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51.
祁连山高山草甸土壤CO2通量的时空变化及其影响分析 总被引:1,自引:0,他引:1
采用Li-6400便携式光合作用测量系统连接Li-6400-09土壤呼吸室,在2004年生长季节对祁连山高山草甸土壤CO2通量沿海拔梯度进行了野外定位试验,统计分析了水热因子及根系生物量对高山草甸土壤CO2通量特征的可能影响.结果表明,土壤CO2通量存在明显的空间变化规律, 沿海拔梯度土壤CO2通量随着海拔梯度的增加而逐渐减小,其变异系数逐渐增加;就日变化而言,土壤CO2通量晚间维持在较低水平,02:00~06:00最低,在07:00~08:30开始升高,11:00~16:00达到峰值,16:00~18:30开始下降,整个过程呈单峰曲线.土壤CO2通量的日平均值介于(0.56±0.32) ~ (2.53±0.76) μmol·(m2·s)-1.从季节变化来看,土壤CO2通量均以夏秋季较高,春冬季排放量较低,7~8月份达到最大值[4.736 μmol·(m2·s)-1],6月与9月份次之,5月与10月份基本一致,整个生长过程总的变化趋势呈单峰曲线形式.高山草甸土壤CO2通量在植物生长季与10 cm土壤温度、土壤含水量、根系生物量都存在不同程度的正相关关系,表明高山草甸土壤CO2通量的空间变异主要受温度、水分和植物根系的综合影响. 相似文献
52.
第二松花江中下游沉积物汞的时空变化规律 总被引:3,自引:1,他引:2
将1973、1976、1983、1991年和本次的研究结果进行对比分析,得出了第二松花江中下游表层沉积物汞含量的时间变化规律.1976年以前汞含量处于增加趋势;1976~1982年汞含量有所下降;1982年汞污染源被切断,汞含量骤降;随后,汞污染浓度处于缓慢净化时期.将本次采集的沉积物样品分为3个粒度等级,最后以63 μm粒级的沉积物汞含量为代表分析了汞的水平变化规律,总体趋势是,排污口处汞含量最高;哨口至朝阳桥断面汞含量增加;朝阳桥至五家站断面,汞含量骤降,在五家站断面汞含量达到最小值;五家站至泔水缸断面汞含量又略有增加.并给出了本次研究中各断面沉积物汞的垂直变化规律. 相似文献
53.
Integrated strategies to reduce vulnerability and advance adaptation,mitigation, and sustainable development 总被引:4,自引:1,他引:3
Indur M. Goklany 《Mitigation and Adaptation Strategies for Global Change》2007,12(5):755-786
Determinants of adaptive and mitigative capacities (e.g., availability of technological options, and access to economic resources,
social capital and human capital) largely overlap. Several factors underlying or related to these determinants are themselves
indicators of sustainable development (e.g., per capita income; and various public health, education and research indices).
Moreover, climate change could exacerbate existing climate-sensitive hurdles to sustainable development (e.g., hunger, malaria,
water shortage, coastal flooding and threats to biodiversity) faced specifically by many developing countries. Based on these
commonalities, the paper identifies integrated approaches to formulating strategies and measures to concurrently advance adaptation,
mitigation and sustainable development. These approaches range from broadly moving sustainable development forward (by developing
and/or nurturing institutions, policies and infrastructure to stimulate economic development, technological change, human
and social capital, and reducing specific barriers to sustainable development) to reducing vulnerabilities to urgent climate-sensitive
risks that hinder sustainable development and would worsen with climate change. The resulting sustainable economic development
would also help reduce birth rates, which could mitigate climate change and reduce the population exposed to climate change
and climate-sensitive risks, thereby reducing impacts, and the demand for adaptation. The paper also offers a portfolio of
pro-active strategies and measures consistent with the above approaches, including example measures that would simultaneously
reduce pressures on biodiversity, hunger, and carbon sinks. Finally it addresses some common misconceptions that could hamper
fuller integration of adaptation and mitigation, including the notions that adaptation may be unsuitable for natural systems,
and mitigation should necessarily have primacy over adaptation.
相似文献
Indur M. GoklanyEmail: |
54.
Preety M. Bhandari Suruchi Bhadwal Ulka Kelkar 《Mitigation and Adaptation Strategies for Global Change》2007,12(5):919-933
India occupies 2.4% of the world’s geographical area with a large percentage of its land under agriculture. About 228 Million
hectares (Mha) of its geographical area (nearly 69%) fall within the dryland (arid, semi-arid and dry sub-humid) region. Of
the total cultivated area of 142 Mha, major part of agriculture in the country is rainfed, extending to over 97 Mha and constituting
nearly 68% of the net cultivated area, therefore making the agricultural sector vulnerable and exposed to the vagaries of
weather conditions. Climate change adds to this dimension of stress. A strong need is felt for targeting programmes in these
areas that address issues related to employing suitable soil and water conservation measures. In this context this paper seeks
to examine the case for watershed development as an adaptive strategy. An examination of the possibility of fortifying the
existing programme with a view to adapting to expected changes in climate in future is undertaken. Also, the possibility of
watershed development integrating into a suitable mitigation strategy for the country is assessed.
相似文献
Preety M. BhandariEmail: |
55.
U. Martin Persson Christian Azar 《Mitigation and Adaptation Strategies for Global Change》2007,12(7):1277-1304
The possibility of adopting national targets for carbon dioxide (CO2) emissions from tropical deforestation in a future international climate treaty has received increasing attention recently.
