Response of riparian vegetation to water-table changes in the lower reaches of Tarim River, Xinjiang Uygur, China

The lower reaches of Tarim River in the Xinjiang Uygur region of western China had been dried out for more than 30 years before water began to be diverted from Konqi (Peacock) River via a 927-km-long channel in year 2000, aimed at improving the riparian ecological systems. Since then, eight intermittent water deliveries have been carried out. To evaluate the response of riparian vegetation to these operations, the groundwater regime and vegetation changes have been monitored along the 350-km-long stem of the river using a network of 40 dug wells at nine transects across the river and 30 vegetation plots at key sites. Results show that the water table rose remarkably, i.e. from a depth of 9.87 m before the water delivery to 3.16 m after the third water delivery. The lateral distance of affected water table extended to 1,050 m from the riverbank after the fourth water delivery. The riparian vegetation has changed in composition, type, distribution, and growing behavior. This shows that the water deliveries have had significant effects on restoration of riparian ecosystems.     

Interactive 3-D computation of fault surfaces using level sets

Deformable implicit surfaces, implemented with level set methods, have demonstrated a great potential in the computational sciences for applications such as modeling, simulation, and segmentation. They allow implicit handling of complex topologies deformed by operations where large changes can occur without destroying the level set representation. The use of level set techniques for the computation and segmentation of plane-like and high positive curvature features is nontrivial. We present a technique for representing and extracting fault surfaces from 3-D seismic attribute data such that 2-manifolds can be interactively computed and segmented. We present our approach as an interactive workflow that generates highly accurate fault surfaces.     

A virtual voyage through 3D structures generated by chaotic mixing of magmas and numerical simulations: a new approach for understanding spatial and temporal complexity of magma dynamics

In this contribution, we present a virtual voyage through 3D structures generated by chaotic mixing of magmas and numerical simulations with the aim to highlight the power of 3D representations in the understanding of this geological phenomenon. In particular, samples of mixed juveniles from Salina island (Southern Italy) are reconstructed in 3D by serial lapping and digital montage and numerical simulations are performed by using a 3D chaotic dynamical system. Natural and simulated magma mixing structures are visualized by using several multimedia tools including animations and “virtual reality” models. It is shown that magma interaction processes can generate large spatial and temporal compositional heterogeneities in magmatic systems. The same topological structures are observed in both 3D reconstructed rock samples and chaotic numerical simulations, indicating that the mixing of magmas is governed by chaotic dynamics. The use of 3D multimedia models gives the opportunity to penetrate into magma mixing structures and to understand their significance in the context of magma dynamics. Such an approach is very powerful since multimedia tools can strongly capture the attention of the reader bringing him/her into an interactive and memorable geological experience. Electronic supplementary material  enclosed:     

鄂尔多斯盆地南部前侏罗纪古地貌对延安组下部油藏的控制作用

三叠纪末的印支运动使鄂尔多斯盆地整体抬升,上三叠统延长组顶部遭受到强烈风化及河流侵蚀等地质作用,形成水系广布、沟壑纵横、丘陵起伏的古地貌景观。通过对下侏罗统延安组延10油层组和富县组地层等厚图及延长组顶面起伏图的编绘,基本恢复了前侏罗纪古地貌形态,并将其划分为河谷、斜坡、阶地、高地、平原和潜丘6种古地貌单元。该种古地貌景观严格控制了下侏罗统富县组及延安组下部的沉积相类型、相带展布及压实披盖构造的形成。古河谷的下切作用不仅使延安组下部与油源层的接触距离缩短,又为油气运移提供了良好的通道,如遇到有利的储集体与背斜、鼻隆等构造,即可有机配置、富集成藏;同时地层水特征表明斜坡带保存条件最好。指出前侏罗纪古地貌斜坡带上的坡嘴、阶地及潜丘是勘探延安组下部油藏的有利地带。     

北京市有机氯农药填图与风险评价

采用1个样/km2的密度、1个分析组合样/16km2的方法,对北京市784km2范围内的土壤、大气干湿沉降物、大气颗粒物中HCH、DDT的含量和空间分布特征进行有机氯农药填图.查明2000年北京市地表土壤HCH和DDT的平均含量分别为8.80±11.83ng/g、108.99±301.90ng/g.2006年大气干湿沉降物中HCH和DDT平均含量分别为10.09±9.60ng/g、12.99±13.51ng/g,HCH和DDT的年沉降通量分别为996.57±939.96g/a·km2、1291.53±1342.28g/a·km2.2006年大气颗粒物PM10和PM2.5中的HCH含量分别为0.294±0.205ng/m3和0.217±0.137ng/m3,DDT的平均含量分别为1.037±1.301ng/m3和0.522±0.773ng/m3,显著高于2002-2003年度大气颗粒物中HCH(PM100.01786ng/m3,PM250.01731ng/m3)和DDT(PM100.01672ng/m3,PM2.50.02353ng/m3)的含量,表明北京市或周边地区仍在使用含HCH和DDT化学成分的农药.以2000年北京地表土壤和2006年大气干湿沉降物中HCH和DDT的含量为基础,对2020年土壤中HCH和DDT的时空演变的预测显示,即使干湿沉降物中HCH和DDT的沉降通量每年以5%的速率递减,到2020年土壤中HCH和DDT的环境质量仍不能显著改善,而控制和削减北京及周边地区含HCH和DDT成分农药的使用将是改善北京地表土壤环境质量的关键措施.     

