Diffusive Reactive Transport of Multicomponent Chemicals Under Coupled Thermal, Hydraulic, Chemical and Mechanical Conditions

This paper presents an investigation of the reactive transport of multicomponent chemicals in clays under coupled thermal, hydraulic, chemical and mechanical framework, considering the diffusion processes in detail. More specifically, combined effects due to the electrochemical and the thermal diffusion potentials are investigated. A theoretical framework for coupling thermal diffusion, i.e. the Soret effect, with electrochemical diffusion in a multi-ionic system is provided. An explicit form of a definition for the thermal diffusion coefficient in a multicomponent chemical transport model is developed. Chemical transport is linked to an advanced geochemical model, PHREEQC (version 2), in order to include chemical reactions. The effects of the combined diffusion potentials on the reactive transport of multicomponent chemicals are investigated by a series of numerical simulations of coupled thermal, hydraulic and chemical behaviour.     

Effects of road-deicing salt (NaCl) and saline water on water quality in the Urmia area,northwest of Iran

Increased application of road salt for winter maintenance has resulted in increased concentration of deicer constituents in the environment. The runoffs from the deicing operation have a deteriorating effect on water quality. The existence of salt super saturated Urmia lake and easy access to it, causes Urmia municipality to over use the super saturated water of this lake and salt (NaCl) during winter for snow melting, freezing prevention and traffic load facilitation. The aim of this study was investigation of surface and groundwater contaminations in consequence of salt (NaCl) and saline water usage in Urmia city and its surroundings. Studying the chloride ion concentration as a tracer in runoff result snowmelts during winter shows that its amount is differential with respect to time and place sampling. Results indicate that runoff result of snowmelts effected groundwater, soil and plant growth. The contamination of groundwater in study area by road salt and saline water is a slow process and directly related to the amount of road salt and saline water applied.     

Using combined AHP–genetic algorithm in artificial groundwater recharge site selection of Gareh Bygone Plain,Iran

Flood spreading is one of the suitable strategies to control and benefit from floods which in turn improve the groundwater recharge, makes soil more fertile, and increases nutrients in soil. It is also a method for reusing sediment, which is usually wasted. Thus, selection of suitable areas for flood spreading and directing the flood water into permeable formations are amongst the most effective strategies in flood spreading projects. Having combined analytic hierarchy process (AHP) of multi-criteria decision analysis and genetic algorithm (GA) of artificial intelligence approaches, this paper addresses the problem of finding the most suitable area location for flood spreading operation in the Gareh Bygone Plain of Iran. To this end, the nine effective geodata layers including slope, alluvium thickness, geology, morphology, electrical conductivity, land use, drainage density, aquifer transmissivity, and elevation were prepared in geographic information system environment. This stage was followed by elimination of the exclusionary areas for flood spreading while determining the potentially suitable ones. Having closely examined the potentially suitable areas using the proposed methodology, the land suitability map for flood spreading was produced. The AHP and GA were used for ranking all the alternatives and weighting the criteria involved, respectively. The results of the study showed that most suitable areas for the artificial groundwater recharge are located in Quaternary Qft ₂ and Qsf geologic units and in morphological units of pediment and Alluvial fans with slopes not exceeding 2 %. Finally, further evidence for the acceptable efficiency of the integrated AHP–GA method in locating most suitable flood spreading areas have been provided by such significant spatial coincidence between the produced map and the control areas located near Kowsar research station, where the earlier flood spreading projects were successfully performed.     

Effects of sheet flow rate and slope gradient on sediment load

Sheet erosion is known as one of the most important forms of erosion, particularly in agricultural land. The purpose of this study was to investigate the effect of flow rate and slope gradient on runoff and sediment discharges in two different soils. Experiments were conducted using a tilting flume facility with the test area of 0.2?×?1.0 m. Overall, 24 experiments on two soils (clay loam and sandy clay loam textures) including six flow rates (75, 100, 125, 150, 175, and 200 ml/s) and two slope gradients (1.5 and 2 %) were performed. The selected flow rates and flume slopes were generated to simulate sheet erosion. The results showed that for both soils and slopes, unit flow discharge (q) and sediment concentration increased with increasing flow rate; however, the effect of slope gradient on flow discharge depends on soil type. In addition, sandy clay loam exhibited higher values of q and sediment concentration and consequently, it showed greater amounts of sediment load. At the start of event, sediment concentration was high but it decreased to approach a steady state. In addition, the time needed to reach a steady state condition was shorter for sandy clay loam than that for clay loam soil and in lower flow rates than higher flow rates. For each soil and slope, there was a direct relationship between sediment load and flow rate. The result implied that the effect of slope gradient on sediment load was almost greater in sandy clay loam soil than clay loam soil. Moreover, the differences between sediment loads of two soils are enlarged at slope 2 %.     

