Effect of Fe2+ amendment on photodegradation kinetics of imidacloprid in moist soil     

Nazia Rafique  Saadia R. Tariq  Mateen Abbas 《Environmental Earth Sciences》2014,71(6):2869-2874

The present study deals with the effect of Fe²⁺ on degradation kinetics of imidacloprid in moist soil under UV system. The moist soil samples were spiked with imidacloprid and irradiated in specially designed UV-photoreactor. The analysis of imidacloprid was carried out by using HPLC–DAD system. UV irradiation caused about ten fold increase in photodegradation rate of the pesticide. Amendment of soil with Fe²⁺ at concentrations of 30 mg/kg led to a further increase in the rate of photodegradation, i.e., a 98 % degradation of imidacloprid was observed in the presence of iron after 32 days of irradiation. Moreover, the half-life of imidacloprid in Fe²⁺ -amended soil was observed to be reduced to 7 days that in the absence of Fe²⁺ was recorded to be 21 days. Iron was also observed to affect the half-life of imidacloprid in dark. When compared with unsterilized Fe²⁺-amended batch treatments, the t _1/2 in sterilized Fe²⁺-amended batch treatments increased from 58 to 96 days. Imidacloprid-urea was detected by HPLC as the only stable photodegradation byproduct of imidacloprid in the soil.  相似文献   

Adaptive state estimation of groundwater contaminant boundary input flux in a 2-dimensional aquifer     

Muhammad Nauman Malik  Mehdi Murtuza  Iqbal Asif  Bakar Muhammad Saifullah Abu  Brahim Aissa  Dk Nur Afiqah Jalwati Puteri  Amer Farhan Rafique 《地下水科学与工程》2014,7(4):373-382

In many circumstances involving heat and mass transfer issues, it is considered impractical to measure the input flux and the resulting state distribution in the domain. Therefore, the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative. Adaptive state estimator (ASE) is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique, thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters. The ASE is particularly designed for a system that encompasses independent unknowns and /or random switching of input and measurement biases. The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE, which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10% in 2-dimensional problems. Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios. Results also show that ASE enjoys a better estimation performance than its competitor, Recursive Least Square Estimator (RLSE) due to its larger error tolerance in greater process noise regimes. ASE’s inherent deficiency of being slower than the RLSE, resulting from the complexity of algorithm, was also noticed. The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location.  相似文献   

Tilted and non-tilted Gödel-type universe     

M. Sharif  Hira Tahir 《Astrophysics and Space Science》2014,353(1):267-270

This paper explores the dynamics of Gödel-type geometry for tilted and non-tilted congruences. The kinematical as well as dynamical quantities are investigated for both congruences with non-vanishing nature of vorticity vector. The obtained vorticity is of kinematical type, i.e., not produced by a circular flow of superenergy on the plane orthogonal to the vorticity vector. We conclude that super-Poynting vector is non-zero for the tilted congruence linked with heat flux of fluid distribution while it vanishes in non-tilted case.  相似文献   

Hohlraum Targets Driven by Cluster Ion Beams for Inertial Confinement Fusion     

C. Deutsch  N.A. Tahir  O. Geb  J.A. Maruhn 《Astrophysics and Space Science》1997,256(1-2):151-159

Correlated ion stopping of charged debris resulting from the fragmentation of energetic cluster ions focussed on Au foam converters is considered for driving indirectly a thermonuclear capsule. The 1D simulation of converter time evolution demonstrates a very high conversion efficiency of projectile energy into hard X-ray photons building up a very hot (T_r > 300 eV) thermal bath. Intense and energetic cluster ion beams thus demonstrate considerable potential as a novel driver for inertial confinement fusion.  相似文献   

Improvement in Engineering Properties of Expansive Soils using Ground Granulated Blast Furnace Slag     

Hassan Mujtaba  Tahir Aziz  Khalid Farooq  Nagaratnam Sivakugan  Braja M. Das 《Journal of the Geological Society of India》2018,92(3):357-362

Improvement in engineering properties of expansive soils by mixing ground granulated blast furnace slag (GGBFS) is the main focus of this research. For this purpose two expansive soil samples were collected from DG Khan and Sialkot areas (Pakistan). Classification tests revealed that DG Khan sample belonged to fat clay (CH) while Sialkot soil was lean clay (CL) as classified by Unified Soil Classification System. GGBFS has been added in varying proportions between 0 and 55% in these soil samples to study its role in stabilizing these expansive soils. Based on the laboratory test performed on composite soil samples, it was observed that maximum dry unit weight increased up to 10 % by adding 50% GGBFS in both samples. California bearing ratio (CBR) value showed an increase from 3.2 % to 11.5% for DG Khan soil while CBR values varied from 2.4% to 10.7% for Sialkot soil by mixing 50% GGBFS. Addition of 30 % GGBFS to DG Khan soil reduced swell potential from 8 % to 2 % while in Sialkot soil, 20 % addition of GGBFS reduced swell potential from 5 % to 2 %. Unconfined compressive strength of remoulded sample cured for 28 days increased by about 35% with the addition of 30%GGBFS. The results indicated that mixing of GGBFS in the expansive soil samples have a marked increase in their engineering properties. Also, it is an affective and environmental friendly means to dispose waste of steel industry.  相似文献   

Residual impact of biochar on cadmium uptake by rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) grown in Cd-contaminated soil     

Muhammad Rizwan  Shafaqat Ali  Tahir Abbas  Muhammad Zia ur Rehman  Mohammad I. Al-Wabel 《Arabian Journal of Geosciences》2018,11(20):630

