长江、黄河源区高寒湿地动态变化研究

长江、黄河源区是中国湿地分布面积最大的地区之一,近年来湿地面积减少、功能退化引起了严重的区域生态环境问题。为了定量分析湿地退化过程,利用1986年的TM和2000年的ETM 卫星遥感数据,在GIS软件支持下,用景观格局指数对长江、黄河源区15a来湿地的分布和变化进行了研究。结果表明,15a间,长江、黄河源区湿地面积减少了2744.77km2,平均减少率为1.2%/a。长江源湿地的退化比黄河源明显。湿地主要是由高寒沼泽草甸湿地向高寒草甸湿地、裸岩裸土地和高寒草原演变,以及由水域向滩地转变。各湿地景观类型斑块数增加,破碎度和分维数提高,优势度降低,湿地景观空间结构趋于复杂,景观异质性增加。15a间研究区湿地生态服务价值降低了37.86×108元。气候干暖化是造成源区湿地变化的主要因素,人类活动加剧了这一进程。     

三江源地区美丽中国建设存在的问题、成功案例与启示

长江、黄河与澜沧江源区（简称三江源区）是中华与亚洲“水塔”,是我国重要的生态安全屏障与水安全保障,是三大河流域经济带的共有源地,稳藏固疆的战略要地,美丽中国建设的战略高地。掌握该地区美丽中国建设进程,发现存在的问题,及时总结典型成功案例,有助于更好建设美丽高原,服务生态文明建设与社会经济高质量发展的全国战略部署。就建设内容与进程看,目前三江源区整体仍处于物质建设阶段,除畜牧业外,缺乏其他产业,忽视文化建设,美丽缺少内涵、不可持续;就建设成效而言,美丽乡村与美丽城镇工程建设成绩显著,但配套设施严重滞后,以及游牧文化与聚落文化的冲突,美丽仍流于形式;尽管存在这些问题,但亦涌现了若干成功案例,“岗龙模式”和“甘达模式”尤为典型,为三江源其他地区美丽中国建设提供了样板与发展启示：（1）找准优势资源,最大化资源潜力、实现经济“美”是高原美丽中国建设成功的物质基础;（2）领导人/团队/致富带头人是高原美丽中国建设成功的关键核心;（3）产业与因地制宜的运作机制是高原美丽中国建设可持续的强大支撑与必由之路;（4）不断探索永远走在发展路上是美丽中国建设成功的坚实动力。     

BOOK REVIEWS

Books Reviewed in this article: Lob Trees in the Wilderness . Clifford and Isabel Ahlgren . Satellite Microwave Remote Sensing . T. D. Allan , ed. Sunbelt Cities: Politics and Growth Since World War II . Richard M. Bernard and Bradley R. Rice , eds. Legacy of Minneapolis: Preservation Amid Change . John R. Borchert , David Gebhard , David Lanegran , and Judith A. Martin . Bloomington, MN: Preparing a Historic Preservation Ordinance. Richard J. Roddewig . The Mountains of Northeastern Tasmania, A Study of Alpine Geomorphology . Nel Caine . Introductory Cartography . John Campbell . Englewood Cliffs, NJ: Changing Climate . Manual of Remote Sensing, Second Edition . 2 Vols. Robert N. Colwell , ed.-in-chief; David S. Simonett and John E. Estes , vol. eds. Remote Sensing in Meteorology, Oceanography and Hydrology . A. P. Cracknell , ed. Multidimensional Scaling . Mark L. Davison . Environmental Karst . Percy H. Dougherty , ed. The Urban Environment . Ian Douglas . Geomorphology of Europe . Clifford Embleton , ed. An Introduction to South Asia . B. H. Farmer . Great Geological Controversies . A. Hallam . Hazardous Waste Management: In Whose Backyard? Michalann Harthill , ed. Energy for Subsistence . Margaret Haswell . Perspective on Ratzel's Political Geography . James M. Hunter . Economic Deposits and their Tectonic Setting . Charles S. Hutchison . Energy Risk Assessment . Herbert Inhaber . Discovering the Vernacular Landscape . John Brinckerhoff Jackson . Climate and Energy Systems: A Review of Their Interactions . Jill Jäger . Dilemmas in Regional Policy . Antoni Kuklinski and J. G. Lambooy , eds. California Farmland: A History of Large Agricultural Landholdings . Ellen Liebman . The Spatial Organization of New Land Settlement in Latin America . Jacob O. Maos . Dark Continent: Africa as Seen by Americans . Michael McCarthy . Westport, CT: Climatology: An Introduction . John E. Oliver and John J. Hidore . Columbus, OH: The Geography of Warfare . Patrick O'Sullivan and Jesse W. Miller . The Expanding City. Essays in Honour of Professor Jean Gottmann . John Patten , ed. Scotland's Environment During the Last 30,000 Years . Robert J. Price . Integrated Urban Models . S. H. Putman . Development and the Environmental Crisis: Red or Green Alternatives? Michael Redclift .     