Competitive heavy metals adsorption on natural bed sediments of Jajrood River,Iran

The presence of heavy metal concentrations was examined in natural sediments from four sites along the Jajrood river in northeast of Tehran, the capital of Iran. Besides determination of elemental concentrations (Pb, Cu, Zn, Cd, Ni and Cr), X-ray fluorescence and X-ray diffraction tests were carried out to determine other chemical components in these adsorbents. Also the ability of sediments to adsorb these heavy metal ions from aqueous solutions was investigated. Results show that the extent of adsorption increases with increase in adsorbent concentration. The amount of adsorbed Pb, Cu and Zn in sediments was much greater than that of the other metals, and Cr was adsorbed much less than others. The adsorbabilities of sediments to heavy metals increased in the order of Pb > Cu > Zn > Cd > Ni > Cr. Based on the adsorption data, equilibrium isotherms were determined at selected areas to characterize the adsorption process. The adsorption data followed Freundlich and Langmuir isotherms in most cases. Correlation and cluster analysis was performed on heavy metals adsorption and sediment components at each site to evaluate main adsorbing compounds in sediments for each metal. Results demonstrated that heavy metals sorption is mostly related to load of organic matter in the Jajrood river sediments.     

Sorption of lead on Iranian bentonite and zeolite: kinetics and isotherms

This study deals with the use of the natural, low-cost sorbents bentonite and zeolite for the removal of lead from aqueous solutions. The mineral material is from large deposits of bentonite and zeolite that have been discovered recently in Iran. Experimental and modeling data from our kinetic and equilibrium investigations reveal that (1) the pseudo-second-order kinetic model gave the best fit, and (2) the Koble–Corrigan sorption model describes the interaction between Pb(II) and the two mineral materials better than the Freundlich and Langmuir models. However, the sorption of Pb(II) ions by zeolite and bentonite is complex and probably involves several mechanisms. The experimental data show that natural zeolite and bentonite used in this study exhibited a reasonable sorption capacity for Pb(II), and thus may be useful for the immobilization of Pb(II) from polluted sites.     

Seismic microzonation for Penang using geospatial contour mapping

Shear wave velocity (V _s) and the fundamental site period of the subsurface condition are the primary parameters that affect seismic soil amplification in particular sites. Within the topmost layer of the soil, which measures 30 m, the average shear wave velocity V _s30 is commonly used to build codes for site classification for the design of earthquake-resistant structures and to conduct microzonation studies. In this study, the development of a microzonation map for V _s30 distribution, National Earthquake Hazard Reduction Program V _s30 site classification, and a fundamental site period for Penang are presented. The multichannel analysis of surface wave (MASW) test was conducted for more than 50 sites with available borehole data to develop the microzonation maps. The ten selected V _s profiles measured by MASW show a good correlation with the data obtained using empirical correlations in a previous study. The highest V _s values were identified at the northeastern and southeastern parts of Penang Island, corresponding to the shallow bedrock and the outcrop zone. Conversely, the lowest V _s values were found in the northwestern and southwestern parts of the Penang mainland owing to the thick layer of soft clay and silt deposits. The site period map shows the variation in site periods, with the highest value of 1.03 s at the western part of the Penang mainland and the lowest value of 0.02 s at the eastern part of the Penang Island. The microzonation maps developed in this study are vital to studies on seismic hazard and earthquake mitigation programs in Malaysia.     

Sorkhe‐Dizaj Iron Oxide–Apatite Ore Deposit in the Cenozoic Alborz‐Azarbaijan Magmatic Belt,NW Iran

The Sorkhe‐Dizaj iron oxide–apatite deposit in the Cenozoic Alborz‐Azarbaijan magmatic belt, NW Iran, is hosted mainly by a Late Eocene to Oligocene quartz‐monzonitic body, and subordinately in the Eocene volcanic and volcanoclastic sequences. The Sorkhe‐Dizaj intrusive body is an I‐type granitoid of the calc‐alkaline series. Mineralization is associated with actinolization, K‐feldspar, sericitic, propylitic, and tourmaline alteration types. The orebodies are massive, banded, stockwork, and breccia in shape and occur mainly along the fault zones within the quartz‐monzonitic intrusion, volcanic, and volcanoclastic rocks. Ore minerals dominantly comprise magnetite, apatite, and monazite, as well as minor amounts of chalcopyrite, bornite, and pyrite. Four major paragenetic stages are discriminated in the mineralization including early, oxide, sulfide, and late stage. The Sorkhe‐Dizaj deposit is similar in the aspects of host rock lithology, alteration, and mineralogy to the Kiruna‐type deposits associated with minor Cu sulfide minerals. Spatial and temporal association of the mineralization with the Late Eocene–Early Oligocene quartz‐monzonite intrusive body suggests that the ore fluid was probably related to magmatic activity.     

Effects of windy sand and LECA mulches on decreasing evaporation from soil surface

Inadequate moisture supply is one of the important factors limiting crop yields in the world. Increasing the efficiency of moisture available has an important role on the crop-producing capacity of the soil. This paper presents the results of the laboratory experiments conducted to assess the influence of two mulches of windy sand and light expanded clay aggregate (LECA) with three thicknesses (1, 3, and 4 cm) on soil surface in soil columns. Loamy soil was taken from the experimental site in Bayaz of Rafsanjan (a city in Kerman province in Iran). These experiments were done as completely randomized design with two treatments of mulches (windy sand and LECA) and tree replicates. The results show that the columns of treated soil with mulches had lower evaporation as compared to the control. The rate of evaporation from the soil surface of columns was decreased with increasing the thickness from 1 to 4 cm of each of the two mulches. The LECA mulch was more effective in reducing evaporation from the soil surface than the windy sand mulch with the same thicknesses. The most effective among the thicknesses for mulches was 3 cm.