Arthur M. Winer

BIOFILTRATION: AN INNOVATIVE AIR POLLUTION CONTROL TECHNOLOGY FOR VOC EMISSIONS

Biofiltration is a relatively recent air pollution control (APC) technology in which off-gases containing biodegradable volatile organic compounds (VOC) or inorganic air toxics are vented through a biologically active material. This technology has been successfully applied in Germany and The Netherlands in many full-scale applications to control odors, VOC and air toxic emissions from a wide range of industrial and public sector sources. Control efficiencies of more than 90 percent have been achieved for many common air pollutants. Due to lower operating costs, biofiltration can provide significant economic advantages over other APC technologies if applied to off-gases that contain readily biodegradable pollutants in low concentrations. Environmental benefits include low energy requirements and the avoidance of cross media transfer of pollutants. This paper reviews the history and current status of biofiltration, outlines its underlying scientific and engineering principles, and discusses the applicability of biofilters for a wide range of specific emission sources.

A Critical Assessment of Chromium in the Environment

This article reviews the emissions, environmental fate and transport, analytical chemistry, uptake and metabolism, toxicology, and human epidemiology of chromium. Chromium is unique among regulated toxic elements in the environment in that different species of chromium, specifically chromium (III) and chromium (VI), are regulated in different ways, in contrast to other toxic elements where the oxidation state is not distinguished. In both industrial and environmental situations chromium (III) and chromium (VI) can inter-convert, with reduction of chromium (VI) to chromium (III) generally being favored in most environmental situations. Chromium released into the air, water, and soil can be transported among the various environmental media through various intermedia transport processes. Once in the environment, chromium can be taken up by human and other ecological receptors. Chromium (III) is generally absorbed through cell membranes albeit to a significantly lesser degree than chromium (VI). Because most ...

Environmental distribution and transformation of mercury compounds

Abstract Health risk assessments for mercury are subject to uncertainties associated with the prediction of exposure from multiple pathways (air, water, and food). In order to accurately predict multipathway exposure, an understanding of the transport and transformation processes that govern mercurys multimedia distribution is required. Modeling and analysis of multimedia exposure requires knowledge of the physicochemical properties, partition coefficients, and intermedia transport properties of a compound. Although a number of reviews of the behavior of mercury in the environment have been published over the last decade, little attention has been given to the environmental multimedia distribution of mercury and the governing intermedia transfer factors. This review provides a comprehensive evaluation of the chemical and physical processes that govern mercury distribution among the major environmental media. Physicochemical properties, partition coefficients, and intermedia transport parameters that can ...

Measurement of nitrate radical concentrations in continental air

Nighttime profiles of the atmospheric concentrations of the nitrate radical (NO/sub 3/), NO/sub 2/, and O/sub 3/ have been obtained by using a mobile differential ultraviolet/visible absorption spectrometer over path lengths from 3 to 17 km. Measurements were carried out at four semiarid/desert sites in the southern California desert (Death Valley, Edwards Air Force Base, Phelan, and Whitewater), and nitrate radicals were observed at all four locations at typical concentrations of approx. 10-100 parts per trillion. A decrease in the calculated NO/sub 3/ lifetime with increasing relative humidity (RH) was observed with lifetimes up to approx. 60 min for less than or equal to50% RH, but less than or equal to10 min for greater than or equal to50% RH. This suggests the involvement of water in the loss process for NO/sub 3/, either in the gas phase or in the aqueous state at the ground or on aerosol surfaces. These experimental field data support our earlier hypothesis that this loss process of NO/sub 3/ may constitute both a major sink for atmospheric NO/sub x/ and a significant formation route for nitric acid, a key component of acid rain and fog.

Observations of nitrous acid in the Los Angeles atmosphere and implications for predictions of ozone-precursor relationships.

Direct measurements of nitrous acid (HONO) were made in downtown Los Angeles and Riverside, CA, during night and early morning hours of July/August 1980 using a long-path differential optical absorption spectrometer. Up to 8 ppb of HONO were observed in Los Angeles, approximately twice the maximum levels previously measured in Riverside during the summer of 1979. Possible sources of the observed HONO are discussed. If the observed HONO levels are included in initial NO, concentration, EKMA isopleth calculations predict that more rigorous control of NO, emissions (especially a t low HC/NO, levels) or of hydrocarbons emissions is necessary to reduce ozone maxima by a given amount compared with predictions based on calculations neglecting initial HONO. Moreover, including HONO in the starting NO, leads to predictions of accelerated rates of oxidant production which results in much larger predicted O3 doses at elevated O3 levels. For example, the predicted O3 dosage at levels above 0.3 ppm ozone in the case of NMHC = 1 ppm and [NO,], = 0.12 ppm is increased by over 250% when 10 ppb of HONO is taken to be initially present.

