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151.
Ma BL Blackshaw RE Roy J He T 《Journal of environmental science and health. Part. B》2011,46(7):590-599
Knowledge about the prevalence and diversity of antibiotic resistance genes in soil bacteria communities is required to evaluate the possibility and ecological consequences of the transfer of these genes carried by genetically modified (GM) plants to soil bacteria. The neomycin phosphotransferase gene (nptII) conferring resistance to kanamycin and neomycin is one of the antibiotic resistance genes commonly present in GM plants. In this study, we investigated kanamycin-resistant (Km(R)) and neomycin-resistant (Nm(R)) soil bacterial populations in a 3-year field trial using a commercial GM corn (Zea mays L.) carrying the nptII gene and its near isogenic line. The results showed that a portion (2.3 - 15.6 %) of cultivable soil bacteria was naturally resistant to kanamycin or neomycin. However, no significant difference in the population level of Km(R) or Nm(R) soil bacteria was observed between the GM and non-GM corn fields. The nptII gene was not detected in any of the total 3000 Km(R) or Nm(R) isolates screened by PCR. Further, total soil bacterial cells were collected through Nycodenz gradient centrifugation and bacterial community DNA was subjected to PCR. Detection limit was about 500 cells per gram of fresh soil. Our study suggests that the nptII gene was relatively rare in the soil bacterial populations and there was no evidence of gene transfer from a GM corn plant to soil bacteria based on the data from total soil bacterial communities. 相似文献
152.
Grace B. Villamor Robert Gilmore Pontius Jr. Meine van Noordwijk 《Regional Environmental Change》2014,14(2):825-834
This paper examines the size and intensity of changes among five land categories during the two time intervals in a region of Indonesia that is pioneering negotiations concerning reducing emissions from deforestation and forest degradation (REDD). Maps at 1973, 1993, and 2005 indicate that land-cover change is accelerating, while carbon loss is decelerating in Jambi Province, Sumatra. Land dynamics have shifted from Forest loss during 1973–1993 to Agroforest loss during 1993–2005. Forest losses account for most reductions in aboveground carbon during the both time intervals, but Agroforest plays an increasingly important role in carbon reductions during the more recent interval. These results provide motivation for future REDD policies to count carbon changes associated with all influential land categories, such as Agroforests. 相似文献
153.
Gebbink WA Letcher RJ Burgess NM Champoux L Elliott JE Hebert CE Martin P Wayland M Weseloh DV Wilson L 《Environment international》2011,37(7):1175-1182
In the present study, we identified and examined the spatial trends, sources and dietary relationships of bioaccumulative perfluorinated sulfonate (PFSA; C(6), C(8), and C(10) chain lengths) and carboxylate (PFCA; C(6) to C(15) chain lengths) contaminants, as well as precursor compounds including several perfluorinated sulfonamides, and fluorotelomer acids and alcohols, in individual eggs (collected in 2008) from four gull species [glaucous-winged (Larus glaucescens), California (Larus californicus), ring-billed (Larus delawarensis) and herring (Larus argentatus) gulls] from 15 marine and freshwater colony sites in provinces across Canada. The pattern of PFSAs was dominated by perfluorooctane sulfonate (PFOS; >89% of ΣPFSA concentration) regardless of egg collection location. The highest ΣPFSA concentrations were found in the eggs collected in the urbanized areas in the Great Lakes and the St. Lawrence River area [Big Chicken Island 308 ng/g ww, Toronto Harbour 486 ng/g ww, and Ile Deslauriers (HG) 299 ng/g ww]. Also, eggs from all freshwater colony sites had higher ΣPFSA concentrations, which were significant (p<0.05) in many cases, compared to the marine sites with the exception of the Sable Island colony in Atlantic Canada off the coast of Nova Scotia. C(6) to C(15) chain length PFCAs were detected in the eggs, although the pattern was variable among the 15 sites, where PFUnA and PFTrA dominated the pattern for most colonies. Like the ΣPFSA, the highest concentrations of ΣPFCA were found in the eggs from Big Chicken Island, Toronto Harbour, Ile Deslauriers (HG), and Sable Island, although not all freshwater sites had higher concentrations compared to marine sites. Dietary tracers [δ(15)N and δ(13)C stable isotopes (SIs)] revealed that PFSA and PFCA exposure is colony dependent. SI signatures suggested that gulls from most marine colony sites were exposed to PFCs via marine prey. The exception was the Mandarte Island colony in Pacific British Columbia, where PFSA and PFCA exposure appeared to be via terrestrial and/or freshwater prey consumption. The same was true for the freshwater sites where egg SIs suggested both aquatic and terrestrial prey consumption as the source for PFC exposure depending on the colony. Both aquatic (marine and freshwater) and terrestrial prey are likely sources of PFC exposure to gulls but exposure scenarios are colony-specific. 相似文献
154.
155.
Russell M. Wise Graham P. von Maltitz Robert J. Scholes Chris Elphinstone Renee Koen 《Mitigation and Adaptation Strategies for Global Change》2009,14(7):579-604
Minimising the cost of repeatedly estimating C (C) stocks is crucial to the financial viability of projects that seek to sell
C credits. Depending on the price of C, this may imply less or more sampling effort than would be applied for science objectives.
