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1.
我国西部地区湖泊水资源利用与湖水咸化状况分析 总被引：19，自引：6，他引：13
湖泊咸化是指湖水含盐量逐步增加．湖泊由淡水湖向咸水湖、再向盐湖和干盐湖的演化过程,这是我国西部干旱、半干旱地区湖泊普遍存在的一种现象。在大量调查的基础上,分析了我国西部干旱、半干旱地区近几十年来湖泊萎缩咸化的状况,湖泊变化的所产生的原因,并初步提出改善我国西部地区湖泊水资源利用的对策。 相似文献
2.
利用历史图件、地形图及遥感数据监测塔里木河下游诸多湖泊水域面积并分析近一百多年的变化情况。根据湖泊水域及其变化,该区湖泊在100多年内变化过程可以分为3个时间段：① 20世纪60年代以前,该区水文条件较好,19世纪末20世纪初湖泊总面积超过2000 km2;20世纪60-70年代至20世纪末,随着水利设施的陆续兴建,湖泊水域缩小,甚至某些湖泊彻底干涸;21世纪随着塔里木河流域综合治理与下游生态输水工程的实施,该区水文条件有所好转,干涸多年的一些湖泊重新形成水域,2013年湖泊水域总面积达760 km2。② 根据湖盆成因及水域变化把该区湖泊分为：河道西侧的风成湖,河道网之间及东侧的河成湖及河道末端的构造湖等三类。③ 初步总结风成湖演变过程,发现该区风成湖与河成湖在形状、深度、水质、形成时间等方面有较大差异。④ 近代人为因素对湖泊水域变化的影响高于自然因素。 相似文献
3.
Limnological responses to warming on the Xizang Plateau,Tibet, over the past 200 years 总被引：1，自引：0，他引：1
Paleolimnological analyses can be used to evaluate limnological responses to changing climate over decadal to centennial timescales,
especially in regions with sparse lake monitoring data. We used a training set with 90 lakes to develop a diatom-based conductivity
transfer function and address climate-driven changes in lakes on the Qinghai-Xizang Plateau, Tibet. This new training set
is an expanded version of a previous model (Yang et al. in J Paleolimnol 30:1–19, 2003) and shows improved performance statistics for the conductivity model. The expanded training set also contains diatom species
not previously identified from the region, such as Stephanodiscus sp. and Cyclotella sp., which are common eutrophic indicator species in other regions, but can also be influenced by water column conductivity.
The new conductivity transfer function was applied to Lakes Nam Co and Chen Co in Tibet. Recent conductivity inferences were
compared with climate data from the Dangxiong weather station and water level records from Yangzhuyong Co, which show increasing
temperature and lower water levels, respectively, since AD 1960. Other studies showed that the water balance for many lakes
on the Qinghai-Xizang Plateau is complex, affected by both evaporation and glacial melting. Our paleolimnological reconstructions,
which include sediment particle size data, indicate that over relatively short timescales glacial meltwater can influence
lake hydrology, but over decadal timescales, increases in evaporation, driven by rising temperatures, dominate. Our findings
suggest that regional warming is lowering water levels at these sites and will continue to do so given predicted future climate
warming. 相似文献
4.
现代南极大陆冰缘地理地貌,形成于１８０００年以来全球气候变化,南极大陆冰盖的退缩,以及随后的大陆均衡抬升和海平面变化等过程。研究表明,在维斯德福尔特丘陵地,这一过程仍在继续,并导致该区许多海生盐湖自然环境和理化因子的改变,以及湖中生物的种群结构的变化和群落演替。本文通过对这些现象的剖析,阐明了南极大陆冰缘环境变迁的客观存在,为进一步研究南极乃至全球气候变化提供生态学佐证。 相似文献
5.
世界上近一半的国家和地区不同程度地受到干旱问题的影响。干旱区的最显著特征是降水的极端稀少和不确定。任何降雨以外的水资源输入,即使数量很微小,也对荒漠生态系统的维持和存续有重要意义,因此凝结水作为可能性水源成为研究热点。基于文献资料,本文从干旱、半干旱地区凝结水对生物的影响,对生物结皮及土壤水分平衡的作用,对地下水的补给以及凝结水的人为利用等几个方面阐述国内外的凝结水研究现状,着重分析凝结水生态水文效应方面的研究历程和趋势,总结凝结水研究中存在的问题,展望未来研究工作的重点。 相似文献
6.
