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91.
Methane and carbon dioxide emission from two pig finishing barns   总被引:3,自引:0,他引:3  
Agricultural activities are an important source of greenhouse gases. However, comprehensive, long-term, and high-quality measurement data of these gases are lacking. This article presents a field study of CH(4) and CO(2) emission from two 1100-head mechanically ventilated pig (Sus scrofa) finishing barns (B1 and B2) with shallow manure flushing systems and propane space heaters from August 2002 to July 2003 in northern Missouri. Barn 2 was treated with soybean oil sprinkling, misting essential oils, and misting essential oils with water to reduce air pollutant emissions. Only days with CDFB (complete-data-full-barn), defined as >80% of valid data during a day with >80% pigs in the barns, were used. The CH(4) average daily mean (ADM) emission rates were 36.2 +/- 2.0 g/d AU (ADM +/- 95% confidence interval; animal unit = 500 kg live mass) from B1 (CDFB days = 134) and 28.8 +/- 1.8 g/d AU from B2 (CDFB days = 131). The CO(2) ADM emission rates were 17.5 +/- 0.8 kg/d AU from B1 (CDFB days = 146) and 14.2 +/- 0.6 kg/d AU from B2 (CDFB days = 137). The treated barn reduced CH(4) emission by 20% (P < 0.01) and CO(2) emission by 19% (P < 0.01). The CH(4) and CO(2) released from the flushing lagoon effluent were equivalent to 9.8 and 4.1% of the CDFB CH(4) and CO(2) emissions, respectively. The emission data were compared with the literature, and the characteristics of CH(4) and CO(2) concentrations and emissions were discussed.  相似文献   
92.
Manifestations of Fanconi Anemia Complementation Group C (FA-C) include multiple major congenital malformations, hypoplastic radius, absent thumb, growth retardation, elfin-like facial features, microphthalmia, microcephaly, café-au-lait spots, early onset of hematologic disease and poor survival (Auerbach, 1997). We describe two cases in which second-trimester sonographic findings led to parental carrier testing for FA-C and subsequent prenatal diagnosis of affected fetuses. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
93.
94.
Abstract: Conservation of rare plant species often involves small, local populations dispersed within apparently suitable habitat. We used enzyme electrophoresis to study genotypic diversity in 32 populations of Calystegia collina , a self-incompatible clonal plant endemic to serpentine substrate in northern California's Coast Range. Genotypic diversity within a population was a good predictor of seed set by randomly marked flowers. Ramets from the most abundant genotypes in a population were most likely to produce flowers, but flowers from abundant genotypes were less likely to produce seed capsules than were flowers from rarer genotypes. These results are consistent with previous findings that reproductive success in C. collina is limited by the availability of compatible pollen. On small serpentine outcrops supporting only one or two populations, C. collina did not show reduced genotypic diversity or heterozygosity compared with populations on large outcrops supporting many populations. Instead, genotypic diversity and outcrop size had strong but independent influences on reproductive success. Although large serpentine outcrops contain more populations and provide better conditions for flower and seed production, significant diversity of unique genotypes clearly exists in isolated serpentine outcrops. Our findings suggest that plant conservation strategies must take into account the natural distribution of populations. The effects of habitat fragmentation on C. collina and other plant species that occur naturally in small, discrete patches may be unlike those that have been documented in more recently fragmented species.  相似文献   
95.
ABSTRACT

The Arizona inspection and maintenance (I/M) program provides one of the first opportunities to examine the costs and effectiveness of vehicle emission repair. This paper examines various aspects of emission reductions, fuel economy improvements, and repair costs, drawing data from over 80,000 vehicles that failed the I/M test in Arizona between 1995 and the first half of 1996. We summarize the wealth of data on repair from the Arizona program and highlight its limitations. Because missing or incomplete cost information has been a serious shortcoming for the evaluation of I/M programs, we develop a method for estimating repair costs when they are not reported. We find surprising evidence that almost one quarter of all vehicles that take the I/M test are never observed to pass the test. Using a statistical analysis, we provide some information about the differences between the vehicles that pass and those that do not. Older, more polluting vehicles are much more likely never to pass the I/M test, and their expected repair costs are much higher than those for newer cars.

This paper summarizes the evidence on costs and emission reductions in the Arizona program, comparing costs and emissions reductions between cars and trucks. Finally, we examine the potential for more cost-effective repair, first through an analysis of tightening I/M cut points and then by calculating the cost savings of achieving different emission reduction goals when the most cost-effective repairs are made first.  相似文献   
96.
Abstract

Comprehensive field studies were initiated in 2002 to measure emissions of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), methane (CH4), nonmethane hydrocarbons (NMHC), particulate matter <10 µm in diameter, and total suspended particulate from swine and poultry production buildings in the United States.

