Determining ammonia nitrogen decay rate of Malaysian river water in a laboratory flume     

M. Nuruzzaman  A. A. Mamun  M. N. B. Salleh 《International Journal of Environmental Science and Technology》2018,15(6):1249-1256

There is lack of information regarding ammonia nitrogen (AN), (i.e. NH₃-N) decay rate of river water in tropical regions like Malaysia. AN decay rate is a very important kinetic parameter to estimate NH₃-N, nitrate nitrogen (NO₃-N) and dissolved oxygen concentrations of river water by using computer models. This study presents determination of ammonia nitrogen decay rate of river water in the tropical environment of Malaysia. A laboratory flume was used to conduct twelve experiments. The flume was used to represent the turbulent condition of a typical river. Ammonia nitrogen decay rate for the tropical environment of Malaysia was observed to be between 0.194 and 0.554 per day. Median value of AN decay rate was 0.26 per day, which is slightly lower than the global median value of 0.295 per day. To check the accuracy of flume experiments, the AN decay rate of Pusu River obtained from the flume experiment was used to calibrate and validate ammonia nitrogen concentration of the river by using water quality analysis and simulation program (WASP). Very good calibration and validation results were achieved, which substantiated the accuracy of the flume experiments.  相似文献   

Green synthesis of magnetic mesoporous silica nanocomposite and its adsorptive performance against organochlorine pesticides     

W. A. El-Said  D. M. Fouad  M. H. Ali  M. A. El-Gahami 《International Journal of Environmental Science and Technology》2018,15(8):1731-1744

Green synthesis of nanomaterials has received increasing attention as an eco-friendly technology in materials science. Here, we have used two types of extractions from green tea leaf (i.e., total extraction and tannin extraction) as reducing agents for a rapid, simple and one-step synthesis method of mesoporous silica nanoparticles/iron oxide nanocomposite based on deposition of iron oxide onto mesoporous silica nanoparticles. Mesoporous silica nanoparticles/iron oxide nanocomposite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray, vibrating sample magnetometer, N₂ adsorption and high-resolution transmission electron microscopy. Mesoporous silica nanoparticles/iron oxide nanocomposite was used as a solid adsorbent for removal of lindane pesticide from aqueous solutions. The developed system possesses the advantages of silica as core that include large surface area and advantages of iron oxide (shell) that include the capability to interact with chlorinated compounds and ability to release by using external magnetic field. UV-Vis technique was used as a simple and easy method for monitoring the removal of lindane. Effects of pH and temperature on the removal efficiency of the developed mesoporous silica nanoparticles/iron oxide nanocomposite toward lindane pesticide were also investigated. Fourier transform infrared spectroscopy, high-performance liquid chromatography and gas chromatography techniques were used to confirm the high ability of mesoporous silica nanoparticles/iron oxide nanocomposite for sensing and the capture of lindane molecules with high sorption capacity (about 99%) that could develop a new eco-friendly strategy for detection and removal of pesticide and as a promising material for water treatment.  相似文献   

Electrical analogy for modelling thermal regime and moisture distribution in sandy soils     

Somenath Mondal  Vikas Sharma  P. Apte 《Geomechanics and Geoengineering》2018,13(1):22-32

The soil mass is subjected to temperature variation due to several human activities (viz. tanks storing heated fluids, buried cables and pipelines, air-conditioning ducts, disposal of nuclear and thermal power plant wastes etc.), which result in heat-induced migration of the moisture in it. Though several studies have been conducted in the past to investigate the mechanism of heat migration through the soil mass, a methodology for ‘real-time measurement of the variations in temperature, flux and moving moisture front, in tandem, with respect to space' has rarely been attempted. In this context, extensive laboratory investigations were conducted to measure real-time flux and temperature variations in the sandy soils, and the validation of results has been done by employing an equivalent electrical circuit programme, LTspice. Subsequently, a mathematical model PHITMDS (i.e. Prediction of Heat-Induced Temperature and Moisture Distribution in Soil) has been developed and its utility and efficacy, for predicting the depth-wise temperature and heat-induced moisture migration, due to evaporation, in terms of position of moving moisture front in the sandy soil has been critically discussed and demonstrated.  相似文献   

Helical probe tests in residual soils of the Appalachian Piedmont     

Shehab S. Agaiby  Zhongkun Ouyang  Paul W. Mayne 《Geomechanics and Geoengineering》2018,13(3):217-225

