广西平桂矿区发现的砷钙铜矿

本砷钙铜矿发现于平桂矿区的岩溶堆积Au、Sn矿体的氧化带。经电子探针分析及湿法化学分析确定其主要成份是Cu、Ca、As,并含H_2O。计算的矿物化学式为(Ca,Mg)(Cu,Fe,Zn)(AsO_4,SiO_4,Al_2O_3)(OH)。单晶X射线分析测得晶胞参数a=7.33A,b=9.12A,c=5.79A,斜方晶系,空间群为P2_12_12_1。     

Interrelationships between atmospheric turbidity,the diffusely reflected visible radiation at the top of the earth's atmosphere and the global solar radiation at the surface

Summary The flux of radiation emerging at the top and bottom of a realistic model of a cloud-free, plane-parallel, vertically inhomogeneous turbid atmosphere has been computed for different values of atmospheric turbidity and surface albedo in 83 unequal spectral intervals over the short-wave or solar radiation (0.285–2.5 m) regime. These computations have been utilized to determine the diffusely reflected radiation at the top of the atmosphere in the spectral interval 0.535–0.7035 m (which covers the visible channels of the radiometers onboard the Geosynchronous Operational Environmental Satellites and the NOAA polar orbiting satellites) and in the spectral interval 0.375–0.7035 m. The total global solar radiation (0.285–2.5 m) reaching the surface has also been determined. Simple linear regression relationships have been established between (i) the reflected radiation at the top and atmospheric turbidity and (ii) between the global radiation at the surface and the reflected radiation at the top. These regression relationships yield coefficients of determination very close to unity. The implications of this strong linear dependence of the reflected radiation on atmospheric turbidity and of the global radiation at the surface on the reflected radiation at the top to satellite-based studies of the feasibility of estimation of the insolation (global radiation) at the surface are briefly mentioned.With 3 Figures     

Longshore grain size trends in the Kakinada-Mulapeta Beach,east coast of India

Shore-normal and shore-parallel variations in grain size statistics of beach sand have been studied over a period of one year along the Kakinada-Mulapeta coast. The southern beaches of this coast have been accretionary while the northern ones erosional since 125 years. The grain size gradings, beach and nearshore processes help in identifying (i) the Groins-fishing harbour beach influenced predominantly by the tidal regime. (ii) the Mulapeta-Vakalapudi beach influenced by refracted wave regime and (iii) the Vakalapudi-fishing harbour beach affected by both wave and tidal regimes at relatively subdued levels.     

Mass movement studies in Kosi catchment,mepal — A semi quantitative approach using aerial photographs

An area of about 5000 sq. km. in the upper parts of river basin of Sun Kosi falling in Nepal has been studied using medium and small scale aerial photographs of two different dates. The temporal variations in relation to mass movements that occur in the study area have been demarcated. The areas which have undergone increased erosion by slope failure and gully erosion over a period of 22 years are evaluated. An attempt has been made to quantify the increase in area of mass movement taking the advantage of three dimensional model of terrain as seen in the aerial photos.     

Sea surface temperature variability over North Indian Ocean — A study of two contrasting monsoon seasons

Using the satellite derived sea surface temperature (SST) data for 1979 (bad monsoon) and 1983 (good monsoon), the SST variability for two contrasting monsoon seasons is studied. The study indicates that large negative anomalies off the Somali and Arabian coasts are associated with good monsoon rainfall over India. The strong monsoonal cooling in these regions can be attributed to strong low level winds and intense upwelling. The reappearance of 27°C isotherm off Somali coast in May/June coincides with the onset of southwest monsoon over India. Further, the influence of zonal anomaly of SST off Somalia Coast (SCZASST) and Central Indian Ocean Zonal Anomaly of SST (CIOZASST) with monsoon rainfall over India is brought out. The former is negatively related to the monsoon rainfall over western and central parts of India, whilst CIOZASST is positively related.     

Base metal exploration by gravity surveys in a part of the Cuddapah basin (India)—A case study

A closely spaced gravity survey was conducted in the Chikativaripally area in the Cuddapah basin, Andhra Pradesh, India for base metal exploration. Analysis of the data using two-dimensional prismatic models suggest a doubly plunging folded structure in the area and also its associated mineralization.     

Geomorphic features of a part of Cuddapah and Nellore districts,Andhra Pradesh — Using remote sensing techniques

An area of about 1000 square kilometres in Cuddapah and Nellore districts of Andhra Pradesh is studied to bring out the different landforms and other geomorphic features, their material content and distribution, the processes that have acted and are acting in the evolution of landscape and ultimately to get an idea of the geomorphic history of the area. The data obtained during the present study is mainly through remote sensing-techniques (Landsat image and airphoto interpretation) with field checks. The study area forms a part of southeastern Cuddapah Basin and consists of structurally disturbed and deformed sedimentary sequence of varied lithology. The impor-tant rock types in the area are granites, gneisses, quartzites, shales, phyllites, limestones and dolomites. The area presently comes under semi-arid climatic zone. The different landforms recognised and mapped in the area are hog-back ridges, piedmont fans, valley fills, river built plain, abandoned channels, point bars, ’ V‘ shaped valleys, piedmont zone, colluvial plain, residual hills, besides lineaments.     

Inferred leaf senescence of rice crop and its relationship with grain yield

The possibility of detecting change in green cover of rice crop and its relationship with the grain yield was studied using the spectral data collected by an airborne scanner. The spectral data in the form of difference in vegetation index over a 35 day interval, from the time of flowering, was observed to show good relationship between change of green cover (a measure of degree of senescence) and grain yield.     

Acute Toxicity of Distillery Effluent on a Freshwater Fish and Three Pond Snails

The LC₅₀ for 12… 96 h of a distillery waste water were determined for Lebistes reticulatus, Lymnaea luteola, Lymnaea acuminata and Viviparus bengalensis in the batch experiment with daily exchange of the medium. The sensitivity of the species increases in the given sequence with values of the LC_{50,96 h} of 10.77 to 3.72 % proportion of wastewater in the medium. Compared with this, with values of the LC_{50,48 h} of 14.06… 15.71 % after 48 h of exposure there is no significant difference in sensitivity, whereas after exposure for 12 and 24 h the sensitivity grows in the following order: V. bengalensis, L. acuminata, L. luteola, Lebistes reticulatus. Toxicity is obviously primarily determined by the sulphides; with increasing time of exposure also the suspended matter and other factors act toxically.     

Global temperature changes: relative importance of greenhouse constituents of the atmosphere as calculated with a 1-d radiative-convective model

Most modelling endeavours concerning the CO₂-climate problem address only the question of the climatic response to increasing atmospheric carbon dioxide, while the amounts of other atmospheric gases remain fixed. But associated changes, either climatologically or anthropogenically induced, of minor atmospheric constituents can also be of significance in producing a substantial global warming. We have analysed the climatic response to changes in a number of atmospheric trace gases as they may enhance or counteract CO₂-induced warming if their abundance should change. A comparison of the increase in equilibrium global-mean surface temperature due to plausible changes in the concentration of several trace gases in the atmosphere based on our calculations with a one-dimensional radiative-convective model is presented in this paper. Our results indicate that roughly 35% of global surface warming could be due to changes in trace gases other than CO₂ and water vapour. The possible climatic consequences of the ongoing anthropogenic changes in the minor constituents of the atmosphere are also discussed.