In systems with heterogeneous C pools, such as savannas, this translates into a variable-effort sampling strategy that maximises
the marginal additional C that can be claimed per incremental unit of effort expended. Analysis of a savanna in north-eastern
South Africa indicates relatively modest returns per hectare due to the small C quantities and low sequestration rates. Under
these conditions, areas in excess of 1,000 ha and infrequent sampling frequencies of 5–10 years are required to make such
projects financially viable. For such projects the sample variance, number of samples, cost per sample and establishment costs
have negligible impacts on financial viability. It was also found that the soil-C pool contributes up to three times the net
returns of the aboveground C pool and provides a strong argument to monitor soil C for certification and market trading. The
financial viability estimates, however, do not include the management or opportunity costs incurred in changing the land use.
The economies of scale identified in this study combined with the massive area covered by savannas indicate that these additional
costs can be covered. Further research is recommended to quantify these costs and interrogate the feasibility of large scale
(in excess of 10,000 ha) C-sink projects in savanna systems. 相似文献
156.
Robert A. Leidy 《Conservation biology》2009,23(4):1060-1061
157.
Robert V. Hendriks Paul S. Nolan 《Journal of the Air & Waste Management Association (1995)》2013,63(4):432-438
This paper describes and discusses key design features of the retrofit of EPA’s Limestone Injection Multistage Burner (LIMB) system to an operating, wall-fired utility boiler at Ohio Edison’s Edgewater Station, based on the preliminary engineering design. It further describes results of pertinent projects in EPA's LIMB program and shows how these results were used as the basis for the design of the system. The full-scale demonstration is expected to prove the effectiveness and cost of the LIMB concept for use on large-scale utility boilers. To date, a preliminary engineering design for the Edgewater unit has been prepared incorporating the technology developed in smaller-scale studies. The schedule calls for system start-up by March 1987. EPA is engaged in a multiyear program to develop an improved control technology for emission of sulfur and nitrogen oxides from the combustion of fossil fuels. The technology involves staged-flow coal burners and injection of a reactive sorbeht into the furnace to reduce emissions. The program includes fundamental studies of reaction chemistry and kinetics, bench and pilot scale experimental studies, a full-scale demonstration, and economic and applicability studies. It is structured to establish a basis for future public sector commercialization, as well as help in understanding the technology’s controlling factors. 相似文献
158.
Harry M. Freeman Robert A. Olexsey 《Journal of the Air & Waste Management Association (1995)》2013,63(1):67-75
The 1984 Amendments to the Resource Conservation and Recovery Act (RCRA), called the Hazardous and Solid Waste Amendments, (HSWA) direct the EPA to determine if dioxin bearing wastes should be prohibited from landfills. This determination is to made by November 1986. Barring a determination by the Agency that the land disposal of dioxin wastes does not represent a threat to the environment, ot that appropriate alternative treatment technology is not available, a land disposal prohibition would go into effect at that time.1 The purpose of this paper is to discuss the state of the art for several treatment processes for dioxin wastes that have been proposed to be used instead of land disposal for disposing of solid and liquid wastes containing dioxins. 相似文献
159.
Robert L. Heath Allen S. Lefohn Robert C. Musselman 《Atmospheric environment (Oxford, England : 1994)》2009,43(18):2919-2928
Ozone interacts with plant tissue through distinct temporal processes. Sequentially, plants are exposed to ambient O3 that (1) moves through the leaf boundary layer, (2) is taken up into plant tissue primarily through stomata, and (3) undergoes chemical interaction within plant tissue, first by initiating alterations and then as part of plant detoxification and repair. In this paper, we discuss the linkage of the temporal variability of apoplastic ascorbate with the diurnal variability of defense mechanisms in plants and compare this variability with daily maximum O3 concentration and diurnal uptake and entry of O3 into the plant through stomata. We describe the quantitative evidence on temporal variability in concentration and uptake and find that the time incidence for maximum defense does not necessarily match diurnal patterns for maximum O3 concentration or maximum uptake. We suggest that the observed out-of-phase association of the diurnal patterns for the above three processes produces a nonlinear relationship that results in a greater response from the higher hourly average O3 concentrations than from the lower or mid-level values. The fact that these out-of-phase processes affect the relationship between O3 exposure/dose and vegetation effects ultimately impact the ability of flux-based indices to predict vegetation effects accurately for purposes of standard setting and critical levels. Based on the quantitative aspect of temporal variability identified in this paper, we suggest that the inclusion of a diurnal pattern for detoxification in effective flux-based models would improve the predictive characteristics of the models. While much of the current information has been obtained using high O3 exposures, future research results derived from laboratory biochemical experiments that use short but elevated O3 exposures should be combined with experimental results that use ambient-type exposures over longer periods of time. It is anticipated that improved understanding will come from future research focused on diurnal variability in plant defense mechanisms and their relationship to the diurnal variability in ambient O3 concentration and stomatal conductance. This should result in more reliable O3 exposure standards and critical levels. 相似文献
160.
Robert Perman Lester Goldner 《Journal of the Air & Waste Management Association (1995)》2013,63(10):472-475
Under the first Federal Air Pollution Act of 1955, which assigned the responsibility for developing a national program to the Public Health Service, a significant phase of the program involved other federal agencies through a series of contractual relationships. These interdepartmental relationships were limited however, to the objective of capitalizing on the diverse research facilities and specialized competencies within the federal establishment, as a means of accelerating the research and technical assistance program authorized under the act. With the passage of the Clean Air Act of 1963, a major new emphasis has been added to the federal air pollution control program—application of technical knowledge, through broadly accelerated control programs. This emphasis is reflected in current trends in the nature and type of the Public Health Service’s developing relationships with other federal agencies. The emerging PHS programs to prevent and control air pollution from federal facilities, the PHS role in preventing pollution arising from transportation systems aided under the new Urban Mass Transportation Act, and other developing interagency relationships and problem areas are discussed in this context. 相似文献