Phytoplankton composition and dynamics in three shallow temporary salt lakes (Monegros, Spain) 总被引：2，自引：0，他引：2
The present study deals with phytoplankton composition and dynamics of three ephemeral saline lakes (La Muerte, Piñol and Sulfúrica) situated in one of the most arid inland zone in Europe (Los Monegros). The lakes show marked differences among one another, although they are all temporary, shallow and saline systems (>30 g l−1). La Muerte is dominated by microbial mats that are absent from the other two. Piñol is more exposed to strong winds than the other two lakes and exhibits higher turbidity. Sulfúrica appears to be the most extreme system, with the highest salinity, which leads to a complete absence of macrozooplankton. Phytoplankton composition in these lakes varies as a consequence of the different physico-chemical conditions; it is fundamentally composed of typical hypersaline species such as Dunaliella sp., Aphanothece sp., and soil benthic species (e.g. Hantzschia amphyoxis) that appear to play an important role in these systems. Comparative analysis of the microbial component (phytoplankton diversity and temporal evolution) under in situ conditions and the presence of various abiotic and biotic factors, including the impact of macrozooplankton grazing, shows that it is easy to overlook large differences in the community structure of apparently similar ecosystems. The present study is a contribution to the understanding of the often-neglected microbial ecology of ephemeral shallow lakes. 相似文献
7.
The mechanical denudation rates of 81 large lake basins (lake area > 500 km2) were determined from long-term river loads and erosion maps. Using the drainage area/lake area ratios the mean sedimentation rates of the lakes were calculated for a porosity of 0.3. The mean sedimentation rates of different lake types vary between 0.1 mm/a (glacial lakes, lowland) and 5.4 mm/a (mostly sag basin lakes). The calculated lifetimes of the lakes are based on the lake volumes and mean sedimentation rates, assuming steady-state conditions and solely clastic material. On average, glacial lakes in highlands and fault-related lakes show the shortest lifetimes (c. 70 ka), glacial lakes in lowlands and rift lakes have the longest lifetimes (c. 1 Ma). Some lakes remain unfilled for very long time spans due to rapid subsidence of their basin floors. The calculated lifetimes are compared with those derived from sediment core studies. Most core studies indicate lower mechanical sedimentation rates than the calculated ones because a major part of the incoming sediment is trapped in deltas. However, a number of lakes (e.g., the Great Lakes of North America) show the opposite tendency which is largely caused by extensive shoreline erosion and resuspension. The lifetimes of large glacial lakes often exceed the duration of interglacials. Hence, their lifetimes are restricted by glaciation and not by sediment infill. Rift lakes persist for long time periods which exceed the calculated lifetimes in some cases. Time-dependent subsidence, basin extension, as well as the impact of climate change are briefly described. 相似文献
8.
BY MAURO GUGLIELMIN ANTONI G. LEWKOWICZ HUGH M. FRENCH A. STRINI 《Geografiska Annaler: Series A, Physical Geography》2009,91(2):99-111
Ice blisters, typically 0.2–0.8 m high and 5–20 m long, develop annually on perennially frozen lakes in Northern Victoria Land. They are believed to be caused by hydrostatic pressures generated through progressive freezing of solute-rich water beneath the lake-ice cover during winter. Lake-ice blisters in the study area differfrom icing blisters described from the northern hemisphere. The latter are caused by hydraulic pressures and are found at locations such as river beds or spring sites on sloping terrain. The Antarctic lake-ice blisters reflect the occurrence of dry-based perennially frozen lakes with high salt contents in an extremely cold and arid environment. 相似文献
9.
