Assessing variability of water quality in a groundwater-fed perennial lake of Kashmir Himalayas using linear geostatistics

This paper presents a study on Manasbal lake, which is one of the high altitude lakes in the Kashmir Valley, India. Eighteen water samples were analysed for major ions and trace elements to assess the variability of water quality of the lake for various purposes. Geostatistics, the theory of regionalized variables, was then used to enhance the dataset and estimate some missing spatial values. Results indicated that the concentration of major ions in the water samples in winter was higher than in summer. The scatter diagrams suggested the dominance of alkaline earths over the alkali elements. Three types of water were identified in the lake that are referred to as Ca–HCO₃, Mg–HCO₃ and hybrid types. The lake water was found to be controlled by rock–water interaction with carbonate lithology as a dominant source of the solutes. The major (Ca^2 +, Mg^2 +, Na⁺, K⁺, NO₃ and HCO₃^-{\rm{HCO}}_{3}^{-}, CO₃ and Cl) and trace elements of the lake water were within the World Health Organization standards, therefore the lake water was considered chemically safe for drinking purposes. Although NO₃ concentration (ranging from 1.72 to 2 mg/L), is within the permissible limit and not very alarming, the gradually increasing trend is not acceptable. It is however, important to guard its spatio-temporal variability as the water is used for domestic as well as agricultural purposes. This study is significant as hydrogeological information on such high altitude lakes in India is scanty.     

Groundwater flow into underground openings in fractured crystalline rocks: an interpretation based on long channels

Rethinking an old tracer experiment in fractured crystalline rock suggests a concept of groundwater flow in sparse networks of long channels that is supported by results from an innovative lattice network model. The model, HyperConv, can vary the mean length of ‘strings’ of connected bonds, and the gaps between them, using two independent probability functions. It is found that networks of long channels are able to percolate at lower values of (bond) density than networks of short channels. A general relationship between mean channel length, mean gap length and probability of percolation has been developed which incorporates the well-established result for ‘classical’ lattice network models as a special case. Using parameters appropriate to a 4-m diameter drift located 360 m below surface at Stripa Mine Underground Research Laboratory in Sweden, HyperConv is able to reproduce values of apparent positive skin, as observed in the so-called Macropermeability Experiment, but only when mean channel length exceeds 10 m. This implies that such channel systems must cross many fracture intersections without bifurcating. A general relationship in terms of flow dimension is suggested. Some initial investigations using HyperConv show that the commonly observed feature, ‘compartmentalization’, only occurs when channel density is just above the percolation threshold. Such compartments have been observed at Kamaishi Experimental Mine (Japan) implying a sparse flow network. It is suggested that compartments and skin are observable in the field, indicate sparse channel systems, and could form part of site characterization for deep nuclear waste repositories.     

Theoretical calculation of Martian airmass

Analysis of spectroscopic observations of Mars requires values of the effective Martian airmass to obtain true abundances. Semi-arbitrary assumptions for the airmass correction have been used in most of the past publications on the subject. We have computed detailed values corresponding to specified slits superimposed on the disk of the planet, giving useful output in the form of curves presenting the average airmass for different regions of the planet and various conditions of planet diameter, seeing and phase angle.     

A direction-sensitive underwater blast detector and its application for managing blast fishing

Little is known about the spatial and temporal distribution of blast fishing which hampers enforcement against this activity. We have demonstrated that a triangular array of hydrophones 1 m apart is capable of detecting blast events whilst effectively rejecting other sources of underwater noise such as snapping shrimp and nearby boat propellers. A total of 13 blasts were recorded in Sepangor bay, North of Kota Kinabalu, Sabah, Malaysia from 7th to 15th July 2002 at distances estimated to be up to 20 km, with a directional uncertainty of 0.2 degrees . With such precision, a network of similar hydrophone arrays has potential to locate individual blast events by triangulation to within 30 m at a range of 10 km.     

Acoustic characteristics of fish bombing: potential to develop an automated blast detector

The use of explosives to catch fish has caused extensive damage to coral reefs throughout Southeast Asia, but the frequency with which they are used is largely unknown. The aim of this work is to develop a detection system capable of distinguishing underwater explosions from background noise, and locating their origin by triangulation. Blast signals have been recorded over a range of distances and the key features that differentiate them from background noise have been determined. For small charges the effective range of such a detector is more than 12 km and may extend up to 50 km depending on the mass of the charges being used. Such a system would help to determine the scale of the problem, identify areas at greatest risk and quantify the effectiveness of management intervention designed to control destructive fishing practices. It may assist with fisheries enforcement in some areas.     

