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Metals in lacustrine sediment have both anthropogenic and natural sources. Because of intensified human activities, the anthropogenic input of metal elements has exceeded the natural variability. How to distinguish the anthropogenic sources in lake sediments is one of the tasks in environmental management. The authors present a case study, which combined the geochemical and statistical methods to distinguish the anthropogenic sources from the natural background. A 56 cm core (core DJ-5) was collected from Dongjiu Lake, Taihu Lake catchment, China. The concentration distributions of Al, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, Ti, V and Zn in core DJ-5 indicated that Dongjiu Lake had serious Cd pollution, and the concentrations of Cr, Cu, Pb, Mn and Zn had also exceeded the Chinese State Standards of Soil Environmental Quality in the upper layer of the core. Using Al as a reference element, the other metals were normalized and compared with their baselines to calculate the enrichment factors (EFs). The principal component analysis (PCA) of metal concentrations was performed using ViSta6.4. The results of EFs and PCA indicated that the concentration variations of Cd, Cu, Pb, Mn and Zn were mainly caused by the anthropogenic sources, and the concentration variations of Cr and Ni were influenced by both the anthropogenic and natural factors, while the other metals were mainly derived from the natural sources. Intensified human activities within the lake catchment area resulted in the increase of heavy metal inputs directly and the acceleration of erosion which caused other metal elements to deposit in the aquatic environment. The results of this work will be useful in probing changes forced by humans in the lake environment and in adjusting human activity in restoring the lake environment.

基于水化学特征的长江源区生态水文学研究进展

气候变暖背景下,冰雪、冻土剧烈消融引起的寒区径流成分改变对流域径流演变规律及水循环机制产生了深刻影响。对长江源区各水体水化学特征及其生态水文学研究进行归纳总结,主要进展包括：长江源区的大气降水的水汽来源主要受西风环流和季风环流的控制。冰雪融水的水化学特征受到消融强度、消融持续时间和新雪融水的影响,同时在冰雪融水、积雪以及冰川融水之间可能存在化学离子的交换。冻土层上水受到降水、冰雪融水、地下冰融水等的混合补给,造成水化学特征变化的随机波动。海拔在4 500 m的地区是冻土层上水水化学特征对研究区离子控制源较为敏感的区域。随着海拔高度的增加,降雨直接补给对河水中化学离子的稀释作用逐渐减弱,同时,海拔从4 500 m到5 000 m的降水对河水中离子浓度的稀释效果最大,而在海拔5 000 m以上河水主要受冰雪融水的补给,降水和消融期的变化对河水水化学的影响很小。研究结果为更系统地认知寒区下垫面变化所引起的水文效应提供科学依据,为流域水资源的合理开发利用提供决策依据。     

多年冻土区斜坡稳定性研究综述

全球变暖、极端天气频发,引发的地质灾害对自然生态环境和人类生产生活造成了很大的影响。尤其对气候变化较为敏感的高温（年平均地温>-1 °C）和高含冰量多年冻土区,气候变暖以及人类活动导致的冻融地质灾害日益频繁。冻土退化条件下,土体结构和物理力学性质发生改变,黏聚力和抗剪强度降低,造成多年冻土区斜坡发生滑坡、崩塌、泥流等灾害。斜坡失稳加剧了多年冻土区脆弱生态环境的恶化,同时对建（构）筑物安全运营产生威胁。与非冻土区相比,多年冻土区斜坡稳定性研究主要针对高含冰量斜坡段,斜坡失稳模式主要以热融滑塌和活动层滑脱为主。热融滑塌由斜坡段地下冰暴露融化引起,而活动层滑脱产生的原因是冻土融化导致土体孔隙水压力过大,形成的超孔隙水压力降低了土体强度,造成斜坡失稳。此外,多年冻土区斜坡失稳模式还包括融冻泥流、崩塌以及蠕变滑坡等。通过综述近期多年冻土区斜坡稳定性研究进展,概括了多年冻土区斜坡失稳的模式、特征、影响因素、失稳机理、分析方法及防治措施等,并对未来多年冻土区斜坡失稳的研究重点提出建议。     

