Storsteinsfjellbreen: Variations in Mass Balance from the 1960s to the 1990s

When the Norwegian State Power Board decided to plan an extensive water power development in the mountainous areas southeast of Narvik in northern Norway, a large mapping project was started. Detailed maps were constructed at a scale of 1:10 000 from aerial photographs taken in 1960. Several hydrometric stations were installed, and three glaciers were selected for mass balance observations. Storsteinsfjellbreen was the largest of these, and a special glacier map with 10 m contours was printed in four colours, to be used in the field work. Mass balance studies were carried out initially during one 5-year period (1964–68), and also later during another 5-year period (1991–95).
Results from these periods are compared with similar data from the Swedish glacier Storglaciären, about 45 km to the southeast. For all the years except one (1968), the net balance of these glaciers shows a similar pattern: positive years and negative years are synchronous.
A new glacier map was made from a special aerial survey in 1993 at the same scale and of similar accuracy as the first map, so a comparison could be made to calculate the change in glacier volume from 1960 to 1993. From digital terrain models it could be shown that the glacier surface had dropped more than 60 m vertically on the tongue, while the thickness increased above the equilibrium line by up to 20 m. The overall mass loss amounted to 16.8×10⁶ m³ water during 33 years, which corresponds to an extra 2.6 l·s⁻¹·km⁻² (litres per sec. per sq. km) delivered to the river, in addition to the "normal" discharge
due to annual precipitation, which is 36 l·s⁻¹·km⁻² in the area.
A copy of the new glacier map is enclosed with this article.     

Disparate Sandstone Weathering Beneath Lichens, Red Mountain, Arizona

Though the ability of lichens to disaggregate and dissolve the substrate is understood, zones of disparate weathering mechanisms examined in this study were previously unobserved. On a steep (60°) northern (340°N) slope on Red Mountain, Arizona, a 5×5 m study plot was chosen for its maximum lichen coverage (33%) of the same lichen genus Xanthoparmelia in varying growth stages, on a sandstone substrate of consistent lithology. From twenty-two (22) representative lichen thalli, portions were removed to examine sub-thallic rhizine density, and others were resin-inbedded for optical, scanning and backscatter electron microscopy.
In every sample, sandstone beneath and adjacent to the lichen thallus displayed disparate weathering mechanisms. Beneath the center of the lichen cortex, where rhizine density was observed to be the greatest, rhizine penetration disaggregated the sand-stone clasts from the matrix, but little chemical dissolution was apparent. This study found physical weathering predominates beneath the lichen cortex, and chemical weathering predominates at the thallus fringe and beyond the thallus boundary. It was generally found that physical weathering decreased (disaggregation) and chemical weathering increased (dissolution) from the cortex center to the thallus edge. Toward the thallus fringe, minimal clast disaggregation was observed, and substrate dissolution was obvious.     

湘桂黔滇藏红色岩溶风化壳发育模式

基于对湘，桂、黔，滇，藏等地岩溶区红色风化壳的野外和室内研究，从表生地貌学，粘土矿物学和地球化学角度分析红色石灰土性质与地貌演化的关系，提出红色岩溶风化壳发育的二阶段模式；1）地貌夷平-风化物质积累阶段，在地貌演化过程中溶蚀残余物质不断积累，最后在夷平面上形成厚层连续的泥质风化壳，夷平面的地貌水文条件有利于粘粒的形成和保存，但限制了富铝化作用的有效进行，造就了岩溶风化壳粘粒含量高，富铝化程度低的特点，这与研究区23个红色岩溶风化壳剖面化学，粒度特征和粘土矿物组合特点一致。2）地貌切割-风化壳淋溶阶段，原始夷平面上的风化壳大多呈灰色，只有在构造隆升和地表微切割导致地下水位降低，淋溶条件开始改善的情况下，风化壳才有可能枞根本上转为红色。     

粘土矿物的提取、鉴定及其古气候意义——以柴达木盆地怀头他拉剖面为例

沉积物中粘土矿物类型主要有自生粘土矿物和碎屑粘土矿物。其中,自生粘土矿物含量较少,是在沉积环境中形成,可能是沉积再循环或成岩作用的产物,可作为沉积环境某方面的指示标志;而碎屑粘土矿物是母岩风化的产物,受沉积环境影响较小,能够有效示踪物源区化学风化过程,进而反映古气候变化。近年来利用碎屑粘土矿物特征来重建物源区古气候的方法得到了广泛的应用。然而,由于粘土矿物主要存在于<2 μm硅酸盐粘粒中,粘土矿物的提取、鉴定比较困难,且自生粘土矿物易受沉积环境等的影响。因此,在利用粘土矿物重建古气候变化时,需慎重选择粘土矿物的提取方法,并考虑物源和沉积环境变化以及成岩作用等对粘土矿物解释的影响。本文以柴达木盆地东北缘怀头他拉剖面硅酸盐粘土矿物的提取、鉴定及其古环境指示意义为例,介绍粘土矿物的提取及应用,为后期粘土矿物研究提供参考。     