Helical probe tests (HPT) are a quick and economical means for manual field testing of soils to depths of 1.5 m with readings taken at 0.15-m intervals in only 10 min. The equipment is lightweight (only 2 kg) and thus amenable to deploy on initial site reconnaissance explorations, shallow pavement projects, earth retention walls, and/or compaction of fills. Although suitable for use in a variety of geomaterials: sands, silts, clays, and mixed soils, the specific application to residual fine sandy silts and silty fine sands of the Appalachian Piedmont and Blue Ridge geologic provinces is shown here. Existing relationships for converting the measured HPT torque reading to equivalent cone penetration testing (CPT) tip resistances are reviewed, as well as other trends.  相似文献   

Factors influencing undrained strength of fine-grained soils at high water contents     

H. B. Nagaraj  M. V. Sravan  B. S. Deepa 《Geomechanics and Geoengineering》2018,13(4):276-287

Understanding the undrained strength of fine-grained soils has been of interest to geotechnical researchers from many practical considerations. In several civil engineering applications, water content of soil is quite high being near or above the liquid limit of soils, and understanding the factors responsible for imparting the strength of soil at high water contents is of great significance. Recently, it has been reported in the literature that the shear strength of soils at these limiting water contents has significant variation. However, the reasons and the factors that probably influence for this variation have not been reported in the literature. This experimental investigation is an attempt in the direction of understanding the reasons for the variation in the undrained strength at higher limiting water content, namely liquid limit considering the various influencing factors like clay mineralogy and fine-sand content present in soil used for determining liquid limit. The results from this study are quite revealing and have been explained based on the mechanisms controlling the undrained strength at liquid limit.  相似文献   

Landfill site selection based on reliability concepts using the DRASTIC method and AHP integrated with GIS – a case study of Bengaluru city,India     

L. G. Santhosh  G. L. Sivakumar Babu 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2018,12(3):234-252

The selection of landfill sites for municipal solid waste (MSW) disposal involves consideration of geological, hydrological and environmental parameters which exhibit large spatial variability. Therefore, it is necessary to define, to what extent the chosen sites are reliable such that the probability of environmental pollution and health risks to population is minimal. In the present study, groundwater vulnerability to contamination has been assessed using the standard DRASTIC method. The results showed that the study region has 9.45% of very less, 32.94% of less, 25.47% of moderate, 22.79% of high and 9.35% of very high vulnerable zones. The study also revealed that none of the landfills are located in safe zones. This suggests that it requires proper remedial measures to avoid environmental pollution. A landfill site selection process has been carried out using the Analytical Hierarchy Process integrated with Geographical Information System tools. The obtained results showed that only 3.59?km² (0.08%) of the total area is suitable for landfills. The reliability analysis of the site suitability revealed that landfills are located at unreliable locations where the probability of risk to environmental pollution is high. The presented approach assists decision-makers in selecting reliable locations for the safe disposal of MSW.  相似文献   

SPH approach for simulating hydro-mechanical processes with large deformations and variable permeabilities     

M. Gholami Korzani  S. A. Galindo-Torres  A. Scheuermann  D. J. Williams 《Acta Geotechnica》2018,13(2):303-316

A simulation framework based on Smoothed Particle Hydrodynamics (SPH) is introduced to model problems involving the interaction between flowing water and soil deformation. Changes in soil porosity and associated permeability are automatically adjusted within this framework. The framework’s capabilities are presented and discussed for three geotechnical problems caused by flowing water. The comparison between simulation results and experiments shows that SPH with the proposed concept is capable of quantitatively simulating the hydro-mechanical processes beyond limit state with satisfactory agreement. To improve the computational stability, a correction procedure and a new algorithm for the selection of the optimal time step are introduced.  相似文献   

Toxic metals in a highly urbanized industry-impacted estuary (Bahia Blanca Estuary,Argentina): spatio-temporal analysis based on GIS     

Melisa Daiana Fernández Severini  María Elizabeth Carbone  Diana Mariel Villagran  Jorge Eduardo Marcovecchio 《Environmental Earth Sciences》2018,77(10):393

