新疆平原沙漠区湖泊干缩生态效应初探   总被引：1，自引：1，他引：0  

王晓峰  章海生 《湖泊科学》1993,5(3):218-224

50年代至80年代初,新疆平原沙漠区湖泊普遍处于退缩状态,一些湖泊干涸或基本干涸,这是湖泊所在流域上、中游地区灌溉事业发展的必然结果。到目前为止,湖泊干缩所引起生态环境的变化,其范围主要限于湖周有限区域;变化的幅度尚未达到对人类生活和生湖泊及湖周有限区域生态环境的恶化中,人类不正确的活动方式占了很大比重。  相似文献   

Trace Metals in Phosphate Fertilizers Used in Eastern Mediterranean Countries     

《洁净——土壤、空气、水》2017,45(1)

  相似文献   

乌审旗近50年干旱气候分析及应对措施   总被引：1，自引：0，他引：1  

罗玉昌  赵平和  徐健 《内蒙古气象》2009,(3):21-22

根据乌审旗气象局1959—2008年4—9月份逐月降水量距平百分率的统计,分析毛乌素沙漠腹地乌审旗的干旱气候特征,从气候学角度提出干旱气候的应对措施,指导当地农牧业生产和生态建设。  相似文献   

西北干旱区生态需水研究   总被引：16，自引：2，他引：14  

赵传燕  程国栋 《地球科学进展》2006,21(11):1101-1108

西北干旱区是水资源稀缺和生态环境相对脆弱的区域。以人类需求为中心的传统水资源开发利用及评价忽视了水资源与生态环境系统之间的关系,引发了众多的生态环境问题。日益恶化的生态环境使得生态需水量受到广泛关注,生态需水量研究由此成为干旱区生态水文学研究新的增长点。文章在综述国内外生态需水研究现状及其面临挑战的基础上,分析西北干旱区水资源转化特点,结合Falkenmark 水资源分类,突出生态需水在水分流中的地位,提出保障生态需水的策略,即：①生态环境稳定性界定;②绿水的保护与高效利用; ③虚拟水战略,旨在为平衡人类需水与自然需水提供重要的理论基础。  相似文献   

降水条件下的典型干旱区陆面特征模拟验证   总被引：6，自引：0，他引：6       下载免费PDF全文

王胜  张强  卫国安 《地球物理学报》2006,49(2):383-390

利用“我国西北干旱区陆－气相互作用观测试验"在敦煌双墩子戈壁站取得的观测资料及最近的一些研究成果对陆面模式中反照率、相似性函数及地表粗糙度(动量粗糙度,标量粗糙度)3个方面的参数化方案进行了改进,然后对一次典型降水过程的陆面特征及近地层的风、温、湿进行了模拟.结果表明：改进的模式能对降水条件下的干旱区陆面特征进行较好的模拟,其中对辐射、地表温度的模拟相当好,而对能量的模拟虽然还有要改进的地方,但总体结果令人满意;另外改进后的模式对近地层的温度和湿度的模拟也有明显的改善.  相似文献   

Regional geologic environs and natural resources of Badia Sector, Jordan     

A. S. Al-Homoud  R. J. Allison  D. L. Higgitt  K. White  B. F. Sunna 《Environmental Geology》1998,36(1-2):18-26

 This paper summarizes the information on the geology and natural resources of the Jordan Badia Research and Development Programme. The research focused on the issue of the environment in arid lands as an aid to provide practical options for sustainable development. This paper presents results of field studies in the following areas related to the sustainable development of the Safawi area in the northern Jordan Badia; geomorphology, including landform, soil, lands, processes and hazards, geology and physical resources and surface water hydrology. Tertiary-Quaternary continental basalt flows and tuffs cover approximately 11 000 km², the majority of the Safawi area. In addition to extensive basalt lava flows, the programme area includes a variety of geological outcrops and potential sources of economic products that include the following: Tuff/Scoria, Zeolite/Olivine, Porcellanite, potential sources of aggregate/construction materials, ornamental stone, building stone, basalt for manufacturing of rock wool, and materials suitable for producing lightweight aggregate. The whole of the eastern Badia exhibits major fault systems, many of which were identified from Landsat TM images. The system of wadis which drains the Badia is extensive, with the general flow from the north to the south and south-west. A noticeable geomorphic surficial deposit occuring throughout much of the Badia is fine-grained, water-lain sediments that vary in size and character. The local designation for the fine sediment deposits is Qaa. An MSS scene for the area under consideration has been studied. Twelve major geomorphic subdivisions or zones can be identified. Individual land system units have been identified by traversing the programme area. Key sites have been visited based on Landsat TM image interpretation. To a large extent, key areas were subdivided after their initial identification on the Landsat scene and corroboration in the field. The surface drainage of the Badia region can be broadly divided into wadi systems, areas of distinct channelized flow, and Qaa, predominantly fine-grained sedimentary basins of low relief. Spatial variability in infiltration rates across the wadi-Qaa system were determined from field experiments. Infiltration rates were found to be medium-high in the wadi channels but decrease rapidly for the Qaa materials. Apparently runoff from wadi side slopes will be high, and water storage occurs along the wadi channels while ponding occurs in the Qaa areas. Received: 13 March 1997 · Accepted: 13 January 1998  相似文献   

How robust are global conservation priorities to climate change?     

