Arsenic Enrichment in the Groundwater of Diphu,Northeast India: Coupled Application of Major Ion Chemistry,Speciation Modeling,and Multivariate Statistical Techniques          下载免费PDF全文

Aparna Das  Manish Kumar 《洁净——土壤、空气、水》2015,43(11):1501-1513

  相似文献   

深埋隧洞即时型岩爆孕育过程的频谱演化特征     

肖亚勋  冯夏庭  陈炳瑞  丰光亮 《岩土力学》2015,36(4):1127-1134

岩爆孕育过程中所记录的微震事件波形本身就包含着丰富的前兆信息。基于深埋隧洞微震波的衰减特征,修正了最大有效振幅,将相对有效振幅和最大有效频率作为频谱分析参数。TBM和钻爆法不同开挖方式下诱发的即时型岩爆孕育过程的频谱演化特征基本一致,有如下特征：（1）无岩爆发生时,每日最大释放能量微震事件频谱对应的相对有效振幅的量级为10-6 m/s及以下,而最大有效频率则多大于300 Hz;（2）中等岩爆发生前,相对有效振幅的量级维持在10-5 m/s,最大有效频率则介于200～300 Hz;（3）强烈岩爆发生前,微震事件对应相对有效振幅的量级增长并保持在10-4 m/s,最大有效频率则基本在200 Hz以下;（4）对于一个完整的即时型岩爆孕育过程,当岩爆发生时,相对有效振幅增至最大,同时最大有效频率降至最低。微震信号的频谱演化特征可为即时型岩爆发生时间及等级的预警提供参考和依据。  相似文献   

大型商场地震应急演练的组织与经验     

程恒瑞  杨坚  余俏宏 《国际地震动态》2015,(4)

介绍了新疆昌吉市汇嘉、隆源、飞马3家大型商场开展地震避险疏散演练的组织策划、培训、内容及流程等情况,探讨了大型商场开展应急演练的经验和存在的问题,指出了大型商场存在的地震安全风险和相应的改进措施,以及对今后演练的意见和建议。  相似文献   

Morphological assessment of reconstructed lowland streams in the Netherlands     

《Advances in water resources》2015

Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Re-meandering is the common practice in restoring these lowland streams. Three reconstructed streams were monitored during the initial two years after construction of a new channel. The monitoring program included morphological surveys, sediment sampling, habitat pattern surveys, and discharge and water level measurements. Adjustments of the longitudinal bed profile formed the main morphological response. These adjustments were most likely caused by a lack of longitudinal connectivity of the streams as a whole, interrupting transport of sediment at locations of weirs and culverts. Bank erosion was observed only in a limited number of channel bends, and was often related to floodplain heterogeneity. Longitudinal channel bed adjustments and bank erosion were mainly caused by exogenous influences. In channel bends, the cross-sectional shape transformed from trapezoidal to the typical asymmetrical shape as found in meandering rivers. This behaviour can be attributed to an autogenous response to the prevailing flow conditions. Due to the prevailing fine sediment characteristics, bed material is readily set in motion and is being transported during the entire year. The existing design principles fail to address the initial morphological development after reconstruction. An evaluation of pre-set targets to realise water depth and flow velocity ranges shows the current procedures to be deficient. Based on this unfavourable evaluation, and the two-dimensional nature of habitat patterns needed to improve the conditions for stream organisms, we recommend to predict morphological developments as part of the design procedures for lowland stream restoration in the Netherlands.  相似文献   

Scattering of water waves by a pair of vertical porous plates     

R. Gayen  Arpita Mondal 《地球物理与天体物理流体动力学》2015,109(5):480-496

  相似文献   

High‐frequency water quality monitoring in an urban catchment: hydrochemical dynamics,primary production and implications for the Water Framework Directive          下载免费PDF全文

Sarah J. Halliday  Richard A. Skeffington  Andrew J. Wade  Michael J. Bowes  Emma Gozzard  Jonathan R. Newman  Matthew Loewenthal  Elizabeth J. Palmer‐Felgate  Helen P. Jarvie 《水文研究》2015,29(15):3388-3407

This paper describes the hydrochemistry of a lowland, urbanised river‐system, The Cut in England, using in situ sub‐daily sampling. The Cut receives effluent discharges from four major sewage treatment works serving around 190 000 people. These discharges consist largely of treated water, originally abstracted from the River Thames and returned via the water supply network, substantially increasing the natural flow. The hourly water quality data were supplemented by weekly manual sampling with laboratory analysis to check the hourly data and measure further determinands. Mean phosphorus and nitrate concentrations were very high, breaching standards set by EU legislation. Although 56% of the catchment area is agricultural, the hydrochemical dynamics were significantly impacted by effluent discharges which accounted for approximately 50% of the annual P catchment input loads and, on average, 59% of river flow at the monitoring point. Diurnal dissolved oxygen data demonstrated high in‐stream productivity. From a comparison of high frequency and conventional monitoring data, it is inferred that much of the primary production was dominated by benthic algae, largely diatoms. Despite the high productivity and nutrient concentrations, the river water did not become anoxic, and major phytoplankton blooms were not observed. The strong diurnal and annual variation observed showed that assessments of water quality made under the Water Framework Directive (WFD) are sensitive to the time and season of sampling. It is recommended that specific sampling time windows be specified for each determinand, and that WFD targets should be applied in combination to help identify periods of greatest ecological risk. © 2015 The Authors. Hydrological Processes published by John Wiley & Sons Ltd.  相似文献   

