共查询到20条相似文献，搜索用时 453 毫秒
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F. Ghassemzadeh J. Sherwood M. C. Geddes W. D. Williams 《International Journal of Salt Lake Research》1997,6(3):269-278
The analysis of nitrate in seawater and hypersaline waters should take account of a significant “salt effect”. Procedures
developed for fresh water and marine waters must be applied cautiously to highly saline waters. The most widely used standard
method for the determination of nitrate-nitrogen (NO3-N) in fresh and marine waters involves the quantitative reduction of nitrate by the Cd column technique followed by colorimetric
procedures. In our study, three approaches to estimate NO3-N in highly saline waters were examined. The first involved dilution. This approach overcame the salt effect but dilution
limited the detection of low concentrations of nitrate in highly saline waters. The second involved the use of standard nitrate
solutions in saline water. This method is not recommended because of nitrate impurities in AR grade salts. The third- and
preferred approach-involved the use of standard additions. “Spikes” of a known volume of NO3-N standard solution were added to natural saline waters. Nitrate values estimated by the stadard addition method were used
to calculate an equation for salt error correction at different salinities applicable to waters with the same relative ionic
composition as seawater. This could then be used to correct nitrate determinations in highly saline waters where standards
made in distilled water were used for calibration. Many previously published data for NO3-N in saline water used methods of analysis which do not take account of salt error and are therefore probably in error. 相似文献
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G. J. Reati M. Florín G. J. Fernández C. Montes 《International Journal of Salt Lake Research》1996,5(3):187-219
Although the Laguna de Mar Chiquita is among the largest saline lakes of the world (2,000–6,000 km2 area), knowledge about it is scarce. Like other large salt lakes, Mar Chiquita undergoes strong inter-annual changes in water level that are primarily linked to the variable expression of three different types of climate throughout its extensive catchment area. Water-level fluctuations and their overall environmental influence, especially on salinity (25–360 g L–1) and biota, have significant results. Comparison of Mar Chiquita with other fluctuating large salt lakes shows an independent long-term pattern of water-level (and salinity) changes. Primary determinants of its limnology are (1) its extensive catchment, (2) the occurrence of three different types of climate on the catchment, (3) the shallowness of the basin and (4) the effects of strong wind, water circulation within the lake, and sediment inputs from rivers. The effects of fluctuation on the lake biota are more evident at the level of dominant organisms at every fluctuation stage and their functions than in overall biodiversity and food-web complexity. 相似文献
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During May and June 1991, the biological and ecological features of sixteen aquatic localities in Zhanjiakou region, Hebei,
northern China, were investigated. Their salinity ranged from 0.98 to 175.2 g L−1. Fish and benthic macroinvertebrates were depauperate. 116 samples were collected. 91 species (or genera) of phytoplankton
and 94 species of zooplankton were recorded. In most of the saline lakes, Cl− and Na+ were dominant, and alkalinity and pH values were higher. For phytoplankton, major species wereChroococcus minutus, Oscillatoria tenuis [blue-green algae];Chlamydomonas spp.,Chlorococcus spp.,Chlorella vulgaris, Crucigenia quadrata, Dunaliella salina, Kirchneriella contorta, Oocystis lacustris, Scenedesmus acuminatus [green algae]; andCyclotella meneghiniana, Navicula spp.,Nitzschia spp. [diatoms]. Other phytoplankton taxa present included:Cryptomonas erosa, Chroomonas acuta, Chromulina pascheri, Euglena viridis. For zooplankton, major species included:Vorticella campanula, Epistylis breviramosa, Euplotes terricola [protozoa];Brachionus plicatilis, Hexarthra fennica, Keratella quadrata, Notholca acuminata quadrata [Rotifera];Daphnia magna, D.longispina [‘Cladocera’];Artemia spp. [Anostraca];Arctodiaptomus rectispinosus andCyclops vicinus [Copepoda]. The species composition, distribution, salinity tolerance of planktonic forms in inland saline waters are discussed
and their relationship with certain environmental factors. 相似文献
