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291.
Nelson A. Kelly Martin A. Ferman George T. Wolff 《Journal of the Air & Waste Management Association (1995)》2013,63(2):150-158
This analysis represents the first characterization of the photochemistry and transport of ozone in the Detroit metropolitan area and provides a basis for comparing data for Detroit to that for other cities. The characterization is based on a comprehensive set of meteorological and chemical measurements obtained at a site in the urban core of Detroit during the summer of 1981, together with measurements of O3, nitrogen oxides (NO X ), and nonmethane organic compounds (NMOC) from rural, suburban, and urban areas in southeastern Michigan and adjacent areas of Ontario. For the quartile (23 days) with highest ozone maxima (97-180 ppb), the maxima occurred 10-70 km north-northeast of the city on days that were warm and hazy with light southsouthwest winds. On such days there was a marked accumulation of ozone precursors (NMOC and NOX) in the early morning, as well as a rapid chemical removal of NO X (NO X half-life of ~5 h) from morning to midday. The timing of the daily ozone increase across the study region suggests that local photochemical generation in a moving plume was responsible for more than half of the ozone measured downwind. However, there was also evidence that ozone transported into Detroit as part of the regional background was a significant part of the O3 maxima on high ozone days. The average contributions of photochemistry and transport for the 23 days with the highest ozone maxima were estimated to be 57 ppb and 47 ppb, respectively. 相似文献
292.
George T. Wolff Nelson A. Kelly Martin A. Ferman Martin S. Ruthkosky David P. Stroup Patricia E. Korsog 《Journal of the Air & Waste Management Association (1995)》2013,63(5):585-591
During August, 1982 and January and February, 1983, General Motors Research Laboratories operated air monitoring sites on the Atlantic Coast near Lewes, Delaware and 1250 km to the east on the southwest coast of Bermuda. The overall purpose of this project was to study the transformations of the principal acid precipitation precursors, NO x and SO x species, as they transport under conditions not complicated by emissions from local sources. In this paper, the measurements of gas and particulate species from Lewes are described and the composition and sources of sulfate aerosol, which is the most important haze-producing species, are investigated. On the average, the total suspended particulate (TSP) concentration was 27.9 μg/m3 while the PM10 (mass of particles with a diameter less than or equal to 10 μm) concentration was 22.0 μg/m3 or 79 percent of the TSP. The PM10 consisted of 6.1 μg/m3 of coarse particles (CPM, diameter = 2.5 ? 10μm) and 15.9 μg/m3 of fine particles (FPM, diameter < 2.5 μm). On a mass basis the most important constituents of the fine particulate fraction were sulfate compounds, 50 percent, and organic compounds, 30 percent. The mean light extinction coefficient corresponds to a visual range of 18-20 km. Most of the extinction can be attributed to the sulfate (60 percent) and organic carbon (13 percent). Particle size measurements show that the mass median aerodynamic diameter for both species is 0.43 μm. This is a typical size for a hydrated sulfate aerosol. For carbon, however, this is a larger size than previously reported and results in a more efficient light scattering aerosol. Principal component analyses indicate that coal combustion emissions from the midwestern U.S. are the most significant source of sulfate in Lewes during the summer and winter. 相似文献
293.
Halogenated 1'methyl-1,2'-bipyrroles (MBPs) have been identified worldwide in marine mammals. Here we present the tentative identification of previously undetected MBP congeners in Delpinus delphis blubber using gas chromatography/electron capture negative ion mass spectrometry (GC/ECNI-MS) and comprehensive two-dimensional gas chromatography/time of flight mass spectrometry (GCxGC/TOF-MS). This is the first report of 26 congeners. The presence of numerous partially halogenated congeners suggests that they are either biosynthesized concomitantly with their perhalogenated counterparts or that their dehalogenation products can also bioaccumulate. The newly found compounds fit the geographic trend that has been previously noted. That is, samples from the Atlantic Ocean are dominated by the more brominated congeners while those from the Pacific are dominated by the more chlorinated congeners. 相似文献
294.
