جستجوی مقالات مرتبط با کلیدواژه « the environment » در نشریات گروه « آب و خاک »

Street dust enters the urban environments due to the resuspension of particles smaller than 100 micrometers. The magnetic properties of street dust and their relationship with the concentration of heavy metals have received less attention from researchers worldwide, and not much study has been performed on this issue in Iran. The objectives of this study were: (i) to investigate the spatial and seasonal changes in street dust, and (ii) to determine their relationships with the concentration of selected heavy metals in several cities in the Isfahan province. Sampling was carried out in the first half of the second month of each season including 20 samples from Isfahan city and 10 samples from Natanz, Shahreza, Falavarjan, Khomeinishahr, and Najafabad. The concentration of selected heavy metals was measured using an atomic absorption spectrometer. Also, the magnetic susceptibility values of the samples at low and high frequencies were determined and frequency-dependent magnetic susceptibility was calculated. The results showed that the presence of ferromagnesian minerals in the parent materials could be the reason for the high values of magnetic receptivity in Natanz City. However, the high level of this characteristic in the street dust of other cities could be due to human activities, especially in Isfahan city. Based on the results of principal component analysis, the high correlation of the first component with magnetic susceptibility and the concentration of zinc, copper, and chromium elements most likely indicates the absorption of these elements by particles close to superparamagnetic (SP). The high correlation of the second component with frequency-dependent magnetic susceptibility and concentration of nickel and cobalt is most likely related to the adsorption of magnetic elements and heavy metals into coarse polyhedral particles that remained on the street floor after the re-deposition of street dust particles. Also, the high correlations between magnetic parameters and the concentration of copper and zinc confirm their anthropogenic origin. On the other hand, low or negative correlations of Pb, Ni, Cr, and Co concentrations with magnetic susceptibility might confirm their natural or non-anthropogenic origin. The higher values of magnetic parameters of street dust in the spring season reflect the significant contribution of magnetic minerals in this season, compared to autumn and winter, and indicate the higher influence of human activities.

Airborne particles, commonly known as aerosols, can carry polluting and harmful particles and elements. Street dust refers to particles smaller than 70 micrometers that enter urban environments due to the resuspension of particles from human activities or dust storms. These particles host various pollutants, including heavy metals, which are produced from various anthropogenic and natural sources. The sources and amounts of these metals can be seasonally and spatially highly variable. The objectives of this research were to investigate seasonal changes in the concentration and pollution level of selected heavy metals in street dust and soil samples around a few cities in Isfahan province, and also to compare them with selected cities in the world.

Street dust samples were taken in the first half of the second month of each of the four seasons in 2018 including 80 samples from Isfahan, and 40 samples for each of the cities of Flavarjan, Najafabad, Shahreza, Khomeinishahr and Natanz Each dust sample (about 300 g) was collected from the surface of pedestrian walkways and stored in plastic containers. All the samples were then extracted by digestion with 6N nitric acid, and the concentration of selected heavy elements including copper, zinc, lead, and cobalt was measured in the extracts by an atomic absorption spectrometer. Finally, the contamination indices including geoaccumulation index and Nemerrow pollution index were calculated in the samples and the seasonal and spatial changes in the concentration and rate of heavy metal pollution were investigated.

Spatial and seasonal changes in the concentration and contamination level of copper and lead showed that the highest pollution rate of these elements happened in Isfahan in spring. They also indicated that the highest degree of street dust pollution with zinc was found for the city of Flavarjan in the spring season. As far as cobalt, the highest pollution level was found in Shahreza city in the winter season. For all the elements, the lowest concentration and level of pollution were obtained for Natanz city in the summer season, and lead showed the lowest concentration in fall. Besides, except for cobalt, soil samples taken from non-urban areas showed the least concentration and pollution level. The comparison of the obtained results with the data reported for other cities of the world showed a higher level of pollution of the street dust in the urban area of Isfahan compared to other big cities of the world. The concentration of copper in the street dust of Isfahan is almost similar to that in Ahvaz and Huainan (China), and that of zinc is lower than Avilés (Spain) and Zhuzhou (China). Furthermore, the concentration of lead is lower than that in Zhuzhou and Huludao (China). Also, cobalt concentration in the street dust of selected cities was higher than that in all the studied cities except for Rabat-Saleh highway (northwestern Morocco) and Huainan (China).

