Eddy correlation measurements of CO2, latent heat,and sensible heat fluxes over a crop surface   总被引：14，自引：0，他引：14  

Dean E. Anderson  Shashi B. Verma  Norman J. Rosenberg 《Boundary-Layer Meteorology》1984,29(3):263-272

Eddy correlation equipment was used to measure mass and energy fluxes over a soybean crop. A rapid response CO₂ sensor, a drag anemometer, a Lyman-alpha hygrometer and a fine wire thermocouple were used to sense the fluctuating quantities.Diurnal fluxes of sensible heat, latent heat and CO₂ were calculated from these data. Energy budget closure was obtained by summing the sensible and latent heat fluxes determined by eddy correlation which balanced the sum of net radiation and soil heat flux. Peak daytime CO₂ fluxes were near 1.0 mg m^–2 (ground area) s^–1.The eddy correlation technique was also employed in this study to measure nocturnal CO₂ fluxes caused by respiration from plants, soil, and roots. These CO₂ fluxes ranged from - 0.1 to - 0.25 mg m^–2s^–1.From the data collected over mature soybeans, a relationship between CO₂ flux and photosynthetically active radiation (PAR) was developed. The crop did not appear to be light-saturated at PAR flux densities < 1800 Ei m^–2 s^–1. The light compensation point was found to be about 160 Ei m^–2 s^–1.Published as Paper No. 7402, Journal Series, Nebraska Agricultural Experiment Station. The work reported here was conducted under Nebraska Agricultural Experiment Station Project 27-003 and Regional Research Project 11–33.Post-doctoral Research Associate, Professor and Professor, respectively. Center for Agricultural Meteorology and Climatology, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, NE 68583-0728.  相似文献   

Correlation of magnetic properties with Δ(Sr) of igneous rocks from the northeast Pacific and Gulf of California     

Surendra P. Verma  Subir K. Banerjee 《Physics of the Earth and Planetary Interiors》1982,30(4):291-299

The magnetic properties of basalts and diabases recovered under Legs 63 and 64 of the Deep Sea Drilling Project are summarized. They are first correlated with the measured grain sizes of the opaque minerals and the overall alteration states of the rocks, the latter measured by conventional chemical parameters such as water content, total volatiles content, and Fe₂O₃/FeO ratio. It is shown, however, that the decrease in ⁸⁷Sr/⁸⁶Sr upon leaching (Δ(^87/86Sr)) is perhaps the best quantifier of the overall alteration state of the whole rocks as well as of the degree of low-temperature oxidation suffered by the titanomagnetites. It is well correlated with Curie-point variations caused by changes in the Fe³⁺/Fe²⁺ ratio.  相似文献   

Spherical shock waves in viscous magnetogasdynamics     

B. G. Verma  R. C. Srivastava  V. K. Singh 《Astrophysics and Space Science》1985,111(2):253-263

The point-source, spherical magnetogasdynamics shock wave moving into a constant density -law gas is considered in the limit of infinite shock strength, from the point of view of the Richtmyer-Von Neumann viscosity technique. Numerical solutions of this problem has been obtained in viscous and non-viscous regions. A similarity solution of this problem is shown to exist. We have shown that field variables change rapidly when the magnetic field is imposed in both the viscous and the non-viscous regions.Supported by CSIR, New DeIhi under the grant No. 7157/287/81-DMR-I.  相似文献   

Lithospheric structure below the eastern Arabian Sea and adjoining West Coast of India based on integrated analysis of gravity and seismic data   总被引：1，自引：0，他引：1  

