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101.
Effects of glyphosate and foliar amendments on activity of microorganisms in the soybean rhizosphere
Nathan E. Means Robert J. Kremer Clifford Ramsier 《Journal of environmental science and health. Part. B》2013,48(2):125-132
A field study was conducted to determine the effects of glyphosate on microbial activity in the rhizosphere of glyphosate-resistant (GR) soybean and to evaluate interactions with foliar amendments. Glyphosate at 0.84 kg ae ha? 1 was applied GR soybean at the V4–V5 development stages. Check treatments included a conventional herbicide tank mix (2003 study only) and no herbicides (hand-weeded). Ten days after herbicide application, a commercially available biostimulant and a urea solution (21.0% N) were applied to soybean foliage at 33.5 mL ha? 1 and 9.2 kg ha? 1, respectively. Soil and plant samples were taken 0, 5, 10, 15, 20 and 25 days after herbicide application then assayed for enzyme and respiration activities. Soil respiration and enzyme activity increased with glyphosate and foliar amendment applications during the 2002 growing season; however, similar increases were not observed in 2003. Contrasting cumulative rainfall between 2002 and 2003 likely accounted for differences in soil microbial activities. Increases in soil microbial activity in 2002 suggest that adequate soil water and glyphosate application acted together to increase microbial activity. Our study suggests that general soil microbial properties including those involving C and N transformations are not sensitive enough to detect effects of glyphosate on rhizosphere microbial activity. Measurements of soil-plant-microbe relationships including specific microbial groups (i.e., root-associated Fusarium spp.) are likely better indicators of impacts of glyphosate on soil microbial ecology. 相似文献
102.
George F. Antonious Lauren Lobel Tejinder Kochhar Terry Berke Robert L. Jarret 《Journal of environmental science and health. Part. B》2013,48(6):621-626
The main objective of this investigation was to evaluate fruits of C. chinense accessions for their concentration of β -carotene, ascorbic acid, and phenols for use as parents in breeding for these phytochemicals. Mature fruits of 63 accessions of C. chinense originally acquired from Belize, Brazil, Colombia, Ecuador, Mexico, Peru, Puerto Rico, and the United States were analyzed for their chemical composition. Fruits of C. chinense accessions PI-152452 (Brazil) and PI-360726 (Ecuador) contained the greatest concentrations of ascorbic acid (1.2 and 1.1 mg g?1 fresh fruit, respectively), while PI-438648 (Mexico) contained the greatest concentration of total phenols content (349 μ g g?1 fresh fruit) among the other 63 accessions tested. Accession PI-355817 from Ecuador contained the greatest concentrations of β -carotene (8 mg g?1fresh fruit). These accessions were identified as potential candidates for mass production of antioxidants with health-promoting properties. 相似文献
103.
Robert J. Tidona Ahtisham A. Nizami Nicholas P. Cernansky 《Journal of the Air & Waste Management Association (1995)》2013,63(6):806-811
Experiments were carried out to determine the relative chemiluminescence quenching efficiencies as a function of third body concentration for each of the common combustion products, H2O, CO2, CO, H2, O2 and Ar. These results are compared with those of other investigators. The effect of reaction chamber pressure on analyzer response and the development of an analyzer design which incorporates an adjustable sample capillary inlet capable of maintaining a constant molar flow rate of sample gas to the reaction chamber are discussed. The effect of carbon monoxide interference on chemiluminescent NOx measurement has been isolated and found to be significant. A means of correcting NO, measurements for these CO interference effects is described. Quantification of NO and NO2 absorption in liquid water in NOx sampling systems has been made. Recommendations for sample system designs to handle the presence of water in the sample gas are made. 相似文献
104.
JoAnn S. Lighty Robert M. Britt David W. Pershing Warren D. Owens Vic A. Cundy 《Journal of the Air & Waste Management Association (1995)》2013,63(2):187-193
With landfill costs increasing and regulations on landfilling becoming more stringent, alternatives to conventional hazardous waste treatment strategies are becoming more desirable. Incineration Is presently a permanent, proven solution for the disposal of most organic contaminants, but also a costly one, especially in the case of solids which require some auxiliary fuel. The goal of this research is to develop an understanding of the phenomena associated with the evolution of contaminants from solids In the primary combustor of an Incineration system. A four-fold approach is being used. First, a bench-scale particle characterization reactor was developed to study the transport phenomena on a particle basis, where the controlling processes are mainly intraparticle. Second, a bed-characterization reactor was built to examine the controlling transport phenomena within a bed of particles, where the processes are primarily interparticle. The results of these studies can be applied to any primary combustor. A pilot-scale rotary kiln was developed to study the evolution of contaminants from solids within a realistic temperature and rotation environment. Finally, in situ measurements are being obtained from a full-scale rotary-kiln. This paper describes results obtained in a study using a commercial sorbent contaminated with toluene. The data are from the particle-characterization reactor and the rotary-kiln simulator. The results show that the method of contamination and charge size do not have a large effect on desorption, while temperature and contaminant concentration are important parameters In the evolution of contaminants in a rotary kiln. 相似文献
105.
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
106.
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
107.
