Ambient site, home outdoor and home indoor particulate concentrations as proxies of personal exposures

Despite strong longitudinal associations between particle personal exposures and ambient concentrations, previous studies have found considerable inter-personal variability in these associations. Factors contributing to this inter-personal variability are important to identify in order to improve our ability to assess particulate exposures for individuals. This paper examines whether ambient, home outdoor and home indoor particle concentrations can be used as proxies of corresponding personal exposures. We explore the strength of the associations between personal, home indoor, home outdoor and central outdoor monitoring site ("ambient site") concentrations of sulfate, fine particle mass (PM(2.5)) and elemental carbon (EC) by season and subject for 25 individuals living in the Boston, MA, USA area. Ambient sulfate concentrations accounted for approximately 70 to 80% of the variability in personal and indoor sulfate levels. Correlations between ambient and personal sulfate, however, varied by subject (0.1-1.0), with associations between personal and outdoor sulfate concentrations generally mirroring personal-ambient associations (median subject-specific correlations of 0.8 to 0.9). Ambient sulfate concentrations are good indicators of personal exposures for individuals living in the Boston area, even though their levels may differ from actual personal exposures. The strong associations for sulfate indicate that ambient concentrations and housing characteristics are the driving factors determining personal sulfate exposures. Ambient PM(2.5) and EC concentrations were more weakly associated with corresponding personal and indoor levels, as compared to sulfate. For EC and PM(2.5), local traffic, indoor sources and/or personal activities can significantly weaken associations with ambient concentrations. Infiltration was shown to impact the ability of ambient concentrations to reflect exposures with higher exposures to particles from ambient sources during summer. In contrast in the winter, lower infiltration can result in a greater contribution of indoor sources to PM(2.5) and EC exposures. Placing EC monitors closer to participants' homes may reduce exposure error in epidemiological studies of traffic-related particles, but this reduction in exposure error may be greater in winter than summer. It should be noted that approximately 20% of the EC data were below the field limit of detection, making it difficult to determine if the weaker associations with the central site for EC were merely a result of methodological limitations.     

Discriminant analysis for the prediction of sand mass distribution in an urban stormwater holding pond using simulated depth average flow velocity data

The approach of this paper is to predict the sand mass distribution in an urban stormwater holding pond at the Stormwater Management And Road Tunnel (SMART) Control Centre, Malaysia, using simulated depth average floodwater velocity diverted into the holding during storm events. Discriminant analysis (DA) was applied to derive the classification function to spatially distinguish areas of relatively high and low sand mass compositions based on the simulated water velocity variations at corresponding locations of gravimetrically measured sand mass composition of surface sediment samples. Three inflow parameter values, 16, 40 and 80 m³ s^?1, representing diverted floodwater discharge for three storm event conditions were fixed as input parameters of the hydrodynamic model. The sand (grain size?>?0.063 mm) mass composition of the surface sediment measured at 29 sampling locations ranges from 3.7 to 45.5 %. The sampling locations of the surface sediment were spatially clustered into two groups based on the sand mass composition. The sand mass composition of group 1 is relatively lower (3.69 to 12.20 %) compared to group 2 (16.90 to 45.55 %). Two Fisher’s linear discriminant functions, F ₁ and F ₂, were generated to predict areas; both consist of relatively higher and lower sand mass compositions based on the relationship between the simulated flow velocity and the measured surface sand composition at corresponding sampling locations. F ₁?=??9.405?+?4232.119?×?A???1795.805?×?B?+?281.224?×?C, and F ₂?=??2.842?+?2725.137?×?A???1307.688?×?B?+?231.353?×?C. A, B and C represent the simulated flow velocity generated by inflow parameter values of 16, 40 and 80 m³ s^?1, respectively. The model correctly predicts 88.9 and 100.0 % of sampling locations consisting of relatively high and low sand mass percentages, respectively, with the cross-validated classification showing that, overall, 82.8 % are correctly classified. The model predicts that 31.4 % of the model domain areas consist of high-sand mass composition areas and the remaining 68.6 % comprise low-sand mass composition areas.     

How interdisciplinary is sustainability research? Analyzing the structure of an emerging scientific field

Sustainability research is expected to incorporate concepts, methods, and data from a diverse array of academic disciplines. We investigate the extent to which sustainability research lives up to this ideal of an interdisciplinary field. Using bibliometric data, we orient our study around the “tripartite model” of sustainability, which suggests that sustainability research should draw from the three “pillars” of the environmental, economic, and social sciences. We ask three questions: (i) is sustainability research truly more interdisciplinary than research generally, (ii) to what extent does research grounded in one pillar draw on research from the other two, and (iii) if certain disciplines or pillars are more interdisciplinary than others, then what explains this variation? Our results indicate that sustainability science, while more interdisciplinary than other scientific fields, falls short of the expectations inherent in the tripartite model. The pillar with the fewest articles published on sustainability—economics—is also the most integrative, while the pillar with the most articles—environmental sciences—draws the least from outside disciplines. But interdisciplinarity comes at a cost: sustainability research in economics and the social sciences is centered around a relatively small number of interdisciplinary journals, which may be becoming less valued over time. These findings suggest that, if sustainability research is to live up to its interdisciplinary ideals, researchers must be provided with greater incentives to draw from fields other than their own.     