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Results from hydrochemical investigations into macrocomponent composition of some of the lakes in the Southeastern Transbaikalia are presented. The region's saline lakes, as a rule, are soda-chloride or chloride-soda lakes according to their chemical composition. The lakes hydrochemistry is determined by a combination of evaporative concentration of salt composition, intra-water body hydrobiological processes, especially by the production of organic matter and reduction of sulfates as well as by hydrogenic sedimentation. 相似文献
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内陆水体水质参数光谱特征与定量遥感 总被引：2，自引：0，他引：2
该文在分析内陆水体及其主要水质参数的光谱特征的基础上 ,讨论了水质遥感监测常用的遥感数据和方法 ,对近年来国内外遥感技术特别是高光谱技术在内陆水体水质监测中的应用研究现状和进展进行了综述 ,并提出未来此领域的发展方向及研究工作的重点 相似文献
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中山站-Dome A断面是表层雪稳定同位素组成分析的理想区域,沿线进行δ18O、δD和d的空间分布及环境影响因素研究对反映东南极地区的气候变化和物质来源具有关键意义。因而,本文基于线性回归及相关性分析方法,详细探究了断面上多种环境因素与表层雪稳定同位素分布的空间关系。结果表明,温度和地理因素与同位素比值之间有显著相关关系,且海拔是地理因素中的主要影响因素,随海拔上升表层雪的δ18O呈线性下降趋势。另外,通过断面上δ-T斜率与南极其他断面对比,发现斜率可能具有冰盖近岸和内陆地区较低的区域性特征,而造成这一现象的原因是水汽源区的改变和低温条件下水汽过饱和时的同位素动力分馏。最后,d的空间分布在沿海区域和内陆区域也有不同,推测主控因素分别是水汽源区条件和温度。 相似文献
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The Monte is a biogeographic province covers an extensive area from the subtropical northern part of Argentina at 24 degrees south, to the temperate northern region of Patagonia at 44 degrees south. Within the province, which is about 2000 km from north to south, lies the Monte Desert, on a strip of land that stretches along the eastern side of the Andes Mountains. The definition of the boundaries of the Monte Desert varies among authors. We present a division of the Monte Desert into three botanical districts: Northern, Eremean, and Southern districts. The Northern and the Southern districts are divided into subdistricts. Different hypotheses have been proposed for the origin of the Monte Desert biota. A few plant genera show a remarkable phylogenetic affinity with plants of the North American deserts of Mojave and Sonora. However, this is an exception because most of the remaining plants, arthropods, and reptiles have an origin more closely related to the biota of the Chaco and Patagonia. Second in importance is the group of taxa that originated in Patagonia, and the most enigmatic of all are the paleoendemic groups composed of relictual taxa of Pangeic or Gondwanic origin. The complexity of the biota of the Monte desert biota is probably a result of the extensive area of contact between the two South American biotas of South America: Brazilian biota (or tropical biota) and Patagonian biota. 相似文献
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This paper studied the basic properties of saline soil at different depths of a sampling site in Da'an, China, through field reconnaissance and laboratory analysis. A series of experiments which comprised the analyses of grain size distribution, mineral composition, soil physical properties, soluble salt concent, pH, organic content and cation exchange capacity were conducted. Through these experiments, the distribution rule of each property and their causes are discussed. These results could provide a fundamental base for the study of moisture migration. 相似文献
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Huimin Yan Zhijun Yao Heqing Huang Dong Jiang Xiaohui Dong Rui Duan Yili Zhang 《地理学报(英文版)》2013,23(5):860-870
As they are products of glacier movement, the water body composition and water quality attributes of glacial lakes have distinct characteristics compared with inland lakes. Although satellite remote sensing provides an effective approach to monitor water quality, lack of in-situ measurement data on the status and environment surrounding glacial lakes presents a major constraint in relating satellite data to water quality indicators. This study presents findings of a preliminary investigation into water quality attributes of 3 glacial lakes in the Mount Qomolangma region. Suspended particulate matter （SPM）, light absorption attributes of phytoplankton, nonalgal particles （NAP）, and colored dissolved organic matter （CDOM） were measured. The suspended substance concentration varies markedly from 0-320 mg/L. This is considered to reflect differing stages of lake development. l-he chlorophyll concentra- tion is much lower than that found for inland lakes, as landscapes that surround these high altitude lakes have almost no vegetation growth. The phytoplankton and CDOM concentration depend on long-term stability of lake slopes. Given the lack of exogenous and endogenous inputs in the Qomolangma region, CDOM in glacial lakes is significantly lower than in inland lakes. These preliminary findings could support efforts to appraise estimates of water quality parameters using remotely sensed images. 相似文献
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Nutrients as a link between ionic concentration/composition and diatom distributions in saline lakes 总被引：1，自引：0，他引：1
