Atmospheric abundance of HULIS during wintertime in Indo-Gangetic Plain: impact of biomass burning emissions     

Varun Kumar  Prashant Rajput  Anubha Goel 《Journal of Atmospheric Chemistry》2018,75(4):385-398

This study reports for the first-time the ambient concentrations of HULIS mass (HULIS-OM, Humic-like substances) and HULIS-C (carbon) in PM₁₀ (particulate matter with aerodynamic diameter?≤?10 μm) from the Indo-Gangetic Plain (IGP at Kanpur, wintertime). HULIS extraction followed by purification and isolation protocol with methanol: acetonitrile (1:1 v/v) on HLB (Hydrophilic-Lipophilic Balanced) cartridge has been established. Quantification of HULIS-C was achieved on a total organic carbon (TOC) analyser whereas HULIS-OM was determined gravimetrically. Consistently high recovery (> 90%) of HULIS-C based on analysis of Humic standard (sodium salt of Humic acid) suggested suitability of our established analytical protocol involving solvent extraction, purification and accurate quantification of HULIS. HULIS-OM varied from 17.3–38 μg m^?3 during daytime and from 19.8–40.6 μg m^?3 during night in this study. During daytime the HULIS-OM constituted 20–30% mass fraction of OM_Total and 10–15% of PM₁₀ mass. However, a relatively low contribution of HULIS-OM has been observed during the night. This observation has been attributed to higher concentrations of OM and PM₁₀ in night owing to nighttime chemical reactivity and condensation of organics in conjunction with shallower planetary boundary layer height. Strong correlation of HULIS-C with K⁺_BB (R²?>?0.80) and significant day-night variability of HULIS-C/WSOC ratio in conjunction with air-mass back trajectories (showing transport of pollutants from upwind IGP) suggest biomass burning emission and secondary transformations as important sources of HULIS over IGP. High-loading of atmospheric PM₁₀ (as high as 440 μg m^?3) with significant contribution of water-soluble organic aerosols (WSOC/OC: ~ 0.40–0.80) during wintertime highlights their plausible potential role in fog and haze formation and their impact on regional-scale atmospheric radiative forcing over the IGP.  相似文献   

Estimation of the waiting time distributions of earthquakes     

S. M. J. R. Goel  S. K. Malasi  P. S. Moharir  H. R. Wason  K. N. Khattri  V. K. Gaur 《Journal of Earth System Science》1983,92(3):223-237

Whether the earthquake occurrences follow a Poisson process model is a widely debated issue. The Poisson process model has great conceptual appeal and those who rejected it under pressure of empirical evidence have tried to restore it by trying to identify main events and suppressing foreshocks and aftershocks. The approach here is to estimate the density functions for the waiting times of the future earthquakes. For this purpose, the notion of Gram-Charlier series which is a standard method for the estimation of density functions has been extended based on the orthogonality properties of certain polynomials such as Laguerre and Legendre. It is argued that it is best to estimate density functions in the context of a particular null hypothesis. Using the results of estimation a simple test has been designed to establish that earthquakes do not occur as independent events, thus violating one of the postulates of a Poisson process model. Both methodological and utilitarian aspects are dealt with.  相似文献   

Diversity as a Measure of Water Pollution and an Aid for Biological Water Analysis     

S. R. Verma  A. K. Sharma  D. P. Goel 《洁净——土壤、空气、水》1987,15(6):559-576

– Five aquatic ecosystems, Yamuna river, Krishna river Eastern Kalinadi, Kadrabad drain and Peacock lake have been studied with reference to diversity and physico-chemical characteristics and biological indices. – A list of species have been selected with reference to polluted, mildly polluted or unpolluted water conditions. Though it is difficult to call any species strictly indicator species, certain species of Bacillariophyceae, bottom biota and Entomostraca can be regarded as indicative species. – The quantitative distributions of the species of different groups have been analysed statistically. Margalef's Community Diversity Index (d), Shannon Weaver Function, coefficient of rank correlation and partial and multiple correlation coefficient were calculated as to find out the order of precedence in different taxonomical groups. – The linear regression against BOD and the whole biocenosis were calculated, which indicate the relation as diversity d=6.7854 –0.0080 BOD±0.9695 where r₂= B=0.7365. Similarly, multiple linear regressions were also calculated using diversity against BOD, pH and temperature for each aquatic ecosystem. – All these observations indicate that diversity of organisms can be used to measure the water pollution intensity.  相似文献   

Identifying threshold storm events and quantifying potential impacts of climate change on sediment yield in a small upland agricultural watershed of Ontario     

Narayan Kumar Shrestha  Nabil Allataifeh  Ramesh Rudra  Prasad Daggupati  Pradeep K. Goel  Trevor Dickinson 《水文研究》2019,33(6):920-931

