基于Hyperion数据的南四湖叶绿素浓度反演研究

通过对2005年5月7日南四湖Hyperion高光谱影像的几何纠正和6S模型辐射校正,以及水体光谱数据分析,对22个水体样点原始光谱数据分别采用归一化处理和包络线消除处理后,以波段比值数据构建叶绿素浓度反演模型,选取相关系数最大的反演模型,获得南四湖叶绿素浓度的空间分布图。研究表明,包络线消除法能很好地去除水体的光谱曲线背景影响,突出光谱曲线的吸收和反射特征,与归一化处理相比,反演模型的相关系数都有很大提高。R700/R560波段比值数据构建的模型相关性最高,相关系数为0.834,可用于叶绿素浓度反演研究。     

北美五大湖区晚更新世劳伦泰德冰盖演化年代学综述及石英光释光测年的初步尝试

北美五大湖区的安大略湖北岸Don Valley Brickyard、Scarborough Bluffs、Bowmanville Bluffs剖面共同构成了北美东北部最长也是最厚的陆地第四纪沉积记录, 较完整地记录了晚更新世劳伦泰德冰盖(the Laurentide Ice Sheet)的演化. 晚更新世劳伦泰德冰盖演化的重建有赖于这些经典剖面中重要沉积地层单元的准确年代学控制. 传统的地层年代学主要是依靠少量¹⁴C年代, 将主要的混杂堆积单元(diamicton)解释为气候变冷环境下的冰川扩张, 并与指示全球冰量变化的深海氧同位素曲线一一比对建立起来的. 这样建立起来的年代学存在很大的不确定性. 20世纪80-90年代的少量热释光年代也不相吻合, 最近的13个长石红外释光定年则只集中于Bowmanville Bluffs的一个分层, 并未建立整个剖面的地层年代学, 使这些经典沉积剖面的年代学一直没有得到系统的建立. 应用石英光释光SAR-SGC法测试了Bowmanville Bluffs剖面Glaciofluvial Sand单元的2个冰水沉积样品, 年代结果分别为(41.6±3.8) ka、(48.1±4.4) ka, 分析表明这一年代结果偏老, 石英颗粒可能晒褪不完全. 由于大测片无法识别晒褪不完全的颗粒, 因此, 测试更多的剖面序列的光释光年代并尝试采用粗颗粒小测片或单颗粒技术解决样品颗粒晒褪不完全的问题将是必要的.     

基于SWAT模型的南四湖流域非点源氮磷污染模拟

本文利用SWAT模型结合实测数据,对南四湖流域2001-2010年年均非点源氮磷污染进行模拟,分析了南四湖流域非点源氮磷负荷空间分布特征,计算各河流流域对南四湖湖区污染的贡献率,并对非点源氮磷污染严重的关键区进行识别.研究表明:(1)先模拟湖东和湖西的两个典型小流域的非点源氮磷污染,并将模型推及整个南四湖流域,该方法不仅提高了计算效率,且得到了较好的模拟结果.通过对比发现,湖东的模拟效果要好于湖西,一定程度上说明SWAT模型在起伏较大的地区能取得更高的精度.(2)南四湖流域非点源氮磷污染严重,几乎所有区域的氮负荷超标,40%以上的区域磷负荷超标严重.湖东非点源氮磷污染较湖西严重,其中洸府河流域是南四湖湖区非点源氮磷污染的主要贡献者.(3)通过对径流量、泥沙负荷、氮负荷、磷负荷的相关分析可以得出,南四湖流域非点源氮负荷以溶解态为主,随径流进入水体;非点源磷负荷以吸附态为主,随泥沙进入水体.     