三山岛断裂在海域北延位置的确定及成矿预测   总被引：1，自引：0，他引：1  

王金辉  田京祥 《地质学报》2017,91(12):2771-2780

胶东金矿集中区是中国最重要的黄金基地,三山岛金矿带位于该金矿集中区之胶西北成矿区的西部,近年来深部和海域隐伏区找矿取得重大突破。作为该区域重要的赋矿构造,三山岛断裂带进入海域后向两端延伸位置未能确定。为了查明三山岛断裂在南北两端进入海域后的延展位置,使用海底重力仪开展了海上大比例尺重力测量工作,对其位置进行了推断。在布伽重力异常图上,三山岛断裂表现为规模大、水平变化率大的重力梯级带,在平面上呈"S"形,向北由三山岛金矿延伸入海,向南从新立西延入渤海,跨海后经仓上、潘家屋子东延入渤海。为了确定三山岛断裂带向北东方向穿过三山岛北部海域超大型金矿床后的延展位置,根据重力异常推断的三山岛断裂北延位置,结合该金成矿带地质矿产特征,部署钻孔进行验证。钻孔内主要岩性有中细粒(含黑云母)二长花岗岩、钾化二长花岗岩、碎裂状二长花岗岩、绢英岩化花岗岩等,暗色脉岩有辉长岩及少量黑云母闪长岩、闪长玢岩等,其中暗色矿物黑云母等略具定向排列,脉岩均发生不同程度的蚀变。构造蚀变(矿化)带宽206.25m(876.59~1082.84m),与上盘围岩分界较为清楚,与下盘围岩呈渐变关系,圈定7层矿体,累计厚度28.3m,最厚的单层矿体视厚度16.06m。钻孔位置位于重力梯度变化宽缓的"鼻状区",且空间位置符合等距分布、对应产出、分段富集等分布规律,钻孔中见到多为黄铜矿化、方铅矿、黄铁矿等多金属硫化物矿化,为典型的第一矿集群特征,可以确定该地区继三山岛北部海域470吨超大型金矿发现之后,其北部区域又出现一个很有找矿前景的靶区。  相似文献   

Utilization of sodium waterglass from sugar cane bagasse ash as a new alternative hardener for producing metakaolin-based geopolymer cement     

《Chemie der Erde / Geochemistry》2017,77(2):257-266

Sugar cane bagasse ash from SOSUCAM company in Cameroon was used to synthesize sodium waterglass as a new alternative hardener. The new hardener was used to prepare metakaolin-based geopolymer cements. The compressive strength of the resulting geopolymer cement cured at room temperature for 28 days was 32.9 MPa. Samples soaked for 28 days in water in parallel experiments revealed a strength of 31.4 MPa. This shows that exposure of water does not lead to any weakening. The value of water absorption was 7.1% in the water-soaked cements, indicating the presence of fewer pores and voids than in the dry cements. However, in SEM micrographs, the microstructure of geopolymer cement appears rather homogeneous and compact without any change by water soaking. It can thus be concluded that sodium waterglass from sugar cane bagasse ash can be used as an alternative hardener or reactive ingredient for producing geopolymer cement with a high degree of cross-linking geopolymer framework. The use of this low-value silica-rich waste for producing sodium waterglass results in environmental benefits including a significant reduction of CO₂ emission and energy consumption compared to the production of commercial sodium waterglass.  相似文献   

Hydrogeochemical characteristics of mine water in the Harz Mountains,Germany     

《Chemie der Erde / Geochemistry》2017,77(4):614-624

Water samples (springs, creeks, mine adits) from different former mining districts of the Harz Mountains and the nearby Kupferschiefer (copper shale) basin of Sangerhausen were analysed for major ions and trace metals. Due to more intensive water rock interactions including the ore minerals, the mine water concentrations of main components and trace metals are generally higher compared to non mining affected surface waters of the mountain range. Furthermore, the content of major ions in mine water is enriched by mixing processes with saline waters from Permian layers in the Kupferschiefer district and at the deeper levels of the mines in the Upper Harz Mountains. The waters of the different mining districts can be distinguished by trace metal occurrences and concentrations derived from the different ore bodies. Water from the Kupferschiefer mines shows the highest Na, Cl, Cu, Mo and U concentrations, whereas a combination of elevated As and Se concentrations is typical for most of the samples from the mines around St. Andreasberg. However, there are exceptions, and some water samples of all the investigated mining districts do not follow these general trends. Despite the influence of mining activities and ore mineralisation, hydrochemical effects due to rain water dilution can be seen in most of the waters. According to the elevation of the mountain range, higher precipitation rates decrease the ion concentrations in the waters of springs, creeks and mine adits.  相似文献   

Framing community entitlements to water in Accra,Ghana: A complex reality     

《Geoforum》2017

Entitlements are generally defined as the commodities/resources (material and non-material), through which one can establish ownership or command access to resources. Applying this analytic to a case study of everyday water access in Accra, Ghana, we evaluate community water entitlements in two low-income communities with different locational and socio-cultural characteristics. We also evaluate how different entitlements to water map against variable dimensions of vulnerability. The study uses a mixed methods approach including a 200 household survey, focus groups with community members, and semi-structured interviews with local opinion leaders. Our results indicate that in both study communities, an entitlements approach provides a significantly richer portrait of water access beyond availability of piped water infrastructure. Among other factors that are important to everyday negotiations and entitlements related to water access, it is important to consider familial and kin networks, water storing options available to households and vendors, the distance and waiting time to fetch water, and local leaders' perceptions of water issues, particularly how these compare with broader citizen understandings. In this way, an entitlements approach broadens the perspective beyond infrastructural endowments (e.g. piped water), to include a range of other socioeconomic, socio-cultural and local institutional characteristics. Drawing on the empirical examples, as well as related conceptual debates, the study questions how water access is defined, and how water governance processes might benefit from a broader understanding of entitlements, as well as links to differentiated vulnerabilities, notably in times of water-related stress or scarcity.  相似文献