Transient‐state groundwater flow in various geometries with wells at arbitrary positions: analytical methods     

M. W. Roth  C. M Wilson  M. Z. Iqbal 《水文研究》2003,17(17):3519-3530

We have developed a method for analytically solving the porous medium flow equation in many different geometries for horizontal (two‐dimensional), homogeneous and isotropic aquifers containing impermeable boundaries and any number of pumping or injection wells located at arbitrary positions within the system. Solutions and results are presented for rectangular and circular aquifers but the method presented here is easily extendible to many geometries. Results are also presented for systems where constant head boundary conditions can be emulated internal to the aquifer boundary. Recommendations for extensions of the present work are briefly discussed. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Effect of aluminum and chromium on the germination and growth of two Vigna species     

S. N. Jamal B. Sc.  M. Sc.  M. Zafar Iqbal B.Sc.  M.Sc  Ph.D.  M. Athar M.Sc  MPhil.  Ph.D.  D.Sc 《International Journal of Environmental Science and Technology》2006,3(1):53-58

The study deals with the effect of metal toxicity (aluminum, chromium and combination of both the metals) on seed germination, root length, shoot length, seedling length and dry biomass of Vigna radiata and V. sinensis. Chromium adversely affected the seedling by significantly reducing the growth whereas aluminum did not show such effect in both the species. Percentage of germination was good in both the species at different concentration of treatment (aluminum, chromium and combined treatment). Shoot length was also not much affected in V. sinensis as it was greatly inhibited in V. radiata. Both the species showed the purpling of stem. Dry biomass of V. radiata showed positive effect than V. sinensis. However, dry biomass decreased to a lesser extent when treated with aluminum, chromium and combined treatment as compared to control.  相似文献   

Nitrogen isotope indicators of seasonal source variability to groundwater   总被引：5，自引：0，他引：5  

M. Z. Iqbal  N. C. Krothe  R. F. Spalding 《Environmental Geology》1997,32(3):210-218

 A nitrogen isotope study of soil water and groundwater in southern Indiana, USA, in 1991–1992 demonstrated considerable variations in nitrate degradation processes compared to an earlier investigation in 1986–1987. Although N-fertilizers were applied in May 1991, the δ¹⁵N values in soil water decreased in February 1992, indicating its delayed release into the system after substantial rainfall. The δ¹⁵N values of groundwater decreased from +12.3‰ in November 1991 to +11.3‰ in February 1992, and to +7.5‰ in March 1992. The increased residence time of nitrate in the soil resulted in increased denitrification, ammonia volatilization and plant uptake, and reduced threat to the groundwater quality. The 1986–1987 study in the area reported that excessive rainfall during the summer rapidly transported the nitrate to deeper horizons and drastically reduced volatilization and microbial reduction of nitrate, thus increasing the immediate threat to the groundwater quality in the area. The present study demonstrated that nitrogen isotopic signatures can be used to determine the effects of local soil type, rainfall, and land-use practices on the fate of nitrate in the subsurface. Received: 18 February 1997 · Accepted: 17 June 1997  相似文献   

Earthquake triggered soft sediment deformational structures (seismites) in the Karewa formations of Kashmir valley–An indicator for palaeo-seismicity     

Gulam Rasool Bhat  Bikram S. Bali  S. Balaji  Vazeem Iqbal  Balakrishna 《Journal of the Geological Society of India》2016,87(4):439-452

The intermontane Karewa basin contains a wide variety of seismically induced soft sediment deformation structures, interpreted as seismites and occurs in 1300 m thick succession of upper and lower Karewas. The Karewa Formation of Kashmir valley are glacio- fluvial-lacustrine and aeolian loess of Plio-Pleistocene age. The soft sediment deformational structures occurs in various formations and members of Karewas and vary greatly in terms of morphology and pattern. The Karewa Formations were frequently confronted with recurrent seismic activities during differential upliftment of Pir Panjal and Zanaskar ranges which resulted in various deformation structures during their evolution and development. In the present study, an attempt has been made to relate the palaeo-seismicity events in Karewa formations with the deformed structures of various formations. The origin of these deformational structures have been interpreted and analyzed from the field evidences by applying paleo-seismological approach. During and after the deposition of Karewas different soft sediment deformation structures (seismites) like load cast, convolute lamination, pseudonodules, recumbent folds, sand dykes etc. were formed during liquefaction and triggered by tectonic impulsive events. The deformational structures are evidenced by their unique nature, distribution, association, behaviour and deformation, and can be used as vital indicators for palaeo-seismicity.  相似文献   