A 1500-year record of climatic and environmental change in ElkLake, Clearwater County, Minnesota II: geochemistry, mineralogy, and stableisotopes

Most of the sediment components that have accumulated in ElkLake, Clearwater County, northwestern Minnesota, over the past 1500 years areauthigenic or biogenic (CaCO₃, biogenic SiO₂, organicmatter, iron and manganese oxyhydroxides, and iron phosphate) and are deliveredto the sediment–water interface on a seasonal schedule where they are preservedas distinct annual laminae (varves). The annual biogeochemical cycles of thesecomponents are causally linked through the carbon pump, and are recapitulatedin longer-term cycles, most prominently with a periodicity of about 400 years.Organic carbon is fixed in the epilimnion by photosynthetic removal ofCO₂, which also increases the pH, triggering the precipitation ofCaCO₃. The respiration and degradation of fixed organic carbon inthe hypolimnion consumes dissolved oxygen, produces CO₂, and lowersthe pH so that the hypolimnion becomes anoxic and undersaturated with respectto CaCO₃ during the summer. Some of the CaCO₃ produced inthe epilimnion is dissolved in the anoxic, lower pH hypolimnion and sediments.The amount of CaCO₃ that is ultimately incorporated into thesediments is a function of how much is produced in the epilimnion and how muchis consumed in the hypolimnion and the sediments. Iron, manganese, andphosphate accumulate in the anoxic hypolimnion throughout the summer.Sediment-trap studies show that at fall overturn, when iron-, manganese-, andphosphate-rich bottom waters mix with carbonate- and oxygen-rich surfacewaters, precipitation of iron and manganese oxyhydroxides, iron phosphate, andmanganese carbonate begins and continues into the winter months.Detrital clastic material in the sediments of Elk Lake depositedover the last 1500 years is a minor component (<10% by weight) that ismostly wind-borne (eolian). Detailed analyses of the last 1500 years of the ElkLake sediment record show distinct cycles in eolian clastic variables (e.g.aluminum, sodium, potassium, titanium, and quartz), with a periodicity of about400 years. The 400-yr cycle in eolian clastic material does not correspond tothe 400-yr cycles in redox-sensitive authigenic components, suggesting that theclastic component is responding to external forcing (wind) whereas theauthigenic components are responding to internal forcing (productivity),although both may ultimately be forced by climate change. Variations in theoxygen and carbon isotopic composition of CaCO₃ are small but appearto reflect small variations in ground water influx that are also driven byexternal forcing.     

邻里环境感知与个体健康对通勤模式选择的影响研究——以南京市为例

通勤是大部分城市就业者日常工作所必须面对的问题。相比宏观层面的城市建成环境,微观层面的邻里环境感知及个体健康与通勤模式选择的联系更为密切。以南京市主城区8个社区为案例地,利用结构方程模型探究邻里环境感知与个体健康对城市就业者通勤模式选择的影响。首先借助问卷调查数据,将通勤模式分为积极通勤、公共交通通勤、电动车/摩托车通勤以及小汽车通勤四类;其次使用因子分析法确定邻里环境感知的潜变量,并将个体健康分为身体健康、心理健康与健康行为3个潜变量;最后构建结构方程模型的理论框架并进行实证分析。研究发现：① 邻里环境感知变量中服务设施感知、环境品质感知对通勤模式选择存在显著的直接效应,交通安全感知对通勤模式选择存在显著的间接效应。② 个体健康变量中,心理健康与健康行为对通勤模式选择存在显著的直接效应。③ 通勤距离与社会经济属性对通勤模式选择存在显著的直接效应,同时社会经济属性对通勤模式选择亦存在显著的间接效应。基于研究结果,提出有效提升就业者对于社区环境的主观感受,进而提高就业者参与健康行为的意愿与就业者的健康水平,从而引导其选择更加健康和绿色的通勤模式。     

A 1500-year record of climatic and environmental change in ElkLake, Minnesota III: measures of past primary productivity

Diatom analysis of a varved sediment core from Elk Lake, Minnesotadocuments important natural and human-caused shifts in primary productivity atdecadal scales for the past 1500 years. Interpretations from a perspective ofplanktic diatom seasonal dynamics and from total phosphorus inferences based ona 111-lake training set of freshwater Canadian lakes reveal a major change tomore productive environments after 1000 years ago probably caused by earlierice-out and stronger, longer periods of lake circulation during the spring.European impacts in the region, principally logging in the Elk Lake drainage,during the past 100 years increased nutrient fluxes and turbulence during theopen water season to promote blooms of Aulacoseiraambigua. High resolution (semi-decadal) diatom analyses suggestsunspot cycle periodicities that may reflect short-term changes in thecharacter of irradiance and (or) sun-climate interactions. Total epilimneticphosphorus inferences from the Canadian training set applied to the Elk Lakediatom record document both long-term and short-term variations inproductivity and reconstruct past phosphorus values consistent with somepresent-day measured values at Elk Lake. The Elk Lake study underscores theneed for neolimnological monitoring of both training set and target lakes aswell as for the application of a multiple proxy protocol to documentpaleo-productivity that approaches neolimnological resolution.     