Agricultural zones are significant sediment sources, but it is crucial to identify critical source areas (CSAs) of sediment yield within these zones where best management practices (BMPs) can be applied to the best effect in reducing sediment delivery to receiving water bodies rather than the economically nonviable alternative of randomly or sweepingly implementing BMPs. A storm event of a specific magnitude and hyetograph profile may, at different times, generate a greater or lesser sediment yield. The widely used agricultural nonpoint source (AGNPS) model was used to identify CSAs for sediment losses in Southwestern Ontario's agriculture‐dominated 374‐ha Holtby watershed. A storm threshold approach was adopted to identify critical periods for higher sediment losses. An AGNPS model for the Holtby watershed was set up, calibrated, and validated for run‐off volume, peak flow rate, and sediment yield for several storms. The calibrated and validated model was run for storms of increasing return periods to identify threshold storm events that would generate sediment yield greater than an acceptable value for early and late spring, summer, and fall seasons. Finally, to evaluate the potential impacts of climate change, we shifted shorter duration summer storms into spring conditions and quantified the changes in sediment yield dynamics. A 6‐hr, 7.5‐year early spring storm would generate sediment losses exceeding the acceptable limit of 0.34 t ha^?1 for the season. However, summer storms (2 hr, up to 100 years) tended to generate sediment yields below those of an identifiable threshold storm. If such shorter duration summer storms occurred in spring, the sediment yield would increase by more than fivefold. A 5‐year future storm would generate an equivalent effect of a 100‐year current spring event. The high sediment delivery to be expected will have significant implications regarding the future management of water quality of receiving waters. Appropriate placement of BMPs at CSAs will thus be needed to reduce such high sediment delivery to receiving waters.  相似文献   

The hemispheric asymmetry of solar activity during the last century and the solar dynamo     

Ashish Goel Arnab Rai Choudhuri 《中国天文和天体物理学报》2009,9(1)

We believe the Babcock-Leighton process of poloidal field generation to be the main source of irregularity in the solar cycle. The random nature of this process may make the poloidal field in one hemisphere stronger than that in the other hemisphere at the end of a cycle. We expect this to induce an asymmetry in the next sunspot cycle. We look for evidence of this in the observational data and then model it theoretically with our dynamo code. Since actual polar field measurements exist only from the 1970s, we use the polar faculae number data recorded by Sheeley (1991, 2008) as a proxy of the polar field and estimate the hemispheric asymmetry of the polar field in different solar minima during the major part of the twentieth century. This asymmetry is found to have a reasonable correlation with the asymmetry of the next cycle. We then run our dynamo code by feeding information about this asymmetry at the successive minima and compare the results with observational data. We find that the theoretically computed asymmetries of different cycles compare favorably with the observational data, with the correlation co-efficient being 0.73. Due to the coupling between the two hemispheres, any hemispheric asymmetry tends to get attenuated with time. The hemispheric asymmetry of a cycle ei-ther from observational data or from theoretical calculations statistically tends to be less than the asymmetry in the polar field (as inferred from the faculae data) in the preceding minimum. This reduction factor turns out to be 0.43 and 0.51 respectively in observational data and theoretical simulations.  相似文献   

Inelastic seismic response of one-storey,asymmetric-plan systems: Effects of stiffness and strength distribution     

Rakesh K. Goel  Anil K. Chopra 《地震工程与结构动力学》1990,19(7):949-970

The effects of plan-wise distribution of stiffness and strength-as determined by the number, location, orientation and yield deformations of resisting elements-on the inelastic response of one-storey systems are evaluated. In particular, various systems are investigated for wide ranges of parameters involved, with the objective of establishing how the response is influenced by: (i) the presence of resisting elements perpendicular to the direction of ground motion; (ii) the number of resisting elements along the direction of ground motion; (iii) the overstrength typical of code-designed buildings; (iv) the relative values of strength and stiffness eccentricities; and (v) whether the asymmetry of the system is due to eccentricity in stiffness or in mass. The results presented for a simple excitation make it possible to explain the inconsistencies in conclusions from various earlier investigations, and to evaluate their applicability to actual buildings.  相似文献   

Trend analysis of hydro-meteorological parameters in the Jhelum River basin,North Western Himalayas     

Umar  Sheikh  Lone  M. A.  Goel  N. K.  Zakwan  Mohammad 《Theoretical and Applied Climatology》2022,148(3-4):1417-1428

Theoretical and Applied Climatology - The Jhelum River basin drains the entire Kashmir valley and is susceptible to floods, surrounded Himalayan Mountain range. The trend analysis of...  相似文献   

Effect of relative humidity on the scattering properties of urban aerosol particles     

R K Goel  N C Varshneya  T S Verma 《Journal of Earth System Science》1984,93(1):17-25

The effect of increase in relative humidity on the angular variation of scattered light intensity distribution function and on asymmetry factor has been studied theoretically for three sizes of particles which are representative of urban aerosols. The increase in relative humidity causes change in physical properties of the particles, like radius (r) and complex refractive index (n?ik). The study is based on these changes in physical characteristics. It has been found that there are almost negligible changes in the functioni at low humidities (≤40%) for all the three aerosol sizes studied, which may be due to insignificant changes in the physical properties. At higher values, however, the physical parameters as well as the functioni show significant changes. The changes ini are systematic for the particle very small compared to the wavelength of incident radiation but for the particles comparable or larger it is not so. The asymmetry factor changes with the increase in relative humidity, for smaller particle it increases and for two larger particles changes are of fluctuative nature.  相似文献   

Total nitrogen in iron meteorites     

P.N. Shukla  P.S. Goel 《Earth and Planetary Science Letters》1981,52(2):251-258

Total nitrogen contents have been measured by RNA of 30 iron and 4 stony-iron meteorites. Wide variations in N concentrations are noted (0.5 ppm to about 200 ppm). As a group, the IA irons have the highest nitrogen. This element is positively correlated with C, Ga, and Ge. Samples of meteorites that have been exposed to shock do not show any abnormal N distribution.  相似文献   

Nitrogen in tektites and natural glasses     

P.N. Shukla  B.K. Kothari  P.S. Goel 《Earth and Planetary Science Letters》1979,46(1):138-140

Nitrogen concentrations in various tektites and natural glasses have been measured using RNAA and are found to be almost constant at about 15 ppm. A terrestrial origin for tektite formation is favoured.  相似文献