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581.

The objectives of this study were to assess sorption and desorption of tylosin, a macrolide antimicrobial chemical used in swine, cattle, and poultry production, in three silty clay loam soils of South Dakota and compare soil sorption to sand and manure sorption. The silty clay loam soils, from a toposequence in eastern South Dakota, standardized sand samples, and swine manure were used in 24-h batch sorption studies with tylosin concentrations ranging from 25 to 232 μ mole/L. Desorption from soil was conducted over a four-day period. Partition coefficients, based on the Freundlich isotherm (K f ) or K d values, were calculated. K f values for the silty clay loams were similar, not influenced by landscape position, and averaged 1350 with isotherm slopes ranging from 0.85 to 0.93. K f values for sand were dependent on solution/sand ratios and pH, ranging from 1.4 to 25.1. K d values of manure were dependent on the solution type and ranged from 840 L/kg with urine to about 175 L/kg when sorbed from water. Desorption of tylosin from each soil over the four-day period was < 0.2% of the amount added. The soils' high K f values and low desorption amounts suggest that once tylosin is in these soils, leaching to lower depths may not occur. However, this does not preclude runoff with soil eroded particles. If tylosin reaches a sand aquifer, through bypass flow or other mechanism(s), movement in the aquifer most likely would occur.  相似文献   
582.
Abstract

This paper presents the simulation and field evaluation results of two approaches to localize pollutant emission sources with open-path Fourier transform infrared (OPFTIR) spectroscopy. The first approach combined the plume’s peak location information reconstructed from the Smooth Basis Function Minimization (SBFM) algorithm and the wind direction data to calculate source projection lines. In the second approach, the plume’s peak location was determined with the Monte Carlo methodology by randomly sampling within the beam segment having the largest path-integrated concentration. We first conducted a series of simulation studies to investigate the sensitivity of using different basis functions in the SBFM algorithm. It was found that fitting with the beta and Weibull basis functions generally gave better estimates of the peak locations than with the normal basis function when the plumes were mainly within the OP-FTIR’s monitoring line. However, for plumes that were symmetric to the peak position or spread over the OP-FTIR, fitting with the normal basis function gave better performance. In the field experiment, two tracer gases were released simultaneously from two locations and the OP-FTIR collected data downwind from the sources with a maximum beam path length of 97 m. For the first approach, the release locations were within the 0.25- to 0.5-probability area only after the uncertainty of the peak locations was included in the calculation process. The second approach was easy to implement and still performed as satisfactorily as the first approach. The distances from the sources to the best-fit lines (i.e., the regression lines) of the estimated locations were smaller than 10 m.  相似文献   
583.
ABSTRACT

This paper compares three analytical methods that are often used to analyze composition of atmospheric aerosol: Ion Chromatography (IC), Proton Induced X-ray Emission (PIXE), and X-Ray Fluorescence (XRF). Three monitoring studies are discussed: (1) a comparison of air particulate data collected by several independent sampler/ analytical technique suites run by different laboratories; (2) a study involving two identical samplers and a single suite of analytical techniques; and (3) analysis of identical aerosol samples by two different techniques (XRF vs. PIXE). While the XRF versus PIXE project shows a very good agreement for most elements, the first interlaboratory study demonstrates the “real-life” noise introduced into the final data set by various sampling complications and different collection characteristics of the samplers used. The XRF versus PIXE study also revealed an unexplained deviation in measured sulphur concentrations for very lightly loaded samples. In the five-sampler comparison, two data sets provided by IC were approximately 20% lower than the three data sets obtained by PIXE and XRF. When two identical IMPROVE-compat-ible samplers were used and samples were subjected to similar procedures and the same analytical techniques, the variability between the two air concentration data sets significantly decreased.  相似文献   
584.
