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排序方式: 共有485条查询结果,搜索用时 15 毫秒
91.
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93.
Acta Geotechnica - Municipal solid waste (MSW) landfills are a major source of anthropogenic methane (CH4) and carbon dioxide (CO2) emissions, which are also major greenhouse gases. Apart from... 相似文献
94.
Ankam Durga Prasad Lori Rastogi Vinod Kumar Verma Vasudevan Krishna Kumari Sudhakar Yadlapalli Kulamani Dash 《Geostandards and Geoanalytical Research》2023,47(3):629-636
The National Centre for Compositional Characterisation of Materials (NCCCM) / Bhabha Atomic Research Centre (BARC) and National Aluminium Company Limited (NALCO), India have produced an Indian origin bauxite certified reference material (CRM), referred to as BARC-B1201, certified for major (Al2O3, Fe2O3, SiO2, TiO2, loss on ignition - LOI) and trace contents (V2O5, MnO, Cr2O3, MgO). Characterisation was undertaken by strict adherence to ISO Guides. A method previously developed and validated in our laboratory, using single step bauxite dissolution and subsequent quantitation (of Al2O3, Fe2O3, SiO2, TiO2, V2O5, MnO, Cr2O3 and MgO) by ICP-AES (SSBD ICP-AES) was used for homogeneity studies and an inter-laboratory comparison exercise (ILCE) of the candidate CRM. LOI was determined by thermo-gravimetric analysis. Property values were assigned after an ILCE with participation from seventeen reputed government and private sector laboratories in India. The CRM was certified for nine property values: Al2O3, Fe2O3, SiO2, TiO2, V2O5, MnO, Cr2O3, MgO and LOI, which are traceable to SI units. 相似文献
95.
K. V. S. Badarinath Shailesh Kumar Kharol V. Krishna Prasad Anu Rani Sharma E. U. B. Reddi H. D. Kambezidis D. G. Kaskaoutis 《Journal of Atmospheric Chemistry》2008,59(3):219-236
Measurements of total ozone column and solar UV radiation under different atmospheric conditions are needed to define variations
of both UV and ozone and to study the impact of ozone depletion at the Earth’s surface. In this study, spectral and broadband
measurements of UV-B irradiance were obtained along with total ozone observations and aerosol optical depth measurements in
the tropical urban region of Hyderabad, south India. We specifically used an Ultra-Violet Multifilter Rotating Shadow band
Radiometer (UVMFR-SR), to measure UV irradiance in time and space. To assess the aerosol and O3 effects on ground-reaching UV irradiance, we used measurements from a Microtops II sun photometer in addition to the Tropospheric
Ultraviolet Visible radiation (TUV) model. We also assessed the Defense Meteorological Satellite Program – Operational Line
Scanner (DMSP-OLS) night time satellite data for inferring biomass burning fires during the study period. Results clearly
suggested a negative correlation between the DMSP-OLS satellite derived fire count data and UVMFR-SR data suggesting that
aerosols from biomass burning are directly attenuating UV irradiance in the study region. Also, correlation analysis between
UV index and ozone measurements from sun photometer and TOMS-Ozone Mapping Instrument (OMI) indicated a clear decrease in
ground reaching UV-B irradiance during higher ozone conditions. The higher levels are attributed to photochemical production
of O3 during the oxidation of trace gases emitted from biomass burning. Results also suggested a relatively high attenuation in
UV irradiance (~6% higher) from smoke particles than dust. We also found a relatively good agreement between the modeled (TUV)
and measured UV irradiance spectra for different atmospheric conditions. Our results highlight the factors affecting UV irradiance
in a tropical urban environment, south India. 相似文献
96.
K. V. S. Badarinath Anu Rani Sharma Shailesh Kumar Kharol V. Krishna Prasad 《Journal of Atmospheric Chemistry》2009,62(1):73-86
Carbon monoxide (CO), Ozone (O3) and Black Carbon (BC) aerosol mass concentrations in relation to planetary boundary layer (PBL) height measurements were
analyzed from January–December, 2008 over tropical urban environment of Hyderabad, India. DMSP-OLS night-time satellite data
were analyzed for fire occurrence over the region and its correlation with pollution concentrations over the urban region.
Results of the study suggested considerable increase in CO and BC concentrations during early morning hours. Higher concentration
of BC, CO and ozone was observed during pre-monsoon, post-monsoon and winter and lowest concentrations exhibited during monsoon
season. NCEP/NCAR reanalysis winds suggested long range transport of aerosols and trace gases from forest fires are enhancing
the pollutant concentrations over the study area. 相似文献
97.
