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151.
Given the key role of biogenic volatile organic compounds(VOCs) to tropospheric chemistry and regional air quality, it is important to generate accurateVOCs emission inventories. However, only a less fraction of plant species, in temperate grassland of Inner Mongolia, has been characterized by quantitative measurements. A taxonomic methodology, which assigns VOCs measurements to unmeasured species, is an applicable and inexpensive alternation for extensive VOCs emission survey, although data are needed for additional plant families and genera to further validate the taxonomic approach in grassland vegetation. In this experiment, VOCs emission rates of 178 plant species were measured with a portable photoionization detector( PID). The results showed the most of genera and some families have consistent feature of their VOCs emission, especially for isoprene, and provide the basic premise of taxonomic methodology to develop VOCs emission inventories for temperate grassland. Then, the taxonomic methodology was introduced into assigning emission rate to other 96 species, which no measured emission rates available here. A systematical emission inventory of temperate grassland vegetation in Inner Mongolia was provided and further evidence that taxonomy relationship can serve as a useful guide for generalizing the emissions behavior of many, but not all, plant families and genera to grassland vegetation. 相似文献
152.
In this paper,the relationship among land productivity,population pressure and the fluctuation mechanism of ecotone is analyzed,taking coumties and banners of southeast Inner Mongolia plateau as an example,which is the most fragile part in the farming and husbandry interleaving belt of north China due to its severe desertification degree and low level of economic development.The Cv for the total output value of agriculture decreases from southeast to northwest,with the same rule as which the overloading population cumulated distributes,and both indicators have close relation with the high linear coefficient of 0.83.These reveal the fluctuation mechanism for ecotone:fluctuation of the level of economic development is a scientific and practical measure both to weakness degree and to instability of ecotone,because it is a synthesized response to the variation of climate as well as irrational land uses,which reinforce and magnify the fluctuation.In detail,the heavier the population overloading,the severer the grassland reclamation,the stronger the dependence of regional productivity on rainfall,the lower the level of economic development,the rougher the fluctuation of ecotone,but the weaker the PRED system. 相似文献
153.
环境影响评价有效性评估理论研究 总被引:7,自引:0,他引:7
结合系统工程理论,初步建立环境影响评价有效性评估的概念方法和理论体系,据此对我国环境影响评价有效性进行初步评估,并提出进一步提高我国环境影响评价有效性的对策及建议。 相似文献
154.
西藏自治区的土地、粮食和人口 总被引:3,自引:1,他引:3
本文讨论了西藏自治区土地系统、农业发展、人口增长和它们之间的相互关系。指出西藏土地类型复杂多样,极少土地能用于种植业,单位产量亦不高。人均占有粮食不足300kg,若干牧区不足50kg。粮食生产不能满足人口增长的需求。这种趋势在今后30年内仍将继续下去。 为了解决土地—粮食—人口三者之间关系的不协调,需采取若干切实措施。文中亦强调人口控制的必要。 相似文献
155.
156.
浙东南下白垩统火山岩极为发育,岩石组合与浙江中部永康群差异甚大,称之为馆头组和朝川组似不合适。文成县峃口镇龙潭山(又称龙井山)剖面具代表性,拟以此部面为基础建立梅坪组和龙潭山组,合称文成群。与永康群对比,梅坪组大体相当馆头组,龙潭山组与朝川组和方岩组对比。 相似文献
157.
中国火葬场二噁英类污染物排放及减排技术研究 总被引:2,自引:0,他引:2
对中国某火葬场9具遗体进行了二(口恶)英类污染物排放测试,测试结果表明,烟气中二(口恶)英类物质总浓度为89~350ng·m-3,毒性当量浓度为1.5~5.4ng·m-3;PCDFs的总浓度高于PCDDs的总浓度;以此估算中国2004年火化遗体过程中二(口恶)英类污染物的年排放量为11.2~46.9 g·a-1.通过实验分别研究了布袋除尘器、布袋除尘器加不同厚度的活性炭纤维毡组合对火化遗体烟气中二(口恶)英类污染物的去除效果.结果表明,布袋除尘器去除火化烟气中二(口恶)英类污染物的效率为57.4%;布袋除尘器分别与厚度为5、15mm的活性炭纤维毡组合去除火化烟气中二(口恶)英类污染物的效率分别为64.0%和89.2%. 相似文献
158.
Liu Zhenyu Yang Fenglin Quan Xie Zhang Xiaohong 《Frontiers of Environmental Science & Engineering in China》2007,1(2):166-171
A QWASI model dependent on temperature is parameterized to describe the long-term fate of persistent organic pollutants (POPs)
in the Liao River. The model parameters, namely fugacity capacity, degradation rate, and transfer coefficient, are profoundly
affected by temperature. This model is used to simulate the fate of γ-hexachlorocyclohexane (γ-HCH) in the lower reaches of the Liao River from 1998 to 2008. Modeling results show that γ-HCH fugacity capacities in air, water, and sediment increase as temperature decreases, and the transfer and transformation
rate coefficients increase as temperature increases. The variations of transfer and transformation parameter D values depend on fugacity capacities, and transfer and transformation coefficients simultaneously. The performance of the
model is evaluated by comparing the predicted and observed concentrations in the water and sediment of the Liao River. The
predicted values agree well with the observed value in the order of magnitude, in most cases within the factor of 3. It is
believed that the model is appropriate for simulating the long term fate of POPs in the Liao River.
Translated from Environmental Science, 2006, 27(1): 121–125 [译自: 环境科学] 相似文献
159.
160.
Atmospheric particulate pollution of Lanzhou using magnetic measurements 总被引:13,自引:0,他引:13
1 IntroductionAtmosphericparticulateisoneofthemainatmosphericpollutantsinChina.Itmaybeharmfulitselfandcanactasacarrieroftoxicmatterswhichmayhaveremarkableimpactsonhumanhealthandatmosphericenvironmentquality.Combustionofcoal,whichstillservesasprimarye… 相似文献