遥感技术在煤炭资源开发状况监督管理中的应用研究

利用高分辨率遥感图象可以快速查明煤炭资源开发状况以及煤炭资源开发的合法性（界内开采、界外开采、越界开采）等,对煤矿安全生产及维护矿业秩序具有重要意义。以我国中部某煤炭开采密集区为试验区,选择不同分辨率的遥感数据,从矿山铺助设施、道路、矿堆、矸石的特征出发,进行矿山开采状况遥感解译;以地理信息系统技术（GIS）为支撑实现采矿权数据、规划数据图层与遥感专题数据的叠加分析和相关分析,判断非法与越界矿山,评价矿产资源开发与保护规划执行情况。     

Geostatistical analysis of arsenic concentration in the groundwater of Malda district of West Bengal, India

The problem of arsenic (As) poisoning in the upper deltaic plain of the Ganga-Bhagirathi river system in the Bengal Basin of West Bengal, India is an alarming issue. Four blocks (Kaliachak-1, 2, 3 and English Bazar) of Malda district, West Bengal were critically studied. Geomorphologically, the area exhibits three terraces: the present Youngest terrace (T₀-terrace), the Older Shaugaon Surface (T₁-terrace) and the Oldest Baikunthapur Surface (T₂-terrace). On the basis of numerous measurements, including As-content, pH, DO, specific conductivity and salinity, it was observed that maximum As-content beyond the permissible limit (0.05 mg/L, Indian standard) occurs within a depth range of 10–30 m with a non-linear distribution pattern. Variance test also found that a block effect was highly significant in an As-distribution pattern. Mean arsenic level of Kaliachak block-1 is 0.2253 mg/L, followed by Kaliachak-2 with arsenic level 0.1923, Kaliachak-3 with arsenic level 0.1755 and English Bazar with arsenic level 0.1324. The arsenious belt lies mainly within the Older terrace (T₁). The very recent flood plain deposits of silvery white, fine sands lying very close to the Ganga River margin do not contain significant amounts of As. Elevated As-concentration in the ground water was observed in alluvial sands, grayish white to brownish in color and occurring away from the Ganga margin. The Oldest terrace (T2) further away from the Ganga margin (e.g. English Bazar) and Barind surface contains less arsenic. Barind surface acts as a hard capping with ferruginous sands and lateritic concretions-chocolate, mottled and purple brown in color-occurring northeast of the studied area. Arsenic content of ground water in the same locality within a radius of ∼ 20 m varies within wide limits. Thus, it poses problem to delineate its distribution pattern. Such a patchy occurrence possibly could not be explained satisfactorily solely by geomorphology. Chemical analysis of aquifer clay samples of the cores shows a maximum Ascontent of up to 3 mg/kg, whereas the bulk samples (sandclay mixture) of the cores contain a maximum of 17 mg/kg As-value. Therefore, it is not always true that clay contains elevated As-value.     

煤炭采空区处理的新方法与实例分析

位于乌鲁木齐市南湖路以西的煤炭采空区面积达67 100.5m^2,区内构造从南到北主要由八道湾向斜和七道湾背斜组成,地层产状变化不大。该矿区开采较深,且采空区塌陷区有明显的地下水活动迹象。在对深孔大体积采空区注浆时,比较各种常见注浆治理方法,均存在不同的制约因素,故决定采用灌浆爆破压密法对采空区进行压实加固。经现场爆破试验,该区重复爆破次数在3～5次左右。灌浆爆破压密处理后,对不同土层进行取样对比分析,得到其相应密度（增加）及空隙比（减少）的变化分别为：杂填土14.1%,-7.9%;素填土5.9%,-3.3%;塌落煤层7.8%,-7.7%。根据压缩数据及现场测量,处理后的土体沉降2～4m,部分空体地段的沉降量达10～20m,治理效果明显。     

Climate changing characteristics of Zhangye City in Heihe River basin during 1968–2005

At present, researches on climate change of the Heihe River basin mainly focus on the relationship between basin climate change and regional water resources, regional desertification and dynamic climatic seasons of sandstorm, but less on climate change of oasis region, where there are more intense and frequent human activities. Based on data of precipitation, temperature, strong wind and dust events frequencies obtained from the six meteorological stations of Zhangye region in Heihe River basin, the features of climate change during 1968–2005 were carefully studied. Results show that the regional temperature rise rate exceeded the average level of China. The annual precipitation changed a little, but the precipitation had a slowly increasing trend in spring and winter. Frequencies of strong wind and sandstorm days show obviously descending trends, which had a close correlation with the regional temperature rise and the precipitation increase in spring and winter. Meanwhile, further human economic activities and exploitations to the oasis in the inland valley of arid regions also affected the climate change of this region, which has a sensitive and fragile eco-environment. __________ Translated from Journal of Desert Research, 2007, 27(6): 1048–1054 [译自: 中国沙漠]     

Rock magnetic record of Cenozoic lake sediments from the Linxia basin and aridification of the Asian inland

High resolution research of rock magnetic records and quartz sands from the Maogou Section in the Linxia basin reveals that after a relatively stable environment between 13.07 Ma and 8.6 Ma, the basin was gradually influxed by eolian dusts at about 8.6 Ma, with two rapid increases at about 6.4 Ma and 5.3 Ma, respectively. The study suggests that drying of northwest China began at 8.6 Ma and strengthened rapidly at about 6.4 Ma and 5.3 Ma. __________ Translated from Marine geology & Quaternary geology, 2007, 27(4): 103–110 [译自: 海洋地质与第四纪地质]