جستجوی مقالات مرتبط با کلیدواژه « منشا » در نشریات گروه « علوم پایه »

Plant pests including insects, mites, fungi, bacteria, viruses, viroids, nematodes, phytoplasmas and weeds cause a lot of damage to the plants annually. These agents can enter the country in different ways, including: Transmission by human and animal food, plant reproductive organs such as seeds, saplings, cuttings, offshoots propagation, onions and tubers, transmission by domestic and wild animals, by water, transmission by scientific research, by transportation vehicles and bioterrorism purposes. The entry of these agents can have important consequences, including: Important economic consequences due to direct damage or the cost of chemical control, political consequences due to food, industrial and scientific dependence, social consequences due to decrease in social welfare, migration to cities and job insecurity, diet change, environmental consequences due to changes in flora, environmental pollution due to the use of pesticides and physical presence of the pest, changing water and soil conditions. Methods of prevention and control of these agents are done in several ways at several levels. Plant quarantine is one of the main and most important ways to prevent damage by these agents, if this principle is not fulfilled, in the next step of control, more activity and cost are needed to control the harmful agent.

Geochemical composition and uranium occurrences in Tahlab aquifer, southeastern Iran, were studied in order to understand the source of U and geochemical processes controlling chemistry of Tahlab aquifer. Also the contamination and health risk assessment of uranium for drinking purposes in 16 sampling wells were investigated. Sulfate, Cl, K and EC for all water samples reveal higher concentrations than the drinking water standard values. Piper diagram of major ions indicated that the water is mostly Na-SO4-Cl type with sulfate and sodium as the dominant anion and cation respectively. The hydrogochemical signature of the investigated groundwater samples suggests that they are mostly affected by a hydrothermal source related to deep circulation waters from Taftan volcano. The results of saturation index (SI) show that the Tahlab aquifer groundwater samples are oversaturated with respect to quartz, chalcedony, hematite, uraninite (68.75% of samples), caffinite (43.75) and U4O9 (31.25%). Principal component analysis (PCA) results and high positive factor loading of U, V, HCO3 and Si revealed that the geogenic activities were major source of uranium in Tahlab aquifer and suggests that the U concentration is controlled by Si-bearing minerals. The results of hazard quotient (HQ) for adults were higher than one in the 81.25% of the groundwater samples, indicating that groundwater of this area may not be safe for drinking purposes. Health risk assessment shows that the consumption of uranium contaminated groundwater poses an emerging health threat to the populations in the study area, and hence needs regular monitoring and management measures.

Currently, nCoV-2019 has affected more than 100 countries around the world, including Iran. This widespread epidemic has caused concern in the scientific and medical community because little information is available about the new virus and there is no specific treatment for it. Therefore, in this article we tried to give deeper information about virus of possible origin of the new coronavirus and its relationship with other previous coronaviruses. So, the mechanism of virus entry into the human cell and the factors involved in this process, such as virus proteins, are described. Other information presented here includes clinical signs of the disease and laboratory methods for detecting the virus, the stability of the virus at different levels, the zoonotic transmission, preventive measures such as strengthening the immune system and and treatment strategies such as plasma therapy. Also, this study provides evidence of amino acid changes in genomic specimens, the creation of new species, and the possibility that the virus may develop or be laboratory. Finally, some of the issues that remain unclear are discussed here.