The biodegradation conducted by microorganisms on herbicide glyphosate (N-phosphonomethylglycine) was investigated. Five strains of filamentous fungi belonging to the Fusarium genre were grown on Czapeck medium without phosphorous and supplemented with the addition of glyphosate. The assays were conducted to determine the ability of use as a phosphorous source, the inhibition caused by presence of herbicide, and the biodegradation in shaker and bioreactor by Fusarium strains. It was observed that the herbicide did not show any negative effect on microrganisms by quantity of the biomass. Among the strains tested, no inhibition was noted by the addition of glyphosate even at a high concentration. All strains studied were able to biodegrade it and use the herbicide as a phosphorous source. The formation of consortium was not better than the strains tested in pure culture. The biodegradation in the bioreactor was better than in the shaker. However, there wasn't any influence on biodegradation rate by changing the amount of oxygen in the system.  相似文献   
585.
Cellulase production was carried out by solid state bioconversion (SSB) method using rice straw, a lignocellulosic material and agricultural waste, as the substrate of three Trichoderma spp. and Phanerochaete chrysosporium in lab-scale experiments. The results were compared to select the best fungi among them for the production of cellulase. Phanerochaete chrysosporium was found to be the best among these species of fungi, which produced the highest cellulase enzyme of 1.43 IU/mL of filter paper activity (FPase) and 2.40 IU/mL of carboxymethylcellulose activity (CMCase). The “glucosamine” and “reducing sugar” parameters were observed to evaluate the growth and substrate utilization in the experiments. In the case of Phanerochaete Chrysosporium, the highest glucosamine concentration was 1.60 g/L and a high concentration of the release of reducing sugar was measured as 2.58 g/L obtained on the 4th day of fermentation. The pH values were also recorded. The range of the pH was about 5.15 to 5.56 in the case of Phanerochaete Chrysosporium.  相似文献   
586.
Combustion of residual, the most common type of fuel oil used in industrial and commercial steam generating plants, accounts for about 600,000 tons or 37 percent of the sulfur oxide emissions in New York state. On the average, residual oil available in New York state contains about 2.2 percent sulfur and is consumed at an annual rate of approximately 85 million barrels. The removal of sulfur from many types of residuals should become economically feasible as a result of the development of the HDS and H-Oil hydrodesulfurization processes. From studies recently made, these methods of desulfurization have been estimated to vary from a minimum of no appreciable increase in overall cost to a maximum of about one cent per gallon. The by-product distillates produced in hydrodesulfurization are a very significant factor in making the process economical and the demand for these is increasing at a greater rate than residual.  相似文献   
587.
This investigation was undertaken to determine the impact of the insecticides Dursban 480 EC (with organophosphate compound chlorpyrifos as the active ingredient) and Talstar 10 EC (with pyrethroid bifenthrin as the active ingredient) on the respiration activity and microbial diversity in a sandy loam luvisol soil. The insecticides were applied in two doses: the maximum recommended dose for field application (15 mg kg?1 for Dursban 480 EC and 6 mg kg?1 for Talstar 10 EC) and a 100-fold higher dose for extrapolation of their effect. Bacterial and fungal genetic diversity was analysed in soil samples using PCR DGGE and the functional diversity (catabolic potential) was studied using BIOLOG EcoPlates at 1, 3, 7, 14, 28, 56 and 112 days after insecticide application. Five bacterial groups (α, β, γ proteobacteria, firmibacteria and actinomycetes) and five groups of fungi or fungus-like microorganisms (Ascomycota, Basidiomycota, Chytridiomycota, Oomycota and Zygomycota) were analysed using specific primer sets. This approach provides high resolution of the analysis covering majority of microorganisms in the soil. Only the high-dose Dursban 480 EC significantly changed the community of microorganisms. We observed its negative effect on α- and γ-proteobacteria, as the number of OTUs (operational taxonomic units) decreased until the end of incubation. In the β-proteobacteria group, initial increase of OTUs was followed by strong decrease. Diversity in the firmibacteria, actinomycetes and Zygomycota groups was minimally disturbed by the insecticide application. Dursban 480 EC, however, both positively and negatively affected certain species. Among negatively affected species Sphingomonas, Flavobacterium or Penicillium were detected, but Achromobacter, Luteibacter or Aspergillus were supported by applied insecticide. The analysis of BIOLOG plates using AWCD values indicated a significant increase in metabolic potential of microorganisms in the soil after the high-dose Dursban application. Analysis of respiration demonstrated high microbial activity after insecticide treatments; thus, microbial degradation was relatively fast. The half-life of the active insecticide compounds were estimated within the range of 25 to 27 days for Talstar and 6 to 11 days for Dursban and higher doses stimulated degradation. The recommended dose levels of both insecticides can be considered as safe for microbial community in the soil.  相似文献   
588.