XinPing Wang YaFeng Zhang Rui Hu YanXia Pan HaoJie Xu Wei Shi YanXia Jin Hiroshi Yasuda 《寒旱区科学》2016,8(6):477-484
Distribution of rainfall event sizes and interval lengths between events are important characteristics of arid and semi-arid climates. Understanding their importance will contribute to our ability to understand ecosystem dynamics in these regions. Rainfall event timing and magnitude are important drivers of ecosystem processes and are instrumental in creating landscape heterogeneity in arid and semi-arid regions. Rainfall event characteristics were analyzed using an automatic tipping-bucket rain-gauge record across the entire summer monsoon season from 2008 to 2015 at the arid desert area of Shapotou in the Tengger Desert, China. Changing the minimum inter-event time (MIT) from 30 min to 24 h alters the number of rainfall events from 64 to 25 for the event depth larger than 0.1 mm. The mean rainfall intensity declined from 0.95 mm/h to 0.53 mm/h, and the geometric mean event duration rose from 0.55 h to 4.4 h. The number of rainfall events, mean rainfall intensity, and geometric mean event duration differed under different criteria of individual rainfall depths, except that for an individual rainfall depth of 0.5, 1.0, and 5.0 mm. The aforementioned features differed only at the lowest range of the mean rainfall intensity and depth for MIT=3 and 6 h. These findings suggest that identification of event-based rainfall in this specific arid region can be better achieved by setting the MIT at six hours. The wide variation in rainfall event properties indicate the need for paying more attention to the proper selection and reporting of event criteria in studies that adopt event-based data analysis. This is especially true in quantifying effective rainfall for soil water replenishment in terms of rainfall depth and intensity with infrequent rainfall events. 相似文献
10.
Almost half the world is suffering from drought at different levels. Since arid and semi-arid regions are characterized by extreme shortage and precipitation uncertainty, water availability is the most important limiting factor in arid lands, and any additional source of moisture, such as condensation water, may have a positive impact upon the ecosystem. Therefore, extensive research has been carried out on condensation. Based on articles and relevant documents on the subject, this paper reviews systematically and comprehensively the latest research achievements in several main aspects, including eco-hydrological effects of condensation water on plants, small animals, microbiotic crusts, soil moisture balance, ground water recharge and anthropogenic utilization. History and trends of research about eco-hydrological effects of condensation water are intensively analyzed in order to summarize existing problems and offer opinions and suggestions for future study. 相似文献
11.
Journal of Geographical Sciences - In recent years, flows of many rivers and lakes have become reduced in arid and semi-arid regions around the world. The most typical examples of this phenomenon... 相似文献
12.
Amany G. Taher 《International Journal of Salt Lake Research》1999,8(2):149-169
The morphology and geochemistry of saline lakes in the Wadi El Natrun depression were studied. All lakes had pH values of 8.5--9.5 and a salinity from 283 to 540 g/L. The main ionic components were sulphate, chloride, carbonate and sodium. Traces of magnesium were also present. The water of the lakes is of the Cl– to SO
4
2–
-Cl– type. Increased Cl– in Wadi El Natrun brines can increase metal solubility due to the formation of soluble chloro-complexes of trace elements. The metal concentrations decrease in the order: Pb > Cu > Cd > Ni > Zn > Fe > Mn. The characteristics of Wadi El Natrun saline lakes are compared with those from other saline lakes. 相似文献
13.
14.
Salt evaporation basins in south-eastern Australia, in contrast with natural saline lakes in this region, were not highly saline and exhibited little seasonal pattern in water depth and salinity over a 2-year sampling period. Lack of seasonality arose from either constant inflow (from continuous groundwater pumping) or erratic inflow (from unpredictable irrigation demands). Differences in zooplankton species composition between the salt evaporation basins and natural saline lakes might reflect the differences in temporal salinity patterns. Some typical saline lake zooplankton were not found in the evaporation basins. Salt evaporation basins therefore may represent additions to the inland water habitats of semi-arid Australia. 相似文献
15.
Javier Alcocer Elva Escobar Alfonso Lugo Laura Peralta 《International Journal of Salt Lake Research》1998,7(2):87-108
Two saline crater lakes in the basin of Oriental, Puebla-Tlaxcala-Veracruz, were investigated for littoral benthic macroinvertebrates.
Fifty taxa were identified with the oligochaetes, amphipods, chironomids and leeches the dominant organisms. These four taxa
made up to 99 per cent in both number and biomass.Limnodrilus hoffmeisteri, Hyalella azteca, Tanypus (Apelopia) sp. andStictochironomus sp. were the most abundant organisms. Unlike other saline lakes which have a littoral benthos dominated by chironomids, Alchichica
and Atexcac were dominated by oligochaetes (70–73 per cent). The gastropod,Physa sp., was found up to a salinity of 8 g L−1; in other studies, it has been found in lower salinities.L. hoffmeisteri is also a typical inhabitant of freshwater lakes, particularly of deep waters. It was dominant in the shallow, saline waters
of the two lakes studied. Salinity did not affect species richness. Alchichica, the most saline of the six crater lakes of
Puebla (salinity, 7.4 g L−1), had 30 per cent more species than the freshwater lakes, and double the species number of Atexcac. It seems the main factor
controlling species richness and the density and biomass of organisms in Alchichica and Atexcac is the presence of aquatic
vegetation. It does this by increasing habitat heterogeneity and providing food and protection against predators. 相似文献
16.
