Concentrations of rare earth elements in topsoil from East China

Fifty topsoil samples collected from 12 different regions of East China have been analyzed for rare earth elements (REEs). The average REE concentrations of the 50 topsoil samples are much higher than world average and are characterized by LREE-enrichment, HREE-depletion, Eu-depletion and Ce-enrichment. However, the REE concentration is not strongly affected by the climate of the sampling site; it is controlled mainly by parent materials. The plot of Ce/Eu against Eu/Sm is proved to be useful to distinguish different parent materials of topsoil. Each element in the 50 topsoil has a good correlation with its neighboring element. Seven of the 13 values are above 0.987.     

A nonstationary nocturnal drainage flow model

The evolution and structure of the steady state of an idealized nocturnal drainage flow over a large uniformly-sloping surface are studied using a nonstationary model with a height-dependent eddy diffusivity profile and a specified surface cooling rate. The predicted mean velocity and temperature profiles are compared with Prandtl's stationary analytical solutions based on the assumption of a constant eddy diffusivity in the drainage layer. The effects of important physical parameters, such as the slope angle, surface cooling, atmospheric stability, and surface roughness, on the steady drainage flow are investigated.Affiliated with Oak Ridge Associated Universities (ORAU).     

Groundwater potential index in a crystalline terrain using remote sensing data

Demand for groundwater for drinking, agricultural and industrial purposes has increased due to uncertainty in the surface water supply. Agriculture is the main occupation of the rural people in Guntur district, Andhra Pradesh, India. Development of groundwater in the district is very less, indicating a lot of scope for further development of groundwater resources. However, assessment of groundwater conditions, particularly in a crystalline terrain, is a complex task because of variations in weathering and fracturing zones from place to place. Systematic studies for evaluation of groundwater potential zones have been carried out in a crystalline terrain of the district. Information on soils, geological formations and groundwater conditions is collected during the hydrogeological survey. Topographical and drainage conditions are derived from the Survey of India topographical maps. Geomorphological units and associated landform features inferred and delineated from the Indian remote sensing satellite imagery (IRS ID LISS III FCC) are moderately buried pediplain (BPM), shallow buried pediplain (BPS), valley fills (VF), structural hill (SH), residual hills (RH), lineaments and land use/land cover. A groundwater potential index (GPI) is computed for relative evaluation of groundwater potential zones in the study area by integrating all the related factors of occurrence and movement of groundwater resources. Accordingly, the landforms, BPM, BPS, VF, SH and RH, of the area are categorized as very good groundwater potential zone, good to moderate groundwater potential zone, moderate to poor groundwater potential zone, poor to very poor groundwater potential zone and very poor groundwater potential zone, respectively, for development and utilization of both groundwater and surface water resources for eliminating water scarcity. This study could help to improve the agrarian economy for better living conditions of the rural people. Taking the total weight-score of the GPI into account, a generalized classification of groundwater potential zones is evaluated for a quick assessment of the occurrence of groundwater resources on regional scale.     

U–Pb zircon geochronology of ferrodiorites and quartz diorites from the Turkel Anorthosite Complex: a Neoarchaean convergent margin in eastern India

The Turkel anorthosite Complex (TAC) in the Eastern Ghats Belt in India is composed of anorthosites and leuconorites at the centre and ferrodiorites and quartz diorites at the periphery. Here we report whole‐rock geochemistry, and zircon U–Pb data and REE geochemistry from a co‐spatial ferrodiorite and two quartz diorites from the TAC. The diorites have low abundance of High Field Strength Elements (HFSE) and REE, exhibit a flat chondrite‐normalized pattern with slight LREE enrichment and negligible or no Eu anomaly. Our results show weighted mean ²⁰⁷Pb/²⁰⁶Pb ages of 2433 ± 33 Ma for the ferrodiorite. Two quartz diorite samples from Turkel yield mean²⁰⁷Pb/²⁰⁶Pb ages of 2419 ± 32 Ma and 2505 ± 31 Ma. The zircons from all the analysed samples show high REE contents, prominent HREE enrichment and a conspicuous positive Eu anomaly, suggesting a common magmatic source. The prominent Neoarchaean to early Palaeoproterozoic magmatic ages from the anorthosite complex deviate from the late Neoproterozoic ages reported from other anorthosite suites in the Eastern Ghats Belt, and suggest an active convergent margin along SE India during Archaean–Proterozoic transition. Copyright © 2014 John Wiley & Sons, Ltd.     

