Description and evaluation of a model of deposition velocities for routine estimates of air pollutant dry deposition over North America.: Part I: model development

This paper describes the development of a detailed dry deposition model for routine computation of dry deposition velocities of SO₂, O₃, HNO₃ and fine particle SO₄²⁻ across much of North America. Four different dry deposition/surface exchange sub-models have been combined with the current Canadian weather forecast model (Global Environmental Multiscale model) with a 3 h time resolution and a horizontal spatial resolution of 35 km. The present model uses the US Geological Survey North American Land Cover Characteristics data to obtain fourteen different land use and five seasonal categories. The four sub-models used are a multi-layer model for gaseous species over taller canopy land-use types, a big-leaf model for gaseous species over lower canopies (including bare soil and water) and for HNO₃ under all surface types and, two different models for SO₄²⁻, one for tall canopies and the other for short canopies. All necessary parameters for each sub-model, chemical species, land-use and seasonal categories have been selected from available data libraries or from the values reported in the literature. The purpose for developing this model (referred to as the Routine Deposition Model (RDM)), when coupled with air concentration data, is to provide estimates of seasonal dry deposition, which can be combined with wet deposition to produce total deposition estimates. Model theory is discussed in this paper and model sensitivity tests and results will be presented in a companion paper.     

Exposure to Fine Particle Acidity and Sulfate in 24 North American Communities: The Relationship Between Single Year Observations and Long-Term Exposures

Abstract

Twenty-four communities in North America were monitored over one year for a variety of air pollutants as part of a crosssectional epidemiological study on the respiratory health effects of exposure to fine particle acidity. The relationships between these single-year observations and the long-term community levels of ambient sulfate and acidity were examined. In the health study it was assumed that the singleyear measurements were indicative of the lifetime or long-term exposures of the participants (eight?, nine?, and ten-year-olds). Therefore, a strong relationship between the long-term and single-year (24-community) particle acidity and sulfate concentrations was important.

Ambient sulfate data from a variety of alternate sources were obtained from monitoring sites close to 20 of the 24 communities. Long-term averages, which were determined for the warm season (May to September), were derived from a minimum of four complete years of monitoring data at each site. Long-term acidity concentrations were derived from these sulfate data because multi-year measurements of acidity were not available. These concentrations were calculated by multiplying the sulfate concentrations by the mean warm season acid-to-sulfate ratios observed during the 24-community study. For each community, 25 random estimates (determined by allowing the observed mean ratio to vary randomly by ±0.2) of the mean warm season acidity were used to determine the community-to-community differences in the long-term acid concentrations.

Overall, the long-term and 24-community warm season sulfate concentrations were correlated with an R2, determined from linear regression, of 0.92 (slope = 0.90±0.13). With only two exceptions, regardless of which of these exposure estimates were used, the communities that were determined to experience high (>8 μg m^?3), moderate (4-8 μg m^?3) and low (<4 μg m^?3) sulfate exposures did not change. Similarly, few communities crossed exposure classes when the long-term and short-term acid concentrations were compared. However, due to the increased uncertainty arising from the lack of information on the long-term acid-to-sulfate ratio, the average correlation (R²) between the long-term and 24-community exposure estimates (the mean of the 25 separate random estimates for each community) was 0.85 (slope = 0.94).     

Social dimensions of mining: Research,policy and practice challenges for the minerals industry in Australia

The social dimensions of the mining industry are increasingly acknowledged as critical to business success, yet remain the least understood aspect of the business concept of sustainable development—the ‘triple bottom line’ of economy, environment and society.     

Book reviews

Sustainable Industrialisation. David Wallace, 1996, London, Royal Institute of International Affairs, (Earthscan), 120 pp. ISBN 1 85383 352 5, £11.95 (pbk)

Managing Green Technologies for Global Competitiveness. Christian Ndubisi Madu, 1996, London, Quorum Books, distributed by Eurospan, ISBN 0 89930 827 9, £47.95 (hbk)

Greening People, Human Resources and Environmental Management. Walter Wehrmeyer (Ed.) 1996, Sheffield, Greenleaf Publishing, 416 pp. ISBN 1 874719 15 2, £29.50 (hbk)

The Environment for Children: understanding and acting on the environmental hazards that threaten children and their parents. David Satterthwaite, Roger Hart, Caren Levy, Diana Mitlin, David Ross, Jac Smit & Carolyn Stephens, 1996, London, Earthscan Publications, 284 pp. ISBN 1 85383 326 6, £13.95

Local Sustainability: managing and planning ecologically sound places. Paul Selman, 1996, London, Paul Chapman, x + 175pp, index. ISBN 1 85396 300 3, £14.95     

Polybrominated diphenyl ethers (PBDEs) in human milk from Australia

Polybrominated diphenyl ethers (PBDEs) are flame retardants added to a multitude of products to reduce flammability. PBDEs have been widely detected and quantified in biota and humans in many industrialised countries from the Northern Hemisphere. However data concerning the levels of these compounds in the Australian population and environment remain limited. The objectives of this study were to determine PBDE concentrations and congener profiles in Australian human milk and compare this to concentrations found in other countries. Pooled human milk samples obtained from mothers residing in 12 regions of Australia were analysed by HRGC/HRMS for 18 PBDE congeners. In total, 157 human milk samples collected in 2002 and 2003 were divided into 17 regional pools. PBDEs were detected in all pools of human milk from Australia. The mean+/-standard deviation and median summation operatorPBDE concentrations were 11.1+/-3.2 and 11.0 ng g(-1) lipid, respectively with a range of 6.1-18.7 ng g(-1) lipid. The congener profile was dominated by BDE-47 followed by BDE-99, -100, -153, -154 and -183. Regional differences were evaluated, but no trends were observed. The data suggest regional differences are likely to be small if they exist at all. The concentrations of PBDEs found in Australian human milk were lower than those reported from North America but higher than those reported from Europe and Asia. Our results suggest that the exposure pathways which contribute to the PBDE body burden in the Australian population require a better understanding in order to determine future policy regarding their use and disposal.