This attention has been prompted by proposals to this end and more intensified talks on possible commitments for developing
countries beyond the United Nations Framework Convention on Climate Change Kyoto Protocol. We analyze four main scientific
and political challenges associated with national targets for emissions from tropical deforestation: (1) reducing the uncertainties
in emission inventories, (2) preserving the environmental integrity of the treaty, (3) promoting political acceptance and
participation in the regime, and (4) providing economic incentives for reduced deforestation. We draw the following conclusions.
(1) Although there are large uncertainties in carbon flux from deforestation, these are in the same range as for other emissions
included in the current Kyoto protocol (i.e., non-CO2 GHGs), and they can be reduced. However, for forest degradation processes the uncertainties are larger. A large challenge
lies in building competence and institutions for monitoring the full spectrum of land use changes in developing countries.
(2 and 3) Setting targets for deforestation is difficult, and uncertainties in future emissions imply a risk of creating ‘tropical
hot air’. However, there are proposals that may sufficiently deal with this, and these proposals may also have the advantage
of making the targets more attractive, politically speaking. Moreover, we conclude that while a full carbon accounting system
will likely be politically unacceptable for tropical countries, the current carbon accounting system should be broadened to
include forest degradation in order to safeguard environmental integrity. (4) Doubts can be cast over the possible effect
a climate regime alone will have on deforestation rates, though little thorough analysis of this issue has been made.
相似文献
U. Martin PerssonEmail: |
56.
开发了一套监测批式废水生物处理系统质子变化的自动滴定测量装置.装置由批式反应器、数据自动采集与保存系统和药品自动投加系统组成.通过实际测量活性污泥氨氧化反应中氢离子产生量与氨消耗量的化学计量比值,考察自动滴定测量装置的测试精度.在1L的反应器中改变氨氮浓度(以N计)分别为1.67、3.33、8.33、16.66和30.00mg/L下实测比值与其理论值十分接近,相对误差在2.09%~6.34%之间;保持氨氮浓度16.66mg/L,在1、2、3和4L的反应器中实测比值相对误差在2.09%~-18.57%之间,随反应器体积增大而明显增大.反应器系统中的碳酸氢盐和氨盐缓冲体系,特别是在较大容积反应器中的滴定动态效应是导致测试误差的重要原因.研究成果为滴定测量方法在废水生物处理过程中监测质子变化提供了一种重要方法. 相似文献
57.
The coupled SWAP-WOFOST model was used to study the effects of increasing salinity of groundwater, drought and water excess on grass production in The Netherlands. WOFOST simulates crop growth and SWAP simulates transport of water, solutes and heat in the vadose zone. The model was tested using several datasets from field experiments. We applied the models at regional scale where we quantified the impact of various groundwater salinity levels on grass growth and production using historical weather data (1971-2000). The salt concentrations in the subsoil were derived from the National Hydrological Instrument. The results show that salinity effects on grass production are limited. In wet years the excess rainfall will infiltrate the soil and reduce salt water seepage. In a next step we used future weather data for the year 2050, derived from 3 Global Circulation Models. From each model we used data from two CO2 emission scenarios. As expected higher temperatures increased drought stress, however, the production reduction as a result of salt water in the root zone is limited. Salt stress mainly occurred when irrigation was applied with saline water. The increased CO2 concentration in combination with the limited drought stress resulted in increasing simulated actual and potential yields. Overall conclusion for grassland in The Netherlands: drought stress is stronger than stress caused by water excess which on its turn is stronger than salinity stress. Future water demand for irrigation may increase by 11-19% and result in water scarcity if water supply is insufficient. 相似文献
58.
Mikael Hildén 《Journal of Cleaner Production》2011,19(16):1798-1811
All member states of the EU have had to develop climate strategies following the commitment to the UN Framework Convention on Climate Change and the Kyoto Protocol. The evolution of the strategies provides insights into the learning that takes place at the level of policy development and offers material for analysing how ex ante and ex post evaluations have contributed to this learning. In the analysis, Finland is used as a case demonstrating different levels and types of learning, from deeper reframing to political learning. The results show that the full potential of the evaluations has not been utilised, partly because they have been constrained by their mandate. Greater openness and transparency in the policy processes would create favourable conditions for independent evaluations that could provide additional input to the policy processes. This would support social and reflexive learning and allow for greater adaptability. 相似文献
59.
Seepage from Hg mine wastes and calcines contains high concentrations of mercury (Hg). Hg pollution is a major environmental
problem in areas with abandoned mercury mines and retorting units. This study evaluates factors, especially the hydrological and
sedimentary variables, governing temporal and spatial variation in levels and state of mercury in streams impacted by Hg contaminated
runo . Samples were taken during di erent flow regimes in theWanshan Hg mining area in Guizhou Province, China. In its headwaters
the sampled streams/rivers pass by several mine wastes and calcines with high concentration of Hg. Seepage causes serious Hg
contamination to the downstream area. Concentrations of Hg in water samples showed significant seasonal variations. Periods of
higher flow showed high concentrations of total Hg (THg) in water due to more particles being re-suspended and transported. The
concentrations of major anions (e.g., Cl??, F??, NO3?? and SO4
2??) were lower during higher flow due to dilution. Due to both sedimentation
of particles and dilution from tributaries the concentration of THg decreased from 2100 ng/L to background levels (< 50 ng/L) within
10 km distance downstream. Sedimentation is the main reason for the fast decrease of the concentration, it accounts for 69% and 60%
for higher flow and lower flow regimes respectively in the upper part of the stream. Speciation calculation of the dissolved Hg fraction
(DHg) (using Visual MINTEQ) showed that Hg(OH)2 associated with dissolved organic matter is the main form of Hg in dissolved
phase in surface waters in Wanshan (over 95%). 相似文献
60.