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951.
952.
Serdar Eyeberenov Baijing Cao Fengting Li 《Frontiers of Environmental Science & Engineering in China》2009,3(2):221-225
Prior to independence, Central Asian countries were closely interconnected through the regional management incorporating water,
energy, and food sectors. This approach, supported by the central government of Union of Soviet Socialist Republics (USSR),
functioned effectively — meeting the needs of both upstream and downstream countries. However, after independence, Central
Asian countries started prioritizing their own economic development policies without due account to regional concerns such
as joint use of water resources, leading to instability. In this study, the case of Syrdarya basin was investigated to show
how such strategies create tension in the region, since primary focus is given to national interests, without consideration
for regional problems. To address this issue, an integrated approach to incorporating water, energy, and agriculture is needed.
It is suggested that a single sector approach on water alone does not lead to stability, and a multi-sectoral approach is
necessary to ensure sustainable development. Countries sharing benefits from the river have to be responsible for costs of
operation and maintenance of the water facilities. 相似文献
953.
植被是土地覆盖中的最主要部分,是连接土壤、大气和生物等要素的自然“纽带”。植被覆盖动态变化对全球能量循环和物质循环具有重要影响,是全球变化研究的重要内容之一。黄河流域作为我国重要的粮食生产基地,其环境变化直接影响到流域经济的可持续发展。为了快速准确地提取地表植被状况,了解黄河流域生态环境,利用1998—2011年的SPOT-VGT遥感数据,结合地理信息技术,采用均值法和趋势分析法对黄河流域植被NDVI时空分布特征和变化趋势进行了动态监测。结果表明,(1)黄河流域14年NDVI均值的空间分布整体特征是东南部平原、盆地和西部山地植被状况要好于北部地区。其次,黄河流域属于干旱半干旱地区,植被发育主要依赖于水文条件,所以沿黄河干流和支流区域也具有较高的植被NDVI值。(2)黄河流域植被NDVl年均值近14年间整体呈缓慢增长趋势,1998--2000年呈现急剧减少态势,2001--2003年出现了较为快速的增长,2004--2011年又出现了较长时间的连续增长过程。(3)黄河流域植被NDVI基本不变的区域约占研究区总面积的71.13%;植被NDVI轻微改善的区域约占流域总面积的27.30%,且主要分布于流域东南部的盆地、平原和西部的山地、丘陵地区,植被NDVI退化的区域面积约占流域总面积的0.98%。黄河流域自1998年以来,植被NDVI整体在不断提高,生态环境在不断改善。 相似文献
954.
对太湖流域某市农业活动区具代表性的14个监测点的土壤(0~10、20~30和50~60 cm)进行采样分析,利用多元统计和地统计学方法,研究了该地区Cd、Pb、Cr和Mn等重金属的空间分布特征及其主要来源. 结果表明,各采样点和各层土壤之间重金属的含量变化较大,变异系数为39.05%~243.52%. 各层土壤中w(Cd)和w(Pb)以及底层土壤中w(Cr)均超过土壤背景值,尤其是w(Cd),表层、中层和底层分别为19.92、17.41和19.97 mg/kg,远高于背景值. 地统计学分析表明,各层土壤中w(Cd)、w(Pb)以及表层土壤中w(Cr)的高值区主要分布在研究区北部,而中层和底层土壤中w(Cr)的高值区主要分布在研究区南部. w(Mn)受自然因素的影响较大,分布较为均匀. 表层、中层和底层土壤中w(Cr)和w(Mn)的相关系数分别为0.715(P<0.01)、0.632(P<0.05)和0.602(P<0.05),w(Pb)与w(Cd)的相关系数分别为0.842(P<0.01)、0.590(P<0.05)和0.874(P<0.01). 主成分分析表明,研究区耕地土壤中w(Mn)主要受地球化学的影响,Cd、Pb和Cr的污染主要来源于工厂所排放的废气、废水,机动车尾气,以及农业活动施入的化肥、农药. 相似文献
955.
956.
Daniel Bekele Tena Alamirew Asfaw Kebede Gete Zeleke Assefa M. Melesse 《Environmental Hazards》2019,18(3):246-265
Unprecedented pace and magnitude of land use/land cover (LULC) change in the Ethiopian highlands is a key problem threatening the natural ecosystem and creates vulnerability to an environmental hazard. A combination of remote sensing, field observations and focus group discussions were used to analyze the dynamics and drivers of LULC change from 1985 to 2011 in the Keleta watershed, Ethiopia. Supervised image classification was used to map LULC classes. Focus group discussions and ranking were used to explain the drivers and causes linked to the changes. The result showed rapid expansion of farmland and settlement (36%), shrublands cover shrinking by 50%, while the size of degraded land increased by 45%. Rapid population growth, rainfall variability and soil fertility decline, lack of fuelwood and shortage of cultivation land were ranked as the main causes of LULC change in the watershed according to the focus group discussion. Further effort is needed to improve the creation of new job opportunity, promotion of improved technologies to boost productivity and soil fertility, provide credit facility, extra push on irrigation infrastructure development and soil, water and natural ecosystem conservation practices. Generally, better community-based land resource management will need to ensure sustainable rural livelihoods. 相似文献
957.
