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71.
Defu Xu Yinjuan Wu Yingxue Li Alan Howard Xiaodong Jiang Yidong Guan Yongxia Gao 《Environmental science and pollution research international》2014,21(17):10108-10119
A surface- and vertical subsurface-flow-constructed wetland were designed to study the response of chlorophyll and antioxidant enzymes to elevated UV radiation in three types of wetland plants (Canna indica, Phragmites austrail, and Typha augustifolia). Results showed that (1) chlorophyll content of C. indica, P. austrail, and T. augustifolia in the constructed wetland was significantly lower where UV radiation was increased by 10 and 20 % above ambient solar level than in treatment with ambient solar UV radiation (p?0.05). (2) The malondialdehyde (MDA) content, guaiacol peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities of wetland plants increased with elevated UV radiation intensity. (3) The increased rate of MDA, SOD, POD, and CAT activities of C. indica, P. australis, and T. angustifolia by elevated UV radiation of 10 % was higher in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland. The sensitivity of MDA, SOD, POD, and CAT activities of C. indica, P. austrail, and T. augustifolia to the elevated UV radiation was lower in surface-flow-constructed wetland than in the vertical subsurface-flow-constructed wetland, which was related to a reduction in UV radiation intensity through the dissolved organic carbon and suspended matter in the water. C. indica had the highest SOD and POD activities, which implied it is more sensitive to enhanced UV radiation. Therefore, different wetland plants had different antioxidant enzymes by elevated UV radiation, which were more sensitive in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland. 相似文献
72.
73.
Judith C. Chow John G. Watson Richard T. Egami Clifton A. Frazier Zhiqiang Lu Andrew Goodrich 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1134-1142
Street sweeping is often proposed as a means of reducing the emissions from paved roads. The objective of this study was to evaluate the effectiveness of street sweeping on ambient particulate matter concentrations and to determine the difference In source contributions to PM10 concentrations between street sweeping and non-street sweeping periods. Chemically-speciated measurements of PM10 and PM2.5 were taken in the commercial section of Reno, Nevada, for a one-month sampling period. The Chemical Mass Balance (CMB) model was applied to these data and an average of approximately 50 percent of the PM10 was apportioned to resuspended geological material. During half of the sampling period, streets In the vicinity of the sampling site were completely swept with a regenerative-air vacuum sweeper, while no sweeping was performed during the remainder of the experiment. Ratios of primary geological contributions divided by primary motor vehicle contributions to PM10 were compared between sweeping and non-sweeping periods using analysis of variance. This ratio of source contributions minimizes the effects of variations in traffic volume and meteorological dispersion. No significant differences in geological contributions to PM10 were detected as a result of regenerative-air vacuum street sweeping. 相似文献
74.
Bart E. Croes John R. Holmes Alan C. Lloyd 《Journal of the Air & Waste Management Association (1995)》2013,63(5):657-661
The California Air Resources Board and the South Coast Air Quality Management District hosted a conference on April 8-9, 1991 to examine the scientific issues associated with reactivity-based hydrocarbon controls, and to identify the obstacles to potential regulatory applications. Owing to residual uncertainties in the underlying science, and the complex emission measurement capabilities required for enforcement, a general consensus emerged on the need for further research before application of reactivity-based controls. A number of recommendations were made for research on the remaining scientific, enforcement, and policy issues, many of which have led to cooperative efforts initiated since the conference. 相似文献
75.
Alan M. Wolsky Edward J. Daniels Bassam J. Jody 《Journal of the Air & Waste Management Association (1995)》2013,63(4):449-454
This paper summarizes the results of research conducted at Ar-gonne National Laboratory (ANL) to develop and design a novel method for the recovery of CO2 from flue gases. The basic process concept Involves the combustion of a hydrocarbon fuel using a mixture of oxygen and carbon dioxide (or CO2 and H20) rather than air as the oxidant, which results In a product stream that contains primarily CO2 and H2O. This stream Is then dried and conditioned to meet the specifications of the end user, A slip stream of CO2 (or CO2, and H20) is used as a diluent in the combustion chamberto maintain a flame temperature equivalent to the temperature that would otherwise be obtained using air as an oxidant. The cost-effectiveness of the process in recovering C02 is dependent on the scale of the operation, the type of fuel used, the cost of oxygen, and the cost of capital. The sensitivity of the cost of the recovered C02 to these variables Is discussed, and a model for estimating the cost of CO2 recovered using the ANL process Is presented. 相似文献
76.
