Modification of the simple mass balance equation for calculation of critical loads of acidity.

Over the last few years, the simple mass balance equation for the calculation of critical loads of acidity has been gradually modified as the underlying critical load concepts have developed and as problems with particular forms of the equation have been identified, through application in particular countries. The first major update of the equation took place following a workshop held in Vienna, Austria (Hojesky et al. 1993). The workshop was held to discuss problems which had been identified when the then current form of the equation was applied in countries with high rainfall. The problems had largely arisen because of simplifications and assumptions incorporated into the early formulation of the equation. The equation was reformulated to overcome the problems identified at the workshop. However, further problems were identified when the reformulated equation was applied in the UK in situations with a combination of high rainfall, large marine inputs and widespread occurrence of organic soils. A small workshop was, therefore held in Grange-over-Sands, UK in late 1993 to dicuss the problems and to further re-evaluate the equation. The problems had arisen in the UK because of simplifications and assumptions made in the formulation concerning, in particular, cation leaching and uptake. As a result, a more rigorous treatment of these variables was incorporated into the equation. The reformulation of the equation, as derived at the September 1993 workshop is described below

Reporting of MMR evidence in professional publications: 1988–2007

OBJECTIVE: To examine how journals and magazines disseminate research evidence and guidance on best practice to health professionals by aligning commentaries on measles, mumps, and rubella vaccine (MMR) evidence in journals with key events in the MMR controversy. DESIGN: Content analysis. DATA SOURCES: Comment articles in six commonly read UK publications. MAIN OUTCOME MEASURES: Number of comment pieces by publication, year and article type; trends in the focus, tone and inclusion of recommendations on MMR. RESULTS: 860 articles met the inclusion criteria (BMJ n = 104, Community Practitioner n = 45, Health Visitor n = 24, Practice Nurse n = 61, Nursing Standard n = 61 and Pulse n = 565). Of these 860 comment pieces, 264 made some reference to evidence endorsing the safety of MMR. Around one in 10 were rated as negative (10.9%, n = 29) or neutral (11.3%, n = 30) in relation to MMR safety, and nearly a quarter (22.7%, n = 60) were rated as mixed. Following the publication of Wakefield et al's 1998 paper there was a period of neutrality. In 2000, despite growing public concerns and widespread media coverage, fewer than 20 comment pieces were published. Less than a quarter of comment pieces (n = 196, 22.7%) included recommendations. CONCLUSION: While a period of neutrality may reflect a professional response to uncertainty by holding back until consensus emerges, it may also represent a missed opportunity to promote evidence-based practice

The development of an approach to assess critical loads of acidity for woodland habitats in Great Britain

International audienceAlongside other countries that are signatories to the UNECE Convention Long Range Transboundary on Air Pollution, the UK is committed to reducing the impact of air pollution on the environment. To advise and guide this policy in relation to atmospheric emissions of sulphur and nitrogen, a critical load approach has been developed. To assess the potential impact of these pollutants on woodland habitats a steady state, simple mass balance model has been parameterised. For mineral soils, a Ca:Al ratio in soil solution has been used as the critical load indicator for potential damage. For peat and organic soils critical loads have been set according to a pH criterion. Together these approaches have been used with national datasets to examine the potential scale of acidification in woodland habitats across the UK. The results can be mapped to show the spatial variability in critical loads of the three principal woodland habitat types (managed coniferous, managed broadleaved/ mixed woodland and unmanaged woodland). The results suggest that there is a wide range of critical loads. The most sensitive (lowest) critical loads are associated with managed coniferous followed by unmanaged woodland on peat soils. Calculations indicate that at steady state, acid deposition inputs reported for 1995?1997 result in a large proportion of all the woodland habitats identified receiving deposition loads in excess of their critical load; i.e. critical loads are exceeded. These are discussed in relation to future modelled depositions for 2010. Whilst significant widespread negative impacts of such deposition on UK woodland habitats have not been reported, the work serves to illustrate that if acid deposition inputs were maintained and projected emissions reductions not achieved, the long-term sustainability of large areas of woodland in the UK could be compromised. Keywords: critical loads, acid deposition, acidification, woodland, simple mass balance model, sustainabilit

West Africa's Cocoa Sector and Development within Africa-EU Relations: Engaging Business Perspectives

The EU is vigorously pursuing Economic Partnership Agreements (EPAs) in its trade and aid relations with African, Caribbean and Pacific (ACP) countries. Justifying the EPAs as being ‘development friendly’, EU officials promise that aid support to private sector development (PSD) in ACP countries will make free trade systems ‘win–win’. This article, based on the authors’ semi-structured interviews conducted in Ghana and Nigeria, examines the perspectives of cocoa stakeholders vis-à-vis EPAs and PSD. Applying critical discourse analysis to interview transcripts, it underscores areas of overlap and, crucially, divergence among cocoa stakeholders’ own narratives on PSD support in the context of EPAs and the official legitimating discourse of EU institutions. In the process, the article draws critical attention to cocoa business interviewees’ concerns regarding the impact of premature trade liberalisation. It also underscores cocoa stakeholders’ concerns that EU PSD promises are not being fulfilled in terms of actual tangible benefits for business people in this vital ACP export sector. Accordingly, the article contributes to, and corroborates, an existing critical scholarly literature which problematises the strategic functions of donor PSD discourse in presenting free trade reforms as being ‘pro-poor’ in the post-Washington Consensus

The effects of H2SO4 and (NH4)2SO4 treatments on the chemistry of soil drainage water and pine seedlings in forest soil microcosms