BOOK REVIEWS

Book Reviewed in this article: Introduction to Climatology for the Tropics . J. O. Ayoade. Conservation and Management of Natural Resources in the United States . Charles F. Bennett. The Keeping of Animals: Adaptation and Social Relations in Livestock Producing Communities . Riva Berleant-Schiller and Eugenia Shanklin, ed. The Evolution of Geographic Thought in America: A Kentucky Root Wilford A. Bladen and Pradyumna P. Karan, eds. Latin America: Geographical Perspectives , 2nd ed. Harold Blakemore and Clifford T. Smith, ed. The Rural Real Estate Market. Department of Geography Publication Series, No. 18 . Chris Bryant. Urban Geomorphology in Drylands . R. U. Cooke, D. Brunsden, J. C. Doornkamp, and D. K. C. Jones with contributions by J. Griffiths, P. Knott, R. Potter, and R. Russell. Italian Geography, 1960–1980. Meeting of the Status of the Geographic Research in Italy, 1960–1980. Treated under the auspices of Consiglio Nazionale delle Ricerche and organized by Istituto di Geografia Umana della Facoltà di Lettere e Filosofia dell'Università degli Studi di Milano , Giacomo Corna Pellecrini and Carlo Brusa, eds. The Changing Fenland . H. C. Darby. The Future for the City Centre . R. L. Davies and A. G. Champion, eds. Saudi Arabia, Energy, Developmental Planning, and Industrialization . Ragaei El Mallakh, Dorothea H. El Mallakh, eds. For We Are Sold, I and My People: Women and Industry in Mexico's Frontier . Maria Patricia Fernández-Kelly. The Great Lakes Forest: An Environmental and Social History . Susan L. Flader, ed. Regional Transformation and Industrial Revolution: A Geography of the Yorkshire Woolen Industry . Derek Gregory Crime in City Politics . Anne Heinz, Herbert Jacob and Robert L. Lineberry, eds. Revitalizing Cities . H. Briavel Holcomb and Robert A. Beauregard. Cartographic Relief Presentation . Eduard Imhof. H. J. Steward, Trans. Soviet Union: A Geographical Survey . S. V. Kalesnik and V. F. Pavlenko, ed. Cognition and Environment . Stephen Kaplan and Rachel Kaplan. Environmental Protection: The International Dimension . David A. Kay and Harold K. Jacobsen, eds. Mathematical Programming Methods for Geographers and Planners , James Killen. Gentrification Amid Urban Decline: Strategies for America's Older Cities . Michael H. Lang. The North Atlantic Sulphur System . Risto Laulajainen. The Jerusalem Cathedra: Studies in the History, Archaeology, Geography and Ethnography of the Land of Israel, Vol. 2 . Lee I. Levine ed. Jerusalem and Detroit: Recreation Planning and Management . Stanely R. Lieber and Daniel R. Fesenmaier, eds. Heartland and Hinterland: A Geography of Canada . L. D. McCann, ed. Scarborough Where We Live: The Residential Districts of Minneapolis and St. Paul . Judith A. Martin and David A. Lanegran. California: The Geography of Diversity . Crane S. Miller and Richard S. Hyslop. Palo Alto The Dilemma of Amazonian Development . Emilio F. Moran, ed. Boulder Nuclear Waste: Socioeconomic Dimensions of Long-Term Storage . Steve H. Murdock, F. Larry Leistritz, and Rita R. Hamm, eds. Boulder Communism and the Politics of Inequalities . Daniel N. Nelson, ed. The Los Angeles Metropolis . Howard J. Nelson. Dubuque An Historical Geography of Urban System Development: Tidewater Virginia in the 18th Century . James O'Mara. Procedures and Standards for a Multipurpose Cadastre . East Asia: Geographical and Historical Approaches to Foreign Area Studies . Clifton W. Pannell, ed. Dubuque Mackinder: Geography as an Aid to Statecraft . W. H. Parker. Beyond the Urban Fringe: Land Use Issues of Nonmetropolitan America . Rutherford H. Platt and George Macinko, eds. Recreation Geography of the USSR . V. S. Preobrazhensky and V. M. Krivosheyev, eds. Missouri: A Geography . Milton D. Rafferty The Invisible Farmers: Women in Agricultural Production . Carolyn E. Sachs. Cayman Islands Seashore Vegetation: A Study in Comparative Biogeography . Jonathan D. Sauer. Hillslope Materials and Processes . Michael J. Selby. Housing in Britain: The Post-War Experience . John R. Short The Study of Population: Elements, Patterns and Processes . George A. Schnell and Mark Stephen Monmonier. Columbus The Soviet Union: A Systematic Geography . Leslie Symons, ed. The Ottoman Slave Trade and Its Suppression . Ehud R. Toledano. The Impact of Recession on Industry, Employment and the Regions, 1976–1981 . Alan R. Townsend. Landslides and Their Control , 2nd ed. Quido Záruba and Vojtech Mencl. Translated from the Czech by H. Zárubová and V. Mencl.     

