditions and research methods. Most comparisons of density between sites and between species have been made without considering whether the estimates represented the true population or some collection of individuals more or less abundant than the population. Threshold area can be used as a standard area against which to estimate and compare population density, in lieu of more appropriately comparing estimates of region-wide density, which generally do not yet exist. Also, threshold area could be predicted with reasonable error rates based on a typical species' body mass, brain mass and home range size. Therefore, conservation biologists may now have a tool to identify the minimum habitat areas needed to conserve populations of carnivore species, and theoretical ecologists can relate ecological space at the population level to allometric variables.

With the closure of many military bases worldwide and a closer scrutiny of practices on remaining bases, the environmental impact of the military is now an important consideration in the operation of bases. Many previously-unknown environmental problems related to chemicals are surfacing. White phosphorus, a chemical commonly used as an obscurant, is a chemical previously thought to be innocuous after use. In 1990, however, it was linked to the deaths of thousands of waterfowl at the Eagle River Flats impact area on Ft Richardson near Anchorage, Alaska, USA, and shortly after, a series of remedial investigations was initiated. This paper describes three of the remedial methods currently under investigation, namely enhanced in-situ remediation, pond draining through ditching or pumping, and dredging. These three approaches are best applied in different environments, but they can be used together or in conjunction with other strategies. Their impacts on the environment will vary as well.

Experience with these remediation strategies has proven very useful in determining the direction that the clean-up effort at Eagle River Flats (ERF) should take. Dredging, an effective means of removing contaminated sediments for off-site remediation, has been shown to be too slow and expensive at the ERF because unexploded ordnance is present. Enhanced natural remediation is effective under favourable climatological conditions in areas that experience intermittent flooding, but desaturation of the sediments is critical to its effectiveness. Pond draining by blasting a ditch effectively removes waterfowl feeding habitat, but attenuation of the contaminant is inhibited because the ditch increases flooding frequency, and the habitat alteration is permanent. Pond pumping, where feasible, has shown great potential for the desaturating of wide areas of ERF, enabling the natural attenuation mechanism to progress. Further investigation will be necessary to confirm these initial conclusions and determine the overall effectiveness of all three methodologies. Methods developed over the course of this work may be applied to other remediation projects where in-situ volatilization can occur and limited disturbance of wetlands is critical.

Despite efforts spanning more than a decade, plastics continue to be the least recycled component of the USA's municipal waste stream. This study addresses a significant gap in knowledge about the operation of the plastics recycling market by investigating and analysing the characteristics and experiences of manufacturers and vendors of consumer products with recycled plastics content.

The study collected information through a survey of this segment of the USA's plastics recycling industry. The analysis of this information confirmed that the industry, as a whole, is young. Nevertheless, it offers a very wide variety of products. These face stiff competition from virgin resin plastic products, or from other virgin competing materials such as wood and cotton. Recycled plastic products are often more expensive than their competitors. Some manufacturers and vendors, especially the younger ones, addressed this problem by finding a niche market with consumers who are willing to pay a premium for environmentally friendly products. On the other hand, companies whose products are successfully competing against virgin products are more likely to have operated longer, to be vertically integrated (producing raw materials and consumer products), and to be more diversified in the number of resins they handle.

Manufacturers and vendors of recycled plastic products in the USA have gained considerable experience since the early years of plastics recycling. Nonetheless, they continue to face some serious challenges. Operators of materials recovery facilities that process PCR have an important role to play in supporting the industry by improving the quality of their product (i.e. PCR). However, the most important factor for securing continued growth of the industry is the expansion of markets for the industry's products. The responses to the survey indicate that, while there are actions that manufacturers and vendors can take to increase their chances of success, the effect of government policy remains overwhelming. Policymakers can facilitate growth in plastics recycling by stepping up their efforts to implement effective demand-side policies and by adopting policies to internalize the environmental and social externalities of plastics manufacturing and use.

There is general consensus that resource-use strategies of recent migrants in tropical rainforests result in extensive deforestation and other negative environmental impacts. Less agreement exists about the nature and extent of the impact of indigenous and long-standing migrant communities living in rainforests. It has often been argued that the high value these communities place on local resources results in environmental conservation in areas under their control, but this is being increasingly challenged. The aim of this study was to contribute to this debate by comparing the regional environmental impact of indigenous and non-indigenous households in North-west Ecuador, with emphasis on tropical deforestation. The basic premise was that long-term resource-use strategies and related decision-making processes should be discernible as characteristic land-use patterns. Three indigenous and non-indigenous populations coexist in the study region, and demographic, land-use and historical sources of information were used to evaluate their relationship to regional deforestation in the period 1983-93. No significant differences were found in the recent deforestation associated with each group based on their cultural or ethnic background, although differences did exist in the past. The need to differentiate between a given environmental impact and the decision-making process behind it was also evident. In North-west Ecuador, markets, factors of production, and access to and control of resources, are key for understanding the environmental impact of local communities. Low-impact resource-uses often result from low-return productive activities in forest environments with low labour opportunity costs, high discount rates for income generated through activities compromising food security, and from uncertainty about future conditions. Environmental policy-making and programme design need to recognize this relationship. Conservation will be possible only if the perceived benefit to local users is greater than that of resource transformation, both of which respond to the dominant environmental, economic and social conditions at a given time and place. Creating or fostering the appropriate conditions should be a key objective of both.