International audienceAn experiment comparing effects of sulphuric acid and reduced N deposition on soil water quality and on chemical and physical growth indicators for forest ecosystems is described. Six H2SO4 and (NH4)2SO4 treatment loads, from 0 ? 44 and 0 ? 25 kmolc ha-1 yr-1, respectively, were applied to outdoor microcosms of Pinus sylvestris seedlings in 3 acid to intermediate upland soils (calc-silicate, quartzite and granite) for 2 years. Different soil types responded similarly to H2SO4 loads, resulting in decreased leachate pH, but differently to reduced N inputs. In microcosms of calc-silicate soil, nitrification of NH4 resulted in lower pH and higher cation leaching than in acid treatments. By contrast, in quartzite and granite soils, (NH4)2SO4 promoted direct cation leaching, although leachate pH increased. The results highlighted the importance of soil composition on the nature of the cations leached, the SO4 adsorption capacities and microbial N transformations. Greater seedling growth on calc-silicate soils under both treatment types was related to sustained nutrient availability. Reductions in foliar P and Mg with higher N treatments were observed for seedlings in the calc-silicate soil. There were few treatment effects on quartzite and granite microcosm tree seedlings since P limitation precluded seedling growth responses to treatments. Hence, any benefits of N deposition to seedlings on quartzite and granite soils appeared limited by availability of co-nutrients, exacerbated by rapid depletion of soil exchangeable base cations. Keywords: acidification, manipulation, nitrogen, ammonium, deposition, soil, drainage, pine, microcosms, fores

Viewpoint – Pouring money down the drain: Can we break the habit by reconceiving wastes as resources?

As water-sector professionals re-discover the value in the 'waste' conveyed in 'waste'water, this Viewpoint argues that the theory of plural rationality (also known as Cultural Theory) may accelerate the switch from waste management to resource recovery. Accordingly, it extends the framing of plural rationality, from its traditional applications in matters of governance and social and economic analysis, to the beginnings of a set of plural schools of engineering thought. This sounds controversial. Indeed, we hope it is. For all too often ways to resolve water issues end up in the impasse of two deeply entrenched positions: the 'technocratic reductionism' of the 'quick engineering fix' to problem solving; and the 'participatory holism' of the 'local, socially sensitive, integrationist' approach. Plural rationality sees this is an impoverished duopoly. Our very strong preference is to find ways of promoting the creative interplay among plural (more than two), mutually opposed, contending ways of framing a problem and resolving it. This, we argue, should not only expand the portfolio of possible alternatives for technology-policy interventions, but also lead to the chosen alternative being preferable — in social, economic, and environmental terms — to what might otherwise have happened. Such solutions are called 'clumsy' in plural rationality theory. We use a synopsis of a case history of restoring water quality in the River Rhine in Europe, within a wider account of the sweep of resource recovery spanning two centuries (late 18th Century through early 21st Century), to illustrate how clumsiness works. This, however, does not extend to our elaborating our proposed set of plural schools of engineering thought beyond just its very beginnings. Our Viewpoint allows us merely to start framing the challenge of developing, and eventually applying, such a notion

Practice and perspectives in the validation of resource management models

Quantitative modelling is commonly used to assist the policy dimension of sustainability problems. Validation is an important step to make models credible and useful. To investigate existing validation viewpoints and approaches, we analyse a broad academic literature and conduct a survey among practitioners. We find that empirical data plays an important role in the validation practice in all main areas of sustainability science. Qualitative and participatory approaches that can enhance usefulness and public reliability are much less visible. Data-oriented validation is prevalent even when models are used for scenario exploration. Usefulness regarding a given task is more important for model developers than for users. As the experience of modellers and users increases, they tend to better acknowledge the decision makers’ demand for clear communication of assumptions and uncertainties. These findings provide a reflection on current validation practices and are expected to facilitate communication at the modelling and decision-making interface

Validation of uncertainty-oriented environmental models: A review of the existing approaches

Environmental modelling is a commonly used tool to assist the policy dimension of sustainability problems. Model evaluation is an important process in such decision-making contexts to ensure credibility, and it is often considered a purpose-dependent activity. Models are increasingly used for the purpose of scenario generation to deal with non-probabilistic uncertainties. This change in the model purpose implies a change in the evaluation process, and may require different validation techniques. In this paper, we investigate the existing validation viewpoints and approaches, and compare the general modeling context to the scenario generation purpose in particular. We employ three methods for this investigation: (i) A literature review about validation in environmental modeling, (ii) a text-mining analysis on a large dataset of validation-related publications, and (iii) an online survey conducted among model developers and users in academia, governmental and non-governmental policy organizations, and industry. The results indicate a data-orientation for systematic validation, and that conventional validation approaches are adopted even for models used for the purpose of scenario exploration. Future studies can develop a validation framework for models used specifically for generating scenarios and decision-making under non-probabilistic uncertainty

Model validation: A bibliometric analysis of the literature

Validation is a crucial step in environmental and economic modeling that establishes the reliability of models to be used in decision-making contexts. It is often said that validation approaches proposed in the literature are not widely adopted, and different modeling fields do not benefit from each other. This study analyses a broad academic literature on model validation, mainly in environmental and decision sciences, by using an innovative combination of bibliometric and text-mining tools. The results show that a data-driven validation practice is prevalent. Although most publications in the studied dataset resemble each other, the most-cited ones tend to be different from the rest in terms of their abstracts’ content. Furthermore, the validation practices in different modeling areas are distinct, and do not extensively cite each other. In future, validation approaches can extend beyond data-oriented reliability for a wider acceptance of modeling in decision-making, and can synthesize the methods and views from various fields