Water levels in Lake Ontario 4230–2000 years B.P.: evidence from Grenadier Pond,Toronto, Canada

Lake Ontario water levels have been rising for the past 11 500 years due to differential isostatic rebound of the St. Lawrence outlet. Small scale fluctuations in water level superimposed on this general trend have received little study, with the exception of the Nipissing Flood.The transgression of a Grenadier Pond was studied from cores along a transect from the bar that separates the pond from Lake Ontario to the marsh on the north shore. Radiocarbon dates of the transition from swamp peat to pond marl in five cores provide estimates of the rate of water level rise since 4230 years B.P. These estimates are supported by changes in sediment type and in abundance of pollen and seeds of aquatic plants. There were three short intervals of accelerated water level rise in Grenadier Pond, around 4200, 3000, and 2000 years B.P., when water levels rose up to 2 m instantaneously, within the resolution of radiocarbon dating. Sedimentological and paleobotanical data suggest that Grenadier Pond was an open embayment of Lake Ontario until 1970–1850 years B.P., when it was isolated by the bar, and therefore sediments deposited prior to this time reflect water levels in Lake Ontario.Short term departure of up to 2 m from the average rate of water level rise over the past 4000 years, as observed in the record at Grenadier Pond, is of the same range as historically observed departures from the mean lake stage of Lake Ontario. This implies that a threshold discharge exists above which broadening of the outflow channel occurs to accommodate further increase in discharge with little rise in lake level. The intervals of accelerated water level rise in Lake Ontario broadly coincide with periods of cool, wet climate, suggesting that increased moisture may have caused the short term fluctuations in water level.This is the second of a series of papers to be published by this journal that was presented in the paleolimnology sessions organized by R. B. Davis and H. Löffler for the XIIth Congress of the International Union for Quaternary Research (INQUA), which took place in Ottawa, Canada in August 1987. Drs. Davis and Löffler are serving as guest editors of this series.     

Maximum snowfall at long-term stations in the U.S./Canadian Great Lakes

Heavy snowfalls can pose natural hazards in the North American Great Lakes region. Maximum annual snowfalls are presented from an extensive data base at 82 long-period-of-record stations. In the absence of site-specific information, these data should be useful to designers, planners, and resource managers in the region. A relationship exists between maximum snowfalls and latitude because the northern Great Lakes climate is cooler and drier than the climate of the southern Great Lakes. A relationship between longitude and maximum snowfalls appears to be based on the longitudinal variation of precipitable water vapor aloft. No apparent relationship exists between maximum snowfall and elevation when station data are analyzed without regard to data from lake-effect zones. However, when one lake-effect region was analyzed in detail, an orographic effect was clearly evident in both maximum and average annual snowfalls.     

