Temporal variation in the arsenic and metal accumulation in the maritime pine tree grown on contaminated soils     

P. J. C. Favas  J. Pratas  M. N. V. Prasad 《International Journal of Environmental Science and Technology》2013,10(4):809-826

The uptake of arsenic and other metals (iron, manganese, copper, zinc, lead, nickel and tungsten) by Pinus pinaster Aiton (the maritime pine tree) growing in soils and tailings around an abandoned mine (northern Portugal) was investigated. Aerial parts of Pinus pinaster trees were sampled from three substrate areas: a background area, in mine contaminated soils and in tailings. Vegetation material was separated into needles and stems and subdivided into tissues of different maturities (1-, 2-, 3- and 4-years-old). The sampling of the substrate in each area was also undertaken. In general, vegetation concentrations were strongly related to substrate concentrations. The results show that the contents of several elements depend as much on the plant organ as on the age of the tissue. For the researched elements, this species shows a great variability in behavior depending on the age of the organ. The data indicate that the older needles constitute the best samples for use in a conjunct biogeochemical analysis of these elements.  相似文献   

An integrated approach to investigate saline water intrusion and to identify the salinity sources in the Central Godavari delta, Andhra Pradesh, India     

Naidu L.S.  G. Rao V.V.S.  T. Rao G.  Mahesh J.  Padalu G.  Sarma V.S.  Prasad P.R.  Rao S.M.  R. Rao B.M. 《Arabian Journal of Geosciences》2013,6(10):3709-3724

The Central Godavari delta is located along the Bay of Bengal Coast, Andhra Pradesh, India, and is drained by Pikaleru, Kunavaram and Vasalatippa drains. There is no groundwater pumping for agriculture as wells as for domestic purpose due to the brackish nature of the groundwater at shallow depths. The groundwater table depths vary from 0.8 to 3.4 m and in the Ravva Onshore wells, 4.5 to 13.3 m. Electrical Resistivity Tomography (ERT) surveys were carried out at several locations in the delta to delineate the aquifer geometry and to identify saline water aquifer zones. Groundwater samples collected and analyzed for major ions for assessing the saline water intrusion and to identify the salinity origin in the delta region. The results derived from ERT indicated low resistivity values in the area, which can be attributed to the existence of thick marine clays from ground surface to 12–15 m below ground level near the coast and high resistivity values are due to the presence of coarse sand with freshwater away from the coast. The resistivity values similar to saline water <0.01 Ω m is attributed to the mixing of the saline water along surface water drains. In the Ravva Onshore Terminal low resistivity values indicated up coning of saline water and mixing of saline water from Pikaleru drain. The SO ₄ ^?2 /Cl^?and Na⁺²/Cl^?ratios did not indicate saline water intrusion and the salinity is due to marine palaeosalinity, dilution of marine clays and dissolution of evaporites.  相似文献   

Change in entropy of non-spinning black holes w.r.t. the radius of event horizon in XRBs     

Dipo Mahto  Ved Prakash  Umakant Prasad  B. K. Singh  K. M. Singh 《Astrophysics and Space Science》2013,343(1):153-159

The present research paper discusses the derivation for the change in entropy of Non- spinning black holes with respect to the change in the radius of event horizon applying the first law of black hole mechanics ( $\delta M = \frac{\kappa}{8\pi} \delta A + \varOmega\delta J - \upsilon\delta Q$ ) with the relation for the change in entropy δS=8πMδM. When the work is further extended with proper operation, the entropy of black hole is obtained almost the same as the Bekenstein-Hawking entropy of black hole. This is the entirely new method to obtain the change in entropy of Non-spinning black holes w.r.t. the radius of event horizon and Hawking entropy of black hole. We have also calculated their values for different types of test non-spinning black holes having masses 5–20M _⊙ found in X-ray binaries (Narayan, gr-qc/0506078v1, 2005).  相似文献   

Removal of Selenium by Adsorption onto Granular Activated Carbon (GAC) and Powdered Activated Carbon (PAC)     

Kailas L. Wasewar  Basheshwar Prasad  Sekhararao Gulipalli 《洁净——土壤、空气、水》2009,37(11):872-883

The present work involves the study of Se(IV) adsorption onto granular activated carbon (GAC) and powdered activated carbon (PAC). The adsorbents are coated with ferric chloride solution for the effective removal of selenium. The physico-chemical characterization of the adsorbents is carried out using standard methods, e. g., proximate analysis, scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), thermo-gravimetric (TGA) and differential thermal analysis (DTA), etc. The FTIR spectra of the GAC and PAC indicate the presence of various types of functional groups, e. g., free and hydrogen bonded OH groups, silanol groups (Si-OH), alkenes, and CO group stretching from aldehydes and ketones on the surface of adsorbents. Batch experiments are carried out to determine the effect of various factors such as adsorbent dose (w), initial pH, contact time (t), and temperature (T) on the adsorption process. The optimum GAC and PAC dosage is found to be 10 g/L and 8 g/L, respectively, for Se(IV) removal with C₀ = 100 mg/L. The percent removal of Se(IV) increases with increasing adsorbent concentration, while removal per unit weight of adsorbent increases with decreasing adsorbent concentration. Se(IV) adsorption onto both the GAC and PAC adsorbents is high at low pH values, and decreases with increased initial pH. The results obtained are analyzed by various kinetic models. The parameters of pseudo-first order, pseudo-second order kinetics, and Weber-Morris intra particle kinetics are determined. It is seen that the sorption kinetics of Se(IV) onto GAC and PAC can be best represented by the pseudo-second order kinetic model.  相似文献   

