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11.
Brian P. Leaderer Theodore R. Holford Jan A. J. Stolwijk 《Journal of the Air & Waste Management Association (1995)》2013,63(2):154-157
A PM10 monitoring network was established throughout the South Coast Air Basin (SOCAB) in the greater Los Angeles region during the calendar year 1986. Annual average PM10 mass concentrations within the Los Angeles metropolitan area ranged from 47.0 µg m-3 along the coast to 87.4 µg m-3 at Rubldoux, the furthest inland monitoring station. Measurements made at San Nicolas Island suggest that regional background aerosol contributes between 28 to 44 percent of the PM10 aerosol at monitoring sites In the SOCAB over the long term average. Five major aerosol components (carbonaceous material, NO- 3, SO= 4, NH+ 4, and soil-related material) account for greater than 80 percent of the annual average PM10 mass at all on-land monitoring stations. Peak 24-h average mass concentrations of nearly 300 µg m-3 were observed at inland locations, with lower peak values (?130–150 µg m-3) measured along the coast. Peak-day aerosol composition was characterized by increased NO- 3 Ion and associated ammonium ion levels, as compared to the annual average. There appears to be only a weak dependence of PM10 mass concentration on season of the year. This lack of a pronounced seasonal dependence results from the complex and contradictory seasonal variations in the major chemical components (carbonaceous material, nitrate, sulfate, ammonium ion and crustal material). At most sites within the Los Angeles metropolitan area, PM10 mass concentrations exceeded both the annual and 24-h average federal and state of California PM10 regulatory standards. 相似文献
12.
Louis Theodore Joseph P. Reynolds 《Journal of the Air & Waste Management Association (1995)》2013,63(7):777-779
This paper is directed to those individuals involved in design of electrostatic precipitators. The Deutsch-Anderson model is usually employed by industry for the design of electrostatic precipitators. The so-called process design variable in this approach is the total capture area in the precipitator. Unfortunately, little is available on the equipment design of this unit, i.e., the geometric arrangement of the plates that constitute the capture area and the external dimensions of the physical structure that houses the precipitator components. These are important economic considerations, and it is to this subject that this paper is directed. It is relatively easy to predict equipment costs for “off-the-shelf” electrostatic precipitators; it is more difficult to closely predict the cost for a custom-made unit, which is more often the case encountered in practice. Once the capture area is calculated, the total precipitator cost becomes a strong function of the outer casing and outer accessories of the physical system. In this paper, a model is presented that can help minimize precipitator cost. An illustrative example complements the development of the model. 相似文献
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14.
Differences between scientist and policy-maker response types and times, or the “how” and “when” of action, constrain effective water resource management in suburbanizing watersheds. Policy-makers are often rushed to find a single policy that can be applied across an entire, homogeneous, geopolitical region, whereas scientists undertake multiyear research projects to appreciate the complex interactions occurring within heterogeneous catchments. As a result, watershed management is often practiced with science and policy out of synch. Meanwhile, development pressures in suburban watersheds create changes in the social and physical fabric and pose a moving target for science and policy. Recent and anticipated advances in the scientific understanding of urbanized catchment hydrology and pollutant transport suggest that management should become increasingly sensitive to spatial heterogeneities in watershed features, such as soil types, terrain slopes, and seasonal watertable profiles. Toward this end, policy-makers should encourage funding scientific research that characterizes the impacts of these watershed heterogeneities within a geopolitical zoning and development framework. 相似文献
15.
The current research analyzed employee perceptions of the completeness of a self-report, point-factor job evaluation system. Complementary qualitative and quantitative techniques were used to identify characteristics of jobs, characteristics of employees, and characteristics of the job evaluation procedure that affected employee perceptions of the system. Analyses indicated that the job evaluation instrument might describe some classes of jobs more completely than others. Situations where job evaluation is particularly problematic are identified and discussed. 相似文献
16.
Sensitivity indices, which rank factors pertinent to surface and subsurface runoff pathways, were used to identify phosphorus
source areas in riparian zones of 15 northern Minnesota lakes. Watershed models were first developed using a geographic information
system (GIS). Empirical models were then developed correlating water quality with land use, lake morphometry, and riparian
sensitivity. Base models of forested, cultivated, pasture/open, wetland and residential land use within 100, 200, 400, and
2000 m of the study lakes were regressed on total phosphorus and chlorophyll-a. Area-weighted groundwater and surface runoff sensitivity indices were then incorporated into each model and tested for significance.
Within the 200-m buffer, the total phosphorus base model was improved by including the groundwater index alone. The chlorophyll-a base model at 200 m was improved by including: (1) the groundwater index alone, and (2) both the groundwater and surface
runoff sensitivity indices. Results suggest that surface and subsurface runoff analysis of potential source areas can improve
decision making for lake riparian management. 相似文献
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19.
Differences between scientist and policy-maker response types and times, or the “how” and “when” of action, constrain effective
water resource management in suburbanizing watersheds. Policy-makers are often rushed to find a single policy that can be
applied across an entire, homogeneous, geopolitical region, whereas scientists undertake multiyear research projects to appreciate
the complex interactions occurring within heterogeneous catchments. As a result, watershed management is often practiced with
science and policy out of synch. Meanwhile, development pressures in suburban watersheds create changes in the social and
physical fabric and pose a moving target for science and policy. Recent and anticipated advances in the scientific understanding
of urbanized catchment hydrology and pollutant transport suggest that management should become increasingly sensitive to spatial
heterogeneities in watershed features, such as soil types, terrain slopes, and seasonal watertable profiles. Toward this end,
policy-makers should encourage funding scientific research that characterizes the impacts of these watershed heterogeneities
within a geopolitical zoning and development framework. 相似文献
20.
William Whipple James M. DiLouie Theodore Pytlar 《Journal of the American Water Resources Association》1981,17(1):36-45
ABSTRACT: In urbanizing areas, the usual increase in flood flows also increases erosional capability of streams. In order to evaluate such tendencies quantitatively, 25 stream reaches were studied, and were classified as to whether erosion of the channel and banks was light, medium, or heavy. Analysis of characteristics indicated that (1) densely developed areas are correlated with greater erosion, (2) wide stream buffers of natural vegetation are correlated with lesser erosion, and (3) there is no definite correlation of erosion to slope or characteristics of soil. Erosional stream instability can be avoided by retention of storm water runoff, creating additional channel roughness or reducing channel slope during floods by drop structures, such as culverts, which restrict flow. Channel straightening and general bank protection should be minimized in such streams. Design of culverts should take such effects into consideration. 相似文献