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951.
环境(非关税)贸易壁垒判析及其对策探讨 总被引:6,自引:0,他引:6
WTO中有关环境的,国际环境公约、ISO14000、等有关条款,本身并非绿色贸易壁垒,基于此,分析了绿色贸易壁垒的起因特征,对其相模糊的条款与规定,有可能成为绿色贸易壁垒的误区作了判析,提出了绿色贸易壁垒的5种形式:环境税、市场准入、环境技术标准、环境标志和贸易制裁,以及我国的对策思路。 相似文献
952.
953.
北京及其周边地区分布的大量裸露沙荒地是北京近年来沙尘暴频发的主要沙源之一,而增加其地表覆盖状况则是遏止就地扬沙起尘的有效措施之一。以北京西北部河北宣化黄羊滩为例,对流动沙丘上铺设生态垫并栽植灌木的防风固沙效果进行了初步研究。研究结果表明,与沙柳沙障相比,生态垫确实可以降低近地表的输沙率,提高生态垫下土壤的养分含量,一定程度上提高柠条的地径和高度,可见生态垫是一种很好的促进流沙固定和植被恢复的地表覆盖材料;与其它两种生态垫铺设方式(品字状和带状)相比,全铺可以显著降低近地表的输沙率,提高其下土壤的养分含量,但柠条的生长状况却略差,这可能与全铺降低了小雨入渗的可能性有关;就两种部分铺设的方式而言,无论从降低近地表的输沙率还是促进柠条的生长上来看,品字状都明显优于带状。从生态和经济的角度综合考虑,品字状铺设显然是该区域流沙防治措施中较好的选择。 相似文献
954.
Effects of Road Fencing on Population Persistence 总被引:6,自引:0,他引:6
Abstract: Roads affect animal populations in three adverse ways. They act as barriers to movement, enhance mortality due to collisions with vehicles, and reduce the amount and quality of habitat. Putting fences along roads removes the problem of road mortality but increases the barrier effect. We studied this trade-off through a stochastic, spatially explicit, individual-based model of population dynamics. We investigated the conditions under which fences reduce the impact of roads on population persistence. Our results showed that a fence may or may not reduce the effect of the road on population persistence, depending on the degree of road avoidance by the animal and the probability that an animal that enters the road is killed by a vehicle. Our model predicted a lower value of traffic mortality below which a fence was always harmful and an upper value of traffic mortality above which a fence was always beneficial. Between these two values the suitability of fences depended on the degree of road avoidance. Fences were more likely to be beneficial the lower the degree of road avoidance and the higher the probability of an animal being killed on the road. We recommend the use of fences when traffic is so high that animals almost never succeed in their attempts to cross the road or the population of the species of concern is declining and high traffic mortality is known to contribute to the decline. We discourage the use of fences when population size is stable or increasing or if the animals need access to resources on both sides of the road, unless fences are used in combination with wildlife crossing structures. In many cases, the use of fences may be beneficial as an interim measure until more permanent measures are implemented. 相似文献
955.
Joon-Sig Jung Jae Won Lee Rajitha Kawshalya Mailan Arachchige Don Duck Shin Park 《International journal of occupational safety and ergonomics》2019,25(1):91-98
We investigated the characteristics of charged aerosols produced by high-voltage power lines (HVPLs) to explore the effects on respiratory disease incidence among those who handle HVPLs. Charged aerosol currents and charged aerosol concentrations were measured over 24?h at 12 sites. Aerosol current effective levels were 2.7 times higher compared to exposed and control sites. This pattern of relative enhancement at exposed sites was seen consistently in all measurements and the difference was 1.7 higher at exposed sites. Correlation analysis among all important variables revealed strong positive correlations between currents and concentration, currents and magnetic field, humidity and concentration, and humidity and particles of 10?µm or less (PM10), while negative correlations were observed between charged aerosol concentrations and wind velocity and between wind velocity and humidity. Estimated production of charged aerosols from HVPLs found that people who work with HVPLs are highly likely to be exposed to charged aerosols. 相似文献
956.
应用等标污染负荷法对大庆三十万吨乙烯装置污水处理场的外排水进行了评价,得知外排水中的主要污染因子为COD、BOD、酚和油,并对影响其合格率的因素进行了分析,同时对如何控制污染物的流失及提高外排水中污染物的合格率提出了的建议。 相似文献
957.
山东省工业废水排放量GM(1,1)高阶残差预测模型 总被引:2,自引:0,他引:2
介绍了GM(1,1)高阶残差预测模型之建模方法。以山东省工业废水排放量为例,建立了GM(1,1)高阶残差预测模型。结果表明,GM(1,1)高阶残差模型经GM(1,1)模型更贴近实际。 相似文献
958.
海洋是人类赖以生存的第二大场所。开发海洋石油资源必须做到既要把石油资源开采出来,又要保护海洋生态环境不遭受污染。概述了溢油的污染机理、计算方法、预防措施。 相似文献
959.
Donald Rundquist Gene Murray Lloyd Queen 《Journal of the American Water Resources Association》1985,21(6):989-994
The Sandhills region represents a tremendous water resource for the State of Nebraska. Small shallow lakes, marshes, and subirrigated meadows are abundant due to interactions between ground water and surface water. One theory relating ground water to lake-flow systems in the Sandhills has been termed the “flow-through” concept. Thermal-infrared remotely acquired images document the flow-through model for a test site in Western Nebraska. 相似文献
960.
Mike S. Brewer Richard Lee J. David Helvey 《Journal of the American Water Resources Association》1982,18(5):755-759
ABSTRACT: Data from a small forested catchment were used to model peak stream flow as a function of basic hydrologic variables associated with 112 rain storms. Rainfall depth and initial stream flow rate accounted for 87.1 percent of peak flow variability. Forty expressions of rainfall intensity (describing both the temporal sequence of intensity for 20 equal storm intervals, and maximum intensity for 20 separate interval lengths) were used in an attempt to improve the predictability of basic models. None of the intensity parameters improved predictability by as much as 2 percent, apparently because the most intense rainfall bursts generally occurred near the beginning of storm periods. Mean rainfall intensity for entire storms was generally as effective as any of the shorter interval intensities, and its use helped to linearize the relationship between peak flow and rainfall depth and duration. 相似文献