New climatic zones in Iran: a comparative study of different empirical methods and clustering technique

Theoretical and Applied Climatology - Recently in agricultural and industrial sectors, researchers have started to classify the climate of a region using empirical methods and clustering. This...     

Studies on the recovery of uranium from nuclear industrial effluent using nanoporous silica adsorbent

In this paper, the sorption of uranium onto nanoporous silica adsorbent in the presence of nitrate, sulfate, chloride, fluoride and phosphate was studied. The effect of contact time between the nanoporous sorbent and aqueous solution, pH and initial concentration of uranium was also investigated. Uranium sorption onto nanoporous silica adsorbent is a very fast process as sorption rate increases with pH increment. Optimum pH for uranium sorption was 4?C8. Experimental sorption isotherm is successfully described by Langmuir and Freundlich models. The results obtained by batch experiments showed that the presence of high concentration of nitrate, sulfate, chloride and phosphate anions alone had no interference with uranium recovery. However, the presence of fluoride ions (>250?mg/L) decreases uranium sorption by about 55?%. The results also showed that the presence of phosphate ions (about 300?mg/L) in solution could remove fluoride interference completely. Finally, the efficiency of the nanoporous silica adsorbent for uranium recovery from wastewater of the uranium conversion facility was investigated.     

Surficial deposits on salt diapirs (Zagros Mountains and Persian Gulf Platform, Iran): Characterization, evolution, erosion and the influence on landscape morphology

The surfaces of salt diapirs in the Zagros Mountains are mostly covered by surficial deposits, which significantly affect erosion rates, salt karst evolution, land use and the density of the vegetation cover. Eleven salt diapirs were selected for the study of surficial deposits in order to cover variability in the geology, morphology and climate in a majority of the diapirs in the Zagros Mountains and Persian Gulf Platform. The chemical and mineralogical compositions of 80 selected samples were studied mainly by X-ray powder diffraction and X-ray fluorescence. Changes in salinity along selected vertical profiles were studied together with the halite and gypsum distribution. The subaerial residuum formed from minerals and rock detritus released from the dissolved rock salt is by far the most abundant material on the diapirs. Fluvial sediments derived from this type of residuum are the second most common deposits found, while submarine residuum and marine sediments have only local importance. The mineralogical/chemical composition of surficial deposits varies amongst the three end members: evaporite minerals (gypsum/anhydrite and minor halite), carbonates (dolomite and calcite) and silicates-oxides (mainly quartz, phyllosilicates, and hematite). Based on infiltration tests on different types of surficial deposits, most of the rainwater will infiltrate, while overland flow predominates on rock salt exposures. Recharge concentration and thick accumulations of fine sediment support relatively rich vegetation cover in some places and even enable local agricultural activity. The source material, diapir relief, climatic conditions and vegetation cover were found to be the main factors affecting the development and erosion of surficial deposits. A difference was found in residuum type and landscape morphology between the relatively humid NW part of the studied area and the arid Persian Gulf coast: In the NW, the medium and thick residuum seems to be stable under current climatic conditions. Large sinkholes and blind valleys with sinking streams are common. On other diapirs, the original thick residuum is undergoing erosion and the new morphology is currently represented by salt exposures and badland-like landscapes or by fields of small sinkholes developed in the thin residuum. Models for evolution of the subaerial residuum and the diapir landscape/morphology are described in this paper. While the thick residuum with vegetation has very low erosion rates, the salt exposures and thin residuum are eroded rapidly. During wet periods (e.g. early Holocene), the diapirs rose and salt glaciers expanded as the influx of salt mass was much faster compared to erosion. After the onset of an arid climate, c. 6 ka BP, the rising of the some diapir surfaces decreased or even reversed due to acceleration of erosion thanks to vegetation degradation and changes in the residuum type and thickness.     

The role of blocking system in heavy precipitation of Iran (a case study: southeast of Iran January 2008)

This article concerns the analysis of the heavy precipitation, which allows investigating the effect of the blocking system on the unusual precipitation and temperature occurrence in Iran. The days of January 2008 have been the coldest days during the history of recorded data in Iran. Variation of precipitation during January 2008 compared with long-term data (30 years) shows the maximum positive anomaly in the stations located in southeast of Iran. However, the precipitation in consecutive days, 14–15 and 15–16 of January, produce a more important proportion of the heavy precipitation in this region. In order to study the role of the blocking system related to heavy precipitation in January 2008, the position and movement of the atmospheric systems including cyclones, anticyclones, fronts, and wind fields have been analyzed by the use of synoptic maps by the environment to circulation approach. Consequently, the weather maps indicated that the blocking system over the north of the Caspian Sea has caused the relatively deep low trough on January 5, 7, 14, 15, and 16, 2008, while the thermal and moisture gradients in the warm section of air masses have produced heavy precipitation. As a result, wind field of low levels (850 hPa) provided remarkable moisture fed by the Arabian Sea, Oman Sea, and Persian Gulf in the study area. Furthermore, the speed of wavelength and the position of the blocking system associated with the heavy precipitation can be clearly identified.     

