Journal of the Air Pollution Control Association 

About: Journal of the Air Pollution Control Association is an academic journal. The journal publishes majorly in the area(s): Air pollution & Air quality index. It has an ISSN identifier of 0002-2470. Over the lifetime, 2702 publications have been published receiving 39066 citations.

Some factors that affect the deposition rates of sulfur dioxide and similar gases on vegetation

Abstract: The deposition of sulfur dioxide on growing vegetation is affected by diverse environmental factors, many of which undergo large diurnal and spatial variations. The aerodynamic resistance to vertical transfer in the surface boundary layer can be formulated in terms of the friction velocity, height of observation, vertical heat flux, and surface roughness. Also important are the resistance in the air layer closest to the surface elements and, in dry vegetation, the average stomatal resistance of the plants. The latter variable is among the most difficult to estimate, but over many agricultural field crops like those in the midwestern U.S., a typical minimum value of average stomatal resistance to SO2 transfer is about 0.7 s cm-1, as is indicated by various experimental data. The deposition velocity can be estimated as the inverse of the sum of the resistances of the layers, necessarily down to where the concentrations are zero; in the surface boundary layer, any of the various resistances might be dominant...

Vegetation: a sink for atmospheric pollutants.

Abstract: The possibility of vegetation being an important sink for gaseous air pollutants was investigated. Plant pollutant uptake measurements were made utilizing a typical vegetation canopy and chambers that were designed specifically for gaseous exchange studies. The data indicate that an alfalfa canopy removed gases from the atmosphere in the following order: hydrogen fluoride (HF) > sulfur dioxide (SO2) > chlorine (Cl2) > nitrogen dioxide (NO2) > ozone (O3) > peroxyacetyl nitrate (PAN) > nitric oxide (NO) > carbon monoxide (CO). The absorption rate of NO was low, and no absorption of CO could be detected with the methods used. In the typical ambient concentration range uptake increased linearly with increasing concentration except for O3 and Cl2 which caused partial stomatal closure at the higher concentrations. Wind velocity above the plants, height of the canopy, and light intensity were shown to affect the pollutant removal rate. A relationship between the absorption rate and solubility of the pollutant in...

Odor Threshold Determinations of 53 Odorant Chemicals

Abstract: In order to assist in assessing potential odor problems arising from chemical manufacturing operations, the odor thresholds of 53 commercially important odorant chemicals have been determined using a standardized and defined procedure. The odor threshold data previously available have shown wide variation reflecting the diversity of procedures and techniques used. Factors that may affect the odor threshold measurement include the mode of presentation of the stimulus to the observer, the influence of extraneous odorants in the presentation system, the type of observer used, the definition of the odor response, the treatment of the data obtained, and the chemical purity of the odorant. The experimental approach used has minimized these variations. The odorants were presented to a trained odor panel in a static air system utilizing a low odor background air as the dilution medium. The odor threshold is defined as the first concentration at which all panel members can recognize the odor. The effect of chemica...

Assessment of Crop Loss from Ozone

Abstract: The National Crop Loss Assessment Network (NCLAN) was set up to determine more accurately crop loss from ozone, sulfur dioxide, and nitrogen dioxide. The NCLAN consists of a group of government and nongovernment organizations cooperating in field work, crop production modeling, and economic studies to assess the immediate and long-term economic consequences of the effects of air pollution on crop production. The program will define the relationships between yields of major agricultural crops and doses of O/sub 3/, SO/sub 2/, NO/sub 2/ and their mixtures. These relationships will be used to assess the primary economic consequences of the exposure of agricultural crops to these pollutants. The program is also designed to advance the understanding of cause-effect relationships with the intent of developing simulation models. These nationally-coordinated field studies are designed to provide crop dose-response data that are as free of artifact as is currently possible using state-of-the-art technology. The basic exposure technique utilizes open-top chambers. These chambers have been well tested and permit control of gas(es) around the plant canopy, allowing specific pollution regimes to be imposed on experimental plants. (JMT)