南阿尔金木纳布拉克地区长城系巴什库尔干岩群LA-ICP-MS锆石U-Pb定年及其地质意义

采用LA-ICP-MS微区原位锆石U-Pb同位素测定技术,测得木纳布拉克地区原划长城系巴什库尔干岩群红柳泉组的二云二长片麻岩和扎斯勘赛河组二云石英片岩的原岩形成年龄分别介于498~840Ma和500~647Ma之间,表明这2种岩石原岩的形成时代均为新元古代,而不是之前认为的中元古代。另外,红柳泉组二云二长片麻岩边部锆石表现为重稀土元素相对富集型稀土配分模式,其Th/U值大部分小于0.1,为变质锆石,测得其变质时代为498±4Ma,与该地区高压麻粒岩的峰期变质时代(486±5Ma)一致,且与南阿尔金阿尔金岩群中的高压-超高压岩石的峰期变质时代一致,推断其为阿尔金俯冲碰撞引发的高压-超高压变质作用的产物,属于南阿尔金高压-超高压变质带的一部分。通过原岩残留碎屑锆石的年代学对比,发现研究区内这2种岩石及已发现的高压麻粒岩均具有与阿尔金岩群相似的锆石年龄信息,表明本区红柳泉组和扎斯勘赛河组的这3种岩石不应再划归为中元古代的长城系巴什库尔干岩群,将其归属为阿尔金岩群更为合适。     

Reservoir rainfall–runoff geomorphological model. I: application and parameter analysis

This article describes and formulates a model designed to simulate runoff in wet weather events, called reservoir rainfall–runoff geomorphological model (R³GeM). In these wetlands, soil saturation is the main mechanism for the generation of surface runoff. To determine the saturated areas, the model applies a relationship based on the topographic index, between watershed storage and saturated surface. Precipitation is separated into surface runoff by saturation, subsurface runoff and losses; then, the flow of surface and subsurface runoff is performed. This hydrological model has five parameters and has been implemented in 37 events in Aixola watershed and 15 in Oiartzun watershed, both located on the Cantabrian coast of Spain. We analysed the influence of these five parameters in their behaviour, and we have proven, noting the efficiency gains, that the proposed model is valid to simulate the rainfall–runoff process. Copyright © 2012 John Wiley & Sons, Ltd.     

Comparative analysis of a geomorphology‐based instantaneous unit hydrograph in small mountainous watersheds

A conceptual insytnataneous unit hydrograph (IUH) based on geomorphologival association of linear reservoirs (GR) previously developed by the authors has been compared with other IUH models: a distributed GR variation (GR(v)), the Nash IUH, the Chutha and Dooge IUH, and the Troutman and Karlinger IUH for the analysis of direct runoff hydrographs recorded in three experimental watershed of the north of Spain. The comparison was made through a calibration‐validation process in which a leave‐one‐out cross‐validation method was applied. The results indicate the satisfactory performance of all the models, with the advantage for the GR model of the dependence on only one parameter, which can be identified from the watershed and event characteristics. This property makes its use easier than that of other models. Copyright © 2011 John Wiley & Sons, Ltd.     

欧拉模型模拟波浪的抑制数值耗散效应的一种简单方法

数值波浪水槽是研究波浪及波浪与结构相互作用的常用工具,可在真实尺度下产生波浪,并提供流场的详细数据。然而,大部分数值波浪水槽都存在数值耗散和数值色散问题,数值耗散使波能缓慢消散,数值弥散在波传播过程中使波频移。本文在有限差分法（FDM）求解欧拉方程的基础上,提出了一种抑制数值耗散效应的简单方法,考虑阻尼项的影响,对波的传播解进行了解析求解。该方法的主要思想是在动量方程中附加一个源项,其强度由数值阻尼效应的强度决定。本文通过对规则线性波、Stokes波和不规则波的数值模拟,验证了该方法的有效性。结果表明,本文方法可有效减小数值波浪水槽中存在的数值耗散现象。     