Environmental controls on food web regimes: A fluvial perspective

Because food web regimes control the biomass of primary producers (e.g., plants or algae), intermediate consumers (e.g., invertebrates), and large top predators (tuna, killer whales), they are of societal as well as academic interest. Some controls over food web regimes may be internal, but many are mediated by conditions or fluxes over large spatial scales. To understand locally observed changes in food webs, we must learn more about how environmental gradients and boundaries affect the fluxes of energy, materials, or organisms through landscapes or seascapes that influence local species interactions. Marine biologists and oceanographers have overcome formidable challenges of fieldwork on the high seas to make remarkable progress towards this goal. In river drainage networks, we have opportunities to address similar questions at smaller spatial scales, in ecosystems with clear physical structure and organization. Despite these advantages, we still have much to learn about linkages between fluxes from watershed landscapes and local food webs in river networks. Longitudinal (downstream) gradients in productivity, disturbance regimes, and habitat structure exert strong effects on the organisms and energy sources of river food webs, but their effects on species interactions are just beginning to be explored. In fluid ecosystems with less obvious physical structure, like the open ocean, discerning features that control the movement of organisms and affect food web dynamics is even more challenging. In both habitats, new sensing, tracing and mapping technologies have revealed how landscape or seascape features (e.g., watershed divides, ocean fronts or circulation cells) channel, contain or concentrate organisms, energy and materials. Field experiments and direct in situ observations of basic natural history, however, remain as vital as ever in interpreting the responses of biota to these features. We need field data that quantify the many spatial and temporal scales of functional relationships that link environments, fluxes and food web interactions to understand how they will respond to intensifying anthropogenic forcing over the coming decades.     

The influence of relative sediment supply on riverine habitat heterogeneity

The diversity of aquatic habitats in streams is linked to physical processes that act at various spatial and temporal scales. Two components of many that contribute to creating habitat heterogeneity in streams are the interaction between sediment supply and transport capacity and the presence of local in-stream structures, such as large woody debris and boulders. Data from previously published flume and field studies and a new field study on tributaries to the South Yuba River in Nevada County, California, USA, were used to evaluate the relationship between habitat heterogeneity, local in-stream structural features and relative sediment supply. Habitat heterogeneity was quantified using spatial heterogeneity measures from the field of landscape ecology. Relative sediment supply, as expressed by the sediment supply/transport capacity ratio, which controls channel morphology and substrate textures, two key physical habitat characteristics, was quantified using a dimensionless bedload transport ratio, q. Calculated q values were plotted against an ecologically meaningful heterogeneity index, Shannon's Diversity Index, measured for each study reach, as well as the percent area of in-stream structural elements. The results indicate two potential mechanisms for how relative sediment supply may drive geomorphic diversity in natural river systems at the reach scale. When less mobile structural elements form a small proportion of the reach landscape, the supply/capacity ratio dictates the range of sediment textures and geomorphic features observed within the reach. In these settings, channels with a moderate relative sediment supply exhibit the highest textural and geomorphic diversity. In contrast, when less mobile structural elements are abundant, forced local scour and deposition creates high habitat heterogeneity, even in the presence of high relative sediment supply.     

