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91.
Joseph D. McCain John P. Gooch Wallace B. Smith 《Journal of the Air & Waste Management Association (1995)》2013,63(2):117-121
This paper presents results of source size distribution measurements over the size range from 0.1 μm to 5 μm for six classes of particulate sources and fractional efficiency measurements on five full scale electrostatic precipitators and one pilot scale precipitator. The precipitators all showed moderately high to high particulate collection efficiencies for particles having diameters larger than a few micrometers or smaller than a few hundredths of a micrometer and a minimum in collection efficiency for particles having diameters of a few tenths of a micrometer. 相似文献
92.
Chemical defenses are thought to contribute to the invasion success and impacts of many introduced plants; however, for most
of these species, little is known about these compounds and how they vary in natural environments. Plant allelochemical concentrations
may be affected by a variety of abiotic and biotic factors, including soil nutrients and herbivores. Moreover, such quantitative
variation is likely to play an important role in species interactions involving these invasive plants. The purpose of this
study was to examine patterns of variation in iridoid glycoside concentrations of the invasive plant Linaria dalmatica (Plantaginaceae). We conducted a greenhouse experiment to investigate the effect of soil nitrogen availability on iridoid
glycoside concentrations. Results from this experiment showed that plant iridoid glycoside concentrations decreased with increased
nitrogen availability. Additionally, plants were collected from multiple field sites in order to characterize the influence
of population, soil nitrogen availability, and herbivore attack on iridoid glycoside variation. Results from field studies
indicated that plants demonstrated considerable seasonal variation, as well as variation within and among populations, with
iridoid glycoside concentrations ranging from approximately 1 to 15% dry weight. The relationship between soil nitrogen and
plant iridoid glycosides varied among populations, with a strong negative correlation in one population, a marginally significant
negative relationship in a second population, and no relationship in the remaining two populations. Additionally, we found
a negative relationship between iridoid glycoside concentrations and plant injury by an introduced biocontrol agent, the stem-mining
weevil Mecinus janthinus (Cucurlionidae). These results show that plant allelochemical concentrations can vary widely in natural environments and
suggest that levels of plant defense may be reduced by increased soil nitrogen availability and herbivore attack in this invasive
plant species. 相似文献
93.
De Maria S Rivelli AR Kuffner M Sessitsch A Wenzel WW Gorfer M Strauss J Puschenreiter M 《Chemosphere》2011,84(9):1256-1261
Although the beneficial effects on growth and trace element accumulation in Salix spp. inoculated with microbes are well known, little information is available on the interactions among trace elements and macronutrients. The main purpose of this study was to assess the effect of phytoaugmentation with the rhizobacteria Agromyces sp., Streptomyces sp., and the combination of each of them with the fungus Cadophora finlandica on biomass production and the accumulation of selected trace elements (Zn, Cd, Fe) and macronutrients (Ca, K, P and Mg) in Salix caprea grown on a moderately polluted soil. Dry matter production was significantly enhanced only upon inoculation with Agromyces sp. Regarding the phytoextraction of Cd and Zn, shoot concentrations were mostly increased after inoculation with Streptomyces sp. and Agromyces sp. + C. finlandica. These two treatments also showed higher translocation factors from roots to the leaves for both Cd and Zn. The accumulation of Cd and Zn in shoots was related to increased concentrations of K. This suggests that microorganisms that contribute to enhanced phytoextraction of Cd and Zn affect also the solubility and thus phytoavailability of K. This study suggests that the phytoextraction of Zn and Cd can be improved by inoculation with selected microbial strains. 相似文献
94.
Bradley S. Williams Ellen D’Amico Jude H. Kastens James H. Thorp Joseph E. Flotemersch Martin C. Thoms 《Environmental monitoring and assessment》2013,185(9):7485-7499
River systems consist of hydrogeomorphic patches (HPs) that emerge at multiple spatiotemporal scales. Functional process zones (FPZs) are HPs that exist at the river valley scale and are important strata for framing whole-watershed research questions and management plans. Hierarchical classification procedures aid in HP identification by grouping sections of river based on their hydrogeomorphic character; however, collecting data required for such procedures with field-based methods is often impractical. We developed a set of GIS-based tools that facilitate rapid, low cost riverine landscape characterization and FPZ classification. Our tools, termed RESonate, consist of a custom toolbox designed for ESRI ArcGIS®. RESonate automatically extracts 13 hydrogeomorphic variables from readily available geospatial datasets and datasets derived from modeling procedures. An advanced 2D flood model, FLDPLN, designed for MATLAB® is used to determine valley morphology by systematically flooding river networks. When used in conjunction with other modeling procedures, RESonate and FLDPLN can assess the character of large river networks quickly and at very low costs. Here we describe tool and model functions in addition to their benefits, limitations, and applications. 相似文献
95.