Impact of environmental variables on spatial and seasonal internal phosphorus loading in a mesoeutrophic lake

Strzeszynskie Lake was formerly a slightly eutrophic (meso-eutrophic) water body. The aim of the current research was to define variables on both spatial and seasonal internal phosphorus loading from bottom sediments at five stations located in zones varying in depth, oxygenation, macrophyte presence, and uses of the neighboring catchment area. Ex situ experiments done with the use of intact bottom sediment cores have shown that the highest phosphorus release occurred in the deepest part of the lake and reached 3.6?mg?P/m²d under anoxic conditions during summer thermal stratification. In turn, the internal loading from littoral sediments, which were well aerated all year round, was clearly lower. Furthermore, phosphorus accumulation in the bottom sediment was observed to reach a maximum of 1.45?mg?P/m² d in autumn. A comparison of the internal loading intensity in lake zones with different land uses of the neighboring catchment area has shown slightly higher values at stations adjacent to the forest catchment area than those used for recreation. Changes in the land use of the catchment area of Strzeszynskie Lake, especially the increase in impermeable surfaces, have led to an increased inflow of external loads after heavy rains, resulting in deterioration in water quality and a delayed increase in internal loading.     

唐古拉山中侏罗统缅甸光牡蛎(Liostrea birmanica REED)壳层的事件沉积成因及其环境意义

唐古拉山地区中侏罗统产出丰富的牡蛎类化石,特别是缅甸光牡蛎Liostrea bir—manica Reed分布更为广泛,而且多以介壳层形式产出。在唐古拉山的冬曲,窝布茸曲及青藏公路108道班等地剖面上,栖息于软基底的表生底栖双壳类Liostrea birmanica形成近原地埋葬的介壳层堆积;内生的Ceratomya动物群则多散布于沉积物中,形成原地埋葬的化石群．它们和以丛藻迹Chondrites为主体的遗迹化石群依次重复出现,构成一个和风暴沉积事件相关的底栖动物群替代序列。Liostrea birmanica介壳层是风暴高峰期的侵蚀和再沉积所形成的,风暴期以后水下沉积间断所形成的轻度固化的软基底则迅速地被潜穴生物占领(丛藻迹Chondrites ich—nosp．和根珊瑚迹Rhizocorallium ichnoSp．);而以深挖穴滤食类型为主的Ceralomya组合则是好天气时的原地埋葬。在大多数情况下,它们指示着介于正常浪基面以下,风暴浪基面以上的低沉积速率浅水碳酸岩台地沉积环境。     

Automatic change detection of buildings in urban environment from very high spatial resolution images using existing geodatabase and prior knowledge

The updating of geodatabases (GDB) in urban environments is a difficult and expensive task. It may be facilitated by an automatic change detection method. Several methods have been developed for medium and low spatial resolution images. This study proposes a new method for change detection of buildings in urban environments from very high spatial resolution images (VHSR) and using existing digital cartographic data. The proposed methodology is composed of several stages. The existing knowledge on the buildings and the other urban objects are first modelled and saved in a knowledge base. Some change detection rules are defined at this stage. Then, the image is segmented. The parameters of segmentation are computed thanks to the integration between the image and the geodatabase. Thereafter, the segmented image is analyzed using the knowledge base to localize the segments where the change of building is likely to occur. The change detection rules are then applied on these segments to identify the segments that represent the changes of buildings. These changes represent the updates of buildings to be added to the geodatabase. The data used in this research concern the city of Sherbrooke (Quebec, Canada) and the city of Rabat (Morocco). For Sherbrooke, we used an Ikonos image acquired in October 2006 and a GDB at the scale of 1:20,000. For Rabat, a QuickBird image acquired in August 2006 has been used with a GDB at the scale of 1:10,000. The rate of good detection is 90%. The proposed method presents some limitations on the detection of the exact contours of the buildings. It could be improved by including a shape post-analysis of detected buildings. The proposed method could be integrated into a cartographic update process or as a method for the quality assessment of a geodatabase. It could be also be used to identify illegal building work or to monitor urban growth.