排序方式: 共有53条查询结果,搜索用时 15 毫秒
31.
32.
Alexey Voinov 《Environment, Development and Sustainability》2008,10(4):487-501
While there is no single definition of sustainability, most would agree that it implies that a system is to be maintained
at a certain level, held within certain limits. Sustainability denies run-away growth, but it also precludes any substantial
set backs or cuts. This sustainability path is hard to reconcile with the renewal cycle that can be observed in most living
systems developing according to their natural intrinsic mechanisms. Besides, since different human dominated systems are in
significantly different states and stages of development, sustaining those states assumes maintaining social disparities in
perpetuity. This creates a challenge in communicating the ideas of sustainability in different regions. Systems are parts
of hierarchies where systems of higher levels are made of subsystems from lower levels. Renewal in components is an important
factor of adaptation and evolution. But then sustainability of a system borrows from sustainability of a supra-system and
rests upon lack of sustainability in subsystems. Therefore by sustaining certain systems beyond their renewal cycle, we decrease
the sustainability of larger, higher level systems. The only way to resolve this contradiction is to agree that the biosphere
as a whole with humans as one of its components is the only system which sustainability we are to seek.
Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
33.
The development and regulatory acceptance of monitored natural attenuation (MNA) as a remedial strategy has forever changed the field of environmental cleanup. MNA is continuing to develop but it is challenged by a lack of a clear definition for the appropriate application of the MNA strategy. This challenge has resulted in the lack of a significant record of restoration and site closure. Environmental professionals face challenges in providing guidance that addresses how to manage these sites when technologies, performance monitoring, and even environmental conditions are subject to further development, refinement, and/or altered perspectives. As our experience and institutional knowledge grows around the implementation of MNA, we have the opportunity to develop “second‐generation” management tools and procedures for optimizing sites utilizing MNA as a part of a comprehensive site management plan. This opportunity is the focus of the Enhanced Attenuation: Chlorinated Organics (EACO) Team of the Interstate Technology Regulatory Council (ITRC). The development of the “second‐generation” tools/procedures has included defining EA and evaluating, through the use of a national survey of state regulators, the experience with MNA and interest in EA. The results of these two efforts formed the basis for developing a framework that provides a “bridge” from active treatment to MNA. © 2007 Wiley Periodicals, Inc. 相似文献
34.
Alexander S. Krapivin Jeanne V. Samsonova Nataliya A. Uskova Nina L. Ivanova Alexey M. Egorov 《毒物与环境化学》2013,95(1):161-172
A range of ELISAs in indirect and direct formats for the determination of bisphenol A (BPA) was developed. Bisphenol A carboxymethyl ether (BPA-CME), (BPA-CPE) and 4,4-bis(4-hydroxyphenyl)valeric acid were coupled with bovine serum albumin (BSA) (immunogens for the production of polyclonal antibodies), ovalbumin (OVA) and horseradish peroxidase. In general, the indirect assay was more sensitive and specific than the direct one. Using heterologous combinations of immunoreagents in the indirect assay allowed to increase assay sensitivity and specificity. The highest sensitivity was obtained for the antibodies produced against a conjugate of BPA-CPE with BSA and a conjugate of 4,4-bis(4-hydroxyphenyl)valeric acid with OVA. The detection limit of BPA in phosphate buffer was 0.03?ng?mL?1. The assay developed was also the most specific towards BPA. Maximum cross-reactivity values did not exceed 11% for 4-cumylphenol, 5% for bisphenol E and 2% for bisphenol S. Finally, the developed assay was used to analyze surface water samples spiked with known amount of BPA. The assay showed good recovery values (85–109%) for surface water with mineralization level lower than 500?mg?L?1. 相似文献
35.