Cadmium, chromium, nickel, and lead were evaluated in the particulate fraction at one of the most industrialized estuaries at the Southwestern Atlantic Ocean, through Geographic Information System (GIS). Concentrations were analyzed at 21 stations during 2008–2010. The highest metal concentrations (Cd: 8,9; Cr: 256,49; Ni: 27,02; Pb: 78,43 µg g^??1 d. w.) were recorded at the stations located near industrial and urban discharges situated along the estuary. In addition, Pb presented a different seasonal and spatial behavior in comparison with Cd, Cr and Ni. Winter and spring presented the higher concentrations of Pb, and the inner stations presented the higher values. The estuary is considered a moderate to strongly polluted and significantly polluted according to the Index of geoaccumulation (I_geo) and the Enrichment Factor of Cd, respectively. The Multidimensional Scaling plot showed three groups of stations: the inner, associated to low levels of metals (G1), middle stations (G2) with intermediate levels and the outer (G3) with the highest ones. In addition, this work reveals the usefulness of the GIS-mapping techniques in the distribution of pollutants along an estuarine environment and the environmental quality assessment of estuarine systems.  相似文献   

Assessing LNRF,FR, and AHP models in landslide susceptibility mapping index: a comparative study of Nojian watershed in Lorestan province,Iran     

M. Abedini  S. Tulabi 《Environmental Earth Sciences》2018,77(11):405

Landslides and slope instabilities are major risks for human activities which often lead to economic losses and human fatalities all over the world. The main purpose of this study is to evaluate and compare the results of Landslide Nominal Risk Factor (LNRF), Frequency Ratio (FR), and Analytical Hierarchy Process (AHP) models in mapping Landslide Susceptibility Index (LSI). The study case, Nojian watershed with an area of 344.91 km², is located in Lorestan province of Iran. The procedure was as follows: first, the effective factors of the landslide basin were prepared for each layer in the GIS software. Then, the layers and the landslides of the basin were also prepared using aerial photographs, satellite images, and fieldwork. Next, the effective factors of the layers were overlapped with the map of landslide distribution to specify the role of units in such distribution. Finally, nine factors including lithology, slope, aspect, altitude, distance from the fault, distance from river, fault land use, rainfall, and altitude were found to be effective elements in landslide occurrence of the basin. The final maps of LSI were prepared based on seven factors using LNRF, FR, and AHP models in GIS. The index of the quality sum (Qs) was also used to assess the accuracy of the LSI maps. The results of the three models with LNRF (40%), FR (39%), and AHP (44%) indicated that the whole study area was located in the classes of high to very high hazard. The Qs values for the three models above were also found to be 0.51, 0.70 and 0.70, respectively. In comparison, according to the amount of Qs, the results of AHP and FR models have slightly better performed than the LNRF model in determining the LSI maps in the study area. Finally, the study watershed was classified into five classes based on LSI as very low, low, moderate, high, and very high. The landslide susceptibility maps can be helpful to select sites and mitigate landslide hazards in the study area and the regions with similar conditions.  相似文献   

Bioaccumulation of heavy metals in <Emphasis Type="Italic">Limnobium laevigatum</Emphasis> and <Emphasis Type="Italic">Ludwigia peploides</Emphasis>: their phytoremediation potential in water contaminated with heavy metals     

M. Rocío Fernández San Juan  Carolina B. Albornoz  Karen Larsen  Roberto Najle 《Environmental Earth Sciences》2018,77(11):404

Contamination with heavy metals in surface and groundwater is a threat to human health and ecosystems. Due to this, the need arises to remediate water polluted through ecological and profitable technologies, such as phytoremediation. The objective of the work was to evaluate the concentration of lead (Pb) and zinc (Zn) in the floating macrophytes Limnobium laevigatum and Ludwigia peploides, after being exposed to contaminated water experimentally. In this way to be able to determine if these plants have mechanisms that allow them to accumulate the metals in the roots and to perform the translocation of these to different vegetative organs, L. laevigatum and L. peploides were placed in solutions contaminated with Pb ([Pb]?=?5 mg/l) and Zn ([Zn]?=?20 mg/l). The concentrations of metals in water, root and leaf samples were evaluated as a function of time (0, 1, 2 and 4 days). The determination of the metals was performed by the atomic absorption spectrophotometry technique. After 4 days of exposure to Pb and Zn, the plants showed high metal removal efficiencies of water, more to 70% in all cases. Pb was accumulated fundamentally by roots, while Zn was accumulated more in the leaves. In addition, the bioconcentration and translocation factors for each metal were calculated.  相似文献