Dose transfer of Bacillus thuringiensis from cabbage to the diamondback moth: A graphical simulator

Abstract

The application of agrichemicals is a highly inefficient process and one of the main causes of the environmental and health risks currently associated with pesticide usage. Efforts to mitigate this inefficiency have largely been unsuccessful, due principally to the poor understanding of the processes involved in the spray application of pesticides, from atomization to biological effect. A generalized model of the application system for pesticides from atomization to biological result is described in this overview. The model allows the investigation of the biological consequences of altering the application parameters for the bacterial insecticide Bacillus thuringiensis when used against the diamondback moth (Plutella xylostella L.) with cabbage as the substrate. Parameters input into the model include the in‐flight droplet size frequency distribution of the spray cloud, spatial distribution of the deposit, spread and subsequent environmental degradation of the deposit, and behavioral and toxicological effects.

It is hoped that such a modelling approach can afford insights into the application process, and, through a better understanding of the inefficient but still highly effective hydraulic application systems used worldwide, reduce that inefficiency to tolerable levels.     

Design and Application of High Voltage Power Supplies in Electrostatic Precipitation

Proper electrical energization methods and equipment are the keys to successful electrostatic precipitation. The design, operation, and application of conventional high voltage power supplies in this process are reviewed. Emphasis is on requirements and methods of achieving the high performance and reliability necessary in modern air pollution control systems. Typical field data on operations and effects in various precipitator applications, including high resistivity ash, high temperature, and/or high pressure gas treatment, are discussed.     

Solving Problems in the Electrical Energization of Electrostatic Precipitators

Achieving and maintaining continuous, reliable performance in electrostatic precipitators depends critically upon the proper design, application, operation, and maintenance of the high voltage electrical energization system. Common problems among these factors are discussed, and effects on performance are illustrated from field experience. Practical recommendations for solving problems and for preventing their occurrence in the electrical aspects of precipitation are presented for effective use by designers, operators, and maintenance personnel.     

Integrating Remote Sensing and Local Vegetation Information for a High-Resolution Biogenic Emissions Inventory— Application to an Urbanized,Semiarid Region

ABSTRACT

This paper presents a methodology for the development of a high-resolution (30-m), standardized biogenic volatile organic compound (BVOC) emissions inventory and a subsequent application of the methodology to Tucson, AZ. The region's heterogeneous vegetation cover cannot be modeled accurately with low-resolution (e.g., 1-km) land cover and vegetation information. Instead, local vegetation data are used in conjunction with multispectral satellite data to generate a detailed vegetation-based land-cover database of the region. A high-resolution emissions inventory is assembled by associating the vegetation data with appropriate emissions factors. The inventory reveals a substantial variation in BVOC emissions across the region, resulting from the region's diversity of both native and exotic vegetation.

The importance of BVOC emissions from forest lands, desert lands, and the urban forest changes according to regional, metropolitan, and urban scales. Within the entire Tucson region, the average isoprene, monoterpene, and     

Nitrogen Oxides Emission Control Options for Coal-Fired Electric Utility Boilers

Abstract

Recent regulations have required reductions in emissions of nitrogen oxides (NO_x) from electric utility boilers. To comply with these regulatory requirements, it is increasingly important to implement state-of-the-art NO_x control technologies on coal-fired utility boilers. This paper reviews NO_x control options for these boilers. It discusses the established commercial primary and secondary control technologies and examines what is being done to use them more effectively. Furthermore, the paper discusses recent developments in NO_x controls. The popular primary control technologies in use in the United States are low-NO_x burners and overfire air. Data reflect that average NO_x reductions for specific primary controls have ranged from 35% to 63% from 1995 emissions levels. The secondary NO_x control technologies applied on U.S. coal-fired utility boilers include reburning, selective noncatalytic reduction (SNCR), and selective catalytic reduction (SCR). Thirty-six U.S. coal-fired utility boilers have installed SNCR, and reported NO_x reductions achieved at these applications ranged from 15% to 66%. Recently, SCR has been installed at >150 U.S. coal-fired utility boilers. Data on the performance of 20 SCR systems operating in the United States with low-NO_x emissions reflect that in 2003, these units achieved NO_x emission rates between 0.04 and 0.07 lb/10⁶ Btu.