In this article, we study the use of thermally reduced graphene (TRG) for oil spill cleanup. TRG was synthesized by thermal exfoliation of graphite oxide and characterized by X-ray diffusion, Raman spectroscopy, SEM, TEM, elemental analysis, and Brunauer–Emmett–Teller (BET) surface area measurement. Various aspects of the sorption process have been studied including the sorption capacity, the recovery of the adsorbed oil, and the recyclability of TRG. Our results shows that TRG has a higher sorption capacity than any other carbon-based sorbents, with sorption capacity as high as 131 g of oil per gram TRG. With recovery of the sorbed oil via filtration and reuse of TRG for up to six cycles, 1 g of TRG collectively removes approximately 300 g of crude oil. Moreover, the effects of TRG bulk density, pore volume, and carbon/oxygen ratio and the oil viscosity on the sorption process are also discussed.  相似文献   
589.
The spatial distribution of persistent organic pollutants (POPs) was examined in soils surrounding the Tanggu Chemical Industrial District in Tianjin, China. The concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzenes (HCBs), and polychlorinated biphenyls (PCBs) were determined in 70 surface soils using accelerated solvent extraction and gas chromatography with electron capture detection. The results showed that the ranges of ∑HCH, ∑DDT, ΣHCB, and ∑PCB concentrations in soils were 2.1–12,549 μg?kg?1 (average, 965 μg?kg?1), n.d.–2,033 μg?kg?1 (average, 88.4 μg?kg?1), n.d.–1,924 μg?kg?1 (average, 349 μg?kg?1), and n.d.–373 μg?kg?1 (average, 46.2 μg?kg?1), respectively. Of these, HCHs were the dominant POPs, accounting for 75 % of the total organochlorine pesticide (OCP) residues. Overall, the spatial distribution of OCP concentrations showed a decreasing trend from the center of the Tanggu District to the surrounding areas. Two major pollution sources were Tianjin Dagu Chemical Co., Ltd. in the district center and the Tianjin Chemical Plant in Hangu District. In contrast, PCB concentrations were relatively high in the Haihe estuary to the east and low to the west of the study area. Component analysis of OCPs in these soils showed that they mainly came from industrial point sources. Compared with soils in other regions, soil DDT pollution was at a medium level in the Tanggu Chemical Industrial District, but associated HCH, HCB, and PCB pollution was relatively heavy. By multivariate statistical analyses, Tianjin Dagu Chemical Co., Ltd. was recognized as the main source of POPs, and soil properties were clarified to play an important role on the distribution and composition of POPs, especially the organic carbon content.  相似文献   
590.
The Bechtel Confined Zone Dispersion (CZD) process for FGD retrofit situations was tested at two sites: one at a level of 5 MWe; the other at 70 MWe. The CZD process involves injecting a finely atomized slurry of hydrated lime into a straight run of duct between a boiler's air heater and its electrostatic precipitator (ESP). The effect of process variables on SO2 removal and ESP performance was investigated for dolomitic/calcitic lime. Removals of SO2 in excess of 50 percent were achieved for either lime type at the 5 MWe site. A very short duct length limited injection rate at the 70 MWe site, limiting sulfur removals to a maximum of 30 percent. SO2 removal data for both sites were successfully correlated on a common basis. ESP performance was not fully acceptable during lime injection at both sites, but it is felt that optimization of ESP operations should eliminate this problem. Additional testing is recommended to further explore ESP performance and to optimize lime injection parameters. The results obtained to date continue to indicate that the CZD process is an attractive and economical candidate for FGD retrofit situations.  相似文献   
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