三江源区径流演变及其对气候变化的响应(英文)

Runoff at the three time scales(non-flooding season,flooding season and annual period) was simulated and tested from 1958 to 2005 at Tangnaihai(Yellow River Source Region:YeSR),Zhimenda(Yangtze River Source Region:YaSR) and Changdu(Lancang River Source Region:LcSR) by hydrological modeling,trend detection and comparative analysis.Also,future runoff variations from 2010 to 2039 at the three outlets were analyzed in A1B and B1 scenarios of CSIRO and NCAR climate model and the impact of climate change was tested.The results showed that the annual and non-flooding season runoff decreased significantly in YeSR,which decreased the water discharge to the midstream and downstream of the Yellow River,and intensified the water shortage in the Yellow River Basin,but the other two regions were not statistically significant in the last 48 years.Compared with the runoff in baseline(1990s),the runoff in YeSR would decrease in the following 30 years(2010-2039),especially in the non-flooding season.Thus the water shortage in the midstream and downstream of the Yellow River Basin would be serious continuously.The runoff in YaSR would increase,especially in the flooding season,thus the flood control situation would be severe.The runoff in LcSR would also be greater than the current runoff,and the annual and flooding season runoff would not change significantly,while the runoff variation in the non-flooding season is uncertain.It would increase significantly in the B1 scenario of CSIRO model but decrease significantly in B1 scenario of NCAR model.Furthermore,the most sensitive region to climate change is YaSR,followed by YeSR and LcSR.     

The aquatic chemistry of rare earth elements in rivers and estuaries

Laboratory experiments were carried out to determine how pH, colloids and salinity control the fractionation of rare earth elements (REEs) in river and estuarine waters. By using natural waters as the reaction media (river water from the Connecticut, Hudson and Mississippi Rivers) geochemical reactions can be studied in isolation from the large temporal and spatial variability inherent in river and estuarine chemistry. Experiments, field studies and chemical models form a consistent picture whereby REE fractionation is controlled by surface/solution reactions. The concentration and fractionation of REEs dissolved in river waters are highly pH dependent. Higher pH results in lower concentrations and more fractionated composition relative to the crustal abundance. With increasing pH the order of REE adsorption onto river particle surfaces is LREEs > MREEs > HREEs. With decreasing pH, REEs are released from surfaces in the same order. Within the dissolved (<0.22 µm) pool of river waters, Fe-organic colloids are major carriers of REEs. Filtration through filters and ultrafilters with progressively finer pore sizes results in filtrates which are lower in absolute concentrations and more fractionated. The order of fractionation with respect to shale, HREEs > MREEs > LREEs, is most pronounced in the solution pool, defined here as <5K and <50K ultrafiltrates. Colloidal particles have shale-like REE compositions and are highly LREE enriched relative to the REE composition of the dissolved and solution pools. The addition of sea water to river water causes the coagulation of colloidal REEs within the dissolved pool. Fractionation accompanies coagulation with the order of sea water-induced removal being LREEs > MREEs > HREEs. While the large scale removal of dissolved river REEs in estuaries is well established, the release of dissolved REEs off river particles is a less studied process. Laboratory experiments show that there is both release and fractionation of REEs when river particles are leached with seawater. The order of sea water-induced release of dissolved REE(III) (LREEs > MREEs > HREEs) from Connecticut River particles is the same as that associated with lowering the pH and the same as that associated with colloidal particles. River waters, stripped of their colloidal particles by coagulation in estuaries, have highly evolved REE composition. That is, the solution pool of REEs in river waters are strongly HREE-enriched and are fractionated to the same extent as that of Atlantic surface seawater. This strengthens the conclusions of previous studies that the evolved REE composition of sea water is coupled to chemical weathering on the continents and reactions in estuaries. Moreover, the release of dissolved Nd from river particles to sea water may help to reconcile the incompatibility between the long oceanic residence times of Nd (7100 yr) and the inter-ocean variations of the Nd isotopic composition of sea water. Using new data on dissolved and particle phases of the Amazon and Mississippi Rivers, a comparison of field and laboratory experiments highlights key features of REE fractionation in major river systems. The dissolved pool of both rivers is highly fractionated (HREE enriched) with respect to the REE composition of their suspended particles. In addition, the dissolved pool of the Mississippi River has a large negative Ce-anomaly suggesting in-situ oxidation of Ce(III). One intriguing feature is the well developed maximum in the middle REE sector of the shale normalized patterns for the dissolved pool of Amazon River water. This feature might reflect competition between surface adsorption and solution complexation with carbonate and phosphate anions.     