The results of this investigation and their comparison with those of other studies indicated that the mean concentration of copper, zinc, and lead elements in street dust was highest in all the cities, except for Natanz. This is mainly due of higher traffic, more population and the density of machinery, the presence of more and larger constructions in big cities, the transit of vehicles, and the presence of more intense atmospheric dust storms in the central areas of Isfahan province, drought and lack of sufficient rain. Lower concentration of selected heavy elements in the street dust of Natanz city is probably due to the lower population density, different types of parent materials as compared to other cities, and its low industrial activities.

The main purpose of this research was to investigate the water quality of Zarrinehrood and Siminehrood rivers for the year 2018 and in 13 and 6 stations of the two rivers, respectively. For this purpose, the unpublished data of Na+, Cl, SO4, TDS, pH, CO3, HCO, EC, Ca, Mg and SAR parameters from both rivers were used and presented in this paper. Graphical methods were used to determine the water quality of the rivers for various human uses based on drinking and agricultural standards, and to determine the water quality in terms of sustainability, Langelier, Ryznar and Pukorius indices were used. Also, the water quality conditions of the studied rivers were compared and studied with the national standards of Iran (1053), the World Health Organization, the United States, the European Union, and the water quality standards of Iran of the Environmental Protection Organization. The results indicate that the type and facies of water is calcium bicarbonate in study stations and water quality of most stations are suitable for drinking and agricultural usages. The SAR value in Shirin-Kond station is 1.51 mEq/L and the EC value is 1144 mmho/cm and its water quality is in class C3-S1 that can be used for agricultural purposes. According to the Results, water quality of studied stations is corrosive for industrial uses.

For a long time the Sistan Plain has been one of the important areas for men’s settlement due to abundant water resources. Following the preparation of the archaeological map of Iran and in methodical surveys of the Sistan plain, settlements of the era were identified and their geographical location was recorded. So far no comprehensive study on relation between water resources and settlements has been conducted. The present survey aims for studying reciprocal relation between Sassanid settlements and natural environment in areas based on water component. This research has been carried out through the descriptive -analytical and historical method using GIS software. To reach the research goals after environmental conditions had been studied, six variables including water resources types, distance from water resources, land slope, soil type, Geology and settlements area were studied and results indicate surface water resources effective role in settlements placement and settlements area. Locating on delta fans would lead to change of direction branching canals of rivers, which causes numerous relocations of settlements. The Water resources existence, gentle land slope and consequently ease of water flow down to different areas of plain, branching canals creation capacity to keep the suitable distance to river and also, placement on the alluvial terrace to avoid flood hazards are among the factors turned the area to population absorbing one despite shortage of aquifers and people’s heavy reliance on surface water resources.

The objective of this study was to investigate the  concentration of heavy metals, dispersed from Khuzestan Steel factory, in the soil and various plants  of surrounding area. For this purpose, the Leaves samples from trees, shrubs, grass and soil samples from their rhizospheres were collected in dominated and opposite wind direction from the factory. Plant samples were divided into two groups; of which one group was washed with distilled water and HCl and another was not washed. Heavy metal concentrations (Fe, Cu, Cd, Pb, Zn) were measured in plant and soil samplesby flame atomic absorption spectroscopy. Results showed that the heavy metals concentration in plants in wind direction is almost 1.5 times more than the opposite direction. Airborne metal deposition has occurred in this region because the heavy metal concentrations in unwashed samples were more than the ones in washed samples. Based on the results obtained from this study, it can be concluded that Khuzestan steel factory activity is one of the pollution  sources in the proposed region which threated the environment of Ahvaz.

In recent years, metal contamination in the aquatic environment has attracted global attention owing to its environmental toxicity, abundance and persistence. This study was carried out to determine the concentration, origin and toxicity of heavy metals (Fe,Mn,As,Ni,Pb,Zn,Cu,Cr) in surface sediments of Bahmanshir River.14 surface sediment samples (0-10 cm) were collected using a grab sampler. Concentration of heavy metals was measured using ICP-OES method. Physico-chemical parameters (pH, Organic Matter (OM)) of sediment were determined by standard methods. In order to assess sediment contamination to heavy metals, different indices, Enrichment Factor, Potential acute toxicity and Ecological risk were calculated. The results showed moderate contamination of sediment with metals of Ni and Cr ºand low risk level of sediments. The Statistical analysis showed that metals Pb,Zn,Cu,Cr may have originated from anthropogenic sources ; As can originate from natural process and Ni seems to have both natural and anthropogenic sources.