Cadmium (Cd) is the family member of toxic heavy metals, and its accumulation in food crops has become a global environmental constraint. Biochar potentially minimizes the metal contents in plants, but limited work has been reported on its residual effect on subsequent crops. The residual effect of various biochar levels (0, 1.5, 3.0, and 5.0% w/w) on Cd accumulation in rice has been investigated in this study. Biochar treatments enhanced the rice growth, photosynthesis, and antioxidant enzymes, whereas diminished the Cd contents and oxidative stress in rice. Cadmium concentration in shoots decreased by 24.4, 36.6, and 57.5% in 1.5, 3.0, and 5.0% biochar treatments over the control. Biochar supply enhanced the soil pH and electrical conductivity, whereas diminished the soil bioavailable Cd. Overall, the results depicted a significant residual impact of rice straw biochar on rice growth attributes and Cd uptake. However, studies are still needed to explore the long-term sustainability of biochars prepared from different feedstocks on bioavailability of toxic metals in soils and uptake by food crops under field conditions.  相似文献   

Ambient indoor/outdoor gamma radiation dose rates in the city and at high altitudes of Muzaffarabad (Azad Kashmir)   总被引：1，自引：1，他引：0  

Muhammad Rafique 《Environmental Earth Sciences》2013,70(4):1783-1790

Preliminary results of ambient indoor/outdoor gamma dose rates measured for Muzaffarabad city, the state capital of Azad Kashmir, are presented. Measurements of indoor/outdoor environmental exposures were carried out using a portable Ludlum Model 19 Micrometer. Effect of altitude on measured values of gamma dose rates has also been investigated. Besides measuring the gamma dose rates for indoor and open environment, measurements have also been taken within two coal mines. Effects of lithology on gamma dose rates have also been investigated. For outdoor measurements, minimum and maximum gamma dose rates were found as 533 ± 4.33 and 1,143 ± 2.96 μGy y^?1, while for indoor environment minimum and maximum gamma dose rate value were found as 533 ± 4.33 and 979 ± 3.2 μGy y^?1. Average values of indoor and outdoor gamma dose rates were found as 761 ± 3.62 and 710 ± 3.75 μGy y^?1. Gamma dose rates have also been calculated with altitude variations. Measured values of gamma dose rates show a weak positive correlation with altitude. For measurements made in coal mines, maximum gamma doses rate value was found as 3,490 ± 1.69 μGy y^?1, situated at a height of 1,098 m, located at Sangri Mera. Results obtained from the current study show that annual effective doses from gamma radiation exposure does not pose health threat to the population of district Muzaffarabad.  相似文献   

Laboratory planetary physics using intense heavy ion beams at the Facility for Antiprotons and Ion Research at Darmstadt: the HEDgeHOB collaboration     

N. A. Tahir  T. Stöhlker  A. Shutov  I. V. Lomonosov  V. E. Fortov  M. French  N. Nettelmann  R. Redmer  A. R. Piriz  C. Deutsch 《Astrophysics and Space Science》2011,336(1):61-65

Development of ultra-high power lasers has lead to the very interesting and important field of Laboratory Astrophysics. Recent progress and expected near future developments in the technology of strongly bunched intense particle beams has opened up the possibility of studying planetary interiors in the laboratory which hopefully will eventually converge in the new field of Laboratory Planetary Physics. GSI Helmholzzentrum für Schwerionenforschung, Darmstadt is a well known laboratory worldwide due to its unique particle accelerator facilities. Construction of the new huge accelerator complex, the Facility for Antiprotons and Ion Research (FAIR), will substantially improve the existing capabilities of the GSI. A dedicated program named, HEDgeHOB, that aims to study different problems in High Energy Density (HED) Physics at the FAIR facility, has been proposed. One of these proposed experiments LAPLAS (LAboratory PLAnetary Science), aim to study materials at extreme conditions as relevant for the interiors of giant planets. In this paper we present simulation results that show that various regions of the high-pressure phase diagram of water can be probed within the LAPLAS experiments. For instance, the plasma and the superionic phase are predicted to occur in the interior of water-rich planets such as Uranus and Neptune as well as in extrasolar planets such as GJ 436b.  相似文献   

Comparison of two snowmelt modelling approaches in the Dudh Koshi basin (eastern Himalayas,Nepal)     

Bijay Kumar Pokhrel  Pierre Chevallier  Vazken Andréassian  Adnan Ahmad Tahir  Yves Arnaud  Luc Neppel 《水文科学杂志》2013,58(8):1507-1518

Abstract

The glaciers in the Nepalese Himalayas are retreating due to rising temperatures. Lack of data and information on Nepal’s cryosphere has impeded scientific studies and field investigations in the Nepalese Himalayas. Therefore, IRD France and Ev-K2 CNR Italy have conducted the PAPRIKA (CryosPheric responses to Anthropogenic PRessures in the HIndu Kush-Himalaya regions: impacts on water resources and society adaptation in Nepal) project in Nepal with the financial support of the French and Italian scientific agencies. This project aims to address the current and future evolution of the cryosphere in response to overall environmental changes in South Asia, and its consequences for water resources in Nepal. Thus, two hydrological models, the GR4J lumped precipitation–runoff model and the snowmelt runoff model (SRM), were used in the Dudh Koshi basin. The GR4J model has been successfully applied in different parts of Europe. To obtain better results in such a harsh and rugged topography, modifications needed to be made, particularly in the snow module. The runoff pattern is analysed herein both for past years and, in a sensitivity analysis, for possible future climatic conditions (i.e. precipitation and temperature) using the SRM and GR4J modelling approaches. The results reveal a significant contribution of snow- and glacier-melt to runoff, and the SRM model shows better performance in Nepalese catchments than the GR4J model.