Robert C. Pegnam Michael J. Pilat 《Journal of the Air & Waste Management Association (1995)》2013,63(3):303-308
Particulate mass concentration, particle size distribution, and particle chemical composition measurements have been conducted on the gases exhausting from a chromic acid anodizing process tank. Particle mass concentrations in the 200 to 20,000 μg/m3 range were measured using open-faced filters (47 mm diameter) adjacent to the process tank liquid and with closed filters (90 mm diameter) in the exhaust duct. Particle size distributions, measured using University of Washington Mark 3 and Mark 20 Cascade Impactors, showed the particle aerodynamic mass median diameter was about 3 microns. Chemical analysis of the particle samples obtained by the Modified EPA Method 5 sampling train, the Mark 20 UW Cascade Impactors, and by the 47 mm and 90 mm diameter filters showed Cr+6 concentrations in the 20 to 1,500 μg/m3 range with over 99 percent of the chromium in particles larger than 1.0 microns diameter. An integrating nephelometer was used to measure the light scattering coefficient of the exhaust gases upstream of the wet scrubber. The light scattering coefficient increased by a factor of about 2–3 over the background level during the 40 minute time period while a part was being anodized. The bscat values ranged from 3 × 10?5 to 3 × 10?4 meters?1 for the aerosol particles less than about 6 microns aerodynamic diameter. 相似文献
108.
Robert F. Mouradiarn Steven P. Levine Hui-Qiong Ke Herbert H. Alvord 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1067-1072
Direct inlet gas chromatography (GC) is becoming one of the most frequently used techniques for measurement of volatile organics in air. Although GC is an effective tool, its usefulness as a field method can be limited by retention times of several minutes or more, and by the limits of detection. In order to address these issues, a high speed GC system featuring a capillary cold trap inlet and variable speed electrometeramplifier was developed and tested. The gas cooled inlet was used to collect and focus organic vapors from injection volumes of up to 1 ml. Resistance heating of the metal cold trap produced a narrow injection band that allowed simple separations to be completed in 5 to 20 seconds. Use of a variable speed electrometer-amplifier allowed the response time and noise suppression characteristics to be adjusted to the needs of the specific analysis. Simple mixtures of organics including aromatics, alkanes and chlorinated hydrocarbons were separated in 20 seconds or less. The limits of detection for 13 test compounds ranged from less than 1 part per billion by volume (ppbv) to about 50 ppbv. Data presented here indicate that high speed GC using a cold trap inlet may be a feasible approach for near real-time measurement of volatile organics in ambient air. 相似文献
109.
Robert McBrien Stephen Ramsay Gregory Crooks 《Journal of the Air & Waste Management Association (1995)》2013,63(8):725-733
Abstract This paper demonstrates how wind tunnel modeling data that accurately describe plume characteristics near an unconventional emission source can be used to improve the near-field downwind plume profiles predicted by conventional air pollution dispersion models. The study considers a vertical, cylindrical-shaped, elevated bin similar to large product storage bins that can be found at many industrial plant sites. Two dispersion models are considered: the U.S. Environmental Protection Agency's ISC2(ST) model and the Ontario Ministry of the Environment and Energy's GAS model. The wind tunnel study showed that plume behavior was contrary to what was predicted using conventional dispersion models such as ISC2(ST) and GAS and default values of input parameters. The wind tunnel data were used to develop a protocol for correcting the dispersion models inputs, resulting in a substantial improvement in the accuracy of the dispersion estimates. 相似文献
110.
Gerald P. Huffman Frank E. Huggins Naresh Shah Robert Huggins William P. Linak C. Andrew Miller 《Journal of the Air & Waste Management Association (1995)》2013,63(7):1106-1114
ABSTRACT Combustion experiments were carried out on four different residual fuel oils in a 732-kW boiler. PM emission samples were separated aerodynamically by a cyclone into fractions that were nominally less than and greater than 2.5 |j.m in diameter. However, examination of several of the samples by computer-controlled scanning electron microscopy (CCSEM) revealed that part of the PM2.5 fraction consists of carbonaceous cenospheres and vesicular particles that range up to 10 |j.m in diameter. X-ray absorption fine structure (XAFS) spectroscopy data were obtained at the S, V, Ni, Fe, Cu, Zn, and As K-edges and at the Pb L-edge. Deconvolution of the X-ray absorption near edge structure (XANES) region of the S spectra established that the dominant molecular forms of S present were sulfate (26-84% of total S) and thiophene (13-39% of total S). Sulfate was greater in the PM2.5 samples than in the PM25+ samples. Inorganic sulfides and elemental sulfur were present in lower percentages. The Ni XANES spectra from all of the samples agreed fairly well with that of NiSO4, while most of the V spectra closely resembled that of vanadyl sulfate (VO?SO4?xH2O). The other metals investigated (i.e., Fe, Cu, Zn, and Pb) also were present predominantly as sulfates. Arsenic was present as an arsen-ate (As+5). X-ray diffraction patterns of the PM2.5 fraction exhibit sharp lines due to sulfate compounds (Zn, V, Ni, Ca, etc.) superimposed on broad peaks due to amorphous carbons. All of the samples contain a significant organic component, with the loss on ignition (LOI) ranging from 64 to 87% for the PM2.5 fraction and from 88 to 97% for the PM2.5+ fraction. Based on 13C nuclear magnetic resonance (NMR) analysis, the carbon is predominantly condensed in graphitic structures. Aliphatic structure was detected in only one of seven samples examined. 相似文献