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1.
Coastal region on the Antarctic continent, where it is under the influences both of ocean and ice sheet, as well as frequent human activities, could be considered as a fragile zone in Antarctic ecological environment. There are many lakes in coastal region, showing much differences from each other in physical-chemical features because of individual evolutionary history in their geographical environments, and suffering from different outside factors, such as climate changes and precipitation. Thus, it results in respective biological distribution and ecological structure in lakes. The present paper reports the results from the studies of chemical components, species distributions and community structures, which mainly consisted of planktons in lakes in the Vestfold Hills (68°38＇S, 78°06＇E), and the Larsemann Hills (69°30＇S, 76°20＇E), East Antarctica. It also treats the biological diversities and nutrient relationships of these different types of lakes. So as to provide more scientific basis for monitoring of climate changes and environmental protection in Antarctica. 相似文献
2.
The investigation of phytoplankton standing stock, euphotic layer and photosynthesis rate were carried out in 19 - 27 of January, 2000 at three longitudinal sections (70°30＇E, 73°00＇E and 75°30＇E). The results showed that the high value of chlorophyll a concentration was in inshore bay, polynya and the continental slope of the investigated sea area. At various investigated stations, average chlorophyll a concentration at sub-surface layer (25 m) was higher than that at surface layer; its concentration at the deeper layers of over 50 m decreased with increasing depth. At anchor station, the maximum chlorophyll az concentration appeared at surface layer in Antarctic summer's afternoon while the minimum value appeared in the morning; chlorophyll a concentration at water layer of 0 - 25 m was obviously higher than that at deep water layer, being related to the releasing of ice-algae. High productivity was in inshore bay and polynya of continental shelf. Chlorophyll a concentration at surface layer is closely correlated to the dissolved oxygen concentration in seawater. The sea ares with chlorophyll a concentration of over 1.0ag/dms may be the convergence of CO2 and that of below 1.0 μg/dms may be the source of CO2. 相似文献
3.
韩嘉福 《地球信息科学学报》2010,12(6):777-783
地图集的地图可视化设计与单幅地图不同,需要以地图集的总体设计思想为依据,在地图设计与表达时反映指标体系的科学完整性,体现地图集的总体协调性。本文以《中华人民共和国人口与环境变迁地图集》为例,详细介绍了以多指标、长时间序列为特征的人口与环境变迁地图的可视化设计与表达方法,包括:系列地图、结构及其数量变化、构成比例变化、数量变化及其对比关系、累积数量变化、多指标数量累积及其对比、相对某一时间基点变化、单指标多年统计特征的变化、单指标两个时期数据的对比等。该方法以对相关指标现状的表达为基础,重点强调制图对象变迁特征,表达指标体系之间的联系和区别。相关地图可视化设计方法可广泛应用于其他类似专题地图的设计过程中。 相似文献
4.
1 Introduction The Grove Mountains is located at Princess Elizabeth land in East Antarctica, about 400 km from Zhongshan station and 160 km east of the Mawson Escarpment, consists of a scattered group of mountains and nunataks. The range extends73°-76°E… 相似文献
5.
现今绝对板块运动 总被引：1，自引：0，他引：1
魏子卿 《地球科学与环境学报》2009,31(4):331-343
根据热点假设,热点对于中间层是固定的.相对热点的板块运动叫做绝对板块运动.绝对板块运动模型可以通过反演火山链传播的速率和走向数据以确定相对板块运动在角速度空间的原点来得到.利用一组近来(0～7.8 Ma)全球分布的热点的迁移速率和走向数据,结合板块运动模型NNR-NUVEL1A,已研制出一个叫做APM2的现今绝对板块运动模型.按照该模型,太平洋板块围绕60.063°S、102.210°E处的极以(0.833 0°±0.013 3°)/Ma的速率运动,非洲板块围绕46.849°N、44.372°W的极以(0.101 5°±0.013 4°)/Ma的速率运动,南极板块的运动则以46.871°N、146.942°E为极,速率为(0.084 6°±0.017 7°)/Ma,欧亚板块的运动更慢,极为27.291°N、171.925°W,速率为(0.065 5°±0.020 6°)/Ma.这一模型表明,岩石圈相对深部地幔有一个以49.423°S、90.625°E为极,速率为(0.198 3°±0.013 5°)/Ma的净旋转.表明太平洋热点同印度-大西洋热点不一致,显示太平洋热点的运动也不一致.为了分析和比较,还给出了仅用全球分布的热点的走向数据和仅用印度-大西洋热点的走向数据得到的板块绝对运动的角速度. 相似文献
6.