Alan T. Herlihy Jean Sifneos Chris Bason Amy Jacobs Mary E. Kentula M. Siobhan Fennessy 《Environmental management》2009,44(2):369-377
We sampled 92 wetlands from four different basins in the United States to quantify observer repeatability in rapid wetland
condition assessment using the Delaware Rapid Assessment Protocol (DERAP). In the Inland Bays basin of Delaware, 58 wetland
sites were sampled by multiple observers with varying levels of experience (novice to expert) following a thorough training
workshop. In the Nanticoke (Delaware/Maryland), Cuyahoga (Ohio), and John Day (Oregon) basins, 34 wetlands were sampled by
two expert teams of observers with minimal protocol training. The variance in observer to observer scoring at each site was
used to calculate pooled standard deviations (SDpool), coefficients of variation, and signal-to-noise ratios for each survey. The results showed that the experience level of
the observer had little impact on the repeatability of the final rapid assessment score. Training, however, had a large impact
on observer to observer repeatability. The SDpool in the Inland Bay survey with training (2.2 points out of a 0–30 score) was about half that observed in the other three basins
where observers had minimal training (SDpool = 4.2 points). Using the results from the survey with training, we would expect that two sites assessed by different, trained
observers who obtain DERAP scores differing by more than 4 points are highly likely to differ in ecological condition, and
that sites with scores that differ by 2 or fewer points are within variability that can be attributed to observer differences. 相似文献
96.
Robert R. Arnts Robert L. Seila Joseph J. Bufalini 《Journal of the Air & Waste Management Association (1995)》2013,63(4):453-460
A relative rate procedure was used to measure hydroxyl rate constants at room temperature in the presence of oxygen. The photolysis of methyl nitrite in the presence of nitric oxide was used to generate OH radicals. The rate of loss of the test compounds was measured relative to that of ethane (kOH = 2.74 × 10-13 cm3 molec-1 s-1). The rates obtained at 297 ± 2 K are: acetylene = (7.8 ± 1.6) × 10-13 cm3 molec-1 s-1,1,2-dichloroethane (2.8 ± Q.6) × 10-13 cm3 molec-1 s-1, 1,2-dibromoethane (2.4 ± 0.5) × 10-13 cm3 molec-1 s-1, p-dichlorobenzene (4.3 ± 0.9) × 10-13 cm3 molec-1 s-1 and carbon disulfide (29 ± 6) × 10-13 cm3 molec-1 s-1. Under a proposed EPA rule, this OH rate determination procedure could be used to determine if a given volatile organic will be subject to control for reduction of photochemical ozone. 相似文献
97.
98.
Joseph Greco Robert O. Ezzell John H. Lytle 《Journal of the Air & Waste Management Association (1995)》2013,63(9):877-880
The objective of this paper is to describe the Tennessee Valley Authority's efforts and plans in designing an operating and maintenance program that will ensure maximum performance of the electrostatic precipitators at our power generating stations. Detailed operating and maintenance manuals are being prepared for each plant for the use of plant personnel. These manuals include instructions on operation, maintenance, and testing of the precipitators. Instructions on internal and external equipment inspections to be performed during unit operation, emergency and scheduled outages, and problem diagnostic procedures are included to help the plant personnel solve problem areas. Performance curves are included in the manuals which show the effect of gas volume flow, gas temperature, gas resistivity, coal changes, and loss of transformer-rectifier sets on the precipitator performance. In addition, opacity monitors that record continuous opacity readings are being installed at all our plants to assist the plant in monitoring precipitator performance. Full-time operating and maintenance crews are being organized at the plants to monitor and maintain the precipitator and ash-removal systems. Also, a staff of technical personnel is being organized at the central office to provide technical advice and assistance in design, operation, and maintenance problems and liaison and coordination for all the plants concerning the precipitators. Periodic precipitator field inspections, performance and operating parameter optimization testing, and review of the equipment operating logs are made by the central office technical personnel. Recommendations and technical assistance are then furnished to the plant with regard to the precipitator overall performance and operating characteristics. 相似文献
99.
Thomas M. Baines Joseph H. Somers Craig A. Harvey 《Journal of the Air & Waste Management Association (1995)》2013,63(6):616-621
For the past several years, EPA has been measuring particulate emissions from a variety of heavy-duty diesel engines through contracts with Southwest Research Institute. Particulate emissions samples have been collected using an exhaust splitter to divert a fraction of the engine exhaust into a standard dilution tunnel. A small fraction of the diluted exhaust from the tunnel is pulled through a filter from which particulate mass and, in some cases, organic content of the particulate is determined. This paper discusses the sampling system and gives particulate emission factors that have been computed from truck and bus fuel consumption data as well as average truck and bus speed data from New York and Los Angeles (freeway and nonfreeway usage). Average particulate emission test results (steady state tests) for 2-stroke engines were 4.74 g/kg fuel and for 4-stroke engines were 2.64 g/kg fuel. Using average particulate emissions results, a particulate emission factor range of 0.8 to 1.3 g/km was computed. Nationwide diesel particulate emissions were calculated to be 88,000 metric tons per year. 相似文献
100.