Darbah JN Kubiske ME Nelson N Oksanen E Vapaavuori E Karnosky DF 《Environmental pollution (Barking, Essex : 1987)》2008,155(3):446-452
We studied the effects of long-term exposure (nine years) of birch (Betula papyrifera) trees to elevated CO(2) and/or O(3) on reproduction and seedling development at the Aspen FACE (Free-Air Carbon Dioxide Enrichment) site in Rhinelander, WI. We found that elevated CO(2) increased both the number of trees that flowered and the quantity of flowers (260% increase in male flower production), increased seed weight, germination rate, and seedling vigor. Elevated O(3) also increased flowering but decreased seed weight and germination rate. In the combination treatment (elevated CO(2)+O(3)) seed weight is decreased (20% reduction) while germination rate was unaffected. The evidence from this study indicates that elevated CO(2) may have a largely positive impact on forest tree reproduction and regeneration while elevated O(3) will likely have a negative impact. 相似文献
295.
The ecological role and the association of Hippolyte zostericola (Smith, 1873) (Decapoda: Natantia) with different seagrass species in the Indian River Lagoon (Florida, USA) were investigated
through field sampling and the analysis of diet, size–frequency distributions and laboratory experiments. Gut contents suggested
that H. zostericola is a mesograzer which may be important in the transfer of primary production to higher trophic levels. Population size–frequency
distributions showed a polymodal pattern variable according to the site. Preference experiments indicated that choice of seagrass
species is not influenced by the available surface area of seagrass blades, nor by the presence of epiphytic food. Significant
responses of the shrimp to the ambient light field, mediated by the seagrass canopy, were detected. A clear negative phototropism
was observed for H. zostericola which may be an adaptive response to improve avoidance of visual predators.
Received: 1 February 1998 / Accepted: 21 December 1998 相似文献
296.
de Souza Camila da Costa Barros García Andrés Calderín Lima Erica Souto Abreu do Amaral Sobrinho Nelson Moura Brasil 《Journal of Material Cycles and Waste Management》2023,25(4):2232-2244
Journal of Material Cycles and Waste Management - This study aimed to elucidate the formation process of humic substances (HS) during poultry litter (PL) composting and its influence on the... 相似文献
297.
Schneider RP Morano SC Gigena MA Missawa SK Rocha RC Da Silva LR Ellert N Kataoka S Katsuragi C Rosa Cda S Filho LC 《Environmental monitoring and assessment》2006,116(1-3):21-52
Five priority areas of potential impact by contaminants (API) were investigated at the Presidente Bernardes Refinery in Cubatão, São Paulo, Brazil with the following aims: (i) to identify both organic and inorganic contaminants present in soil and groundwater; (ii) to define the environmental conditions relevant for microbial activity at the site and (iii) to evaluate the feasibility of employing natural attenuation for treatment of the hydrocarbon contamination. One area (API 1) was an uncontrolled landfill, where waste materials from the refinery were deposited between 1954 and 1986, and four areas (API 4, 5, 7 and 11) were located in the operational section of the refinery. Soil contamination by regulated BTEX compounds (benzene, toluene, total xylenes) was restricted to two samples from API 1. Nonregulated ethylbenzene was detected in one soil sample from API 4, one from API 5 and two from API 1. No soil contained regulated PAH above threshold levels. Several nonregulated PAHs were found in 6 soil samples from API 1, 3 soil samples from API 4 and 1 soil sample from API 5. Site soils contained very high aluminium concentrations, but metal contamination was restricted to one soil sample from API 1, which contained nickel above threshold limits. BTEX contamination of groundwater was due mostly to benzene. Of the 17 PAH molecules tested, only naphthalene and 2-methylnaphthalene occurred in groundwater. The sum of total BTEX and total PAH exceeded 200 μg/L in only a few monitoring wells in API 4, 5 and 11 and was always below 2.640 μg/L. Be, Cd, Cr, Cu, Hg, Ni, Se, Ag, Tl and Zn were not detected in groundwater, which was contaminated in a few locations by aluminium (mostly below 1 mg/L), lead (<0.066 mg/L) and arsenic (<0.056 mg/L). S, K, Ca, Mg and Fe were present in groundwater in excess of physiological requirements for microbial growth, but low concentrations of N and P could become growth limiting. However, BTEX were efficiently degraded in saturated and unsaturated zone microcosms