高原湖泊和平原湖泊遥感动态监测的对比分析——以洱海和鄱阳湖为例

湖泊及其动态变化在区域生态环境保护中占据极其重要的作用,监测并对比分析不同类型的湖泊动态变化对区域生态环境保护意义重大。应用Landsat TM遥感数据,基于ENVI遥感图像处理软件和Arc GIS空间分析软件,分别以洱海和潘阳湖为例,利用单波段阈值法、波段组合法等方法提取了湖泊水体现状信息;通过波段运算、波段替换等方法提取了湖泊的动态变化信息;对比分析了高原湖泊和平原湖泊两类湖泊动态变化信息提取监测效果。研究表明:应用波段组合法提取湖泊水体信息有较高的准确度,而缨帽变换法提取湖泊水体信息准确度偏低;受湖泊界限标准不统一、季节性水域变化,湖泊周边地理环境等影响,平原湖泊水体分布状况较高原湖泊水体分布状况复杂,多种遥感图像处理方法结合使用更适用于平原湖泊遥感动态监测。     

论南四湖蓄水位稳定控制的战略对策

本文分析了南四湖蓄水位不稳定的原因,论述了稳定控制蓄水位的重要性,这对减灾,满足沿湖工农业供水需求,稳定发展渔湖产养殖业,有成效地综合开发利用南四湖水资源,加速发展济宁市经济,将起到举足轻重的作用。     

Remedial measures against radioactive Caesium in Swedish lake fish after Chernobyl

The aim of this work is to give a summary of the work on Cs-137 in Swedish lakes carried out mainly by our group (the Liming-mercury-caesium project) between 1986 and 1990. The focus is on results from extensive field experiments carried out in 41 lakes testing various remedial measures to speed up the natural recovery of Cs-137 in lakes: Lake liming and wet land liming with primary rock lime, sedimentary rock lime and so-called mixed lime, which also contains nutrients; potash treatment and intensive fishing. Selected results: The remedies have given the intended water-chemical response. None of the methods used works effectively as cure, i.e., no rapid and clear reduction in the concentrations of radioactive caesium in fish is obtained in comparison with lakes where the waterchemical or biological conditions are not changed. In lakes with long water turnover time and with low values of, foremost, conductivity, hardness and potassium, the fish had relatively higher concentrations at the same fallout levels. The differences present between the lakes as regards the continued magnitude of the change in concentration in fish can foremost be linked to factors controlling the secondary load (i.e., the internal loading and the input from the catchment). A successful potash treatment (in oligotrophic lakes) may imply that the natural recovery will be at the most 5% faster compared to no treatment. This would give quite positive implications in the long run since the ecological half-life for Cs-137 in pike (the top predator in these lake types) is very long. The time interval between the remedies and the latest fish analyses (about 2 years on average) is not sufficient to obtain (statistically) clear-cut results on these the small effects of the remedies. A longer time series of data is required for this.     

Spatio‐temporal variability of Great Lakes basin snow cover ablation events

In the Great Lakes basin of North America, annual run‐off is dominated by snowmelt. This snowmelt‐induced run‐off plays an important role within the hydrologic cycle of the basin, influencing soil moisture availability and driving the seasonal cycle of spring and summer lake levels. Despite this, relatively little is understood about the patterns and trends of snow ablation event frequency and magnitude within the Great Lakes basin. This study uses a gridded dataset of Canadian and United States surface snow depth observations to develop a regional climatology of snow ablation events from 1960 to 2009. An ablation event is defined as an interdiurnal snow depth decrease within an individual grid cell. A clear seasonal cycle in ablation event frequency exists within the basin and peak ablation event probability is latitudinally dependent. Most of the basin experiences peak ablation frequency in March, while the northern and southern regions of the basin experience respective peaks in April and February. An investigation into the interannual frequency of ablation events reveals ablation events significantly decrease within the northeastern and northwestern Lake Superior drainage basins and significantly increase within the eastern Lake Huron and Georgian Bay drainage basins. In the eastern Lake Huron and Georgian Bay drainage basins, larger ablation events are occurring more frequently, and a larger impact to the hydrology can be expected. Trends in ablation events are attributed primarily to changes in snowfall and snow depth across the region.