南方涛动与我国东部盛夏季风雨北进程度的年际遥联

上年6月南方涛动指数(SOI)和盛夏(7-8月)我国东部季风雨带位置及江淮下游雨量存在显著的相关,经过分析,发现此种遥联是通过长达15个月的如下海-气相互作用形成的:偏强(弱)的南方涛动会伴随着赤道中-东太平洋海面水温偏低(高);此种趋势会从上年6月持续到次年初春,而同时冬季中太平洋中低纬经向海温梯度(△T)即趋向减弱(增强),向中高纬的热量输送偏少(多).△T和随后春夏各月北半球100hPa高度场和500-100hPa厚度场的相关计算表明,正高相关区从热带中太平洋区逐步向东亚中纬输送,这可能反映出高空热量经由一系列行星波西传并于盛夏抵达东亚中纬,从而影响到100hPa层青藏高压东部的伸缩、我国东部季风雨带的南北位置和江淮下游的旱涝趋势.     

1991年初夏江淮大水的天文因素──太阳质子耀斑爆发

研究了1991年初夏江淮大水前,北半球环流的异常与太阳上的一系列质子耀斑之间的关系.研究结果表明:太阳上连续不断的质于耀斑爆发是1991年初夏江淮大水的重要天文因素.太阳质子耀斑可能触发或加剧了极涡的冷空气南下,低空西南急流的东移和西太平洋副热带高压的西伸北移过程.由于冷热气流多次在长江中下游和淮河地区相遇.因而形成了频繁的暴雨和特大暴雨过程,造成了江淮地区的特大洪涝灾害.     

Contrasting textures in metamorphic and anatectic migmatites: an example from the Scottish Caledonides

Abstract. A method for the quantitative analysis of the spatial relations of minerals is described. Dispersed distributions are formed by annealing and destroyed in post-tectonic migmatization. Aggregate distributions characterize solid-state differentiation, whereas leucosomes formed in systems of high fluid:rock ratio (in the examples studied, anatectic melts) show random distributions.
Quantitative textural analysis can be used to indicate whether migmatization was post-tectonic or earlier, though caution is necessary if post-migmatite cooling is slow or if there is some minor deformation. More importantly, it can be used to discriminate melt-present from melt-absent leucosomes; this is exemplified by a suite of metamorphic and anatectic migmatites from the Scottish Caledonides.
The textural evolution of anatexites with increasing melt percentage is traced. Initial feldspar porphyroblastesis occurs by Ostwald ripening via grain boundary melts; subsequently ophthalmites develop with fabrics and chemistry inherited from the palaeosome. At greater than 30% melt these inherited fabrics are wholly destroyed. Deformation prompts segregation into melanosome and leucosome; resultant leucosomes contain no inherited crystals. The scale of anatectic systems is fixed at the point at which segregation begins; ophthalmites provide evidence for melt and crystal transfer beyond original palaeosome boundaries. In contrast, metamorphic migmatites are necessarily small-scale systems because of diffusive constraints, and melanosomes are invariably produced.