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931.
With China's rapid economic development, environmental problems have become more and more serious. Particulate air pollution is terrible in cities with large and dense population. It may lead to adverse health effects and economic costs. In this study, we calculated the health effects of pollution caused by particulate matter with aerodynamic diameters less than 10mum (PM(10)) in 111 Chinese cities in 2004 according to statistical data and epidemiological exposure-response functions. Using economic burden of disease analysis, an economic assessment of these health risks was also presented. In contrast to many previous studies that have examined individual cities, this study covered most large and medium-sized cities in China, which accounted for more than 70% gross domestic product (GDP) of China in 2004. The total economic cost caused by PM(10) pollution was estimated as approximately US$ 29,178.7 million. Mega cities such as Beijing, Shanghai, and Tianjin contribute relatively more to the total costs. The results will help policy makers in formulating more effective countermeasures and increasing public awareness to enhance environmental protection. 相似文献
932.
933.
The degradation of polyacrylamide (PAM) in simulate wastewater was studied in UV/Fenton/C4H4O62? system. The factors such as molecular ratio of H2O2/Fe2+/C4H4O62?, pH, and the dosage of Fenton reagent that could affect the PAM degradation in the UV/Fenton/C4H4O62? system were investigated. The experimental results showed that adding C4H4O62? to UV/Fenton system could form photosensitive ferrous complexes, which led to higher degradation efficiency of PAM. The degradation rate of PAM could be up to 95.2% under the following conditions: the concentration of H2O2, Fe2+, and C4H4O62? were 22.5, 2.25, and 2.25 mmol/L, respectively (i.e., molecular ratio of H2O2/Fe2+/C4H4O62? was 10:1:1), the pH value was 3.0. 相似文献
934.
Exergo-economic analysis of the pinch point temperature difference (PPTD) in both evaporator and condenser of sub-critical organic Rankine cycle system (ORCs) are performed based on the first and second laws of thermodynamics. Taking mixture R13I1/R601a as a working fluid and the annual total cost per net output power Z as exergo-economic performance evaluation criterion, the effects of PPTD in evaporator ΔTe, and the PPTD ratio of condenser to evaporator y, on the exergo-economic performance of ORCs are analyzed. Moreover, how some other parameters influence the optimal PPTD in evaporator ΔTe,opt and the optimal PPTD ratio of condenser to evaporator yopt are also discussed. It has been found that the exergo-economic performance of ORCs is remarkably influenced by ΔTe and y, and there exists ΔTe,opt and yopt. In addition, ΔTe,opt and yopt are affected by heat transfer coefficient ratio of condenser to evaporator ß, the temperature of working fluid at dew point in condenser T1a, and composition of R13I1/R601a: larger ß and T1a lead to lower ΔTe,opt and yopt; by contraries, larger mass fraction of R13I1 makes ΔTe,opt and yopt increase, and yopt increases linearly. The effects of the temperature of working fluid at bubble point in evaporator T3a, mass flow rate of exhaust flue gas mg, and inlet temperature of exhaust flue gas Tgi on ΔTe,opt and yopt are very slight. For comparison, three additional working fluids, namely R601a, R245fa, and 0.32R245fa/0.68R601a, are also taken into account. 相似文献
935.
Guoyi Zhou Ge Sun Xu Wang Chuanyan Zhou Steven G. McNulty James M. Vose Devendra M. Amatya 《Journal of the American Water Resources Association》2008,44(1):208-221
Abstract: It is critical that evapotranspiration (ET) be quantified accurately so that scientists can evaluate the effects of land management and global change on water availability, streamflow, nutrient and sediment loading, and ecosystem productivity in watersheds. The objective of this study was to derive a new semi‐empirical ET modeled using a dimension analysis method that could be used to estimate forest ET effectively at multiple temporal scales. The model developed describes ET as a function of water availability for evaporation and transpiration, potential ET demand, air humidity, and land surface characteristics. The model was tested with long‐term hydrometeorological data from five research sites with distinct forest hydrology in the United States and China. Averaged simulation error for daily ET was within 0.5 mm/day. The annual ET at each of the five study sites were within 7% of measured values. Results suggest that the model can accurately capture the temporal dynamics of ET in forest ecosystems at daily, monthly, and annual scales. The model is climate‐driven and is sensitive to topography and vegetation characteristics and thus has potential to be used to examine the compounding hydrologic responses to land cover and climate changes at multiple temporal scales. 相似文献
936.
以可持续发展相关理论为基础,利用系统工程的理论和方法建立了河北省县域可持续发展指标体系及其评价标准,并在全省范围应用,对全省136个县(市)可持续发展能力做出了评价。结合评价结果,阐述了河北省县域可持续发展能力的特征,提出了河北省县域可持续发展的方向和思路。 相似文献
937.
