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71.
Helen H. Suh George A. Allen Petros Koutrakis Robert M. Burton 《Journal of the Air & Waste Management Association (1995)》2013,63(6):442-452
Abstract Acidic sulfate concentrations were measured in metropolitan Philadelphia during the summers of 1992 and 1993, as part of a continuing effort to characterize particle concentrations in urban environments. Sampling was performed simultaneously at eight sites located within and around metropolitan Philadelphia. Sites were selected based on their population density and on their distance and direction from the city center. Air pollution sampling was conducted every other day during the summer of 1992 and every day during the summer of 1993. All samples were collected for 24-h periods beginning at 9 a.m. (EDT). All acidic sulfate and ammonia samples were collected using modified Harvard-EPA Annular Denuder Systems (HEADS). In this paper, we examine the spatial variation in acidic sulfate and ammonia concentrations within the metropolitan Philadelphia area. We also identify factors that may influence their variation and develop models to predict their concentrations. Outdoor sulfate (SO4 2?) concentrations were uniform within metropolitan Philadelphia; however, aerosol strong acidity (H+) concentrations varied spatially. This variation generally was independent of wind direction, but was related to local factors, such as the NH3 concentration, population density, and distance from the center of the city. Physico-chemical models, which were developed using data collected during the summer of 1992, were excellent predictors of 24-h and mean summertime H+ concentrations measured during the summer of 1993. Models accounted for 78% of the variation in 24-h H+ levels. Results suggest that a single stationary ambient (SAM) monitor would be sufficient to estimate SO4 2? exposures for populations living in Philadelphia. For H+, however, multiple monitoring sites or models should be used to determine the outdoor H+ exposures of populations living in urban environments, although a single SAM site may provide an excellent index of H+ variation over time. 相似文献
72.
Niazi NK Singh B Van Zwieten L Kachenko AG 《Environmental science and pollution research international》2012,19(8):3506-3515
This field study investigated the phytoremediation potential of two arsenic (As) hyperaccumulating fern species, Pityrogramma calomelanos var. austroamericana and Pteris vittata over 27-month duration at a disused As-contaminated cattle-dip site located at Wollongbar, NSW, Australia. Ferns planted in January 2009 were harvested following 10, 22 and 27 months of growth. A detailed soil sampling was undertaken in June 2009 (initial, n?=?42 per plot) and limited sampling in April 2011 (after 27 months, n?=?15 per plot) to measure total and phosphate-extractable As concentrations in soil at 0?-?20-, 20?-?40- and 40?-?60-cm depths. The choice of the limited number of samples was considered sufficient to estimate the changes in soil As concentration following phytoremediation based on a geostatistical model. The average frond dry biomass, As concentration and As uptake were significantly (P?0.001?-?0.05) greater in P. calomelanos var. austroamericana than P. vittata, at all three harvests (1.6?-?4.3, 1.3?-?1.5 and 2.2?-?5.7 times, respectively). After 27-months of growth, P. calomelanos var. austroamericana removed 8,053 mg As (i.e. cumulative over three harvests) in plot B (25.4 kg As ha(-1)) that was 2.65 times higher than that depleted by P. vittata (3,042 mg As in plot A (9.7 kg As ha(-1))). The cumulative frond As uptake data of the two fern species revealed that P. calomelanos var. austroamericana extracted 1.7?-?3.9 % and P. vittata removed 0.53?-?1.5 % of total As from soil at three depths. However, for the surface (0?-?20 cm) and subsurface (40?-?60 cm) layers, the (post-experiment) soil As data indicated that total As concentration in soil was reduced by 49 and 63 % (P?0.05), respectively, using P. calomelanos var. austroamericana; and 17 and 15 % (P?>?0.05), respectively, by P. vittata. Our results show that phytoremediation time based on observed changes in soil As based on limited sampling is not reliable; hence, it is recommended that the frond As uptake should be considered in order to evaluate the phytoremediation efficiency of the two fern species at the experimental site. Using As uptake of the two fern species, we estimate that with P. calomelanos var. austroamericana it would take 55?-?125 years to decrease mean total As content below the ecological investigation level (20 mg kg(-1)) in the surface and subsurface soils, whereas with P. vittata 143?-?412 years would be required to achieve this target. 相似文献
73.