A simple simulation model was developed to describe the growth trends of Cymodocea nodosa (Ucria) Ascherson based on data sets from the Venice lagoon. The model reproduces the seasonal fluctuations in the above and belowground biomass and in shoot density. The modeling results are in good agreement with data on net production, growth rates and chemical–physical parameters of water. It was assumed that light and temperature are the most important factors controlling C. nodosa development, and that the growth was not limited by nutrient availability. The aim was to simulate biomass production as a function of external forcing variables (light, water temperature) and internal control (plant density). A series of simulation experiments were performed with the basic model showing that among the most important phenomena affecting C. nodosa growth are: (1) inhibition of production and recruitment of new shoots by high temperature and (2) light attenuation due to seasonal fluctuation. 相似文献
36.
Aziz Khan Daniel Kean Yuen Tan Fazal Munsif Muhammad Zahir Afridi Farooq Shah Fan Wei Shah Fahad Ruiyang Zhou 《Environmental science and pollution research international》2017,24(30):23471-23487
Cotton (Gossypium hirustum L.) is grown globally as a major source of natural fiber. Nitrogen (N) management is cumbersome in cotton production systems; it has more impacts on yield, maturity, and lint quality of a cotton crop than other primary plant nutrient. Application and production of N fertilizers consume large amounts of energy, and excess application can cause environmental concerns, i.e., nitrate in ground water, and the production of nitrous oxide a highly potent greenhouse gas (GHG) to the atmosphere, which is a global concern. Therefore, improving nitrogen use efficiency (NUE) of cotton plant is critical in this context. Slow-release fertilizers (e.g., polymer-coated urea) have the potential to increase cotton yield and reduce environmental pollution due to more efficient use of nutrients. Limited literature is available on the mitigation of GHG emissions for cotton production. Therefore, this review focuses on the role of N fertilization, in cotton growth and GHG emission management strategies, and will assess, justify, and organize the researchable priorities. Nitrate and ammonium nitrogen are essential nutrients for successful crop production. Ammonia (NH3) is a central intermediate in plant N metabolism. NH3 is assimilated in cotton by the mediation of glutamine synthetase, glutamine (z-) oxoglutarate amino-transferase enzyme systems in two steps: the first step requires adenosine triphosphate (ATP) to add NH3 to glutamate to form glutamine (Gln), and the second step transfers the NH3 from glutamine (Gln) to α-ketoglutarate to form two glutamates. Once NH3 has been incorporated into glutamate, it can be transferred to other carbon skeletons by various transaminases to form additional amino acids. The glutamate and glutamine formed can rapidly be used for the synthesis of low-molecular-weight organic N compounds (LMWONCs) such as amides, amino acids, ureides, amines, and peptides that are further synthesized into high-molecular-weight organic N compounds (HMWONCs) such as proteins and nucleic acids. 相似文献
37.
Andrew J. Kean Robert F. Sawyer Robert A. Harley 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1929-1939
ABSTRACT The use of diesel engines in off-road applications is a significant source of nitrogen oxides (NOx) and particulate matter (PM10). Such off-road applications include railroad locomotives, marine vessels, and equipment used for agriculture, construction, logging, and mining. Emissions from these sources are only beginning to be controlled. Due to the large number of these engines and their wide range of applications, total activity and emissions from these sources are uncertain. A method for estimating the emissions from off-road diesel engines based on the quantity of diesel fuel consumed is presented. Emission factors are normalized by fuel consumption, and total activity is estimated by the total fuel consumed. Total exhaust emissions from off-road diesel equipment (excluding locomotives and marine vessels) in the United States during 1996 have been estimated to be 1.2 × 109 kg NOx and 1.2 x 108 kg PM10. Emissions estimates published by the U.S. Environmental Protection Agency are 2.3 times higher for both NOx and exhaust PM10 emissions than estimates based directly on fuel consumption. These emissions estimates disagree mainly due to differences in activity estimates, rather than to differences in the emission factors. All current emission inventories for off-road engines are uncertain because of the limited in-use emissions testing that has been performed on these engines. Regional- and state-level breakdowns in diesel fuel consumption by off-road mobile sources are also presented. Taken together with on-road measurements of diesel engine emissions, results of this study suggest that in 1996, off-road diesel equipment (including 相似文献
38.