张虎才 《中国地理科学(英文版)》1998,8(4):377-382
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7.
《中国海洋湖沼学报》2018,(6)
Our sustainable environmental management must be based on adequate ecological concepts. The question arises: what concept is better to use for understanding and management of ecosystems? To look for an answer, we concentrate our attention on saline lakes. Every ecosystem has several alternative stable states and may demonstrate regime shifts, which are large, abrupt, persistent changes in the structure and function of a system. To understand the dynamics of ecosystems the Concept of Multiplicity of Ecosystem Alternative Stable States as a new ecological paradigm has been developed recently. The author analyzes the emerging paradigm using the case of saline lakes, and discusses how to base our adaptive environmental management on the developing paradigm. Different issues of development of the concept and its application to salinology as a scientific basis of an integrated management of a saline lake and its watershed are discussed. The concept may serve as one of the key theoretical elements of the scientific basis in sustainable environmental management. 相似文献
8.
1 Introduction Itiswellknownthatseaiceinthepolarregionplaysanimportantroleintheglobal climatechangesasapartofclimatesystem(Carleton1989;YuanandMartinson2000, 2001;ChengandBian2002;LiuandMartinson2002;LiuandZhang2004;Gigorand Wallace2002etal).Infact,numerousmodelingstudiessuggestanimportantinfluence throughtheseaicefieldsalone(Grumbine1994,Meehl1990,Rindetal.1995).Inor dertounderstandthevariabilityofArcticandAntarcticseaicealongwiththepossiblecon nectionswithclimaticanomaliesindetail… 相似文献
9.
Response of rotifer community to environmental changes in five shallow lakes in the middle reach of Changjiang River,China 总被引：2，自引：0，他引：2
We evaluated the response of a rotifer community to environmental changes in five shallow lakes in the middle reach of the Changjiang （Yangtze） River in summer and autumn 2010. These five lakes differed in trophic status and rotifer community structure. Twenty-nine rotifer species were collected, of which Keratella cochlearis, Polyarthra dolichoptera, and Trichocerca elongate were dominant. The mean density, Shannon-Wiener diversity, and equitability among the five lakes differed significantly （P〈0.05）. The mean rotifer density was positively correlated with trophic state. The diversity was higher in lakes with high macrophyte coverage. The composition of rotifer species was closely associated with the trophic gradient. Five environmental variables, Secchi depth, conductivity, TN, NHa-N, and TP, significantly affected the composition of rotifer species. Keratella quadrata, Brachionus calyciflorus, and B. forficula were more common in eutrophic conditions. Our results suggest that eutrophication has a significant influence on the rotifer community structure and highlight the potential for using rotifer community structure as an indicator of trophic status in subtropical lakes. 相似文献
10.
Zhang Hucai 《中国地理科学(英文版)》1997,8(4):377-382
Chronology establishment and dating data analyses on lacustrine deposits in northeastern Sahara show that vast fresh lakes
existed over there between 9900–2400 a B. P. Especially, great continuous lakes developed and got their maximum extent during
the period from 9800 a B. P. to 6450 a B. P. From 6000 a B. P. to 3600 a B. P., the evolution of the lakes experienced a new
stage with a property of drastic fluctuations and a periodicity of 600 years, which was the response to the climatic environment
changes. On the aspect of the relation between natural environment and the human, the warm-humid period in the Holocene was
not only a very important time for human development and evolution, but also was a moment for human reproduction and division.
On the other hand, this warm-humid period was also a distinguished time to natural environment changes, the accumulation of
the strong weathered debris and fine materials formed the basements for the formation of the Sahara Desert.