The presence of potentially toxic elements in the environment and especially in soil has been one of the greatest concerns due to their health implications. Potentially toxic elements from anthropogenic sources tend to be more mobile than those from lithogenic or pedogenic sources. Generally, the distribution of potentially toxic elements is influenced by the nature of parent materials, climatic conditions, and their relative mobility depending on soil parameters, such as mineralogy, texture and class of soil. In the inhabited, and industrial areas, vicinity to the un-engineered landfills, excess accumulation of toxic elements in surface soils can directly threaten wellbeing of exposed inhabitants via ingestion, inhalation and dermal contact routes. A few studies conducted on risk assessment of potentially toxic elements in soils of Kermanshah province, west of Iran. Soil in the study area is susceptible to contamination by anthropogenic activities in the form of industrial wastewater, agricultural activities, solid waste, runoff, atmospheric deposition and especially un-engineered landfills. The presence of toxic elements in soil around of un-engineered landfills without proper consideration to the environmental protection measures, will certainly lead to a significant environmental hazard in Kermanshah province. Therefore, the main purposes of this study are to evaluate the contamination levels, health risk assessment, and source identification of As, Cd, Cr, Cu, Ni, Pb and Zn in the Gasre Shirin, Gilane Gharb, Paveh, Javanrood, Eslamshahr, Ravansar, Kermanshah and Sanghar un-engineered landfills.
Material and A total of 30 topsoil samples were collected (0-20 cm depth) from the eight un-engineered landfills of the Kermanshah province. In order to achieve a representative sample, composite samples were prepared by mixing the four subsamples taken at each corners of 2×2 m square cell because composite sampling yields homogenized samples for analyses. The subsamples were mixed and a final sample of 1 kg was taken by repeated coning and quartering. To determine background concentration of heavy metals, eight soil samples were collected from areas far from known sources of contamination (40-60 cm depth).
The collected samples were immediately stored in polyethylene bags and air-dried in the laboratory at room temperature. Then, samples passed through a 2mm stainless steel sieve. The 1, it is likely that there will be adverse health effects, whereas if the ADD is less than the RfD, HQ1 show possible adverse health effects. Carcinogenic risk is regarded as the probability of an individual developing any type of cancer in the whole life time due to exposure to carcinogenic hazards and was calculated for As and Cd as follows: (1) The value of SF represents the probability of developing cancer per unit exposure level of mg/kg day. The acceptable risk range for carcinogens is set to 10-6 to by the USEPA, so that RI values below 10-6 do not require further action, while risks greater than 10-4 are considered to be of concern and require additional action to reduce the exposure and resulting risk.
The soil pH ranges from 7.01 to 8.06, with an average value of 7.51 suggesting neutral conditions. Organic carbon (OC) contents of soil samples ranged from 0.06% to 4.91% (average 1.59%). In this study, based on the USDA textural triangle the main soil textures are loamy, clay loam and sandy loam, respectively.
The average abundance order of selected elements content is: Zn>Ni>Pb>Cr>Cu>As>Cd. Comparison of mean concentration of the potentially toxic elements in the soil samples with mean worldwide values reveals higher Zn, Pb and Ni contents in this area.
The results of contamination factor indicate very high contamination for Cd, Cu, Pb and Zn. Modified Degree of Contamination (mCd) calculated based on background values proves very high degrees of contamination for selected trace elements in Gasre Shirin and Eslamshahr landfills soil samples The results of enrichment factor evaluation similarity to contamination factor indicate that Cd, Cr, Pb, Cu and Zn have more influence from anthropogenic sources. The maximum EF of Pb, Zn and Cd and Cu is 346.7,124 and 51.9 respectively, which means very high enrichment in Ghasre Shirin landfill soil samples.
Exposure doses of 7 heavy metals in soil samples of un-enggenerd landfills for children and adults were calculated. The total exposure HQs calculated based on adults from ingestion, dermal contact, and inhalation for Cd, Cu, Ni, Zn, As and Pb was less than 1(except Ghasreshirin landfill). The hazard quotient values based on the adult risk for Cr were greater than 1.0. The results show that HQ for Pb and As in children by dermal and ingestion pathway is exceeded 1.0 in soil samples of Paveh, Javanrood, Ravansar, Kermanshah and Sangher landfills and Ghasreshirin and Eslamshahr landfills, respectively.
The concentration, pollution level, potential sources and health risk of potentially toxic elements in eight landfills top soil of Kermanshah province were investigated in this study. The following conclusions were drawn from this research.
- Compared with the background values of As, Cd, Cr, Cu, Ni, Pb and Zn in soils of Kermanshah Province, landfills soil have elevated metal concentrations as a whole.
- According to high contamination level and health risk of some studied potentially toxic elements, and also due to the proximity of contamination sources to residential district of the study area, more attention should be paid to manage and reduce contamination.
- These results provide basic information of toxic elements pollution control and environment management in the area..