This paper focuses on the quasicontinuous gas concentration measurement at multiple locations among paired barns in seven states. Documented principles, used in air pollution monitoring at industrial sources, were applied in developing quality assurance (QA) project plans for these studies. Air was sampled from multiple locations with each gas analyzed with one high quality commercial gas analyzer that was located in an environmentally controlled on-farm instrument shelter. A nominal 4 L/min gas sampling system was designed and constructed with Teflon wetted surfaces, bypass pumping, and sample line flow and pressure sensors. Three-way solenoids were used to automatically switch between multiple gas sampling lines with ≥10 min sampling intervals. Inside and outside gas sampling probes were between 10 and 115 m away from the analyzers. Analyzers used chemiluminescence, fluorescence, photoacoustic infrared, and photoionization detectors for NH3, H2S, CO2, CH4, and NMHC, respectively. Data were collected using personal computer-based data acquisition hardware and software. This paper discusses the methodology of gas concentration measurements and the unique challenges that livestock barns pose for achieving desired accuracy and precision, data representativeness, comparability and completeness, and instrument calibration and maintenance.  相似文献   
97.
The purpose of this study was to determine the response of antibiotics and antibiotic resistance genes (ARG) to manure management. A pilot field study was conducted using horse manure containing no antibiotics, into which chlortetracycline (CTC), tylosin (TYL), and monensin (MON) were spiked and compared to unspiked controls. Subsequently, a large-scale field study was conducted comparing manure from a dairy with minimal use of antibiotics and a feedlot with regular subtherapeutic use of antibiotics. The manures were subjected to high-intensity management (HIM) (amending, watering, and turning) and low-intensity management (LIM) (no amending, watering, or turning) and were monitored for antibiotic concentrations and levels of tetracycline ARG [tet(W) and tet(O)] using quantitative real-time polymerase chain reaction. All three antibiotics in the pilot study dissipated more rapidly in HIM manure, with half-lives ranging from 4 to 15 d, compared to LIM manure, with half-lives ranging from 8 to 30 d. Levels of tet(W) were significantly higher after 141 d of treatment, but levels of tet(O) were significantly lower in all treatments. In the large-scale study, the feedlot manure had higher initial concentrations than the dairy manure of tetracycline (TC), oxytetracycline (OTC), and CTC as well as tet(W) and tet(O). Tetracycline and OTC dissipated more rapidly in HIM manure, with half-lives ranging from 6 to 15 d, compared to LIM manure, with half-lives ranging from 7 to 31 d. After 6 mo of treatment, tet(W) and tet(O) decreased significantly in feedlot manure, whereas dairy manure required only 4 mo of treatment for similar results.  相似文献   
98.
We evaluated the influences of several ecological, biological, and methodological factors on post-fledging survival of a shortgrass prairie bird, the Lark Bunting (Calamospiza melanocorys). We estimated daily post-fledging survival (n = 206, 82 broods) using radiotelemetry and color bands to track fledglings. Daily survival probabilities were best explained by drought intensity, time in season (quadratic trend), ages < or = 3 d post-fledging, and rank given drought intensity. Drought intensity had a strong negative effect on survival. Rank was an important predictor of fledgling survival only during the severe drought of 2002 when the smallest fledglings had lower survival. Recently fledged young (ages < or = 3 d post-fledging) undergoing the transition from nest to surrounding habitat experienced markedly lower survival, demonstrating the vulnerable nature of this time period. Survival was greater in mid and late season than early season, corresponding to our assumptions of food availability. Neither mark type nor sex of attending parent influenced survival. The model-averaged product of the 22-d survival calculated using mean rank and median value of time in season was 0.360 +/- 0.08 in 2001 and 0.276 +/- 0.08 in 2002. Survival estimates that account for age, condition of young, ecological conditions, and other factors are important for parameterization of realistic population models. Biologists using population growth models to elucidate mechanisms of population declines should attempt to estimate species-specific of post-fledging survival rather than use generalized estimates.  相似文献   
99.
Howe HF  Zorn-Arnold B  Sullivan A  Brown JS 《Ecology》2006,87(12):3007-3013
We ask whether vole herbivory in experimental grassland plots is sufficient to create an unpalatable community. In a six-year experiment, meadow voles (Microtus pennsylvanicus) reduced plant standing crop between 30% and 72%, well within the range of ungulate effects. Moreover, meadow voles reduced their available forage species by changing the plant community composition: four grass species and a legume upon which they foraged declined sharply in cover and/or number of individuals, five forbs avoided by voles increased, and two forbs neither declined nor increased with either measure. Reductions of diversity occurred when voles first defoliated the plots in 2000 but disappeared as plant species avoided by voles replaced vulnerable plants. Within six years, meadow voles created plant communities dominated by species that they did not eat.  相似文献   
100.
This study is a part of an ongoing investigation of the types and locations of emission sources that contribute fine particulate air contaminants to Underhill, VT. The air quality monitoring data used for this study are from the Interagency Monitoring of Protected Visual Environments network for the period of 2001-2003 for the Underhill site. The main source-receptor modeling techniques used are the positive matrix factorization (PMF) and potential source contribution function (PSCF). This new study is intended as a comparison to a previous study of the 1988-1995 Underhill data that successfully revealed a total of 11 types of emission sources with significant contributions to this rural site. This new study has identified a total of nine sources: nitrate-rich secondary aerosol, wood smoke, East Coast oil combustion, automobile emission, metal working, soil/dust, sulfur-rich aerosol type I, sulfur-rich aerosol type II, and sea salt/road salt. Furthermore, the mass contributions from the PMF identified sources that correspond with sampling days with either good or poor visibility were analyzed to seek possible correlations. It has been shown that sulfur-rich aerosol type I, nitrate aerosol, and automobile emission are the most important contributors to visibility degradation. Soil/dust and sea salt/road salt also have an added effect.  相似文献   
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