Influence of ambient (outdoor) sources on residential indoor and personal PM2.5 concentrations: Analyses of RIOPA data

The Relationship of Indoor, Outdoor and Personal Air (RIOPA) study was designed to investigate residential indoor, outdoor and personal exposures to several classes of air pollutants, including volatile organic compounds, carbonyls and fine particles (PM2.5). Samples were collected from summer, 1999 to spring, 2001 in Houston (TX), Los Angeles (CA) and Elizabeth (NJ). Indoor, outdoor and personal PM2.5 samples were collected at 212 nonsmoking residences, 162 of which were sampled twice. Some homes were chosen due to close proximity to ambient sources of one or more target analytes, while others were farther from sources. Median indoor, outdoor and personal PM2.5 mass concentrations for these three sites were 14.4, 15.5 and 31.4 μg/m3, respectively. The contributions of ambient (outdoor) and nonambient sources to indoor and personal concentrations were quantified using a single compartment box model with measured air exchange rate and a random component superposition (RCS) statistical model. The median contribution of ambient sources to indoor PM2.5 concentrations using the mass balance approach was estimated to be 56% for all study homes (63%, 52% and 33% for California, New Jersey and Texas study homes, respectively). Reasonable variations in model assumptions alter median ambient contributions by less than 20%. The mean of the distribution of ambient contributions across study homes agreed well for the mass balance and RCS models, but the distribution was somewhat broader when calculated using the mass balance model with measured air exchange rates.

Low-emitting urban forests: A taxonomic methodology for assigning isoprene and monoterpene emission rates

Large-scale tree planting programs have been proposed, and are being implemented, as a means of reducing energy demand, mitigating urban heat islands, and improving air quality. However, many species of trees emit highly photochemically reactive hydrocarbons and the rates of such emissions can vary by four orders of magnitude, depending upon the tree species. Thus, planting of high-emitting trees species on a massive scale has the potential to adversely affect air quality rather than leading to improvement. However, the selection of low-emitting trees is difficult because emission rates have been experimentally determined for only a limited number of species. The present study describes a methodology for assigning biogenic emission rates based on taxonomic relationships. Using this methodology, direct emission measurements from 124 tree and shrub species found in the California South Coast Air Basin (SoCAB) are used to assign emission rates to 253 other species found in the SoCAB but for which there are no measured emission rates. The combined listing of 377 species is ranked according to total (isoprene and monoterpenes) biogenic emission rate on an hourly basis. Although the ranking of trees developed here is specific to Southern California, the methodology described can be applied to other geographic areas to assist in the planting of low-emitting urban forests.

The relationship of respiratory and cardiovascular hospital admissions to the southern California wildfires of 2003

Objective: There is limited information on the public health impact of wildfires. The relationship of cardiorespiratory hospital admissions (n = 40 856) to wildfire-related particulate matter (PM2.5) during catastrophic wildfires in southern California in October 2003 was evaluated. Methods: Zip code level PM2.5 concentrations were estimated using spatial interpolations from measured PM2.5, light extinction, meteorological conditions, and smoke information from MODIS satellite images at 250 m resolution. Generalised estimating equations for Poisson data were used to assess the relationship between daily admissions and PM2.5, adjusted for weather, fungal spores (associated with asthma), weekend, zip code-level population and sociodemographics. Results: Associations of 2-day average PM2.5 with respiratory admissions were stronger during than before or after the fires. Average increases of 70 μg/m3 PM2.5 during heavy smoke conditions compared with PM2.5 in the pre-wildfire period were associated with 34% increases in asthma admissions. The strongest wildfire-related PM2.5 associations were for people ages 65–99 years (10.1% increase per 10 μg/m3 PM2.5, 95% CI 3.0% to 17.8%) and ages 0–4 years (8.3%, 95% CI 2.2% to 14.9%) followed by ages 20–64 years (4.1%, 95% CI −0.5% to 9.0%). There were no PM2.5–asthma associations in children ages 5–18 years, although their admission rates significantly increased after the fires. Per 10 μg/m3 wildfire-related PM2.5, acute bronchitis admissions across all ages increased by 9.6% (95% CI 1.8% to 17.9%), chronic obstructive pulmonary disease admissions for ages 20–64 years by 6.9% (95% CI 0.9% to 13.1%), and pneumonia admissions for ages 5–18 years by 6.4% (95% CI −1.0% to 14.2%). Acute bronchitis and pneumonia admissions also increased after the fires. There was limited evidence of a small impact of wildfire-related PM2.5 on cardiovascular admissions. Conclusions: Wildfire-related PM2.5 led to increased respiratory hospital admissions, especially asthma, suggesting that better preventive measures are required to reduce morbidity among vulnerable populations.

Estimating the ozone-forming potential of urban trees and shrubs

Abstract A method is presented for estimating the ozone-forming potential of biogenic hydrocarbon emissions from trees and shrubs, using the California South Coast Air Basin (SoCAB) as a case study. Hourly isoprene and monoterpenes emission rates for 308 tree and shrub species found in the SoCAB were combined with diurnal temperature and light intensity data for a representative summer day in the SoCAB to develop daily emission rates. These daily emission rates for each species were then normalized to a per tree basis using vegetation class biomass factors derived from reported leaf mass constants and tree canopy volumes. The ozone-forming potential for each of the tree and shrub species was estimated by combining the daily per tree emission rates with published maximum incremental reactivities (MIRs) for isoprene and monoterpenes. The resulting ranking of trees by ozone-forming potential can be used in tree species selection for future large-scale tree planting programs, and provides a more appropriate basis for selection than using only mass emissions of biogenic hydrocarbons.

Trace pollutant concentrations in a multiday smog episode in the California South Coast Air Basin by long path length Fourier transform infrared spectroscopy.

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