Diatom profiles in closed-basin lake sediments are commonly used to reconstruct climate change based on the observed correlations between salinity (ionic concentration) and modern diatom assemblages. Diatom assemblages are strongly correlated not only with salinity but also anion composition, with certain taxa characteristic of carbonate systems and others sulfate-dominated waters. Although strong correlations exist, the actual mechanisms behind these correlations are unknown. Here we briefly review the influence of salinity and ionic composition on nutrient dynamics in saline lakes and suggest that these interactions may drive shifts in diatom species composition along gradients of ionic concentration/composition. We discuss the influence of salinity and anion composition on nutrient availability, as well as on nutrient requirements and uptake by diatoms. 相似文献
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The sea ice community plays an important role in the Arctic marine ecosystem. Because of the predicted environmental changes in the Arctic environment and specifically related to sea ice, the Arctic pack ice biota has received more attention in recent years using modern ice-breaking research vessels. Studies show that the Arctic pack ice contains a diverse biota and besides ice algae, the bacterial and protozoan biomasses can be high. Surprisingly high primary production values were observed in the pack ice of the central Arctic Ocean. Occasionally biomass maximum were discovered in the interior of the ice floes, a habitat that had been ignored in most Arctic studies. Many scientific questions, which deserve special attention, remained unsolved due to logistic limitations and the sea ice characteristics. Little is know about the pack ice community in the central Arctic Ocean. Almost no data exists from the pack ice zone for the winter season. Concerning the abundance of bacteria and protozoa, more studies are needed to understand the microbial network within the ice and its role in material and energy flows. The response of the sea ice biota to global change will impact the entire Arctic marine ecosystem and a long-term monitoring program is needed. The techniques, that are applied to study the sea ice biota and the sea ice ecology, should be improved. 相似文献
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The interaction of geomorphic and ecologic landscape components has been largely conceptualized as independent. In one direction, geomorphic processes and landforms shape the distribution of biota. Conversely, in the other direction, biota modify geomorphic processes and landforms. Increasingly, the interactions between geomorphic and ecological components are more circular and developmentally intertwined. In this paper, I integrate these two independent perspectives within the framework of complexity theory. I outline four themes that characterize complex systems in biogeomorphology: multiple causality and the concept of recursivity, the influence of organisms that function as ecosystem engineers, the expression of an ecological topology, and ecological memory. Implicit in all of these themes is the recognition that biogeomorphic systems are open and path dependent. They may exhibit a range of assembly states, from self-reinforcing stability domains to more transient configurations of organisms and environment. 相似文献
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基础设施互联互通是不同区域之间空间网络形成的支撑,对区际生产要素流动、市场融合和资源配置具有重要作用,也是“一带一路”建设的重点内容和前提条件。立足于综合基础设施网络,以“一带一路”沿线国家/地区为分析地域,设计数理模型,评价了中国与沿线国家的基础设施网络连通性,考察其基本特征与空间格局,然后分别从铁路、公路、航运、通讯、能源等各种基础设施方式的视角,分析了不同基础设施网络的互联互通水平,探讨了基础设施连通的类型分异及其主导因素,凝练基础设施连通的空间模式。主要结论如下：① 从海陆属性来看,岛屿型国家与中国设施连通性最高,其次为综合型国家,内陆型国家最低。对国际区域而言,俄蒙和东南亚地区与中国的设施连通性最高,中东欧地区连通性最低。从国家尺度来看,俄罗斯和越南是与中国设施连通水平最高的国家,巴勒斯坦、东帝汶等5个国家与中国尚未形成设施连通性。从连通方式的构成来看,航运网络的连通性最高,其次为航空和光缆。② 空间距离、连通方式和重大交通走廊共同主导了设施连通性的类型分异。③ “一带一路”沿线国家/地区与中国的设施连通形成了四种典型模式,包括海陆融合型外缘连通模式、陆路通道直接连通模式、陆心内生性低水平连通模式、远距离不均衡连通模式。 相似文献
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通过对111篇国际SCI和SSCI期刊内陆港（Inland Port）文献的分析,结果发现：1）从20世纪90年代以来,国际上对内陆港的相关研究逐渐增多,尤其是自2016年以来,文献数量增长迅速。研究者的地区分布以亚洲、欧洲和北美洲最多,研究主题多与交通运输、物流等领域结合,表明内陆港已经成为交通运输体系和供应链运输网络的重要组成部分,但其概念至今尚未统一。其概念探讨主要集中在不同地理背景下对内陆港功能和作用、与海港的便捷交通链接,以及随经济发展延伸出来的附加功能方面。2）内陆港的空间布局体系大致可以分为供应链导向型布局和产业集群型布局,腹地经济基础、交通基础设施与地方政策因素等都影响内陆港的选址和布局。3）内陆港对区域的影响广泛而深远,在城市空间规划和土地利用、区域经济发展和就业以及降低能耗和减排、实现区域可持续发展等方面产生持续的空间效应、经济效应和环境效应。4）内陆港的运营和管制需要特别关注港口规划与各管理主体之间及其与管理制度的关系,以实现内陆港高效、持续、健康的发展。文章最后着眼于全球内陆港研究新趋势和新发展格局背景下中国对内陆港发展实践需求,指出未来内陆港研究需要重点关注概念再界定与评价实证、空间布局与规划、区域影响与港城关系研究、开发投资与潜在效益之间的风险关系研究等方面。 相似文献
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内陆水体环境遥感监测研究评述 总被引：1，自引：0，他引：1
应用遥感技术进行水质监测较常规监测具有巨大优势,能快速、大尺度、低成本的监测水质参数在时空上的变化状况。本文首先简要阐述了内陆水体环境遥感监测的基本原理;其次,介绍了常用水质参数的遥感监测研究现状,包括叶绿素a(Chl-a)、悬浮物(SS)、有色可溶性有机物(CDOM)以及总磷(TN)、总氮(TP)等其他水质参数,并将其划分为经验模型和生物光学模型两种监测方法;再次,对常用的遥感数据源进行了介绍和优缺点的评述;最后,讨论了内陆水体环境遥感监测误差来源,并对今后内陆水体环境遥感监测研究重点进行了展望。 相似文献