Takuya Iwamura  Antoine Guisan  Kerrie A. Wilson  Hugh P. Possingham 《Global Environmental Change》2013,23(5):1277-1284

International conservation organisations have identified priority areas for biodiversity conservation. These global-scale prioritisations affect the distribution of funds for conservation interventions. As each organisation has a different focus, each prioritisation scheme is determined by different decision criteria and the resultant priority areas vary considerably. However, little is known about how the priority areas will respond to the impacts of climate change. In this paper, we examined the robustness of eight global-scale prioritisations to climate change under various climate predictions from seven global circulation models. We developed a novel metric of the climate stability for 803 ecoregions based on a recently introduced method to estimate the overlap of climate envelopes. The relationships between the decision criteria and the robustness of the global prioritisation schemes were statistically examined. We found that decision criteria related to level of endemism and landscape fragmentation were strongly correlated with areas predicted to be robust to a changing climate. Hence, policies that prioritise intact areas due to the likely cost efficiency, and assumptions related to the potential to mitigate the impacts of climate change, require further examination. Our findings will help determine where additional management is required to enable biodiversity to adapt to the impacts of climate change.  相似文献   

Environmental isotopic study on the recharge and residence time of groundwater in the Heihe River Basin, northwestern China   总被引：9，自引：2，他引：7  

Zongyu Chen  Zhenlong Nie  Guanghui Zhang  Li Wan  Jianmei Shen 《Hydrogeology Journal》2006,14(8):1635-1651

The recharge and origin of groundwater and its residence time were studied using environmental isotopic measurements in samples from the Heihe River Basin, China. δ¹⁸O and δD values of both river water and groundwater were within the same ranges as those found in the alluvial fan zone, and lay slightly above the local meteoric water line (δD=6.87δ¹⁸O+3.54). This finding indicated that mountain rivers substantially and rapidly contribute to the water resources in the southern and northern sub-basins. δ¹⁸O and δD values of groundwater in the unconfined aquifers of these sub-basins were close to each other. There was evidence of enrichment of heavy isotopes in groundwater due to evaporation. The most pronounced increase in the δ¹⁸O value occurred in agricultural areas, reflecting the admixture of irrigation return flow. Tritium results in groundwater samples from the unconfined aquifers gave evidence for ongoing recharge, with mean residence times of: less than 36 years in the alluvial fan zone; about 12–16 years in agricultural areas; and about 26 years in the Ejina oasis. In contrast, groundwater in the confined aquifers had ¹⁴C ages between 0 and 10 ka BP.  相似文献   

Arbuscular mycorrhizal associations in Solanum centrale (bush tomato), a perennial sub-shrub from the arid zone of Australia     

A.L. Dennett  L.W. Burgess 《Journal of Arid Environments》2011,75(8):688-694

Arbuscular mycorrhizal (AM) fungi convey well documented benefits to plant growth in domesticated species. We investigated AM in Solanum centrale, a desert shrub of central Australia and traditional food for Indigenous Australians. AM were observed in roots of S. centrale from wild and cultivated stands of different ages and management regimes. Greenhouse seedlings grown in sterilised sand were provided with no or minor additions of phosphorus, with or without AM fungi. Inoculated seedlings not fertilised with phosphorus exhibited moderate AM formation. Added phosphorus resulted in an absence of AM. Inoculation did not significantly affect dry weight, root length and plant height of seedlings fertilised with phosphorus but significantly increased the size of unfertilised seedlings. Inoculation significantly increased root phosphorus content, decreased root to shoot ratio and decreased root biomass at all phosphorus additions, despite the absence of observable AM. Thus it appears AM fungi in the root zone influenced certain plant characteristics, regardless of phosphorus nutrition. Overall, S. centrale benefited from the presence of AM through increased phosphorus uptake, but only when the seedlings were growing in soil with extremely low available phosphorus. The response was immediate in our experimental system and is likely to be important in the wild.  相似文献   

Flow transmission along an arid zone anastomosing river,cooper creek,australia     

A. David Knighton  Gerald C. Nanson 《水文研究》1994,8(2):137-154

Cooper Creek is characterized by an exceptionally wide floodplain and a complex system of anastomosing channels which together can accommodate a large range of highly variable flows. In consequence flood frequency curves are unusually steep. With minimal tributary contribution over the two study lengths — Currareva-Nappa Merrie (> 400 km) and Nappa Merrie-Innamincka (32 km) — downstream output is largely controlled by upstream input, so that similar flow regimes and hydrograph forms can be maintained despite transmission losses and the variable activation of channels. Input-output relationships defined in terms of total flow volume and peak discharge suggest that, above a threshold flow of about 25% duration, transmission losses exceed 75% on average over the Currareva-Nappa Merrie length. The large difference in absorption between primary channels on the one hand and subsidiary channels and the floodplain surface on the other means that transmission losses vary non-linearly with stage. They are relatively low when flow is confined to the primary channels, but increase at higher stages as lesser channels and the floodplain are activated. Early levels do not recur until flows of < 0.5% duration are attained when output/input ratios increase rapidly with discharge. The influences of seasonality and background flow on output discharge are small relative to that of input discharge. Despite the long river distance, peak flows at Currareva and Nappa Merrie are well correlated. However, over the shorter Nappa Merrie-Innamincka length with its more confined system of channels, correlations are better and transmission losses less. They vary from 60% just above the threshold discharge to <10% at flows below 20% duration. Over this length outflow hydrographs can be effectively estimated by the three parameter Muskingum procedure, at least on an event by event basis, but further application must await additional records to understand fully how the parameters vary in an environment where streamflow is transmitted through a highly variable system of channels.  相似文献