Supported by the National Natural Science Foundation of China, German Research Foundation and Gansu Provincial Natural Science
Foundation. 相似文献
11.
《中国海洋湖沼学报》2017,(2)
Freshwater shallow lakes typically exhibit two alternative stable states under certain nutrient loadings:macrophyte-dominated and phytoplankton-dominated water regimes.An ecosystem regime shift from macrophytes to phytoplankton blooming typically reduces the number of species of invertebrates and fishes and results in the homogenization of communities in freshwater lakes.We investigated how microbial biodiversity has responded to a shift of the ecosystem regime in Dianchi Lake,which was previously fully covered with submerged macrophytes but currently harbors both ecological states.We observed marked divergence in the diversity and community composition of bacterioplankton between the two regimes.Although species richness,estimated as the number of operational taxonomic units and phylogenetic diversity(PD),was higher in the phytoplankton dominated ecosystem after this shift,the dissimilarity of bacterioplankton community across space decreased.This decrease in beta diversity was accompanied by loss of planktonic bacteria unique to the macrophyte-dominated ecosystem.Mantel tests between bacterioplankton community distances and Euclidian distance of environmental parameters indicated that this reduced bacterial community differentiation primarily reflected the loss of environmental niches,particularly in the macrophyte regime.The loss of this small-scale heterogeneity in bacterial communities should be considered when assessing long-term biodiversity changes in response to ecosystem regime conversions in freshwater lakes. 相似文献
12.
Relationship between changes of river-lake networks and water levels in typical regions of Taihu Lake Basin, China 总被引：1，自引：0，他引：1
The typical regions of the Taihu Lake Basin,China,were selected to analyze the variation characteristics of river-lake networks under intensive human activities.The characteristics of the fractal dimension of river networks and lakes for different periods were investigated and the influences of river system evolution on water level changes were further explored through the comparison of their fractal characters.The results are as follows:1) River network development of the study area is becoming more monotonous and more simple;the number of lakes is reducing significantly,and the water surface ratio has dropped significantly since the 1980s.2) The box dimension of the river networks in all the cities of the study area decreased slowly from the 1960s to the 1980s,while the decrease was significant from the 1980s to the 2000s.The variations of lake correlation dimension are similar to those of the river network box dimensions.This is unfavorable for the storage capacity of the river networks and lakes.3) The Hurst exponents of water levels were all between 0.5 and 1.0 from the 1960s to the 1980s,while decreased in the 2000s,indicating the decline in persistence and increase in the complexity of water level series.The paper draws a conclusion that the relationship between the fractal dimension of river-lake networks and the Hurst exponents of the water level series can reveal the impacts of river system changes on flood disasters to some extent:the disappearance of river networks and lakes will increase the possibility of flood occurrence. 相似文献
13.
Antarctic krill (Euphasia superba Dana) is a key organism of the Antarctic marine ecosystem and a potential fishery resoure. Its ecology was the major biological
project in the First Chinese Antarctic Expedition (1985). Acoustic observations and IKMT tows were madecin waters north and
west of Antarctic Peninsula. Environmental factors were also observed. Analyses of the population structure, i.e. the sex
percentage distribution and other data obtained show that among the 3,640 individuals of determinable sex, only 38.1% were
males and that the larger the body length the smaller the percentage of males, for example, male percentage dropped to 8.3%
for size group >55 mm. The population's relations to environmental factors are also discussed.
Contribution No. 1711 from the Institute of Oceanology, Academia Sinica. 相似文献
14.