Sediment transport occurs through various processes, whereby their origin is of great importance. Surface sediments of the Semnan province and NE Isfahan province (Khour and Biabanak) were sampled to examine the possibility of transportation by wind. Hence, 43 samples collected from surficial sediments of the Semnan and Isfahan provinces were analyzed using ICP method in the geochemistry lab of the Geological Survey of Iran. After testing outlier data were excluded from any further processing. To ensure confidence of any possible relation between elements, multiple statistical approach including principal component analysis (Pearson correlation), correlation analysis, cluster analysis, factor analysis and varimax boxes were applied. The results show that the elements including Zn, V, Ti, Sn, Sc, P, Ni, Mn, Cu, Cr, Co, Cd, Ba, represent reasonable correlation for samples of the Semnan province. Coeval existing of Co, Mn and Ni may reflect their geogenic source, particularly from intermediate to basic volcanic rocks exposed around the area. In Khour and Biabanak area, V, Ti, Sn, Sc, Pb, P, Ni, Mn, Cu, Cr, Co, Cd, Zn are closely related, which probably points to their origin from altered ultramafic rocks of the Proterozoic-early Paleozoic exposed around the area. There are positive factors in levels 1, 3 and 4 may be affected by various geological formations exposed around the studied areas. However, combined role of human or agricultural activity are more plausible for level 3 in factor analysis.

Carbonate deposits of members 1 to 2 of the Mila Group (Middle Cambrian) in Central Alborz that call the Deh-Sufiyan Formation in this research, were studied in Shahmirzad, Tueh-Darvar, Mila-Kuh and Deh-Molla sections. The Unit 2 of Deh-Sufiyan Formatrion in Central Alborz of Northern Iran consists mainly of shallow marine carbonates and contains a variety of limestone conglomerates. Limestone conglomerate is an important component of Unit 2 of Deh-Sufiyan Formatrion, but its origins remain enigmatic. These limestone conglomerates have a diverse set of characteristics that range clast to matrix supported with scattered flat pebbles. These conglomerates are largely comprised of oligomictic, rounded lime–mudstone clasts of various sizes and shape (equant, oval, discoidal, tabular, and irregular). According to composition and characteristic sedimentary structures and fabric, limestone conglomerates in the Unit 2 of Deh-Sufiyan Formatrion consist of: (1) Intraformational limestone conglomerate beds were formed by depositional processes (2) Limestone pseudoconglomerate beds were produced by diagenetic processes. The common characteristics of the Unit 2 of Deh-Sufiyan Formatrion pseudoconglomerates, such as oligomictic lithology of lime–mudstone clasts, mosaic fabric, disorganized/edgewise fabric, variable and gradational fabric, transitions adjacent or underlying facies and the complete lack of depositional structures, are typical of pseudoconglomerates formed by early diagenetic sediment deformation under shallow burial conditions. These characteristics are different those of intraformational limestone conglomerate showing primary depositional features such as normal or inverse grading, internal stratification, (hummocky) cross-stratification and sharp erosional bases. Diagenetic conglomerates in ribbon rocks resulted soft-sediment deformation of ribbon rocks during early diagenesis. In contrast, the dimension and thickness, sizes of the clasts, clast-rich beds, size ingredient of matrix, tendency to amalgamate with amalgamation scours within depositional conglomerates suggest that high energy and strong erosion above storm wave base was responsible for the disintegration of the carbonate material.

The Ghale-rig granitoid is located at southwest of Nehbandan city (southern Khorasan province) in east of Lut Block. Compositionally, this granitoid ranges of alkali feldspar granite, synogranite, granite, porphyritic granodiorite and biotite bearing quartz syenite with mostly mean grained granular texture. The main minerals consist of quartz, plagioclase, microcline and orthoclase. The Ghale-rig Granitoid issedimentary type (S), calk- alkaline and based on aluminous saturation index (ASI) is peraluminous. This pluton is syn-collision zone Tectonomagmatic. Most of the rocks in the pluton show, enrichment of Large Ion Lithophile element(LILE), Light Rare Earth Elements (LREE) and depleted of HREE, HFSE and negative anomalies in Sr, Ti, Nb and Ba elements. Petrogenesis diagrams display felsic pelite source for Ghale-rig granitoid and it seems, this pluton is probably originated from melting of sediment of the upper crust.