M. Radha Krishna  R.K. Verma  Arts K. Purushotham 《Marine Geophysical Researches》2002,23(1):25-42

Four uniformly spaced regional gravity traverses and the available seismic data across the western continental margin of India, starting from the western Indian shield extending into the deep oceanic areas of the eastern Arabian Sea, have been utilized to delineate the lithospheric structure. The seismically constrained gravity models along these four traverses suggest that the crustal structure below the northern part of the margin within the Deccan Volcanic Province (DVP) is significantly different from the margin outside the DVP. The lithosphere thickness, in general, varies from 110–120 km in the central and southern part of the margin to as much as 85–90 km below the Deccan Plateau and Cambay rift basin in the north. The Eastern basin is characterised by thinned rift stage continental crust which extends as far as Laxmi basin in the north and the Laccadive ridge in the south. At the ocean–continent transition (OCT), crustal density differences between the Laxmi ridge and the Laxmi basin are not sufficient to distinguish continental as against an oceanic crust through gravity modeling. However, 5-6 km thick oceanic crust below the Laxmi basin is a consistent gravity option. Significantly, the models indicate the presence of a high density layer of 3.0 g/cm³ in the lower crust in almost whole of the northern part of the region between the Laxmi ridge and the pericontinental northwest shield region in the DVP, and also below Laccadive ridge in the southern part. The Laxmi ridge is underlain by continental crust upto a depth of 11 km and a thick high density material (3.0 g/cm³) between 11–26 km. The Pratap ridge is indicated as a shallow basement high in the upper part of the crust formed during rifting. The 15 –17 km thick oceanic crust below Laccadive ridge is seen further thickened by high density underplated material down to Moho depths of 24–25 km which indicate formation of the ridge along Reunion hotspot trace.  相似文献   

Wheat production forecast using remote sensing nd agromet variables in haryana state     

Urmil Verma  D. S. Ruhal  Manoj Yadav  A. P. Khera  R. S. Hooda  C. P. Singh  M. H. Kalubarme  I. S. Hooda 《Journal of the Indian Society of Remote Sensing》2003,31(2):141-144

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A Revised Analytical Method for HCO₃^- and CO₃^2-Determinations in Geothermal Waters: An Assessment of IAGC and IAEA Interlaboratory Comparisons     

Mahendra P. Verma 《Geostandards and Geoanalytical Research》2004,28(3):391-409

A statistical evaluation of the results of HCO₃^‐ determinations in geothermal waters during the interlaboratory comparison programmes of the International Association of Geochemistry and Cosmochemistry (IAGC) and International Atomic Energy Agency (IAEA) indicated that the analytical uncertainty increases with decreasing concentration of HCO_3‐ and was ? 25% for 50 μg ml^‐1 and ? 60% for 25 μg ml^‐1 of HCO₃^‐. The analytical method (Method 1) used by chemists and hydrologists works well for waters containing carbonic alkalinity, whereas Method 2 used by geochemists is conceptually incorrect. A stepwise comparison between the theoretical and experimental titration results for a given concentration Na₂CO₃ (0.0988 mol l^‐1) solution was performed to understand the limitations of the titration method for geothermal water analysis. Backward titration from the carbonic acid equivalence point (H₂CO₃EP) to the original pH after CO₂ removal, as had been practised earlier in the geothermal industry, in order to estimate the contribution of silicic and boric alkalinities to the total alkalinity, is incorrect because the amount of standard base (NaOH) added is equivalent to silicic and boric alkalinities plus some OH^‐ alkalinity. In a Na₂CO₃ solution, the added NaOH is equivalent to OH^‐ alkalinity only. Backward titration is only needed from the forward titration end point to the H₂CO₃EP in order to correct the total alkalinity for the excess of standard acid (HCl) added during the forward titration. In the case of a Na₂CO₃ solution, the H₂CO₃EP, after removal of CO₂ during the forward titration, is at pH = 7, not at pH = 4.5 (3.8) as has been considered in literature. Similarly, the liberation of CO₂ during titration occurs well before the point expected theoretically and it is less for shorter titration time. The revised procedure for the determination of carbonic species concentration is presented and illustrated for a water sample from Alchichica Lake, Puebla, Mexico.  相似文献   

Reserve Growth in Oil Fields of West Siberian Basin, Russia     

Mahendra K. Verma  Gregory F. Ulmishek 《Natural Resources Research》2003,12(2):105-119

Although reserve (or field) growth has proved to be an important contributing factor in adding new reserves in mature petroleum basins, it is a poorly understood phenomenon. Although several papers have been published on the U.S. fields, there are only a few publications on fields in other petroleum provinces. This paper explores the reserve growth in the 42 largest West Siberian oil fields that contain about 55% of the basin's total oil reserves.The West Siberian oil fields show 13-fold reserve growth 20 years after the discovery year and only about 2-fold growth after the first production year. This difference in growth is attributed to extensive exploration and field delineation activities between discovery and the first production year. Because of the uncertainty in the length of evaluation time and in reported reserves during this initial period, reserve growth based on the first production year is more reliable for model development. However, reserve growth models based both on discovery year and first production year show rapid growth in the first few years and slower growth in the following years. In contrast, the reserve growth patterns for the conterminous United States and offshore Gulf of Mexico show a steady reserve increase throughout the productive lives of the fields. The different reserve booking requirements and the lack of capital investment for improved reservoir management and production technologies in West Siberia are the probable causes for the difference in the growth patterns.The models based on the first production year predict that the reserve growth potential in the 42 largest oil fields of West Siberia for a five-year period (1998–2003) ranges from 270–330 million barrels or 0.34–0.42% per year. For a similar five-year period (1996–2001), models for the conterminous United States predict a growth of 0.54–0.75% per year.  相似文献   