Krishna R. Reddy 《Geotechnical and Geological Engineering》2010,28(3):211-221
Throughout the world, subsurface contamination has become a widespread and pervasive problem. Toxic chemicals such as heavy
metals and organic compounds are commonly used in a myriad of industries. However, largely through inadvertent or accidental
release, these chemicals are presently polluting sites across the United States. In order to protect public health and the
environment, further pollution must be prevented and sites with existing contamination urgently need remediation. Unfortunately,
remediating subsurface contamination has proved to be a daunting task. Heavy metals and organic compounds often coexist and
their distribution within the subsurface is highly dependent on particle and macro-scale heterogeneities. Vast resources have
been invested to develop efficient remediation technologies, yet very few of these technologies have been successful. In-situ
remediation is often preferred due to minimal site disturbance, safety, simplicity, and cost-effectiveness. The effectiveness
of in-situ remediation technologies depends largely on the contaminant chemistry and subsurface heterogeneities (including
particle-scale heterogeneities such as fine-grained soils, soils with reactive minerals, and/or soils rich in organic matter
as well as macro-scale heterogeneities such as irregular soil layers and/or lenses). Under such heterogeneous conditions,
integrated electrokinetic remediation technology has great potential. As a safe and economical remedial option for so many
contaminated sites, the application of integrated electrokinetic remediation offers enormous public health, environmental,
and financial benefits. 相似文献
98.
M. Bala Krishna Prasad Mathew R. P. Sapiano Clarissa R. Anderson Wen Long Raghu Murtugudde 《Estuaries and Coasts》2010,33(5):1128-1143
A retrospective analysis of freshwater discharge, riverine dissolved nutrient loads, dissolved nutrients, and chlorophyll in the Chesapeake Bay from 1985 to 2008 is presented. It is evident that each field displays an interannual variability averaged over the Bay. The N and P loads peaked in 1997 and have fluctuated with a decreasing trend since early 2004. Dissolved nutrient concentrations in the Bay appear to be largely controlled by riverine nutrient loads. The temporal variability of chlorophyll is positively correlated with nutrient loads and concentrations. Over the study period, N:P (DIN:DIP) molar ratios were consistently higher than the Redfield ratio (N:P?=?16:1) and strongly correlated with river discharge (R 2?=?0.68, p?0.05) with high discharge periods corresponding to high DIN levels. The N:P stoichiometric analysis indicates that P is the limiting nutrient in spring (N:P?>?16:1), and N is the limiting nutrient in summer and early autumn (N:P?16:1), pointing to an uptake of dissolved nitrogen by the phytoplankton and the release of PO4 from anoxic sediments. Long-term climate indices, such as El Niño Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO), appear to exert only a moderate control over the riverine discharge to the Bay or over the ecosystem response in terms of chlorophyll in the Bay. While not all related mechanisms can be inferred from available data, this analysis should help in determining future data needs for monitoring water quality and human and climate influence on the health of the Bay. 相似文献
99.
A. Routray U. C. Mohanty Dev Niyogi S. R. H. Rizvi Krishna K. Osuri 《Meteorology and Atmospheric Physics》2010,106(1-2):107-125
We present the results of the impact of the 3D variational data assimilation (3DVAR) system within the Weather Research and Forecasting (WRF) model to simulate three heavy rainfall events (25–28 June 2005, 29–31 July 2004, and 7–9 August 2002) over the Indian monsoon region. For each event, two numerical experiments were performed. In the first experiment, namely the control simulation (CNTL), the low-resolution global analyses are used as the initial and boundary conditions of the model. In the second experiment (3DV-ANA), the model integration was carried out by inserting additional observations in the model’s initial conditions using the 3DVAR scheme. The 3DVAR used surface weather stations, buoy, ship, radiosonde/rawinsonde, and satellite (oceanic surface wind, cloud motion wind, and cloud top temperature) observations obtained from the India Meteorological Department (IMD). After the successful inclusion of additional observational data using the 3DVAR data assimilation technique, the resulting reanalysis was able to successfully reproduce the structure of convective organization as well as prominent synoptic features associated with the mid-tropospheric cyclones (MTC). The location and intensity of the MTC were better simulated in the 3DV-ANA as compared to the CNTL. The results demonstrate that the improved initial conditions of the mesoscale model using 3DVAR enhanced the location and amount of rainfall over the Indian monsoon region. Model verification and statistical skill were assessed with the help of available upper-air sounding data. The objective verification further highlighted the efficiency of the data assimilation system. The improvements in the 3DVAR run are uniformly better as compared to the CNTL run for all the three cases. The mesoscale 3DVAR data assimilation system is not operational in the weather forecasting centers in India and a significant finding in this study is that the assimilation of Indian conventional and non-conventional observation datasets into numerical weather forecast models can help improve the simulation accuracy of meso-convective activities over the Indian monsoon region. Results from the control experiments also highlight that weather and regional climate model simulations with coarse analysis have high uncertainty in simulating heavy rain events over the Indian monsoon region and assimilation approaches, such as the 3DVAR can help reduce this uncertainty. 相似文献
100.