基于广州实证的后改革时代中国城市住房权问题

社会公正是当前地理学的一个热点也是传统研究课题。住房问题往往是社会公正研究和实践的重点案例。中国住房制度改革之后,中国住房拥有率及人均住房面积均大幅度提高。然而在住房分配的过程中,不平等和不公正现象时有发生。如何区别平均和公正,如何看待中国住房改革中的社会公平与不公共存的现象,是了解中国新城市现象的一个重要途径。本文从近期西方政治学和地理学关于住房权（housing rights）、社会公正以及城市权利等文献的讨论出发,通过在广州的实证研究,运用结构方程模型和Pratt指数对涉及住房权主要方面的住房分异的发生途径及其公正性进行综合分析。实证研究说明在住房分配领域,存在着制度因素延续下来所导致的分异。一些制度因素已经转化为市场因素,直接或间接影响个人居住条件和住房所有权的获得,并通过后者进一步影响住房分异。与此同时,纯粹市场因素的影响则相对薄弱。上述结论有助于了解当前中国城市住房权的核心问题,认识社会公正的发展前景,以及探寻减少社会不公正的制度利器。     

A 1500-year record of climatic and environmental change in ElkLake, Minnesota I: Varve thickness and gray-scale density

The deepest part (29.5 m) of Elk Lake, ClearwaterCounty, northwestern Minnesota, contains a complete Holocene section that iscontinuously varved. The varve components are predominantly autochthonous(CaCO₃, organic matter, biogenic silica, and several iron andmanganese minerals), but the varves do contain a minor detrital-clastic(aluminosilicate) component that is predominantly wind-borne (eolian) andprovides an important record of atmospheric conditions. Singular spectrumanalysis (SSA) and wavelet analysis of varve thickness recognized significantperiodicities in the multicentennial and multidecadal bands that varied inpower (i.e., variable significance) and position (i.e., variable period) withinthe periodic bands. Persistent periodicities of about 10, 22, 40, and 90 years,and, in particular, multicentennial periodicities in varve thickness and otherproxy variables are similar to those in spectra of radiocarbon production, aproxy for past solar activity. This suggests that there may be a solar control,perhaps through geomagnetic effects on atmospheric circulation. Multicentennialand multidecadal periodicities also occur in wavelet spectra of relativegray-scale density. However, gray-scale density does not appear to correlatewith any of the measured proxy variables, and at this point we do not know whatcontrolled gray scale.     

A Small Glacier as an Index of Regional Mass Balance: Baby Glacier, Axel Heiberg Island, 1959–1992

Baby Glacier, Axel Heiberg Island, N.W.T., Canada is a small (0.6 km²), high-latitude (79°N), high-altitude (700–1200 m) glacier with a mass balance record extending from 1959–60 to the present. The record demonstrates shrinkage of the glacier, but a statistically significant trend is not evident. Correlations are strong between the mass balance of Baby Glacier and that of the nearby and much larger White Glacier, and also those of even larger, more distant glaciers. Thus programmes of measurement on small, simple ice bodies such as Baby Glacier can be representative of a large region. However, inter-annual changes are more accentuated for Baby Glacier. Baby Glacier does not meet all of the usual criteria for a representative glacier, but it straddles the regional equilibrium zone, a fact which helps to offset the disadvantages of its small size and limited altitudinal range. The equilibrium zone deserves to be an important focus for studies of high-arctic mass balance, with the aim of facilitating future measurement programmes which will rely on satellite remote sensing.     

中国干旱沙区的生态重建与恢复:沙坡头站60年重要研究进展综述

中国科学院沙坡头沙漠研究试验站建站60年来,服务于国家需求,推动了沙漠科学的发展。在沙害治理、沙漠生态重建与恢复、荒漠生态系统长期生态学、沙地生态水文学\,人工植被稳定性及干旱胁迫生理生态学方面取得了重要进展\.解决了在降水量小于200 mm的干旱沙漠地区植被建设的关键技术,证实了通过人为促进生态恢复是可行的,创造了人类活动(治理和利用)与沙漠自然和谐持续发展的模式;探讨了干旱沙区土壤水循环的植被调控机理,提出了生态恢复的关键技术及其应用模式;理论上探明了人工植被稳定性维持的生态学机理,提出了荒漠系统生态恢复的理论模型;揭示了荒漠生态系统碳、氮循环及其对环境因子的响应;引领了生物土壤结皮的生理生态功能及其水文学研究;拓展了干旱逆境生理生态学的研究。沙坡头站已成为国际沙漠科学与荒漠长期生态学研究的重要平台。