Spatial control of groundwater contamination,using principal component analysis

A study on the geochemistry of groundwater was carried out in a river basin of Andhra Pradesh to probe into the spatial controlling processes of groundwater contamination, using principal component analysis (PCA). The PCA transforms the chemical variables, pH, EC, Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO \(_3^- \) , Cl^?, SO \(_4^{2-} \) , NO \(_3^-\) and F^?, into two orthogonal principal components (PC1 and PC2), accounting for 75% of the total variance of the data matrix. PC1 has high positive loadings of EC, Na⁺, Cl^?, SO \(_4^{2-} \) , Mg²⁺ and Ca²⁺, representing a salinity controlled process of geogenic (mineral dissolution, ion exchange, and evaporation), anthropogenic (agricultural activities and domestic wastewaters), and marine (marine clay) origin. The PC2 loadings are highly positive for HCO \(_3^- \) , F^?, pH and NO \(_3^- \) , attributing to the alkalinity and pollution controlled processes of geogenic and anthropogenic origins. The PC scores reflect the change of groundwater quality of geogenic origin from upstream to downstream area with an increase in concentration of chemical variables, which is due to anthropogenic and marine origins with varying topography, soil type, depth of water levels, and water usage. Thus, the groundwater quality shows a variation of chemical facies from Na⁺ > Ca²⁺ > Mg²⁺ > K⁺: HCO \(_3^- \) > Cl^? > SO \(_4^{2-}>\) NO \(_3^- \) > F^?at high topography to Na⁺ > Mg²⁺ > Ca²⁺ > K⁺: Cl^? > HCO \(_3^- \) > SO \(_4^{2-}>\) NO \(_3^- \) > F^? at low topography. With PCA, an effective tool for the spatial controlling processes of groundwater contamination, a subset of explored wells is indexed for continuous monitoring to optimize the expensive effort.     

On the crosscorrelation between drought indices and solar activity

Summary Crosscorrelation structure between solar activity and drought indices is investigated by analyzing the cross correlation of the residual time series of solar activity and drought indices. Double Sunspot Cycle, Zürich Sunspot number, Palmer's Drought Index and Drought Area Index data are used in the study. White residual series derived from the observed data series by using valid time series models are used for the crosscorrelation analysis. Weak correlations between solar activity and drought area indices are inferred. The lags of significant correlation appear to vary for the different time series used in the study.With 3 Figures     

Charnockite genesis across the Archaean–Proterozoic terrane boundary in the South Indian Granulite Terrain: Constraints from major–trace element geochemistry and Sr–Nd isotopic systematics

Major, trace element compositions and Sr–Nd isotopic characteristics of charnockitic gneisses from the Southern Granulite Terrain (SGT), South India are presented. The study region encompasses the central segment of the Cauvery Shear Zone system (CSZ) and regions within the Madurai Block (MB) immediately south of it (designated here as the CSZ/MB and MB domains). Differences in the compositions and source characteristics between charnockitic rocks of the CSZ vis-à-vis those of the CSZ/MB and MB regions are highlighted. Foremost, the charnockites and enderbites of the CSZ show highly fractionated REE patterns with positive Eu-anomalies, depleted HREE, Y and near chondritic εNd₀ and initial-⁸⁷Sr/⁸⁶Sr at ca. 2.5 Ga, consistent with hydrous partial melting of amphibolitic crust with residual garnet and hornblende for the parental melts. By contrast, modeled at ca. 1.8 Ga and 0.8 Ga, the CSZ/MB and MB charnockitic rocks, which show a wider range of Ti and P, relatively lower degree of HREE depletion, commonly negative Eu-anomalies and undepleted Y, present clear evidence for involvement of Archaean crustal components in sources of their magmatic protoliths. There is also evidence for significant intracrustal melting processes within a thickened crust at elevated temperatures between 800 and 1000 °C. Implications to the controversial Archaean–Neoproterozoic terrane boundary problem of the SGT are discussed.     