Retardation of Fin Regeneration in Freshwater Fish Oreochromis mossambicusby Zinc     

Yogendra Verma 《洁净——土壤、空气、水》2004,32(6):429-433

Regeneration of partially amputated caudal fin was studied in freshwater fish Oreochromis mossambicus exposed to sublethal concentrations of zinc (5.0 mg L^—1 and 10.0 mg L^—1) under ambient laboratory conditions over a period of 20 days. Caudal fin regeneration was measured on 5th, 10th, 15th and 20th day of exposure and after amputation. Significant ( p < 0.05) retardation in fin regeneration was observed on day 5th and 10th in fish exposed to the nominal concentration of 5.0 mg L^—1 Zn, while retardation was found highly significant ( p < 0.01) at all the observations in 10.0 mg L^—1. The maximum inhibition in caudal fin regeneration (20.8 % and 24.3 %) was found during the initial observation at both of the concentrations (5.0 mg L^—1 and 10.0 mg L^—1) of zinc exposure. Later on the regeneration rate was almost as good as in the control group. Thus in this study fin regeneration was significantly inhibited at all time points following Zn exposure as a detrimental effect of Zn to fish. This study demonstrates that fish caudal fin regeneration is a simple assay, sensitive and easy to perform, and can serve as a model to determine the toxicity of pollutants in aquatic environment.  相似文献   

Landslide hazards and mitigation measures at Gangtok, Sikkim Himalaya   总被引：6，自引：0，他引：6  

Rajinder Bhasin  Eystein Grimstad  Jan Otto Larsen  Ashok K. Dhawan  Rajbal Singh  S. K. Verma  K. Venkatachalam 《Engineering Geology》2002,64(4):351-368

Landslides and other mass movements are serious geo-environmental hazards in the Himalayas. Massive landslides killing tens of thousands of people with catastrophic damages have occurred in the Eastern Himalayan State of Sikkim, which shares common borders with Tibet, Nepal, and Bhutan. This paper describes the investigations carried out on recent landslides in Gangtok, Sikkim, India, with emphasis on the triggering mechanisms that have contributed to the release and creep of natural slopes in the region. It is believed that the intense rainfall in the region not only contributes to rapid erosion and weathering of the rock mass, but also increases the groundwater level that leads to reduction in the stability of natural slopes. A landslide instrumentation programme that includes placement of settlement pillars and piezometers is underway to predict the behaviour of landslides in the area.  相似文献   

Biocides in Relation to Water Pollution. Part 2: Bioassay Studies of Few Biocides to a Fresh Water Fish,Channa gachua.     

S. R. Verma  M. C. Bhatnagar  R. C. Dalela 《洁净——土壤、空气、水》1978,6(2):137-144

The present paper deals with the determination of LT_m values of zolone, rogor, sumithion and abate for Channa gachua by conducting static bioassay experiments. The TL_m values for zolone came out to be 0.08275 mg/l, 0.08225 mg/l, 0.0815 mg/l and 0.0810 mg/l; for rogor 5.155 mg/l; 4.955 mg/l, 4.65 mg/l and 4.475 mg/l; for sumithion 12.60 mg/l, 12.50 mg/l, 12.30 mg/l and 12.20 mg/l and for abate 217.25 mg/l, 225.575 mg/l, 221.575 mg/l and 217.25 mg/l for 24, 48, 72 and 96 hours, respectively. Relative susceptibility indicates that this fish is not susceptible to zolone and less to rogor, sumithion and abate, respectively. Present studies also show that increased temperature and pH increase the toxicity of all the biocides, but increased hardness of water decreases the toxicity of biocide solutions. The safe concentrations for zolone, rogor, sumithion and abate came out to be 0.02437 mg/l, 1.3733 mg/l, 3.6907 mg/l and 66.678 mg/l, respectively.  相似文献