2007年9-11月T213与ECMWF及日本模式中期预报性能检验

2007年9-11月冷空气频繁,气温变幅大,热带气旋活跃,给中期天气预报增加了一定的难度.为积累预报经验,提高中期预报准确率,对9-11月T213模式96小时预报产品进行了天气学检验,并与ECMWF、日本模式进行对比分析.结果表明,T213、ECMWF和日本模式对亚洲中高纬大气环流调整具有较好的中期预报性能,对转折性、灾害性天气的预报有较强指示意义.综合来看,ECMWF对天气系统和要素的预报误差最小,T213模式误差最大,日本模式温度预报性能与ECMWF相当.对0713号台风登陆前的位置和移速,ECMWF预报较为准确,T213模式对台风登陆前移速预报偏慢,对台风登陆后的位置预报偏差最小,日本模式对台风位置和强度预报较为失败.     

Benthic fluxes in a tropical Estuary and their role in the ecosystem

In-situ measurements of benthic fluxes of oxygen and nutrients were made in the subtidal region of the Mandovi estuary during premonsoon and monsoon seasons to understand the role of sediment–water exchange processes in the estuarine ecosystem. The Mandovi estuary is a shallow, highly dynamic, macrotidal estuary which experiences marine condition in the premonsoon season and nearly fresh water condition in the monsoon season. The benthic flux of nutrients exhibited strong seasonality, being higher in the premonsoon compared to the monsoon season which explains the higher ecosystem productivity in the dry season in spite of negligible riverine nutrient input. NH₄⁺ was the major form of released N comprising 70–100% of DIN flux. The benthic respiration rate varied from −98.91 to −35.13 mmol m⁻² d⁻¹, NH₄⁺ flux from 5.15 to 0.836 mmol m⁻² d⁻¹, NO₃⁻ + NO₂⁻ from 0.06 to −1.06 mmol m⁻² d⁻¹, DIP from 0.12 to 0.23 mmol m⁻² d⁻¹ and SiO₄⁴⁻ from 5.78 to 0.41 mmol m⁻² d⁻¹ between premonsoon to monsoon period. The estuarine sediment acted as a net source of DIN in the premonsoon season, but changed to a net sink in the monsoon season. Variation in salinity seemed to control NH₄⁺ flux considerably. Macrofaunal activities, especially bioturbation, enhanced the fluxes 2–25 times. The estuarine sediment was observed to be a huge reservoir of NH₄⁺, PO₄³⁻ and SiO₄⁴⁻ and acted as a net sink of combined N because of the high rate of benthic denitrification as it could remove 22% of riverine DIN influx thereby protecting the eco system from eutrophication and consequent degradation. The estuarine sediment was responsible for ∼30–50% of the total community respiration in the estuary. The benthic supply of DIN, PO₄³⁻ and SiO₄⁴⁻ can potentially meet 49%, 25% and 55% of algal N, P and Si demand, respectively, in the estuary. Based on these observations we hypothesize that it is mainly benthic NH₄⁺ efflux that sustains high estuarine productivity in the NO₃⁻ depleted dry season.     

Injected radiotracer techniques in hydrology

Radioactive tracers which have several advantages over conventional tracers made significant contributions to the development of the injected tracer method in hydrology. A review of the nuclear and the physico-chemical characteristics of the possible radiotracer compounds leads us to conclude that the most effective groundwater tracers are tritiated water (HTO),⁸²Br⁻ and⁵⁸Co or⁶⁰Co as a hexacyanocobaltate complex. A discussion of the various case studies in India and abroad covering the three groups of applications mentioned helps us to conclude that well established radiotracer methods with associated interpretational techniques are available for many short range studies in surface and subsurface hydrology.     

论长英质隐爆角砾岩的气热流体溶浸成矿机制——以赣南6722铀矿床为例

通过对6722铀矿床地质－地球化学特征及长英质隐爆角砾岩和围岩超微构造研究，结合U，Th等元素溶浸实验结果，得出“隐爆气热流体溶浸成矿富集机制”；来自深部的富含挥发组分（H2O、F、CO2等）的高热安粗岩浆，在早白垩世末（107Ma）沿富城花岗岩体西部蚀变带发育的火山机构中发生隐爆作用，致使围岩发生强烈脆性变形，生成长英质隐爆角砾岩带和震裂花岗岩带；压力、温度降低导致安粗岩浆中挥发组分逸出形成气热流进入稳隐爆裂隙中，并将蚀变花岗岩中的活动性成矿元素（U）浸出转移；成矿物质在物理化学条件（p,t,Eh,pH,化学组分等）急剧变化的部位（长英质隐爆角砾岩及碎裂花岗岩）沉淀富集。     

Regional gravity and magnetic studies over the continental margin of the central west coast of India

Gravity studies over the continental margin of the central west coast of India show a sediment thickness of 2–3 km on the shelf associated with deeper horst and graben structures, of 6 km in the shelf margin basin, and about 1 km in the deep sea. The upward trend in free-air gravity anomaly toward the deep sea region is interpreted as crustal thinning. Model studies indicate a 25-km-thick crust in the shelf region and a minimum of 18 km in the more offshore region. An abrupt magnetic signature change suggests differential basement depths in the shelf region. Major faulting in the region is confirmed in water depths of approximately 100–200 m.