Alison J. Smith 《Journal of Paleolimnology》1993,8(2):121-134
The modern ostracode distribution in lakes of the north-central United States shows how ostracode abundances are related to concentrations of major ions such as calcium, sulfate, and bicarbonate. These relationships are quantified for species living in lakes that range from fresh water (200 S cm-1) to saline water (17 000 S cm-1). Lakes located in the Minnesota forests have different ostracode assemblages and different water chemistry than lakes located on the prairie of North Dakota and South Dakota. These differences are attributed to differences in precipitation and rock-water interactions. Multivariate analyses of the ostracode and water chemistry data set indicate that different ostracode species are associated with different water types. For example, Limnocythere sappaensis and Heterocypris glaucus are found in bicarbonate-enriched sulfate-dominated waters, whereas Limnocythere staplini is found in bicarbonate-depleted sulfate-dominated waters. Candona ohioensis and Limnocythere itasca are found in fresh water, and Candona rawsoni is eurytopic and found in both bicarbonate-enriched and bicarbonate-depleted sulfate-dominated waters. Ostracodes can be used to identify changes in both ionic composition (solutes) and ionic concentration.This publication is the second of a series of papers presented at the Conference on Sedimentary and Paleolimnological Records of Saline Lakes. This Conference was held August 13–16, 1991 at the University of Saskatchewan, Saskatoon, Canada. Dr Evans is serving as Guest Editor for this series. 相似文献
17.
Monitoring degradation in arid and semi-arid forests and woodlands: The case of the argan woodlands (Morocco) 总被引：1，自引：0，他引：1
Yann le Polain de Waroux 《Applied geography (Sevenoaks, England)》2012,32(2):777-786
Arid and semi-arid forests and woodlands (hereafter called «dryland forests»), in spite of their ecological and social importance, have received little attention in land change studies. Growing evidence shows that these forests have been receding at very high rates in many places, suggesting a need for a better understanding of the processes and causes of dryland forest degradation. Changes in the extent of dryland forests are debated in part because estimates of forest and woodland areas in drylands are uncertain. Causal explanations of the degradation tend to draw on the literature on desertification and tropical deforestation, and to emphasize either local or remote, and either social or biophysical drivers. This study contributes to a better understanding of dryland forest degradation as a basis for conservation policies. Firstly, we argue that monitoring arid and semi-arid forests and woodlands using area estimates may lead to an underestimation of the severity of change because tree density change often exceeds area change. Secondly, we argue that the analysis of degradation processes in these multifunctional landscapes should integrate both local and remote, and both social and biophysical factors. We use a case study of degradation in the argania woodlands in semi-arid to arid Southwest Morocco to test these two claims. We used gridded tree counts on aerial photographs and satellite images to estimate forest change between 1970 and 2007, and we tested several possible causes of change on the basis of original socio-economic field surveys and climatic and topographic data. We found that forest density declined by 44.5% during this period, a figure that is significantly underestimated if forest area change is used as a measure of degradation. Increasing aridity and, to a lesser extent, fuelwood extraction were related to forest decline. No effect of grazing by local livestock was found. 相似文献
18.
A study on two closed salt lake basins, Tal Chapar and Parihara in the eastern margin of the Thar Desert, Rajasthan, was carried
out to unravel late Quaternary geomorphic evolution of these saline lakes. Both lakes are elliptical in shape bordered by
stabilised dunes, and are oriented in a NE-SW direction, i.e., in the direction of the prevailing summer monsoon wind. Both
lakes have been formed in the wind-shadow zones of isolated hills of Precambrian quartzite. Our study indicates that the late
Quaternary sediments in the lakes began with the cyclic deposition of laminated fine silt layers (0.5 m thick), rich in organic
matter, alternating with ripple cross-bedded sand layers (each ∼1.5–2 m thick). Sand layers that are moderately sorted are
separated by laminated silt-clay layers with gypsum/calcite and this unit occurs in the upper most 4 m sequence in deeper
sections. The presence of gypsum crystals within the laminated sediments suggests a high concentration of Ca in the inflowing
water.