Seasonal variation of polycyclic aromatic hydrocarbons in soil and air of Dalian areas, China: an assessment of soil-air exchange 总被引:1,自引:0,他引:1
The seasonal variations of concentrations of PAHs in the soil and the air were measured in urban and rural region of Dalian, China in 2007. In soil, mean concentrations of all PAHs in summer were larger than those in winter, whereas the concentrations of heavier weight PAHs in winter were larger than those in summer. Winter/summer concentration ratios for individual PAHs (R(W/S)) increased with the increase of molecular weight of PAHs in soil, indicating that PAHs with high molecular weight were more easily deposited to soil in winter than summer. In air, mean concentrations of all PAHs in winter were larger than those in summer. In comparison with the R(W/S) in soil, all the values of R(W/S) in air were larger than one indicating that the entire individual PAH concentrations in winter were larger than those in summer. The average concentration composition for each PAH compound in soil and air samples was determined and the seasonal change of PAH profile was very small. It was suggested that PAHs in soils and air had the same or similar sources both in winter and summer. The approach to the soil-air equilibrium was assessed by calculating fugacity quotients between soil and air using the soil and air concentrations. The calculated soil-air fugacity quotients indicated that soil acted as a secondary source to the atmosphere for all lighter weight PAHs (two-three rings) and it will continue to be a sink for heavier weight PAHs (five-six rings) in the Dalian environment, both in winter and summer. Medium weight PAHs (four-five rings) were close to the soil-air equilibrium and the tendency shifted between soil and air when season or function region changed. The fugacity quotients of PAHs in summer (mean temperature 298 K) were larger than those in winter (mean temperature 273 K), indicating a higher tendency in summer than winter for PAHs to move from soil to air. The variation of ambient conditions such as temperature, rainfall, etc. can influence the movement of PAHs between soil and air. Most of the fugacity quotients of PAHs for the urban sites were larger than that for the rural site both in winter and summer. This phenomenon may be related with that the temperatures in urban sites were higher than those in the rural site because of the urban heat island effect. 相似文献
938.
介绍了环境空气质量、分析用水、接种液加入量、曝气方法的选择等因素对BOD5测定的影响。提出测定过程中实验室空气质量、分析用水的选择、接种液的选择和加入量以及曝气方法应注意事项,以期得到较为准确的测定结果,提高废水中BOD5测定质量。 相似文献
939.
In this article, we introduce China’s major forest types and discuss the historical development of forest management in China,
including actions taken over the last decade toward achieving SMF. Major challenges are identified, and a strategy for SFM
implementation in China is presented. China’s forests consist of a wide variety of types with distinctive distributional patterns
shaped by complex topography and multiple climate regimes. How to manage this wide array of forest resources has challenged
forest managers and policy-makers since the founding of the country. Excessive exploitation of China's forest resources from
the 1950s to the late 1990s contributed to environmental problems and calamities, such as floods, soil erosion, and desertification.
At the start of the new millennium, the Chinese government decided to shift its emphasis from timber production towards the
achievement of sustainable forest management (SFM). With a series of endeavors such as the implementation of the “Six Key
Forestry Projects” and the reform of forest tenure policies, and the adoption of a classification system for China's forests,
a beginning has been made at reversing the trend of environmental degradation that occurred throughout the latter half of
the last century. At the same time, huge challenges remain to be tackled for the development of forestry in China. 相似文献
940.
The management of wild mushroom is interdisciplinary in nature, whereby the biophysical considerations have to be incorporated
into the context of a wide range of social, economic and political concerns. However, to date, little documentation exists
illustrating an interdisciplinary approach to management of wild mushrooms. Moreover, the empirical case studies necessary
for developing applicable and practical methods are even more rare. This paper adopted an interdisciplinary approach combining
participatory methods to improve the habitat management of Thelephora ganbajun, an endemic and one of the most economically valuable mushroom species in Southwest China. The paper documents an empirical
case of how an interdisciplinary approach facilitated the development of a scientific basis for policy and management practice,
and built the local capacity to create, adopt and sustain the new rules and techniques of mushroom management. With this integrative
perspective, a sustainable management strategy was developed, which was found not only technically feasible for farmers, but
also acceptable to the government from an ecological and policy-related perspective. More importantly, this approach has greatly
contributed to raising the income of farmers. The paper highlights how the integration of biophysical and socioeconomic factors
and different knowledge systems provided a holistic perspective to problem diagnosis and resolution, which helped to cope
with conventional scientific dilemmas. Finally, it concludes that the success of this interdisciplinary approach is significant
in the context of policy decentralization and reform for incorporating indigenous knowledge and local participation in forest
management. 相似文献