W. Alan Bowman 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1124-1128
Equations are derived from the Gaussian plume mode! and prescribe the critical downwind distance, wind speed, and plume rise values that result in maximum ground-level concentrations (MGLC) under downwash conditions. The derivations apply to bent-over plumes and encompass the Schulman-Scire and Huber-Snyder building downwash treatments. 相似文献
77.
78.
Anthony D.A. Hansen Douglas H. Lowenthal Judith C. Chow John G. Watson 《Journal of the Air & Waste Management Association (1995)》2013,63(4):593-600
ABSTRACT Aerosol light absorption as black carbon (BC) was measured from November 19, 1995, to February 6, 1996, at a location 0.65 km downwind of the center of McMurdo Station on the Antarctic coast. The results show a bimo-dal frequency distribution of BC concentrations. Approximately 65% of the measurements were found in a mode at a low range of concentrations centered at ~20 ng/m3. These concentrations are higher than those found at other remote Antarctic locations and probably represent contamination from the station. The remaining measurements were in a high-concentration mode (BC ~300 ng/m3), indicating direct impact of local emissions from combustion activities at the station. High values of BC were associated with winds from the direction of the station, and the BC flux showed a clear directionality. Maximum BC concentrations occurred between 7:00 and 11:00 a.m. The "polluted" mode accounted for more than 80% of the BC frequency-weighted impact at this location. 相似文献
79.
Alan Eschenroeder 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1423-1427
ABSTRACT Previous greenhouse gas studies comparing landfilling with combustion of municipal solid waste (MSW) are limited to examinations of the emissions weighted by their relative radiative activity. This paper adds another dimension by analyzing the atmospheric response to these emissions. The heart of the analysis is a time-dependent model using a perturbation analysis of the IS92a results of the Intergovernmental Panel on Climate Change (IPCC). Using as inputs the emissions from the two technologies, the model calculates atmospheric concentration histories. Scenarios for a landfill and a combustor envision each accepting 1000 Mg refuse/day for a 30-year operating period followed by a 70-year postclosure period. The baseline scenario examines the basic greenhouse impact of each technology. The other scenario adds active gas collection at the landfill and energy offset credits for avoided power plant carbon emissions. For both scenarios, CH4 and trace gases from the landfill persist in the atmosphere, and they are relatively potent at forcing IR heating. The combination of these features place the landfill much higher than previously expected on the greenhouse impact scale. For the baseline scenario, the time-integrated radiative forcing from landfilling is 115 times that of combustion, and this ratio is 45 for the second scenario. 相似文献
80.
D. Alan Hansen Eric S. Edgerton Benjamin E. Hartsell John J. Jansen Navaneethakrishnan Kandasamy 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1460-1471
Abstract This paper presents an overview of a major, long-term program for tropospheric gas and aerosol research in the southeastern United States. Building on three existing ozone (O3)-focused research sites begun in mid-1992, the Southeastern Aerosol Research and Characterization Study (SEARCH) was initiated in mid-1998 as a 7-year observation and research program with a broader focus including aerosols and an expanded geographical coverage in the Southeast. The monitoring network comprises four urban-rural (or urban-suburban) site pairs at locations along the coast of the Gulf of Mexico and inland, including two moderately sized and two major urban areas (Pensacola, FL; Gulfport, MS; Atlanta, GA; and Birmingham, AL). The sites are equipped with an extensive suite of instruments for measuring particulate matter (PM), gases relevant to secondary O3 and the production of secondary aerosol particles, and surface meteorology. The measurements taken to date have added substantially to the knowledge about the temporal behavior and geographic variability of tropospheric aerosols in the Southeast. Details are presented in four papers to follow. 相似文献