Endophytic Burkholderia sp. strain PsJN Improves Plant Growth and Phytoremediation of Soil Irrigated with Textile Effluent          下载免费PDF全文

Muhammad Afzal  Ghulam Shabir  Razia Tahseen  Ejaz‐ul Islam  Samina Iqbal  Qaiser M. Khan  Zafar M. Khalid 《洁净——土壤、空气、水》2014,42(9):1304-1310

  相似文献   

Comparison of numerical simulation of solute transport with observed experimental data in a silt loam subsoil   总被引：1，自引：0，他引：1  

A. I. Paseka  M. Z. Iqbal  J. C. Walters 《Environmental Geology》2000,39(9):977-989

 Solute transport experiments were conducted on loamy soils of north-eastern Iowa, USA, and the results were compared with a numerical solution of a classical advection-dispersion transport model developed in this study. Flow experiments in the laboratory on undisturbed soil columns showed a flow rate of water much higher than was estimated from the soil properties and grain-size analysis data, suggesting preferential flow regime in the soil. In contrast, the relative concentration peaks of Cl^– and Br^– in the effluent were only approximately 70% of those predicted by the classical advection-dispersion equation (ADE). In addition, the experimental breakthrough curves (BTCs) showed greater tailings of these ions than the model solution. These observations suggest a loss of solute mass during transport from the dynamic flowing regions to a stagnant, immobile water phase in the soil matrix. Experiments in small disturbed soil columns showed that movement of Cl^– and Br^– is in good agreement with predictions of the classical ADE when the tracers are applied as a continuous source. However, in the case of a pulse source, the BTCs of Cl^– and Br^– matched the model only in the ascending part of the curves. Such variation indicates greater retardation of these ions than that of simulation, probably caused by the decrease in soil permeability due to cation exchange reactions in the soil involving monovalent and divalent cation pairs such as K⁺–Ca²⁺ and K⁺–Mg²⁺. In addition, retardation occurred as a result of the continuous saturation of soil columns which seemed to have caused an expansion of clay minerals, thus resulting in decreased soil permeability. In both the continuous and the pulse-source experiments, K⁺ was not detected in the effluent samples, which seemed to have been lost in exchange reactions and adsorption. Received: 20 November 1998 · Accepted: 19 July 1999  相似文献   

Chemical Characterization and Source Apportionment of Atmospheric Particles Across Multiple Sampling Locations in Faisalabad,Pakistan   总被引：1，自引：0，他引：1       下载免费PDF全文

Wasim Javed  Anthony S. Wexler  Ghulam Murtaza  Muhammad Mazhar Iqbal  Yongjing Zhao  Tayyaba Naz 《洁净——土壤、空气、水》2016,44(7):753-765

  相似文献   

Prediction of rainfall‐induced shallow landslides in the Loess Plateau,Yan'an,China, using the TRIGRS model          下载免费PDF全文

Jianqi Zhuang  Jianbing Peng  Gonghui Wang  Javed Iqbal  Ying Wang  Wei Li  Qiang Xu  Xinghua Zhu 《地球表面变化过程与地形》2017,42(6):915-927

In this work, a transient rainfall infiltration and grid‐based regional slope‐stability model (TRIGRS) was implemented in a case study of Yan'an City, Northwest China. In this area, widespread shallow landslides were triggered by the 12 July 2013 exceptional rainstorm event. A high‐resolution DEM, soil parameters from in‐situ and laboratory measurements, water table depths, the maximum depth of precipitation infiltration and rain‐gauge‐corrected precipitation of the event, were used as inputs in the TRIGRS model. Shallow landslides triggered on the same day were used to evaluate the modeling results. The summarized results are as follows: (i) The characteristics and distribution of thirty‐five shallow landslides triggered by the 12 July 2013 rainfall event were identified in the study area and all were classified as shallow landslides with the maximum depth, area and volume less than 3 m, 200 m² and 1000 m³, respectively, (ii) Four intermediate factor of safety (F_S) maps were generated using the TRIGRS model to represent the scenarios 6, 12, 18 and 24 hours after the storm event. The area with F_S < 1 increased with the rainfall duration. The percentage of the area with F_S < 1 was 0.2%, 3.3%, 3.8% and 5.1% for the four stages, respectively. Twenty‐four hours after the rainstorm, TRIGRS predicted that 1255 grid cells failed, which is consistent with the field data. (iii) TRIGRS generated more satisfactory results at a given precipitation threshold than SINMAP, which is ideal for landslide hazard zoning for land‐use planning at the regional scale. Comparison results showed that TRIGRS is more useful for landslide prediction for a certain precipitation threshold, also in the regional scale. (iv) Analysis of the responses of loess slope prone to slope failure after different precipitation scenarios revealed that loess slopes are particularly sensitive to extended periods of heavy precipitation. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Radish (Raphanus sativus L.) Cultivar‐Specific Response to O3: Patterns of Biochemical and Plant Growth Characteristics          下载免费PDF全文