Anatoly V. Skalny Margarita G. Skalnaya Alexey A. Tinkov Eugeny P. Serebryansky Vasily A. Demidov Yulia N. Lobanova Andrei R. Grabeklis Elena S. Berezkina Irina V. Gryazeva Andrey A. Skalny Oksana A. Skalnaya Nikolay G. Zhivaev Alexandr A. Nikonorov 《Environmental monitoring and assessment》2015,187(11):1-8
39.
Michael P. Ensminger Robert Budd Kevin C. Kelley Kean S. Goh 《Environmental monitoring and assessment》2013,185(5):3697-3710
Urban pesticide use has a direct impact on surface water quality. To determine the extent of pesticide contamination, the California Department of Pesticide Regulation initiated a multi-area urban monitoring program in 2008. Water and sediment samples were collected at sites unaffected by agricultural inputs in three areas: Sacramento (SAC), San Francisco Bay (SFB), and Orange County (OC). Samples were analyzed for up to 64 pesticides or degradates. Multiple detections were common; 50 % of the water samples contained five or more pesticides. Statewide, the most frequently detected insecticides in water were bifenthrin, imidacloprid, fipronil, fipronil sulfone, fipronil desulfinyl, carbaryl, and malathion. Bifenthrin was the most common contaminant in sediment samples. Key differences by area: OC had more pesticides detected than SAC or SFB with higher concentrations of fipronil, whereas SAC had higher concentrations of bifenthrin. The most frequently detected herbicides were 2,4-D, triclopyr, dicamba, diuron, and pendimethalin. Key differences by area: OC and SFB had higher concentrations of triclopyr, whereas SAC had higher concentrations of 2,4-D and dicamba. Detection frequency, number of pesticides per sample, and pesticide concentration increased during rainstorm events. In water samples, all of the bifenthrin, malathion, fipronil, permethrin, and λ-cyhalothrin detections, and most of the fipronil sulfone and cyfluthrin detections were above their lowest US EPA aquatic benchmark. Diuron was the only herbicide that was detected above its lowest benchmark. Based on the number of pesticides and exceedances of aquatic benchmarks or the high number of sediment toxicity units, pesticides are abundant in California surface waters. 相似文献
40.
Kurbatova EI Ksenofontov AI Dmitriyev AM Regens JL 《Environmental science and pollution research international》2007,14(4):251-255
Background, Aims and Scope Advances in radioecology can support improvements in environmental remediation technologies, especially by illuminating interaction
processes between polymorphic metal radionuclides and various materials and their ions in aqueous solutions. This study modeled
interaction processes of 90Sr with transitive metals to delineate the behavior of polymorphic metal radionuclides. Experimental and modeling results
confirmed Sr sedimentation was sensitive to the physical impact of radionuclides on various sorbents and possible chemical
reactions occurring between the radionuclides and sorbents.
Methods Models were developed to simulate 90Sr sedimentation process, and the potential physical and chemical reactions accompanying the process. Models were verified,
inorganic salts were used as sorbents to absorb metal cations, activity levels were recorded before and after mixing the inorganic
salts while the efficiency of sedimentation using the heavy metals composites was quantified.
Results and Discussion This research demonstrates that the process of the sedimentation is complex and occurs in several stages. Micro-structural
analysis shows that zones of interaction between the sorbent and source metal are formed during the irradiation of the target’s
metal surface. Electrical-microscopic analysis indicates that the composition of the formed zones of interaction of Ti (Sr)
with target metals has various structures. Roentgenophase analysis indicates that the interaction of the ions of a precipitable
source and a target occurs according to constitution diagrams of equilibrium systems. The results indicate that application
of inorganic salts composites based on modeling increases the efficiency of the deactivation of aqueous solutions when compared
to standard aluminum sulfate composite.
Conclusions Experimental and modeling results confirm 90Sr sedimentation is sensitive to the physical impact of radionuclides on various sorbents and possible chemical reactions
occurring between the radionuclides and sorbents. The models support estimation of the physical impact of polymorphic metal
radionuclides on various components of sorbents and possible chemical reactions occurring between the radionuclides and sorbents
during the interaction. Inorganic salt composites deactivate and clear 90Sr and Sr+2 from water.
This paper is openly accessible! 相似文献