Deterministic Approach for the Seismic Microzonation of Bucharest

— The mapping of the seismic ground motion in Bucharest, due to the strong Vrancea earthquakes is carried out using a complex hybrid waveform modeling method which combines the modal summation technique, valid for laterally homogeneous anelastic media, with finite-differences technique, and optimizes the advantages of both methods. For recent earthquakes, it is possible to validate the modeling by comparing the synthetic seismograms with the records. We consider for our computations the frequency range from 0.05 to 1.0 Hz and control the synthetic signals against the accelerograms of the Magurele station, low-pass filtered with a cut-off frequency of 1.0 Hz of the 3 last major strong (M_w > 6) Vrancea earthquakes. Using the hybrid method with a double-couple seismic source approximation, scaled for the source dimensions and relatively simple regional (bedrock) and local structure models, we succeeded in reproducing the recorded ground motion in Bucharest at a satisfactory level for seismic engineering. Extending the modeling to the entire territory of the Bucharest area, we construct a new seismic microzonation map, where five different zones are identified by their characteristic response spectra.     

松辽盆地早白垩世火山岩地球化学特征及其构造意义

松辽盆地早白垩世发育基性岩类的橄榄玄武岩、玄武岩,中性岩类的玄武安山岩、安山岩、粗安岩,酸性岩类的粗面岩、粗面英安岩、英安岩和流纹岩。早白垩世火山岩都具有大离子亲石元素(LILE)、轻稀土元素(LREE)相对富集的特征,并具有较低的(~(87)Sr/~(86)Sr)_i值和较高的(~(143)Nd/~(144)Nd)_i值。基性岩类Ce/Nb=1.92～8.31,Th/Nb=0.08～0.44,(~(87)Sr/~(86)Sr)_i=0.7031～0.7047,ε_(Nd)(t)=+1.7～+5.2;中性岩类Ce/Nb=3.70～15.80,Th/Nb=0.34～2.58,(~(87)Sr/~(86)Sr)_i=0.7040～0.7054,ε_(Nd)(t)=0～+3.0;酸性岩类Ce/Nb=4.29～15.80,Th/Nb=0.11～1.02,(~(87)Sr/~(86)Sr)_i=0.7038～0.7066,ε_(Nd)(t)=+1.0～+3.3。基性岩类岩浆主要来自被富集了的亏损地幔源的部分熔融,受混染程度很小;中性岩类岩浆源于年轻地壳组分被来自亏损地幔岩浆的再次部分熔融;酸性岩类浆岩可能主要来自源于亏损地幔的初生地壳部分熔融,并受到了上地壳的混染。晚侏罗世-早白垩世,由于蒙古-鄂霍次克洋关闭引发强烈的挤压造山后,发生的岩石圈拆沉作用致使来自亏损地幔的岩浆熔融上涌导致岩石圈主动伸展拉张,地表则表现出大规模的裂谷断陷作用和大范围的火山活动。这个阶段的伸展拉张以主动拉张为主。     

现代海底烟囱中流体包裹体的研究

大洋中脊的海底块状硫化物矿床是当前地球科学的一个热点。因为他不仅具有经济效益,而且可以直接观测到这些矿床的形成过程。这些矿床均有许多黑烟囱和白烟囱。在这些烟囱中成矿流体不断地流过,并同时沉淀出Cu,Pb,Zn硫化物和脉石矿物。本研究的样品是取自北纬21°N的太平洋洋脊中现代大洋海底的Zn(Cu)型硫化物烟囱。对这些烟囱的矿物共生组合进行研究发现其矿物组合相当简单,分硫化物和脉石矿物两种。硫化物中以其含量多少排列为闪锌矿,黄铁矿,黄铜矿和磁黄铁矿。脉石矿物以硬石膏为主,见少量重晶石。在烟囱中这些硫化物和脉石矿物的分布是有分带性的。从外到内为硬石膏带,黄铁矿带,闪锌矿带。闪锌矿带向里可见到少量黄铜矿和磁黄铜矿,及硬石膏,但它们尚未构成一个带。烟囱的中心常常是空的,因为是原来的热液通道。 发现两类流体包裹体:一类为水溶液相包裹体。另一类为CH_4的包裹体。其均一温度是从180～265℃。最外面的硬石膏带,均一温度从180～245℃(平均212℃)。黄铁矿带均一温度从185～260℃(平均218℃)。闪锌矿带均一温度从190～265℃(平均229℃)。从平均的均一温度看似乎从边上到中心从212—218—229℃向上升,说明一个趋势,中间的温度较高,边上的较低。成矿溶液的盐度与海水相差不大,但略大於海水     

On the abundance of NO2 in the Martian atmosphere

Spectrophotometric scans of Mars and the Moon in the region 4000–5000 Å were obtained and ratioed. No evidence of any absorption greater than 3% is visible in the Martian spectrum. Using our own laboratory spectra of NO₂ as well as the published work of Hall and Blacet (1952) we confirm Marshall's (1964) upper limit of 8 μm atmospheres (0.0008 cm amagat) for the abundance of NO₂ in the atmosphere of Mars.     

Laboratory Experiments and Grain Based Discrete Element Numerical Simulations Investigating the Thermo-Mechanical Behaviour of Sandstone

Geotechnical and Geological Engineering - Thermo-mechanical loading can occur in numerous engineering geological environments, from both natural and anthropogenic sources. Different minerals and...