Ibrahim A. Hassan  Nigel B. Bell  Mike R. Ashmore  Lorenzo Cotrozzi  Nesreen S. Haiba  Jalal M. Basahi  Ahmad Summan  Talal Almeelbi  Iqbal M. Ismail 《洁净——土壤、空气、水》2018,46(6)

  相似文献   

Farmers’ perceptions of and adaptations to drought in Herat Province,Afghanistan     

Mohammad Wasim Iqbal  Somchai Donjadee  Bancha Kwanyuen  Shi-yin Liu 《山地科学学报》2018,15(8):1741-1756

Drought is a significant natural hazard in Herat Province, Afghanistan. The objective of this study was to explore farmers’ perceptions of the drought’s prevalence and characteristics, its socioeconomic and environmental impacts, their strategies for coping with and mitigating it, and types of conflicts and resolution mechanisms. A questionnaire was completed by 147 farming households. The results indicate that farmers' perceptions regarding drought are in line with the results obtained using the precipitation data. Even though the respondents have religious belief in interpreting the weather related issues, they also perceived drought as the climatic and environmental factors such as increased temperature, decreased precipitation, and other factors like war, financial weakness, deforestation, over-exploitation of groundwater, lack of electricity supply etc. The results show that drought has had serious economic impacts, including loss of employment and reduction in crop yield and livestock production, which have reduced farmers’ livelihood options and weakened their financial situation. Social impacts have included migration, a sense of hopelessness and loss, conflicts over water, health problems, impacts on the schooling of children, malnutrition, and limits to food options. Significant environmental impacts such as an increase in temperature, pasture and forest degradation, deterioration of water quality, damage to fish and wildlife habitats, and groundwater depletion were also reported. Farmers used local techniques to adapt to drought and lessen its effects. Farmers perceived irrigation water to be a major source of conflict. Local elders, water-user associations, and formal courts were reported to be the most successful conflict resolution methods. It is expected that the results of this study will support policy makers within government and development agencies in Afghanistan to develop future drought adaptation policies.  相似文献   

Probability Prediction Model for Landslide Occurrences in Xi’an,Shaanxi Province,China   总被引：1，自引：0，他引：1  

ZHUANG Jian-qi  IQBAL Javed  PENG Jian-bing  LIU Tie-ming 《山地科学学报》2014,11(2):345-359

Landslides are increasing since the 1980s in Xi’an, Shaanxi Province, China. This is due to the increase of the frequency and intensity of precipitation caused by complex geological structures, the presence of steep landforms, seasonal heavy rainfall, and the intensifcation of human activities. In this study, we propose a landslide prediction model based on the analysis of intraday rainfall （IR） and antecedent effective rainfall （AER）. Primarily, the number of days and degressive index of the antecedent effective rainfall which affected landslide occurrences in the areas around Qin Mountains, Li Mountains and Loess Tableland was established. Secondly, the antecedent effective rainfall and intraday rainfall were calculated from weather data which were used to construct critical thresholds for the 10%, 50% and 90% probabilities for future landslide occurrences in Qin Mountain, Li Mountain and Loess Tableland. Finally, the regions corresponding to different warning levels were identified based on the relationship between precipitation and the threshold, that is; “A” region is safe, “B” region is on watch alert, “C” region is on warning alert and “D” region is on severe warning alert. Using this model, a warning program is proposed which can predict rainfall-induced landslides by means of real-time rain gauge data and real-time geo-hazard alert and disaster response programs. Sixteen rain gauges were installed in the Xi’an region by keeping in accordance with the regional geology and landslide risks. Based on the data from gauges, this model accurately achieves the objectives of conducting real-time monitoring as well as providing early warnings of landslides in the Xi’an region.  相似文献   