Maria P. Papadopoulou Emmanouil A. Varouchakis George P. Karatzas 《Environmental Modeling and Assessment》2010,15(5):319-328
Karst aquifers are characterized by spatial heterogeneity due to the presence of highly permeable channels and conduits in
low-permeable fractured rocks (matrix block). Recent studies have reported a close relationship between surface and subsurface
water in karstic regions due to the water flow through a complicated network of paths formed by fracture intersections. Subsurface
flow in karstified aquifers ranges between conduit flow, in large passages with relatively high flow velocities, and diffuse
flow, in the matrix block where Darcy’s law is still valid. In this paper, we present the simulation of a complex karstified
aquifer system in Crete, Greece, where the presence of main faults drastically affects the regional flow. A discrete fracture
approach in conjunction with an equivalent porous medium approach was adopted to simulate the mixed flow in the area of interest.
The simulation results have shown that the length and the orientation of the dominant faults, primarily during the rainy season,
affect the flow field. 相似文献
74.
Alebel Abebe Belay Henry Musoke Semakula George James Wambura Labohy Jan 《中国人口.资源与环境(英文版)》2010,8(1):8-17
River Nile is one of the longest transboundery rivers and it is shared and used by Burundi,Democratic Republic of Congo,Egypt,Ethiopia,Eritrea,Kenya,Rwanda,Sudan,Tanzania and Uganda.As of today,the Nile is a crucial resource for the economic development of the Nile Basin countries and a vital source of livelihood for 160 million inhabitants as well as 300 million people living in the 10 riparian countries.The Nile Basin Initiative(NBI) is one of the international cooperative river basin management program and regional partnership where all the Nile Basin countries except Eritrea unite to pursue long-term sustainable development,improved land use practices and management.This review therefore focused on the challenges not faced on NBI in terms of integrated use of the river and conducted analysis of strengths,weaknesses,opportunities and threats(SWOT) based on secondary data.The result of the review revealed that for decades,the Nile Basin people have been facing many complex environmental,social,economic and political challenges that have made it difficult for the proper management and sustainability of Nile water.The initiative provides training to develop skills in government ministries,non-governmental organizations and local communities in each country.It is also working to raise awareness of critical environmental issues by strengthening networks of environmental education practitioners;developing curriculum in the education sector.The challenges of NBI include the involvement and funding of World Bank,lack of sufficient staff,procedural and policies conflicts,lack of coordination and linkage with other regional institutions and lack of recognition as river basin organization.Considering the complex nature of the project,it is recommended that the NBI should come up with a strong multi-disciplinary monitoring and evaluation team to follow up all implemented projects.The NBI should carry out participatory land use planning in communities along the river basin.Moreover,livelihood analysis should be carried out especially in communities along the Nile to come up with poverty eradication projects which are socially acceptable,applicable,economically viable and affordable. 相似文献
75.
James C. F. Wang Harvey Patashnick George Rupprecht 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1018-1021
A new real-time dust mass monitor has been developed by combining an automatic isokinetic sampling probe with a tapered element oscillating microbalance (TEOM). Fly ash from a room temperature wind tunnel is sampled through the isokinetic sampler and collected on an astroquartz mat filter in the TEOM detector. The filter is first excited and oscillated at low frequency (about 200 Hz). As the particles deposit on the filter, the mass increase of the filter is reflected in a frequency reduction which yields the collected particle mass directly in real time. The TEOM detector normally has a high mass resolution (10?9 g) and wide dynamic range (1055–1066). It is desensitized for high particle loading applications. Good agreement has been obtained between the mass collected through the isokinetic sampling system and the weight loss of the dust feeder, in real time. The body of information presented in this paper is directed to those concerned with particle emission and control in fossil fuel combustion systems. 相似文献
76.