and nutrient amendments did not stimulate biodegradation rates measurably. The inorganic carbon pool in groundwater was up to one order of magnitude larger than the organic carbon pool. Total inorganic carbon (TIC) in API groundwater exceeded TIC of clean groundwater by factors of 2 (API 4), 6 (API 5, 7 and 11) or 10 (API 1). Most of the inorganic carbon incorporated into groundwater beneath the refinery originated from biodegradation in the unsaturated soil, which contained a microbiota (106 cells/g on average) capable of growth with most of the pure (benzene, toluene, ethylbenzene and xylene) and mixed hydrocarbons tested (diesel oil, gasoline, naphtha, condensate, aromatic residue and fuel oil). A viscous hydrocarbon paste uncovered in API 1 was insoluble in water but dissolved in dichloromethane. Many organic components of this paste were biodegradable as evidenced by weight reduction of the hydrocarbon paste and by the growth of suspended and attached biomass in saturated zone microcosms, where the paste was the only carbon source. This study indicates that monitored natural attenuation may be a technically feasible and efficient means for plume control in API 1, 4 and 5, provided the plumes in API 4 and 5 are not expanding. This technique is not suitable for contaminant reduction in API 11. 相似文献
298.
Lake Vela, located in the Portuguese littoral-centre, is a temperate shallow lake exhibiting a high trophic status. This aquatic
ecosystem has been potentially exposed to contamination generated by agricultural and livestock activities held in their drainage
basin, which seriously compromise their health. This work summarizes some background information and presents the problem
formulation step of the ERA. Therefore, it evaluates the characteristics of the stressor(s), describes the ecological system
and receptors and suggests a conceptual model, which predicts the potential exposure pathways, relating suspected sources
to the defined endpoints. This introductory step also described an analysis plan on the entire study, which includes a delineation
of the assessment design, data needs, measures, and methods for conducting the analysis phase of the risk assessment process. 相似文献
299.
Prior SA Torbert HA Runion GB Rogers HH Ort DR Nelson RL 《Journal of environmental quality》2006,35(4):1470-1477
Elevated atmospheric CO2 can result in larger plants returning greater amounts of residue to the soil. However, the effects of elevated CO2 on carbon (C) and nitrogen (N) cycling for different soybean varieties have not been examined. Aboveground residue of eight soybean [Glycine max (L.) Merr.] varieties was collected from a field study where crops had been grown under two different atmospheric CO2 levels [370 micromol mol(-1) (ambient) and 550 micromol mol(-1) (free-air carbon dioxide enrichment, FACE)]. Senesced residue material was used in a 60-d laboratory incubation study to evaluate potential C and N mineralization. In addition to assessing the overall effects of CO2 level and variety, a few specific variety comparisons were also made. Across varieties, overall residue N concentration was increased by FACE, but residue C concentration was only slightly increased. Overall residue C to N ratio was lower under FACE and total mineralized N was increased by FACE, suggesting that increased N2 fixation impacted residue decomposition; total mineralized C was also slightly increased by FACE. Across CO2 levels, varietal differences were also observed with the oldest variety having the lowest residue N concentration and highest residue C to N ratio; mineralized N was lowest in the oldest variety, illustrating the influence of high residue C to N ratio. It appears (based on our few specific varietal comparisons) that the breeding selection process may have resulted in some varietal differences in residue quality which can result in increased N or C mineralization under elevated CO2 conditions. This limited number of varietal comparisons indicated that more work investigating varietal influences on soil C and N cycling under elevated CO2 conditions is required. 相似文献
300.
Survival of juvenile bay scallops, Argopecten irradians, after 96 h of exposure to mercury at various salinity and temperature regimes was studied. Scallop survival was significantly affected by mercury concentration and by salinity, as well as by the interaction between temperature and concentration and between temperature and salinity. Toxicity of mercury at low concentrations was enhanced by high temperature and low salinity, whereas at high mercury concentrations this effect diminished. 相似文献