Flood susceptibility mapping using frequency ratio and weights-of-evidence models in the Golastan Province,Iran

Flood is one of the most devastating natural disasters with socio-economic and environmental consequences. Thus, comprehensive flood management is essential to reduce the flood effects on human lives and livelihoods. The main goal of this study was to investigate the application of the frequency ratio (FR) and weights-of-evidence (WofE) models for flood susceptibility mapping in the Golestan Province, Iran. At first, a flood inventory map was prepared using Iranian Water Resources Department and extensive field surveys. In total, 144 flood locations were identified in the study area. Of these, 101 (70%) floods were randomly selected as training data and the remaining 43 (30%) cases were used for the validation purposes. In the next step, flood conditioning factors such as lithology, land-use, distance from rivers, soil texture, slope angle, slope aspect, plan curvature, topographic wetness index (TWI) and altitude were prepared from the spatial database. Subsequently, the receiver operating characteristic (ROC) curves were drawn for produced flood susceptibility maps and the area under the curves (AUCs) was computed. The final results indicated that the FR (AUC = 76.47%) and WofE (AUC = 74.74%) models have almost similar and reasonable results. Therefore, these flood susceptibility maps can be useful for researchers and planner in flood mitigation strategies.     

Alkaline basalt from the Central Iran, a mark of previously subducted Paleo-Tethys oceanic crust

In western part of the CEIM (Central-East Iranian Microcontinent) (Bayazeh area, Isfahan province, Iran), a series of Paleozoic basaltic rocks, occur. Major minerals of these basalts are olivine, clinopyroxene (diopside, augite), plagioclase (albite), sanidine, amphibole (kaersutite), phlogopite, ilmenite and magnetite. Secondary minerals include epidote, pumpellyite, albite, calcite and chlorite. Olivine and clinopyroxene are as phenocryst, while feldspars are restricted to groundmass. Chemical composition of clinopyroxenes indicates crystallization during ascending of magma. Geochemical analysis of whole rock samples shows that these rocks are characterized by low SiO₂ (43.21–48.45 wt %), high TiO₂ (1.81–3.00 wt %) and P₂O₅ (0.18–0.34 wt %). Petrography, chemistry of clinopyroxenes and whole rock analyses reveal an alkaline nature of these basalts. They are enriched in alkalis (Na₂O + K₂O = 4.1–7.7 wt %), LILE, HFSE and LREE. The Bayazeh alkali-basalts present strong enrichment in LREE relative to HREE (La/Lu ratio = 77.6–119.6) and were dominantly derived from partial melting of a metasomatized asthenospheric garnet-amphibole lherzolite. Field relationships reveal that junction of faults in west of the Bayazeh prepared a suitable path for ascending of magma from deep regions to surface and intra-plate continental magmatism. The Paleo-Tethys subduction from lower to upper Paleozoic is too enough for mantle enrichment in volatiles and basaltic alkaline magmatisrn in upper Paleozoic of Bayazeh area.     

Copper isotope fractionation in the Meiduk porphyry copper deposit,Northwest of Kerman Cenozoic magmatic arc,Iran

The Meiduk deposit possesses three different Cu reservoirs each with a unique Cu isotope signature. δ⁶⁵Cu for the leached cap minerals ranges from ?2.5 to +0.49‰ to ?0.45 to +0.3‰ for hypogene minerals and from +1.3 to +4.4‰ for supergene enrichment minerals. Oxidation of hypogene sulphides and effective trapping of copper (from solutions derived from the leached cap) in the supergene enrichment zone caused this relationship. A systematic pattern of low Cu isotope values close to the surface and higher isotope values with depth reveals a palaeo‐fluid pathway in the northwest–southeast direction over the deposit. Thus, the copper isotope data from leached cap and enrichment minerals can be used to monitor copper migration during supergene weathering at the Meiduk deposit.     

Anthropogenic activities amplify wildfire occurrence in the Zagros eco-region of western Iran

Natural Hazards - The aim of this study was to improve our understanding of factors that affect the spatial distribution of wildfire occurrences at the regional scale. We employed the random...     

Compounding effects of human activities and climatic changes on surface water availability in Iran

Climatic Change - By combining long-term ground-based data on water withdrawal with climate model projections, this study quantifies the compounding effects of human activities and climate change...     

Intense extreme hydro-climatic events take a toll on society

Natural Hazards - In March 2019, the Iranian meteorological organization warned of the formation of several dense precipitation systems throughout the country. This was followed by a chain of storm...