Sequence stratigraphic analysis of Eocene Rock Strata,Offshore Indus,southwest Pakistan     

Natasha Khan  Khaista Rehman  Sajjad Ahmad  Jamil Khokher  M. Iqbal Hajana  M. Hanif 《Marine Geophysical Researches》2016,37(3):207-228

In this study, seismic data from two wells (Pak G2-1 and Indus Marine-1C) and age diagnostic larger benthic foraminifera (LBF) within drill cuttings has been used for the first time to identify depositional sequences within the carbonates in the Offshore Indus Basin, Pakistan. The Offshore Indus is tectonically categorized as a passive continental margin where carbonates occur as shelf carbonates in the near offshore and on volcanic seamounts in deeper waters. Seismic data analysis has indicated the presence of minor faults and carbonate buildups above the igneous basement in the south. Patterns of the seismic reflections enabled definition of three seismic facies units identified as: Unit 1 basement, represented by chaotic, moderate amplitude reflection configuration; while parallel bedding and the drape of overlying strata is typical character of Unit 2, carbonate mound facies. The younger Miocene channels represent Unit 3. The diagnosis of Alveolina vredenburgi/cucumiformis biozone confirmed the Ilerdian (55–52 Ma) stage constituting a second order cycle of deposition for the Eocene carbonates (identified as Unit 2). The carbonate succession has been mainly attributed to an early highstand system tract (HST). The environmental conditions remained favorable leading to the development of keep-up carbonates similar to pinnacle buildups as a result of aggradation during late transgressive system tract and an early HST. The carbonate sequence in the south (Pak G2-1) is thicker and fossiliferous representing inner to middle shelf depths based on fauna compared to the Indus Marine-1C in the north, which is devoid of fossils. Three biozones (SBZ 5, SBZ 6 and SBZ 8) were identified based on the occurrence of LBF. The base of the SBZ 5 zone marks the larger foraminifera turnover and the Paleocene–Eocene (P–E) boundary. The LBF encountered in this study coincides with earlier findings for the P–E boundary. Our findings indicate that the entire Ilerdian stage ranges from 55.5 to 52 Ma that was the episode of warmer water conditions on the carbonate shelves leading to the diversification of K-strategist larger foraminifera. The larger foraminiferal assemblage encountered in this study confirms the findings. The possible indication of stratigraphic-combination traps, revealed as reflection terminations, make carbonate mounds in the south a potential exploration target.  相似文献   

Contamination of soil and carrots irrigated with different sources of water in Punjab,Pakistan     

Kafeel Ahmad  Zafar Iqbal Khan  Sumaira Yasmin  Asma Ashfaq  Ijaz Rasool Noorka  Nudrat Aisha Akram  Hazoor Ahmad Shad  Abrar Hussain  Fahim Arshad  Muhammad Sher  Hafiz Muhammad Tahir  Humayun Bashir  Asma Zafar 《Environmental Earth Sciences》2016,75(5):426

  相似文献   

Seismic stratigraphy of the Mianwali and Bannu depressions,north-western Indus foreland basin     

Farid  Asam  Khalid  Perveiz  Ali  Muhammad Y.  Iqbal  Muhammad Asim  Jadoon  Khan Zaib 《International Journal of Earth Sciences》2018,107(5):1557-1578

International Journal of Earth Sciences - Regional seismic reflection profiles, deep exploratory wells, and outcrop data have been used to study the structure and stratigraphic architecture of the...  相似文献   

High-performing antifouling bacterial consortium for submerged membrane bioreactor treating synthetic wastewater     

H. Waheed  S. Pervez  I. Hashmi  S. J. Khan  S.-R. Kim 《International Journal of Environmental Science and Technology》2018,15(2):395-404

