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991.
E. Le Cadre F. Gérard S. Génermont T. Morvan S. Recous 《Environmental Modeling and Assessment》2009,14(4):539-544
We compared three formalisms derived from (1) medical sciences, (2) environmental, and (3) agronomic models to simulate the
effects of pH and temperature on the nitrification rate in arable soils. We evaluated these formalisms by implementing them
in a simple growth model by comparing modelled and measured nitrate contents of soil samples with different initial soil pH
after incubation at two temperatures. We found that the formalisms derived from medical sciences were more accurate and easily
adapted to the data, suggesting that such formalisms may be profitably used in agronomic or environmental models. 相似文献
992.
Caesium-137 activity concentration in the water columns of the Gulf of Patras (Central Greece) and the North-Eastern Aegean Sea (easterward to Lemnos Island) was investigated in selected sampling stations during the period September 2004–June 2006. The methodology followed was based on the sorption of caesium (Cs) on cotton wound cartridge filters impregnated by Cu2[Fe(CN)6] via in-situ pumping. In terms of the horizontal and vertical records, the activity concentrations of 137Cs in the Gulf of Patras ranged between 1.2 and 6.7 Bq m−3, depending on the sampling period and the prevailing physicochemical regime at the sampling station. The general pattern of the decreased activity concentrations of 137Cs with increasing depth was reversed in the Gulf of Patras during the cold period attributed to the prevailing advective processes of the area. The activity concentrations of 137Cs in the North-Eastern Aegean Sea ranged from 2.6 to 12.8 Bq m−3, whereas significant stratified curves were observed during the warm period and also, in one station during the cold period. In terms of temporal variation, the discharges in the Gulf of Patras resulted in enhanced levels of 137Cs, whereas in the North Aegean Sea the incoming water masses form the Black Sea had an apparent influence throughout the year by increasing the 137Cs levels, hence presenting a weak seasonal variation. Comparing the two studied areas, one could say that the North Aegean Sea, as an open sea environment, presented higher concentrations due to the influence of the Black Sea water masses. The estimated inventories of 137Cs in the Gulf of Patras ranged 0.25 ± 0.03–0.79 ± 0.03 kBq m−2, whereas in the North-Eastern Aegean Sea they ranged 0.33 ± 0.02–0.92 ± 0.03 kBq m−2. 相似文献
993.
Sbastien Denys Guillaume Echevarria Louis Florentin Elisabeth Leclerc Jean-Louis Morel 《Journal of environmental radioactivity》2009,100(10):884-889
Parameters regarding fate of 63Ni in the soil–plant system (soil: solution distribution coefficient, Kd and soil plant concentration ratio, CR) are mostly determined in controlled pot experiments or from simple models involving a limited set of soil parameters. However, as migration of pollutants in soil is strongly linked to the water migration, variation of soil structure in the field and seasonal variation of evapotranspiration will affect these two parameters. The aim of this work was to explore to what extent the downward transfer of 63Ni and its uptake by plants from surface-contaminated undisturbed soil cores under cultivation can be explained by isotopic dilution of this radionuclide in the pool of stable Ni of soils. Undisturbed soil cores (50 cm × 50 cm) were sampled from a brown rendzina (Rendzic Leptosol), a colluvial brown soil (Fluvic Cambisol) and an acidic brown soil (Dystric Cambisol) using PVC lysimeter tubes (three lysimeters sampled per soil type). Each core was equipped with a leachate collector. Cores were placed in a greenhouse and maize (DEA, Pioneer®) was sown. After 44 days, an irrigation was simulated at the core surfaces to supply 10 000 Bq 63NiCl2. Maize was harvested 135 days after 63Ni input and radioactivity determined in both vegetal and water samples. Effective uptake of 63Ni by maize was calculated for leaves and kernels. Water drainage and leaching of 63Ni were monitored over the course of the experiment. Values of Kd in surface soil samples were calculated from measured parameters of isotopic exchange kinetics. Results confirmed that 63Ni was strongly retained at the soil surface. Prediction of the 63Ni downward transfer could not be reliably assessed using the Kd values, since the soil structure, which controls local water fluxes, also affected both water and Ni transport. In terms of 63Ni plant uptake, the effective uptake in undisturbed soil cores is controlled by isotope dilution as previously shown at the pot experiment scale. 相似文献
994.
上海高温和低温气候变化特征及其影响因素 总被引:1,自引:0,他引:1
基于上海11个气象站逐日最高、最低气温、降水资料和西太平洋副热带高压(简称副高,下同)环流指数,分析了上海夏季高温和冬季低温的气候变化特征及其影响因素。结果表明,1873~2007年,上海高温日数表现为少-多-少-多的年代际变化,低温日数则表现为多-少的年代际变化。2001~2007年,上海年均高温日数、各级高温过程数和高温过程日数都最多,低温日数、低温过程数和低温过程日数都最少。1960~2007年,上海每年高温日数与当年夏季副高面积和强度指数显著正相关,低温日数与当年冬季副高面积和强度指数显著负相关。降水对上海极端气温有一定的缓解作用,上海高温日数与夏季降水量弱显著负相关,低温日数与冬季降水量显著负相关。上海高温过程数受城市化影响较大,其时间变化具有明显的城郊差异,低温过程数则受城市化影响较小。 相似文献
995.
Ola Busari 《Environment, Development and Sustainability》2009,11(1):71-83
This paper captures the lessons learned from the implementation of water supply and sanitation interventions in Mayiwane community
in the rural northeastern region of the Kingdom of Swaziland, relating to water system rehabilitation, water quantity and
quality improvements, and the promotion of latrine construction. The issues examined include both the dimensions of implementation
efficiency and project effectiveness: first identifying the inputs, activities and final outputs and, then, tracking the entire
project cycle, from design to implementation and monitoring. To draw meaningful lessons for the sustainability of similar
interventions, project evaluation involved extensive fieldwork, water sampling and testing, review of documentation, and interviews
with community members and officials of governmental, civil society and collaborating external agencies.
Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
996.
China's water scarcity 总被引:1,自引:0,他引:1
China has been facing increasingly severe water scarcity, especially in the northern part of the country. China's water scarcity is characterized by insufficient local water resources as well as reduced water quality due to increasing pollution, both of which have caused serious impacts on society and the environment. Three factors contribute to China's water scarcity: uneven spatial distribution of water resources; rapid economic development and urbanization with a large and growing population; and poor water resource management. While it is nearly impossible to adjust the first two factors, improving water resource management represents a cost-effective option that can alleviate China's vulnerability to the issue. Improving water resource management is a long-term task requiring a holistic approach with constant effort. Water right institutions, market-based approaches, and capacity building should be the government's top priority to address the water scarcity issue. 相似文献
997.
Emergy theory and method were used to evaluate the economy of China and the contributions of water resources in Chinese rivers
to the real wealth of the Chinese economy. The water cycle and energy conversion were reviewed, and an emergy method for evaluating
the natural value of water resources in a river watershed was developed. The indices for China calculated from the emergy
evaluation were close to those of developing countries. Despite a small surplus in its balance of payments, China had a net
emergy loss from its trade in 2002. The efficiency of Chinese natural resource use was still not high and did not match its
economic growth rate. Furthermore, the Chinese economy placed a stress on its ecological environment and natural resources.
Several indices of Chinese rivers from the emergy evaluation were close to those of average global river water. The main average
indices of Chinese rivers were transformity (4.17 × 104 sej/J), emergy per volume (2.05 × 1011 sej/m3), and emdollar per volume (0.06 $/m3). The total value of all the rivers’ water made up 13.0% of the GDP of China in 2002, and that of water consumption accounted
for 2.1%. The value of the water resources in the Haihe-luanhe River (11.39 × 104 sej/J) was the highest, followed by the Yellow River (10.27 × 104 sej/J), while the rivers in Southwest China had the lowest values (2.92 × 104 sej/J). 相似文献
998.
Moving Beyond Strawmen and Artificial Dichotomies: Adaptive Management When an Endangered Species Uses an Invasive One 总被引:1,自引:1,他引:0
Daniel Simberloff 《Journal of Agricultural and Environmental Ethics》2009,22(1):73-80
Evans et al. (Journal of Agricultural and Environmental Ethics, 2008) have attempted to enmesh me in their dispute with the Florida Bureau of Invasive Plant Management about a specific
system, Kings Bay/Crystal River. In so doing, they repeatedly mischaracterize my positions in order to depict, incorrectly,
invasion biology as monolithic and me as a representative of one extreme of a false dichotomy about management of introduced
species. In addition, they introduce an issue irrelevant in this case (extinctions) and cite incorrect data. Proposing to
manage people, manatees, introduced plants, and cyanobacteria in Kings Bay by participative adaptive management, they ignore
the fact that living organisms can both disperse autonomously and hitchhike. Finally, they present few details on any aspect
of their management proposal and do not address the myriad problems that have beset previous attempts at scientific adaptive
management, especially at large scales. Until such a management approach is fleshed out and implemented, it is impossible
to assess its validity for Kings Bay, and it is very premature to suggest it as a general model for dealing with invasive
species disputes. 相似文献
999.
The objective of this study is to develop an alternative evaluation index (AEI) in order to determine the priorities of a range of alternatives using both the hydrological simulation program in FORTRAN (HSPF) and multicriteria decision making (MCDM) techniques. In order to formulate the HSPF model, sensitivity analyses of water quantity (peak discharge and total volume) and quality (BOD peak concentrations and total loads) are conducted and a number of critical parameters were selected. To achieve a more precise simulation, the study watershed is divided into four regions for calibration and verification according to landuse, location, slope, and climate data. All evaluation criteria were selected using the Driver–Pressure–State–Impact–Response (DPSIR) model, a sustainability evaluation concept. The Analytic Hierarchy Process is used to estimate the weights of the criteria and the effects of water quantity and quality were quantified by HSPF simulation. In addition, AEIs that reflected residents' preferences for management objectives are proposed in order to induce the stakeholder to participate in the decision making process. 相似文献
1000.
Situating Hazard Vulnerability: People’s Negotiations with Wildfire Environments in the U.S. Southwest 总被引:1,自引:1,他引:0
This article is based on a multimethod study designed to clarify influences on wildfire hazard vulnerability in Arizona’s
White Mountains, USA. Findings reveal that multiple factors operating across scales generate socially unequal wildfire risks.
At the household scale, conflicting environmental values, reliance on fire insurance and firefighting institutions, a lack
of place dependency, and social vulnerability (e.g., a lack of financial, physical, and/or legal capacity to reduce risks)
were found to be important influences on wildfire risk. At the regional-scale, the shift from a resource extraction to environmental
amenity-based economy has transformed ecological communities, produced unequal social distributions of risks and resources,
and shaped people’s social and environmental interactions in everyday life. While working-class locals are more socially vulnerable
than amenity migrants to wildfire hazards, they have also been more active in attempting to reduce risks in the aftermath
of the disastrous 2002 Rodeo-Chediski fire. Social tensions between locals and amenity migrants temporarily dissolved immediately
following the disaster, only to be exacerbated by the heightened perception of risk and the differential commitment to hazard
mitigation displayed by these groups over a 2-year study period. Findings suggest that to enhance wildfire safety, environmental
managers should acknowledge the environmental benefits associated with hazardous landscapes, the incentives created by risk
management programs, and the specific constraints to action for relevant social groups in changing human-environmental context. 相似文献