Gol-Gohar mining complex, located southwest of Sirjan (Kerman Province) and within the Sanandaj-Sirjan structural zone, has a number of iron-rich deposits that provides 30% of steel demand in the country. The main ore in this deposit is magnetite with subordinate amounts of hematite and accessory pyrite and chalcopyrite phases. Comparison of rare earth element (REE) distribution patterns of Gol-Gohar magnetite with those of magmatic magnetite (Kiruna) and also magnetite associated with granite and basalts show similar enrichment in light REE relative to the heavy REE and negative Eu anomaly. Such features can also be observed in apatite from Kiruna, Iron Spring, Choghar and Esfordi Fe ore deposits, the origin of all of which have been ascribed as magmatic due to a lack REE distribution patterns similar to phosphorites. Based on these characteristics, it seems that the magnetite in Gol-Gohar Fe deposit has dominantly originated from a magmatic fluid.

In this study، Neogene deposits of eastern Kopet-Dagh and east central Iran have been investigated. These deposits in the eastern Kopet-Dagh Basin consist of two lithofacies associations including gravelly (Gcm، Gmm، Gmg، Gh) and sandy (Sm) that form within four structural elements (SG، GB، SB، CH). From base to up، they were deposited in the braided river with sandy bed load in the alluvial fan depositional systems near the source area. Sequence stratigraphic analysis of Neogene deposits، based on lithofacies variations، indicated that these sediments formed in an area with the low accommodation space. Petrography study indicates that they were derived from collision and recycled orogen tectonic setting. Neogene deposits in the studied area in the east Central Iran are composed of four lithofacies associations including gravelly (Gcm، Gmm، Gmg، Gh، Gt، Gp)، sandy (Sm، Sh، St، Sp)، fine grain (siltstone) (Fm) and evaprite (P) that formed within five structural elements including SG، GB، SB، CH، FF. These sediments، from base to up، were deposited in playa and proximal to mid sandy-gravelly bed braided river in alluvial fan depositional systems. Sequence stratigraphic analysis indicates that these deposits consist of two sedimentary sequences. The first sequence belongs to high accommodation space and the second one formed during the low accommodation space. Sandstones and conglomerates composition as well as tectonic position of area indicate that the tectonic settings of the source area was probably arc orogen and continental block.

Two cases of tungsten-copper vein-type mineralization have been studied in the Nezam-abad and Deh-hossein areas، in southwest of Shazand. The hydrothermal quartz-tourmaline mineralized veins have different host rocks (biotitic-granite and meta-sandstone). Considering similar ore metals (tungsten-copper-tin-lead-zinc) in the Nezam-abad and Deh-hossein areas، same mineralogy of veins (quartz-dravite) and similar REE variation patterns in the two areas، it is suggested that the Nezam-abad and Deh-hossein mineralized veins have the same origin. It means، when the Br-bearing fluids were active، they caused the quartz-tourmaline vein-type mineralization in this area. Considering the barren intrusions in the area and other mineralogical-geochemical evidences in this study، it could be concluded that tungsten and other metallic elements in the Nezam-abad and Deh-hossein ore-bearing veins have a sedimentary/metamorphic origin.

Approximately 50 chromite outcrops are observed in the Esfandagheh Paleozoic ophiolite complex, of which few are economically important. Rock types in Abdasht area are mostly dunite and harzburgite and the chromite deposits occur as lens- shaped bodies in dunite. Texture of the bodies is nodular, disseminated and massive which occasionally all these textures can be seen together in one orebody. These deposits are rich in chromium and poor in aluminum. Moreover, there is no mineral concentration of elements such as Ni, Co and PGE in the chromite ore and host rocks. The chromite deposits in Abdasht region are of Alpine type (podiform).