At Parihara Lake the organic carbon-rich sediments at 95 cm depth was dated to 7,375 + 155/−150 year BP. At Tal Chapar radiocarbon
dates of 7,190 + 155/−150 and 9,903 + 360/−350 was obtained from the sediments rich in organic carbon occurring at a depth
of 1.35 m and 1.80 m, respectively. The study reveals strong hydrologic oscillations during the past ∼14,000 year BP (13,090 + 310/−300 year
BP).
Quaternary geomorphic processes, especially the strong aeolian processes during dry climatic phases, played a major role in
the formation of the lake basins, as well as the fringing linear dunes. Geochemical and mineralogical analyses of the lacustrine
sediments, supported by radiocarbon dates indicate the existence of an ephemeral lake earlier than ∼13,000 year BP as sediments
began to be deposited in a lacustrine environment implying sustained runoff in the catchments. A freshwater lake formed between
9,000 year and 7,000 year BP. The lake dried periodically and this strong fluctuating regime continued until about ∼7,000 year
BP. Mid-Holocene was wet and this was possibly due to higher winter rains A saline lake existed between 6,000 year and 1,300 year
BP and finally present day semi arid conditions set in since 1,200 year BP. Remnants of a habitation site (hearth and charred
bones) on stabilised dune at Devani near Tal Chapar were dated to 240 ± 120 year, while that at Gopalpura was dated to 335 ± 90 year.
These historical sites on stabilised dunes were, according to the local accounts, settlements of people who used the lake
brine for manufacturing salt. 相似文献
19.
Diatoms reveal complex spatial and temporal patterns of recent limnological change in West Greenland
Bianca B. Perren Marianne S. V. Douglas N. John Anderson 《Journal of Paleolimnology》2009,42(2):233-247
Diatoms in sediment cores were analysed across a range of stratigraphic resolutions along a transect of 23 lakes spanning
the ice-free margin of the west coast of Greenland (~67°N), to explore spatial and temporal patterns of recent (last ~150 years)
environmental change in the region. These records display heterogeneous lake development trajectories over the last several
centuries. Estimates of species composition turnover (beta-diversity) since 1850 AD are among the lowest for lakes in the
Arctic, and are comparable to “unimpacted” reference lakes from temperate regions. Most of the change that occurred in West
Greenland lakes pre-dates potential industrial anthropogenic effects, while post-1850 change is well within the natural range
of variability for these systems. Nonetheless, a spatial pattern in core “top–bottom” changes is apparent across the transect:
lakes in the arid interior of the region, adjacent to the ice sheet, and those with higher pH, register greater change than
those in the more maritime climate of the coast. This suggests that climate plays an indirect role in the recent development
of these lakes, and that recent anthropogenic forcing has not yet exceeded major ecological thresholds in this region. 相似文献
20.
过去45年中国干湿气候区域变化特征 总被引：24，自引：4，他引：24
利用中国1960-2004年降水、平均气温、风速和相对湿度等资料,分别采用降水指数和干湿分类函数作为干湿区域的划分标准,将中国划分成三个干湿等级的区域:干旱区、半干旱区和湿润区。结果发现无论以哪种指数作为衡量干湿的标准,我国过去45年的干旱总面积,即干旱区面积和半干旱区面积之和,均为扩大趋势,湿润面积则为减小趋势,这种情况在近十年表现得尤为显著。而半干旱区面积在分析时段变化的幅度最大,是干湿变化的敏感区。但两种结果之间也存在不同:降水指数的结果表明干旱区和湿润区的面积减小,半干旱区的面积增大;而干湿分类函数得到的各个干湿区域的面积则表明干旱区的增大,半干旱区和湿润区的减小。从定量的角度讲,干湿分类函数估算的干旱区面积的45年平均值比降水指数估算的干旱区面积的45年平均值约大15%,其估算的半干旱面积的45年平均值比降水指数的结果约小9%,而两者湿润区面积的45年平均值相差约6%。最后给出了仅分析降水指数就能反映干湿状况的地区和必须分析干湿分类函数才能确定干湿状况的区域。 相似文献