George R. Offen David Eskinazi Michael W. McElroy John S. Maulbetsch 《Journal of the Air & Waste Management Association (1995)》2013,63(7):864-871
From March 23rd to 26th, 1987, the city of New Orleans hosted 350 attendees, including representatives from 15 foreign countries, at the 1987 Joint Symposium on Stationary Combustion NOx Control. Cosponsored by the Electric Power Research Institute (EPRI) and the U.S. Environmental Protection Agency (EPA), the symposium provided attendees the opportunity to hear 49 papers in nine sessions covering technological and regulatory developments on NOx control in the United States and abroad since the May 1985 symposium in Boston. Session topics included general environmental issues, low-NOx combustion equipment (i.e., low-NOx burners, reburning, etc.), flue gas treatment, fundamental combustion research, and special issues for cyclone coal-fueled boilers, oil- and gas-fired boilers, and industrial combustion applications. Advances to the state-of-the-art presented at this symposium include: improved and/or newly applied combustion modifications for pulverized coal-fired boilers; further analyses of reburning, the leading combustion modification option for cyclone-equipped boilers; initial experiences with catalytic flue gas treatment in Europe; studies of NOx control retrofit options for oil- and gas-fired utility systems; and new technology developments for coal, oil, and gas fueled utility and industrial combustors. This paper summarizes those presentations that discussed significant changes since May 1985 in areas of potential interest to EPRI and its utility members. Where appropriate, they include our perspectives on the applicability of these newly disclosed findings to utility systems. 相似文献
77.
George F. Antonious Eric T. Turley Regina R. Hill John C. Snyder 《Journal of environmental science and health. Part. B》2013,48(4):299-304
Organic matter and nutrients in municipal sewage sludge (SS) and chicken manure (CM) could be recycled and used for land farming to enhance fertility and physical properties of soils. Three soil management practices were used at Kentucky State University Research Farm, Franklin County, to study the impact of soil amendments on kale (Brassica oleracea cv. Winterbar) and collard (Brassica oleracea cv. Top Bunch) yields and quality. The three soil management practices were: (i) SS mixed with native soil at 15 t acre?1, (ii) CM mixed with native soil at 15 t acre?1, and (iii) no-mulch (NM) native soil for comparison purposes. At harvest, collard and kale green plants were graded according to USDA standards. Plants grown in CM and SS amended soil produced the greatest number of U.S. No. 1 grade of collard and kale greens compared to NM native soil. Across all treatments, concentrations of ascorbic acid and phenols were generally greater in kale than in collards. Overall, CM and SS enhanced total phenols and ascorbic acid contents of kale and collard compared to NM native soil. We investigated the chemical and physical properties of each of the three soil treatments that might explain variability among treatments and the impact of soil amendments on yield, phenols, and ascorbic acid contents of kale and collard green grown under this practice. 相似文献
78.
George Foy 《Environmental management》1990,14(6):771-778
The core requirement of sustainability is that current economic activities should not result in an excessive burden on future
generations. This criterion is general enough to imply different decision rules for the preservation of environmental assets.
Neoclassical economics does not have a sustainability criterion for environmental assets independent of the intertemporal
efficiency criterion, which allocates environmental and man-made capital based on projected monetary benefits and costs. This
criterion is examined in terms of the feasibility of valuing the benefits of environmental assets, the substitution possibilities
between natural and man-made capital, and the ethical grounds for using efficiency as the sole determinant of the allocation
of environmental assets. An alternative ecological sustainability criterion is the preservation of safe minimum levels of
environmental assets in physical terms rather than the dollar value of a composite of natural and man-made capital. Safe minimum
standards for environmental assets constrain the efficiency criterion in order to ensure the sustainability of economic systems.
It is argued that the ecological approach to sustainability should limit the economic approach for decisions involving the
allocation of environmental assets. 相似文献
79.
80.
Thomas Carlisle George Mulamoottil Bruce Mitchell 《Journal of the American Water Resources Association》1991,27(3):419-427
ABSTRACT: The objective was to survey individuals from different interest groups in Ontario to ascertain attitudes towards the use of artificial wetlands for stormwater management and to provide waterfowl habitat. In total, 166 questionnaires were distributed and 124 cempleted returns were received. The results of the survey show that the provision of wetlands as waterfowl habitats in the context of stormwater impoundments is severely limited and is not considered an important management option. The overwhelming rejection of this integrated approach seems to be due to a lack of understanding and its comparative newness. Some of the perceived problems and concerns could be addressed by improvements in the design of the artificial wetlands. The design and implementation of an artificial wetland prototype as part of an education program in Ontario is recommended. A few research opportunities also are outlined. 相似文献