南极洲被巨厚冰雪覆盖,地质构造以南极横断山脉为界,总体分为东南极地盾和西南极活动带。数字高程模型（DEM）是研究南极冰盖变化的基础数据之一。通过多期次数字高程模型相比较获得高程的变化信息,是分析南极冰盖厚度变化和物质平衡的重要手段。然而不同类型DEM之间存的平面误差和垂直误差影响分析结果的精度。首先利用配准消除DEM间的水平误差,然后计算并按坡度提取CryoSat DEM与其他DEM的平均高程差和标准差,最后分析高程差的时空变化特征。通过分析发现,DEM之间存在不同的平面误差。其中TanDEM_X DEM与CryoSat DEM的高程平面偏差最小,而ICESat DEM与CryoSat DEM的高程平面偏差最大。在垂直方向上,0°~1°的坡度范围内,CryoSat DEM与TanDEM_X DEM的平均高程差在3.5~5.5 m之间,标准差小于18.0 m;CryoSat DEM和Bamber 1km DEM的平均高程差在-2.5~+1.0 m之间,标准差小于24.2 m;CryoSat DEM与ICESat DEM的平均高程差在-25.0~-1.0 m之间,标准差小于47.2 m;CryoSat DEM与RAMPv2 DEM的平均高程差在1.3~3.2 m之间,标准差小于45.6 m。通过研究发现南极冰盖内部高程增加,但西南极冰盖和东南极冰盖高程均在降低,且西南极降低明显,同时南极边缘地区高程降低明显。本研究为全球变化研究和南极物质平衡研究提供了重要参考。 相似文献
15.
KAPHLE Binija WANGJun-bo KAI Jin-lei LYU Xin-miao PAUDAYAL Khum Narayan ADHIKARI Subash 《山地科学学报》2021,(1):141-158
High-altitude Himalayan lakes act as natural storage for environmental evidence related to climate change and environmental factors.A great number of lakes are distributed in the southern slope area of the central Himalayas;however,research concerning the hydrochemical processes of these lakes is still insufficient.Herein,we present a comprehensive study on the water chemistry of the lake waters and the inlet stream waters from Rara Lake in western Nepal based upon samples collected in November 2018.The p H,dissolved oxygen,chlorophyll-aconcentration(chl-a),water temperature,electric conductivity(EC)and total dissolved solids(TDS)were measured in situ,and the concentrations of major ions(Ca2+,Mg2+,K+,Na+,Cl-,SO42-,and NO3-)were analyzed in the laboratory.The results revealed that the water in Rara Lake is slightly alkaline,with p H values ranging from 7.6-7.98.The cations,in decreasing order of concentration in the lake water,are Ca2+>Mg2+>K+>Na+with average concentrations of20.64 mg·L-1,11.78 mg·L-1,1.48 mg·L-1 and 0.72 mg·L-1,respectively;the order and concentrations for the anions is HCO3->SO42->Cl->NO3-,with average concentrations of 122.15 mg·L-1,2.15 mg·L-1,0.46mg·L-1 and 0.55 mg·L-1,respectively.The dominant cation and anion in the lake water are Ca2+and HCO3-and they account for 48.14%and 71.8%of the totals,respectively.The range of lake water TDS is from 95mg·L-1 to 98 mg·L-1,with an average of 96.85 mg·L-1.The high ratio of(Ca2++Mg2+)to total cations and the low ratio of(Na++K+)to total cations indicate that Rara Lake receives ions from rock weathering,especially from carbonate rocks.Similarly,Gibbs boomerang diagrams and Piper diagrams also support the hydrochemistry of Rara Lake as being dominated by rock-weathering patterns.Likewise,other statistical analysis tools,such as Principal Component Analysis(PCA)and correlation strongly suggest the dominance of weathering of calcium and magnesium bicarbonate rocks as the major source of ions in Rara Lake.However,several traces of anthropogenic inputs into the lake were noticed,and the hypolimnion in the lake appears to be oxygen deficient,which may not be an issue at present but cannot be ignored in the future. 相似文献
16.
????2004??2008???ICESat???????????????GLA12???????????????????????????????????????仯????????????????????????????????????仯??????????????????????????????3 m??????????????????????仯????????????????????????????????? 相似文献
17.
A Gram negative bacterium Ar/W/b/75°25＇N/1 producing extracellular alkaline protease was isolated from surface water of latitude 75°25＇N, and longitude 162°25＇W in Chukchi sea, Arctic. The strain can grow at the temperature range from 7℃ to 30℃, and grow better at 30(℃. It can not grow at 40℃. Keeping certain salinity concentration in medium is necessary for cell growth. It grows well in medium containing salinity concentration from 0. 5 % to 10 % sodium chloride. Glucose, sucrose and soluble starch can be utilized by the strain, among which glucose is the optimal carbon source. Peptone is the optimal organic nitrogen source for cell growth and protease producing, and ammonium nitrate is the optimal inorganic nitrogen source.About 75.7% of total protease of the strain are extracellular enzyme. Optimal temperature for proteolytic activity is at 40℃. Protease of the strain keeps stable below 40℃, and shows high proteolytic activity within the pH range from 7 to 11. 相似文献
18.