Interannual variability of Kelvin wave propagation in the wave guides of the equatorial Indian Ocean,the coastal Bay of Bengal and the southeastern Arabian Sea during 1993–2006

The observed variability of the Kelvin waves and their propagation in the equatorial wave guide of the Indian Ocean and in the coastal wave guides of the Bay of Bengal (BoB) and the southeastern Arabian Sea (AS) on seasonal to interannual time scales during years 1993–2006 is examined utilizing all the available satellite and in-situ measurements. The Kelvin wave regime inferred from the satellite-derived sea surface height anomalies (SSHA) shows a distinct annual cycle composed of two pairs of alternate upwelling (first one occurring during January–March and the second one occurring during August–September) and downwelling (first one occurring during April–June and the second one occurring during October–December) Kelvin waves that propagate eastward along the equator and hit the Sumatra coast and bifurcate. The northern branches propagate counterclockwise over varied distances along the coastal wave guide of the BoB. The potential mechanisms that contribute to the mid-way termination of the first upwelling and the first downwelling Kelvin waves in the wave guide of the BoB are hypothesized. The second downwelling Kelvin wave alone reaches the southeastern AS, and it shows large interannual variability caused primarily by similar variability in the equatorial westerly winds during boreal fall. The westward propagating downwelling Rossby waves triggered by the second downwelling Kelvin wave off the eastern rim of the BoB also shows large interannual variability in the near surface thermal structure derived from SODA analysis. The strength of the equatorial westerlies driven by the east–west gradient of the heat sources in the troposphere appears to be a critical factor in determining the observed interannual variability of the second downwelling Kelvin wave in the wave guides of the equatorial Indian Ocean, the coastal BoB, and the southeastern AS.     

滇西菲红超基性岩风化壳铂族元素地球化学行为

近年来在世界不同地区进行了风化过程中铂族元素的地球化学行为研究。作为中国西南部的第一个实例,本文研究了云南西部菲红超基性岩体上发育的红土风化剖面。矿物学和微量元素地球化学研究证明该风化壳是超基性岩风化的结果。文中详细讨论了风化壳的地质、矿物学、红土化和铂族元素地球化学特征。结果表明,风化壳的红土化程度不高,仍处于红色粘土阶段;风化壳上部的表层土壤带和铁质粘土带中铂族元素总量至少富集了3．57－7．87倍,其中Ru和Pd的富集程度较大,Ir的富集程度中等,Pt和Rh的富集程度较小,使得铂族元素的配分模式由基岩的Pt富集型转变为风化壳的Ru-Pt富集型,证明红土化过程中铂族元素发生了分异。     

川滇地区电离层多参量异常监测系统的设计与实现

介绍了川滇地区电离层多参量异常监测系统的设计思路与功能实现,并将该系统应用于2019年6月17日四川长宁MS6.0地震的监测试验.结果表明:该系统实现了全球和中国区域垂直总电子含量VTEC、站点VTEC和F2层临界频率foF2异常变化的实时监测,有助于开展示范性地震电离层异常监测工作,其图形及数据结果可为地震-电离层异...     

Application of data assimilation for improving forecast of water levels and residual currents in Singapore regional waters

Hydrodynamic models are commonly used for predicting water levels and currents in the deep ocean, ocean margins and shelf seas. Their accuracy is typically limited by factors, such as the complexity of the coastal geometry and bathymetry, plus the uncertainty in the flow forcing (deep ocean tide, winds and pressure). In Southeast Asian waters with its strongly hydrodynamic characteristics, the lack of detailed marine observations (bathymetry and tides) for model validation is an additional factor limiting flow representation. This paper deals with the application of ensemble Kalman filter (EnKF)-based data assimilation with the purpose of improving the deterministic model forecast. The efficacy of the EnKF is analysed via a twin experiment conducted with the 2D barotropic Singapore regional model. The results show that the applied data assimilation can improve the forecasts significantly in this complex flow regime.     

Ultraviolet variability of HD 62001 – The central star of the missing nebula V-V 1-7

IUE observations of HD 62001 do not confirm the ultraviolet variability of 0.15 mag seen from the ANS observations. These intriguing variations in ANS observations seem to be caused by a nearby (∼ 70 arcsec away) B star getting in and out of the field of view of the telescope, which had a jitter of 20 arcsec. There seems to be no evidence for the presence of a hot companion, either from the energy distribution or from UV variability. However, visual light variations are present. This, coupled with the radial velocity variations, indicates a binary nature probably of Algol type. Based on observations obtained with IUE satellite at the Villafranca Satellite Tracking Station of the European Space Agency.     

Evidence for short term changes in the intensity and spectrum of hard X-rays from Cyg X-1

The paper presents experimental evidence for the existence of fast intensity fluctuations with time scales of the order of a minute in the X-ray emission from Cyg X-1 at energies greater than 29 keV. Spectral variations over time intervals of 20–25 min are also observed in the same energy range. Whereas, similar intensity and spectral fluctuations have been reported earlier at lower energies the observations presented here is the first evidence for the existence of similar fluctuations at high energies.