Relaxed magnetic field structures in multi-ion plasmas     

M. Iqbal  P. K. Shukla 《Astrophysics and Space Science》2012,339(1):19-23

The steady state solution of a three species magnetoplasma is presented. It is shown that relaxed magnetic field configuration results in a triple curl Beltrami equation which permits the existence of three structures. It is the consequence of inertial effects of the plasma constituents. One of the three vortices is of large scale while the remaining two relaxed structures are of small size of the order of electron skin depth. The magnetic field profiles are given for different Beltrami parameters. The study could be helpful to understand large magnetic field structures in three species plasmas found in space and laboratory.  相似文献   

Biosorption of Cr(III) and Cr(VI) species from aqueous solution by Cabomba caroliniana: kinetic and equilibrium study     

P. K. Dileepa Chathuranga  Namal Priyantha  Sithy S. Iqbal  M. C. Mohomed Iqbal 《Environmental Earth Sciences》2013,70(2):661-671

This study reports the potential ability of non-living biomass of Cabomba caroliniana for biosorption of Cr(III) and Cr(VI) from aqueous solutions. Effects of contact time, biosorbent dosage, pH of the medium, initial concentration of metal ion and protonation of the biosorbent on heavy metal–biosorbent interactions were studied through batch sorption experiments. Cr(III) was sorbed more rapidly than Cr(VI) and the pH of the medium significantly affected the extent of biosorption of the two metal species differently. Surface titrations showed that the surface of the biosorbent is positively charged at low pH while it is negatively charged at pH higher than 4.0. Protonation of the biosorbent increased its capacity for removal of Cr(III), while decreasing that of Cr(VI). FT-IR spectra of the biosorbent confirmed the involvement of –OH groups on the biosorbent surface in the chromium removal process. Kinetic and equilibrium data showed that the sorption process of each chromium species followed pseudo second-order kinetic model and both Langmuir and Freundlich isothermal models. A possible mechanism for the biosorption of chromium species by non-living C. caroliniana is suggested.  相似文献   

Initiation process of debris flows on different slopes due to surface flow and trigger-specific strategies for mitigating post-earthquake in old Beichuan County, China   总被引：1，自引：1，他引：0  

Jian-qi Zhuang  Peng Cui  Jian-bing Peng  Kai-heng Hu  Javed Iqbal 《Environmental Earth Sciences》2013,68(5):1391-1403

The 12 May 2008 Wenchuan earthquake (Ms 8.0) in China, produced an estimated volume of 28 × 10⁸ m³ loosened material, which led to debris flows after the earthquake. Debris flows are the dominant mountain hazards, and serious threat to lives, properties, buildings, traffic, and post-earthquake reconstruction in the earthquake-hit areas. It is very important to understand the debris flow initiation processes and characteristics, for designing debris flow mitigation. The main objective of this article is to examine the different debris flow initiation processes in order to identify suitable mitigation strategies. Three types of debris flow initiation processes were identified (designated as Types A, B, and C) by field survey and experiments. In “A” type initiation, the debris flow forms as a result of dam failure in the process of rill erosion, slope failure, landslide dam, or dam failure. This type of debris flow occurs at the slope of 10 ± 2°, with a high bulk density, and several surges following dam failure. “B” type initiation is the result of a gradual increase in headward down cutting, bank and lateral erosion, and then large amount of loose material interfusion into water flow, which increases the bulk density, and forms the debris flow. This type of debris flow occurs mainly on slopes of 15 ± 3° without surges. “C” type debris flow results from slope failures by surface flow, infiltration, loose material crack, slope failure, and fluidization. This type of debris flow occurs mainly on slopes of 21 ± 4°, and has several surges of debris flow following slope failure, and a high bulk density. To minimize the hazards from debris flows in areas affected by the Wenchuan earthquake, the erosion control measures, such as the construction of grid dams, slope failure control measures, the construction of storage sediment dams, and the drainage measures, such as construction of drainage ditches are proposed. Based on our results, it is recommend that the control measures should be chosen based on the debris flow initiation type, which affects the peak discharge, bulk density and the discharge process. The mitigation strategies discussed in this paper are based on experimental simulations of the debris flows in the Weijia, Huashiban, and Xijia gullies of old Beichuan city. The results are useful for post-disaster reconstruction and recovery, as well as for preventing similar geohazards in the future.  相似文献