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51.
52.
This paper was one of several presented at the Workshop on Air Pollution Control in Portland, Oregon, on May 6, 1968. The Workshop was sponsored by the Manufacturing Chemists Association and the Chemical Industry Council of the Pacific Northwest in cooperation with the Association of Oregon Industries, Association of Washington Industries, and the Environmental Committee of the Portland Chamber of Commerce. While many of the papers were of localized interest, this paper speaks to anyone designing air pollution control systems. 相似文献
53.
J. O. Ivie M. D. Thomas O. C. Taylor C. Ray Thompson W. M. Dugger JR. B. L. Richards 《Journal of the Air & Waste Management Association (1995)》2013,63(8):355-359
A discussion of the methods used to determine the most economic design of chimney for a new thermal power station or large industrial plant is presented, with the objective that ground level concentration of pollutants will be kept at a minimum. Attention is paid to the geography and climatology of the site, with special reference to the frequency and height of inversions and the prevailing wind direction and speed. A method is illustrated in using a large thermal power station as an example. The maximum sulfur dioxide concentrations at ground level are computed for several chimney heights and gas exit velocities. The values of these sulfur dioxide concentrations, the capital cost of the chimney, the pumping costs, and the gas pressures within the chimney are considered in selecting a suitable chimney height and a gas exit velocity which will meet most economically the stated objective. The paper deals primarily with chimneys for industrial or power boiler plant of maximum continuous rating greater than 450 million Btu/hr (about 450,000 lbs of steam/hr), or to chimneys serving furnaces burning fuel at a maximum rate greater than 50,000 lbs/hr of coal, or 80,000 lbs/hr of oil. For chimneys serving plant with smaller heat inputs, chimney selection by reference to Clean Air Act 1956, Memorandum on Chimney Heights is suggested. 相似文献
54.
The high degree of physical disturbance associated with conventional response options to oil spills in wetlands is driving
the investigation of alternative cleanup methodologies. In March 1995, a spill of gas condensate in a brackish marsh at Rockefeller
Wildlife Refuge in southwestern Louisiana was remediated through the use of in situ burning. An assessment of vegetation recovery
was initiated in three treatment marshes: (1) oil-impacted and burned, (2) oil impacted and unburned, and (3) a nonoiled unburned
reference. We compared percent cover, stem density, and biomass in the treatment marshes to define ecological recovery of
the marsh vegetation and soil hydrocarbon content to determine the efficacy of in situ burning as a cleanup technique. Burning
led to a rapid decrease in soil hydrocarbon concentrations in the impacted-and-burned marsh to background levels by the end
of the first growing season. Although a management fire accidentally burned the oil-impacted-and-unburned and reference marshes
in December 1995, stem density, live biomass, and total percent cover values in the oil-impacted-and-burned marsh were equivalent
to those in the other treatment marshes after three years. In addition, plant community composition within the oil-impacted-and-burned
marsh was similar to the codominant mix of the grasses Distichlis spicata (salt grass) and Spartina patens (wire grass) characteristic of the surrounding marsh after the same time period. Rapid recovery of the oil-impacted-and-unburned
marsh was likely due to lower initial hydrocarbon exposure. Water levels inundating the soil surface of this grass-dominated
marsh and the timing of the in situ burn early in the growing season were important factors contributing to the rapid recovery
of this wetland. The results of this in situ burn evaluation support the conclusion that burning, under the proper conditions,
can be relied upon as an effective cleanup response to hydrocarbon spills in herbaceous wetlands. 相似文献
55.
We assessed relationships between the extent to which farmers reported exposure to relevant information and their attitudes
towards, knowledge about, and degree of adoption of riparian management strategies. We also examined associations between
knowledge of, or receipt of, financial assistance for riparian fencing/planting and intentions for and extent of adoption
of this strategy. A mail survey of 718 pastoral farmers in Otago and Southland in New Zealand [294 surveys returned (41%)]
yielded 279 usable questionnaires. Indices were developed to reflect range and frequency of information use and range of practices
adopted. Attitudes were measured using Likert-type responses to 11 statements, and knowledge as a score on a ten-question
true/false test. Positive relationships between information and the three main response variables (attitude, knowledge, and
adoption) were weak but significant and systematic. These associations remained significant when important demographic and
farm characteristics were taken into account. Informed farmers were more likely to report intentions to carry out riparian
fencing or planting within the next year. Farmers who were aware that funding was available were also more likely to state
this intention, independent of information level. The reported extent to which waterways had been fenced to exclude stock
was related to receipt of funding, but not to information level. Financial factors were the most influential barrier preventing
adoption of permanent fencing. Our research shows a positive correlation between the receipt of information and funding and
the adoption of specific riparian management measures. 相似文献
56.
57.
MALCOLM L. HUNTER JR. 《Conservation biology》2005,19(4):1025-1029
Abstract: Setting aside entire ecosystems in reserves is an efficient way to maintain biodiversity because large numbers of species are protected, but ecosystem conservation constitutes a coarse filter that does not address some species. A complementary, fine-filter approach is also required to provide tailored management for some species (e.g., those subject to direct exploitation). Mesofilter conservation is another complementary approach that focuses on conserving critical elements of ecosystems that are important to many species, especially those likely to be overlooked by fine-filter approaches, such as invertebrates, fungi, and nonvascular plants. Critical elements include structures such as logs, snags, pools, springs, streams, reefs, and hedgerows, and processes such as fires and floods. Mesofilter conservation is particularly appropriate for seminatural ecosystems that are managed for both biodiversity and commodity production (e.g., forests managed for timber, grasslands managed for livestock forage, and aquatic ecosystems managed for fisheries) and is relevant to managing some agricultural and urban environments for biodiversity. 相似文献
58.
PHILIP C. STOUFFER† RICHARD O. BIERREGAARD JR ‡. CHERYL STRONG§ THOMAS E. LOVEJOY†† 《Conservation biology》2006,20(4):1212-1223
Abstract: The rainforests of the Amazon basin are being cut by humans at a rate >20,000 km2 /year, leading to smaller and more isolated patches of forest, with remaining fragments often in the range of 1–100 ha. We analyzed samples of understory birds collected over 20 years from a standardized mist-netting program in 1– to 100-ha rainforest fragments in a dynamic Amazonian landscape near Manaus, Brazil. Across bird guilds, the condition of second growth immediately surrounding fragments was often as important as fragment size or local forest cover in explaining variation in abundance. Some fragments surrounded by 100 m of open pasture showed reductions in insectivorous bird abundance of over 95%, even in landscapes dominated by continuous forest and old second growth. These extreme reductions may be typical throughout Amazonia in small (≤10 ha), isolated fragments of rainforest. Abundance for some guilds returned to preisolation levels in 10- and 100-ha fragments connected to continuous forest by 20-year-old second growth. Our results show that the consequences of Amazonian forest loss cannot be accurately described without explicit consideration of vegetation dynamics in matrix habitat. Any dichotomous classification of the landscape into "forest" and "nonforest" misses essential information about the matrix. 相似文献
59.
60.
Dr William Cusick Michael Bork Betsy Fabri Peter Benn John F. Rodis Louis Buttino JR 《黑龙江环境通报》1995,15(11):1078-1081
A 27-year-old gravida 4, para 3 was found to have anhydramnios at 14 weeks' gestation following a size/date discrepancy noted at her routine prenatal visit. A detailed ultrasound revealed multiple fetal anomalies including congenital heart defect, chest hypoplasia, and bilateral dysplastic kidneys. Karyotype revealed trisomy 16 in 15/15 cells from a tissue specimen obtained from the fetal cord insertion site following elective pregnancy termination. 相似文献