Biofouling, associated with membranes, is considered as a major operational challenge in membrane bioreactor (MBR) technology. Interrupting the process for the formation of biofilm by the action of interspecies quorum quenching (QQ) has received a significant attention since recent years. An antifouling bacterial consortium was identified to improve biofouling inhibition performance during MBR operation. For this purpose, various QQ bacteria were isolated from laboratory-scale MBR using enrichment culture method and identified via 16S rRNA. Potential quenching strains including Enterobacter cloaca, Delftia sp., and Pseudomonas sp. were utilized to control biofouling in the MBR operated in the continuous mode for 38 days. Three laboratory-scale MBRs, including two MBRs with different anti fouling consortium and a control, were operated in parallel under similar operating conditions. Biofouling control by QQ bacteria was compared based on the membrane permeability and EPS secretion from biofilm on the membrane. Both MBRs with antifouling consortium (AC-MBRs) experienced around three times less biofouling as compared to conventional MBR leading to significant decrease in acyl homoserine lactones (AHLs) concentration in the biocake. More than 90, 45, and 49% of COD, NH₄–N, and PO₄ ^3?–P removal efficiencies elucidate that QQ bacterial consortium could effectively reduce membrane biofouling without compromising the MBR efficiency. Comparatively lower concentration of bound EPS in AC-MBRs restricted the bacterial adhesion to membrane resulting in enhanced membrane permeability depicting that a broader range of signal molecules could be hydrolyzed using antifouling consortium than single or no QQ strain in the submerged MBR.  相似文献   

Geospatial assessment of soil erosion intensity and sediment yield: a case study of Potohar Region,Pakistan   总被引：2，自引：0，他引：2  

Saleem Ullah  Amjad Ali  Muhammad Iqbal  Muhammad Javid  Muhammad Imran 《Environmental Earth Sciences》2018,77(19):705

Estimation of spatial extent of soil erosion, one of the most serious forms of land degradation, is critical because soil erosion has serious implications on soil fertility, water ecosystem, crop productivity and landscape beauty. The primary objective of the current study was to assess and map the soil erosion intensity and sedimentation yield of Potohar region of Pakistan. Potohar is the rainfed region with truncated and complex topography lying at the top of the Indus Basin, the world’s largest irrigation networks of canals and barrages. Spatially explicit Revised Universal Soil Loss Equation (RUSLE) Model integrated with Remote Sensing-GIS techniques was used for detecting/mapping of erosion prone areas and quantification of soil losses. The results show that the Potohar region is highly susceptible to soil erosion with an average annual soil loss of 19 tons ha^?1 year^?1 of which the maximum erosion (70–208 tons ha^?1 year^?1) was near the river channels and hilly areas. The sediment yield due to the erosion is as high as 148 tons ha^?1 year^?1 with an average of 4.3 tons ha^?1 year^?1. It was found that 2.06% of the total area falls under severe soil erosion, 13.34% under high erosion, 15.35% under moderate soil erosion while 69.25% of the area lies in the low (tolerable) soil erosion. Chakwal and Jhelum districts of the region are seriously affected by erosion owing to their topography and soil properties. The information generated in this study is a step forward towards proper planning and implementation of strategies to control the erosion and for protection of natural resources. It is, hence, necessary that suitable water harvesting structures be made to control water to prevent soil erosion and provision of water in the lean season in this region. Tree plantation and other erosion control practices such as strip cropping can also minimize soil erosion in this region.  相似文献   

Long-term seasonal rainfall forecasting: efficiency of linear modelling technique     

Iqbal Hossain  H. M. Rasel  Monzur Alam Imteaz  Fatemeh Mekanik 《Environmental Earth Sciences》2018,77(7):280

Using the lagged (past) climate indices, including El Nino–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) as input parameters and long-term spring rainfall as outputs, calibration and validation of the linear multiple regression (MR) models have been performed. Since Australian rainfall varies both temporally and spatially, the analysis on the linear MR models was performed on regional scale. These models show the capability of linear MR technique for long-term predictions of Western Australian spring rainfall. The emphasis was given to assess the statistical correlations between Western Australian spring rainfall and dominating large-scale climate modes. The efficiency of linear modelling technique was evaluated to predict seasonal rainfall forecasting. At the same time, the Pearson correlation (R), mean absolute error, root-mean-square error and Willmott index agreement (d) were used to assess the capability of MR models. The models which fulfilled the limits of statistical significances were used for the prediction of future spring rainfall using independent data set. The results indicate that during calibration periods maximum achievable correlations varied from 0.47 to 0.53 for the selected stations. In regard to predict peaks and troughs of rainfall time series, it was found that correlations between predicted and actual peaks varied from 0.82 to 0.94 and between predicted and actual troughs varied from 0.53 to 0.91.  相似文献