Interactions between two introduced species: Zostera japonica (dwarf eelgrass) facilitates itself and reduces condition of Ruditapes philippinarum (Manila clam) on intertidal flats

Dwarf eelgrass (duckgrass; Zostera japonica) and Manila clams (Ruditapes philippinarum) are two introduced species that co-occur on intertidal flats of the northeast Pacific. Through factorial manipulation of clam (0, 62.5, 125 clams m⁻²) and eelgrass density (present, removed by hand, harrowed), we examined intra- and interspecific effects on performance, as well as modification of the physical environment. The presence of eelgrass reduced water flow by up to 40% and was also observed to retain water at low tide, which may ameliorate desiccation and explain why eelgrass grew faster in the presence of conspecifics (positive feedback). Although shell growth of small (20–50 mm) clams was not consistently affected by either treatment in this 2-month experiment, clam condition improved when eelgrass was removed. Reciprocally, clams at aquaculture densities had no effect on eelgrass growth, clam growth and condition, or porewater nutrients. Overall, only Z. japonica demonstrated strong population-level interactions. Interspecific results support an emerging paradigm that invasive marine ecosystem engineers often negatively affect infauna. Positive feedbacks for Z. japonica may characterize its intraspecific effects particularly at the stressful intertidal elevation of this study (+1 m above mean lower low water).     

How Stable are Public Responses to Changing Local Environments? A 'Before' and 'After' Case Study of River Restoration

This paper considers the stability of public responses to an urban river restoration scheme on the River Skerne, Darlington, UK, by comparing the results from surveys of local residents carried out before and after scheme implementation. This case study provides evidence of strong and generally consistent positive responses to the proposals and implemented scheme to return the straightened and channelized river to a more natural condition although support was more qualified after than before implementation. Although the scheme design and construction costs were high, nearly two-thirds regarded the scheme as value for money. Exploratory contingent valuation results on whether or not local residents were prepared to pay for the scheme were broadly stable over the two surveys.     

Contrasting the core beliefs regarding the effective implementation of wind power. An international study of stakeholder perspectives

This paper analyses patterns in beliefs about the implementation of wind power as part of a geographical comparison of onshore wind power developments in the Netherlands, North-Rhine Westphalia and England. Q methodology is applied, in order to systematically compare the patterns in stakeholder views on the institutional conditions and changes in the domains of energy policy, spatial planning and environmental policy. Three factors represent support for wind power implementation from fundamentally different perspectives. The fourth perspective is critical opposed to wind power developments as well as critical to the manner in which wind projects are proposed, planned and implemented. These four perspectives exist across the geographical cases; however, some perspectives are prominent in one case and marginal in another. This relates to different legacies and varying implementation achievements in the three cases. The analysis shows that an approach that focuses on implementing as much wind power as possible, relying on technocratic reasoning and hierarchical policies is in practice the least successful, whereas collaborative perspectives with more emphasis on local issues and less on the interests of the conventional energy sector were particularly dominant in the most successful case, North-Rhine Westphalia.     

Evolutionary social and biogeophysical changes in the Amazon,Ganges–Brahmaputra–Meghna and Mekong deltas

Policy-making in social-ecological systems increasingly looks to iterative, evolutionary approaches that can address the inherent complexity of interactions between human wellbeing, provision of goods, and the maintenance of ecosystem services. Here, we show how the analysis of available time-series in tropical delta regions over past decades can provide important insight into the social-ecological system dynamics in deltaic regions. The paper provides an exploratory analysis of the recent changes that have occurred in the major elements of three tropical deltaic social-ecological systems, such as demography, economy, health, climate, food, and water. Time-series data from official statistics, monitoring programmes, and Earth observation data are analysed to explore possible trends, slow and fast variables, and observed drivers of change in the Amazon, Ganges–Brahmaputra–Meghna and Mekong deltas. In the Ganges–Brahmaputra–Meghna delta zone, increasing gross domestic product and per capita income levels since the 1980s mirror rising levels of food and inland fish production. In contrast, non-food ecosystem services, such as water availability, water quality, and land stability appear to be deteriorating. In the Amazon delta, natural and anthropogenic perturbations are continuously degrading key ecosystem services, such as carbon storage in biomass and soils, the regulation of water balance, and the modulation of regional climate patterns. In the Mekong delta, rapid economic development, changing land-use practices, and salinity intrusion are progressively putting more pressure on the delivery of important provisioning services, such as rice and inland aquaculture production, which are key sources of staple food, farm incomes, and export revenue. Observed changes in many key indicators of ecosystem services point to a changing dynamic state and increased probability of systemic threshold transformations in the near future.     

A Special Issue from the NARSTO Symposium on Tropospheric Aerosols

This dedicated issue of the Journal of the Air & Waste Management Association contains nine peer-reviewed scientific papers that were presented at the NARSTO Symposium on Tropospheric Aerosols: Science and Decisions in an International Community, held October 24-26, 2000, in Querétaro, Mexico.¹ Other peer-reviewed papers^2-9 appear in a companion issue of Science of the Total Environment to be published in February 2002. More than 130 papers were presented in platform and poster sessions at the meeting. Approximately 28% of the technical presentations dealt with topics from Mexico, and 15% related to Canada, with the remainder discussing U.S. and global topics.     

Organic compounds in the flue gas from a power station with circulating fluid bed combustion of coal

Numerous organic compounds have been analyzed by coupled gas chromatography-mass spectroscopy (GC-MS) in flue gas after fluid bed combustion of four coal species from South Africa, Poland, Spitsbergen and Ruhr area (Germany). Polynuclear aromatic hydrocarbons, aliphatic hydrocarbons, chlorinated, heterocyclic and nitro compounds as well as phthalate esters are detected.     

Validity and uncertainty in the calculation of an emission inventory for ammonia arising from agriculture in Great Britain

Emissions of ammonia have received increasing attention recently, following concern about the environmental consequences, especially in The Netherlands where levels are high due to intensive livestock farming. Direct local effects and more widespread consequences for a range of ecosystems have been attributed to ammonia emissions. As the most prevalent alkaline gas in the atmosphere, ammonia interacts with acidic species, changing their characteristics, chemical and physical behaviour, and enhancing their potential for acidification of soils. Ammonia also forms an important component of the nitrogen cycle and of nitrogen deposition. In the UK, as in many other European countries, there has been a considerable increase in the emission of ammonia within the last 30 years, estimated at about 50%. This results mainly from increases in agricultural production based on the steadily rising number of livestock and increasing fertilizer consumption. This paper discusses the various sources to emissions of ammonia from agricultural sources in the United Kingdom, and some of the uncertainties involved in constructing a national emissions inventory.