Measurement of ice velocities of the Antarctic glaciers is very important for studies on Antarctic ice and snow mass balance. The polar area environmental change and its influences on the global environment. Conventional methods may be used for measuring the ice velocities, but they suffer from severe weather conditions in the Polar areas. Use of satellite multi-spectral and muki-temporal images makes it easier to measure the velocities of the glacier movements. This paper discusses a new method for monitoring the glacial change by means of multi-temporal satellite images. Temporal remotely sensed images in the Ingrid Christensen coast were processed with respect to geometric rectification, registration and overlay, The average ice velocities of the Polar Record Glacier and the Dark Glacier were then calculated, with the changing characteristics analyzed and evaluated. The advantages of the method reported here include promise of all-weather operation and potentials of dynamic monitoring through suitabl 相似文献
19.
Finu Shrestha Xiao Gao Narendra Raj Khanal Sudan Bikash Maharjan Rajendra Bahadur Shrestha Li-zong Wu Pradeep Kumar Mool Samjwal Ratna Bajracharya 《山地科学学报》2017,14(10):1969-1984
Changes in glacial lakes and the consequences of these changes, particularly on the development of water resources and management of glacial lake outburst flood(GLOF) risk, has become one of the challenges in the sustainable development of high mountain areas in the context of global warming. This paper presents the findings of a study on the distribution of, and area changes in, glacial lakes in the Koshi basin in the central Himalayas.Data on the number of glacial lakes and their area was generated for the years 1977, 1990, 2000, and 2010 using Landsat satellite images. According to the glacial lake inventory in 2010, there were a total of 2168 glacial lakes with a total area of 127.61 km~2 and average size of 0.06 km~2 in the Koshi basin. Of these,47% were moraine dammed lakes, 34.8% bedrock dammed lakes and 17.7% ice dammed lakes. The number of glacial lakes increased consistently over the study period from 1160 in 1977 to 2168 in 2010, an overall growth rate of 86.9%. The area of glacial lakes also increased from 94.44 km~2 in 1977 to 127.61 km~2 in 2010, a growth rate of 35.1%. A large number of glacial lakes in the inventory are small in size(≤ 0.1km~2). End moraine dammed lakes with area greater than 0.1 km~2 were selected to analyze the change characteristics of glacial lakes in the basin. The results show that, in 2010, there were 129 lakes greater than 0.1 km~2 in area; these lakes had a total area of 42.92km~2 in 1997, increasing to 63.28 km~2 in 2010. The distribution of lakes on the north side of the Himalayas(in China) was three times higher than on the south side of the Himalayas(in Nepal).Comparing the mean growth rate in area for the 33 year study period(1977-2010), the growth rate on the north side was found to be a little slower than that on the south side. A total of 42 glacial lakes with an area greater than 0.2 km~2 are rapidly growing between 1977 and 2010 in the Koshi basin, which need to be paid more attention to monitoring in the future and to identify how critical they are in terms of GLOF. 相似文献
20.
同其他卫星相比,NOAA卫星搭载的AVHRR积雪产品,具有长达10 a的长时间序列数据集,能够应用于长时间、较大区域范围的积雪覆盖变化分析。由于不同卫星使用的反演算法,波谱宽度和大气订正等不完全相同,故需对不同卫星积雪产品数据集进行一致性检验,将卫星积雪产品更好地应用于气候分析研究。本文采用一种新的评估方法,对空间分辨率为0.05o×0.05o的AVHRR积雪产品与IMS和MOD10A1积雪产品,分别在空间和时间变化上进行对比分析,对AVHRR积雪产品数据集进行检验,发现AVHRR与MODIS积雪产品具有较好的一致性。 相似文献