Harieth Hellar-Kihampa Sanja Potgieter-Vermaak Katleen Van Meel Giuliana Gatto Rotondo Michael Kishimba Réne Van Grieken 《毒物与环境化学》2013,95(3):525-544
River-bed sediments from the Pangani basin, Tanzania, were characterized for elemental compositions, following contamination risks from rapid expansions of human activities in the area. Samples were collected during two individual seasons and analyzed by high-polarizing beam energy dispersive X-ray fluorescence (EDXRF) for eight major and 14 trace elements. Evaluation of enrichment factors (EFs) was used to investigate the elemental flux and assess the contributions of natural and anthropogenic influences. The abundances of the major elements followed the order Si?>?Al?>?Fe?>?Ca?>?K?>?Ti?>?Mn?>?P, similar to that of the upper earth's crust, and were generally from the weathering of the bed-rock. The high concentrations of typical anthropogenic trace-elements (Cr?160?mg?kg?1, V?85?mg?kg?1, Ni?60?mg?kg?1, Cu?87?mg?kg?1, La?90?mg?kg?1) coupled with high EFs (>2) in some locations indicated contamination associated with agricultural and industrial activities. Factor analysis extracted five principal components that contributed to 96.0% of the total observed variance. The results indicated that river-bed sediments of the Pangani basin were influenced to a larger extent by lithogenic sources than anthropogenic impacts. 相似文献
958.
太湖流域典型地区农村生活污水中污染物在表层土壤中的削减特征与测算 总被引:2,自引:0,他引:2
原位采集太湖流域典型平原河网地区农户化粪池排污口附近的表层土壤及化粪池出水,人工模拟研究区域典型降雨(夏季30 mm·次-1,冬季5mm·次-1)、气温(夏季27℃,冬季5℃)条件以及排污负荷[TN:(2.35±0.06) g·m^-2 ·d^-1,NH4+-N:(2.08±0.04)g·m^-2· d^-1,TP:(0.21±0.01)g·m^-2·d^-1,COD:(11.14±0.59)g·m^-2·d^-1],并进行室内模拟土柱试验,测算不同季节(夏季和冬季)、不同天气过程(雨前、雨天和雨后)排污口表层土壤对农村生活污水各类污染物的削减率并探讨其削减规律.结果表明:在季节差异上,雨前、雨天和雨后TN削减率均表现为夏季<冬季(P<0.05或P<0.001),NH4+-N削减率则均表现为夏季>冬季(P<0.01);雨前和雨后TP削减率表现为夏季>冬季(P<0.001),COD削减率无显著季节性差异;雨天TP和COD削减率则均表现为夏季<冬季(P<0.01或P<0.001).在天气过程差异上,夏季土壤TN削减率表现为雨后>雨前>雨天(P<0.01),夏季TP和COD削减率表现为雨前≈雨后>雨天(P>0.05,P<0.01),而夏季NH4+-N,冬季TN、NH4+-N、TP和COD削减率在不同天气过程之间无显著差异(P>0.05).据此划分,夏季雨前、雨天和雨后及冬季TN削减率分别为38.5%、-25.0%、46.0%和50.4%,夏季和冬季NH4+-N削减率分别为91.5%和85.5%,夏季雨天、夏季其余时间及冬季TP削减率分别为63.3%、93.1%和82.7%,夏季雨天及其余时间COD削减率分别为8.2%和66.2%. 相似文献
959.
The results of the daNUbs-project deliver a basis for a proper management of nutrients in the Danube Basin. The understanding of the sources, pathways, and sinks of nutrients in the Basin and their effects on the Western ad North-Western Black Sea (WBS) ecosystem has been improved. Quantitative models on the emission of nutrients, their transport along the rivers, and their impact on the WBS have been further developed and combined. Phosphorus loads discharged by the Danube are 30–50% lower than in the 1980s (dissolved P even to a higher extent). Nitrogen emissions have decreased considerably as well. The lower nutrient discharges from the Danube have led to a significant improvement in the WBS ecosystem. Current low discharges of N and P to the WBS are the result of (1) improved nutrient removal from waste water in Germany, Austria, and Czech Republic, (2) reduced P-discharges from detergents and (3) the consequences of the economic crisis in central and eastern European countries following the political changes of 1989/1990. As the decrease is partly due to the economic breakdown in the formerly communist countries, economic development in these countries has to go along with proper nutrient management. Otherwise, the situation in the WBS ecosystem will deteriorate again. 相似文献
960.
大同盆地是典型的高砷地下水分布区。利用从地方性砷中毒严重病区山阴县采集的高砷地下水样品,用稀释培养法实验研究了外加砷源对地下水中微生物数量的影响;同时基于生物学可培养法和16SrDNA序列比对法,选取代表性高砷水样,研究了耐砷菌的种群特征。结果表明,外加砷源对地下水中微生物数量影响显著,高浓度砷会抑制大部分微生物生长,使微生物数量减少;低浓度砷对微生物生长具有一定促进作用。通过多次分离、纯化从3个不同砷含量地下水样中分离到多株砷抗性菌,经鉴定属于主要为Bacillus、Pseudomonas、Paenibacillus、Aeromonas、Enterobacter5个属。从RDP(RibosomalDatabaseProject)分析显示3个水样可培养微生物组成不同,都有生存能力强能够耐低浓度NaAsO2的Bacillales,优势耐砷菌是γ-proteobacteria,其中Enterbacter具有耐高浓度NaAsO2的能力。 相似文献