Adsorption of Selenium Using Bagasse Fly Ash     

Kailas L. Wasewar  Basheshwar Prasad  Sekhararao Gulipalli 《洁净——土壤、空气、水》2009,37(7):534-543

The present work involves the study of Se(IV) adsorption onto bagasse fly ash. The adsorbents were coated with a ferric chloride solution for the effective removal of selenium. The physico‐chemical characterization of the adsorbent was carried out using standard methods, e. g., proximate analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, thermo‐gravimetric analysis and differential thermal analysis. Batch experiments were carried out to determine the effect of various parameters such as adsorbent dose, initial pH, contact time, and temperature on the adsorption process. Results obtained from these studies were analyzed using various kinetic models and isotherms. Se(IV) adsorption onto adsorbent was high at low pH values, and decreased with an increase in initial pH. A temperature study showed that the uptake of Se(IV) was greatest at 293 K, within the temperature range studied. The parameters of pseudo first order, pseudo second order, and Weber‐Morris intra‐particle kinetic models were determined. Equilibrium isotherms were analyzed using Langmuir, Freundlich, and Temkin isotherms. Error analyses were also carried out using hybrid fractional error function and Marquardt's percent standard deviation.  相似文献   

Characteristics of Flaring Sites in Solar Active Regions     

C. Debi Prasad 《Astrophysics and Space Science》2000,274(3):463-471

The properties of the flaring sites in the active region NOAA 6555 and 6659 are presented in this paper. Although, several locations of these active regions displayed high magnetic shear, the X-class flares occurred only at one of them. Our investigations show that these locations are characterized by the `crossing' of magnetic and velocity field neutral lines. Based on a new parameter to define the stressed magnetic fields, we show that some of these flaring locations possessed highly stressed magnetic field which disappeared after the flare. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Shifting cultivation in Mizoram,India: An empirical study of its economic implications     

Vishwambhar Prasad SATI 《山地科学学报》2019,(9)

Shifting cultivation is the major occupation and the main source of income of the marginal farmers(Jhumias) in Mizoram. At present, net area sown in Mizoram State is only 5.5%, of which, 16.9% area is devoted to shifting cultivation. Meanwhile, about 54% people, living in the rural areas, are engaged in practicing it. This paper examines economic implications of shifting cultivation in Mizoram, the eastern extension of the Himalaya. A total of 16 villages from eight districts(two villages from each district), were selected for case study, based on their location and distance from the district's headquarter. Household level survey was conducted and a purposive random sampling method was employed to select households with 34.2% sampling size. The case study reveals that production and yield of the principal crops grown under shifting cultivation has decreased during the last 17 years(2000-2017), whereas, there is a slight increase in area sown. It further shows that although, a large group of Jhumias are practicing shifting cultivation and growing subsistence cereals, yet, their economic viability is significantly less than cash crops. As a result, a large section of people in rural areas are living below poverty line. The study suggests that for sustainable livelihood, cash crops can replace subsistence crops and shifting cultivation can be converted into permanent cultivation through terracing the Jhum plots.  相似文献   

Equations of motion of the restricted problem of (2 + 2) bodies when primaries are magnetic dipoles and minor bodies are taken as electric dipoles     

A. Prasad  Bhola Ishwar 《Celestial Mechanics and Dynamical Astronomy》1996,64(4):305-312

In this problem of the restricted (2 + 2) bodies we have considered two magnetic dipoles of masses M ₁ and M ₂(M ₁ > M ₂) moving in circular Keplarian orbit about their centre of mass. Two minor bodies of masses m ₁, m ₂(m _j< M ₂) are taken as electric dipoles in the field of rotating magnetic dipoles. These minor bodies interact with each other but do not perturb the primaries.We have found equations of motions which differ from that of Goudas and Petsagouraki's (1985).  相似文献   

The role of critical velocity ionization phenomena in the atmosphere of Io     

Prasad C. Debi 《Earth, Moon, and Planets》1995,71(1-2):65-71

The Alfvén's critical ionization velocity (CIV) have been observed in a number of laboratory and space experiments. In the Io-torus system, relative velocity of the plasma species in the torus with respect to the neutral species in the Io's atmosphere and neutral cloud exceeds the critical velocity required for CIV. Townsand condition is satisfied up to 6r _io , in the neutral cloud when Io passes through the torus. In this paper it is shown that during the passage of Io through the plasma torus, apart from critical velocity and Townsand condition, a number of other requirements are also satisfied. Therefore, it is concluded that, the CIV mechanism must play an important role in ionizing the neutral cloud and enriching the plasma torus.  相似文献   

MHD flow of an elasto-viscous fluid past a porous flat plate     

N. K. Samria  M. U. S. Reddy  R. Prasad 《Astrophysics and Space Science》1990,172(2):231-234

An analytical study is performed to examine the laminar flow of an electrically-conducting elasto-viscous fluid (Walters's liquidB) past an infinite porous flat plate to a step function change in suction velocity in the presence of a transverse magnetic field. The influence of the various parameters, entering in the problem, on the velocity field and shearing stress is extensively discussed.  相似文献