جستجوی مقالات مرتبط با کلیدواژه "enrichment factor" در نشریات گروه "محیط زیست"

Rivers are considered as a vital resource for mankind from the past to the present day.Considering the ever-increasing population, industrial developments and the expansion of modern urban societies, it is expected that the rivers located near densely populated urban and rural areas to be in danger of destruction due to a large part of urban, rural, domestic, industrial and agricultural pollutants to the sources of surface and groundwater in the riparian and riverside more than any other water ecosystems. On the other hand, regarding Iran's arid and semi-arid climate, the use of sediment qualitative indicators in research and investigation is crucial in order to predict, evaluate and provide a sustainable solution for controlling the amount of pollutants and also improving the quality of river water. The Karaj River is one of the main freshwater and energy production resources in the region, which plays a vital part in creating an ecological balance in parameters affecting the quality of this water ecosystem. The purpose of this research is to measure the concentration of heavy metals in the sediments of the river bed and to evaluate and analyze it using Geoaccumulation index and Enrichment Factor, which led to the suggested solutions in order to avert and control the further spreading of pollution.

In this research, nine stations were selected based on the land use of the area. The sediments of the river bed in each station were sampled. Sediment samples were prepared and later transferred to the laboratory and the total concentration of heavy metals was measured by Inductively Coupled Plasma Mass Spectroscopy (ICP) device.

The results obtained from the measurements using the mentioned indices assessed that the level of heavy element pollution is relatively low in the Karaj River. Nevertheless, part of this slight pollution is related to human activities such as road construction, tourism and the leakage of local runoff and sewage into the river and its riparian zone, which led to the increase of the Geoaccumulation of elements including copper and chromium to the numbers of 1.01 and 1.96 in downstream stations P8 and P9, respectively. Also, the highest average amount of Geoaccumulation for copper in 9 sampling stations was 0.23. On the other hand, these anthropogenic activities have significantly increased the arsenic Enrichment up to 17.81 in station P4 and the average Enrichment Factor of Arsenic in 9 sampling stations up to 13.12. But since each heavy element has its own unique nature, part of the quantity of the pollution present in the sedimentary environment of the river is related to natural factors, geology, soil erosion and weathering of riverbed rocks.

The process of changes in the amount and distribution of elements in the sediments were compared and the factors affecting their alignment or mismatch were discussed and researched. Generally, the results of this research show that the Karaj River, taking into account the Geoaccumulation index and Enrichment Factor, has negligible contamination of heavy metals in the riverbed sediment. However, the trend of index changes along the river route shows the direct effects of destructive human activities in the region.

Particulate matters are one of the most important air pollutants in Tehran and very dangerous for hu-man health according to the epidemiological studies. The ambient particles contain heavy metals, some of which are toxic and carcinogenic components. Therefore, in this study, the content of heavy metals in airborne particulate matters)PM4(of Tehran was measured and the related health risk was assessed.

Sampling of PM4 was conducted every six days using Chrono PM Sampler with a 10 L/min flow rate at two residential areas including Tehranpars in the east and Ekbatan in the west of Tehran. The concentration of PM4 was calculated with Gravimetric analysis. After the preparation of the samples using the extraction solution)HCl and HNO3(, the concentration of heavy metals was measured by ICP-MS. The metal rich-ness was assessed using the enrichment factor. For health risk assessment of heavy metals in PM4, excess cancer risk was calculated.

At both sampling stations, the highest concentrations in all PM4 samples were related to Al and Fe due to the high abundance of these elements in the earth’s crust. The results of the enrichment factor indicated that Al, Fe, Ti and Mn in PM4 had low enrichment degree and the source of these metals might mainly be the earth’s crust. Ni and Cr had a high enrichment degree. In addition, Zn, Pb, Cu, Sn, As, and Cd had a very high enrichment degree and were mainly anthropogenic. The concentration of PM4 was not significantly different between the two stations in the east and west, but the comparison of the mean concentration of metals in PM4 samples between the two stations showed that the concentrations of Mn, Cu, Sn, Ni, and As at the eastern station were significantly higher than the western station. The comparison of the enrichment factor between the two sam- 
مظلومی و همکاران1399، بهار 1، شماره 18فصلنامه علوم محیطی، دوره 15pling stations also showed that the EF values of the studied elements at the eastern station were higher than those at the western station, which could indicate a higher contribution of anthropogenic sources in the east. Among the studied elements, the highest excess cancer risk was related to Cr)VI(due to its high toxicity. The total excess cancer risk based on the average concentrations of toxic metals in PM4 was 120.1×10-6 at the eastern station and 83.1×10-6 at the western station.

Most of heavy metals in PM4 in the east and west of Tehran had mainly anthropogenic sources and were generated by human activities, especially transportation. The average concentration of heavy metals in PM4at the east of Tehran was higher than the west, and as a result, the excess cancer risk of toxic metals in PM4 was also higher in the east. The most dangerous carcinogenic element in particulate matters of Tehran was Cr)VI(,which should be taken more under consideration and its anthropogenic emission sources must be controlled.

The purpose of this research is investigation of the heavy metals pollution in PM10 aerosols in atmosphere in city of Kermanshah. The concentrations of thirteen elements consisting of Cu, Ni, Pb, Cd, Se, Zn, Fe, Cr, Co, As, Mo, V were analyzed by ICP for 55 soil samples (in various point of the height of 600-1600m) and 41 aerosols samples. The heavy metals pollution have been investigated using geo- accumulation index, contamination factor, enrichment factor, factor analysis. The results obtained from this studying, showed that elements of Cu, Ni, Pb, Cd, Se, Co, As, V have low pollution, elements of Fe, Cr have medium pollution, element of Zn has high pollution, element of Mo has very high pollution. Based on results of enrichment factor, Zn is the most enriched element. Mo have located after Zn. These elements have high EF-values. This indicates that they are probably dependent on non-soil sources such as vehicle exhaust. Enrichment Factor for Cu, Pb, Ca, Ni, V and Cr are in the range of 1 to 10. This implies that these elements were influenced not only by crust, but also by other pollution sources. Enrichment Factor of other elements (selenium, arsenic, cobalt) are less than 0.1. This indicates that these elements have originated from the crust. Based on results of enrichment factor and factor analysis, these elements have anthropogenic source that emissions of vehicle and industry-oil burning emissions have the main role in emission to atmosphere.

Dust-fall particles originated of soils' wind erosion are considered as air pollution factors which displace some amount of earth surface materials throughout the atmosphere and consequently downgrade environmental quality evaluable using various indices. In this study contents of the two metals of Fe and Mn alongside with the six metals of Ni, Cr, Ag, As, Cu, Zn were obtained using furnace and flame atomic absorption spectroscopy, respectively, in the samples of dust-fall collected for one year with 10 days intervals from three cities of western Iran (Andimeshk, Khorramabad and Sanandaj) having different latitudes. Then, level of pollution for these heavy metals in the obtained samples were evaluated in using EF (Enrichment Factor), Eri (Ecological Risk), PLI (Pollution Load Index) and CD (Coefficient of Divergence) indices. The results revealed high level of pollution danger for Ag and Cu in the dust-fall of the three cities by EF and Eri indices. Moreover, PLI index confirmed more heavy metals pollution for Sanandaj dust-fall. Additionally, CD index showed more similarity between Khorramabad and Andimeshk considering heavy metals concentration measured during sampling period while the level of heavy metals pollution in the three cities were the highest for winter.

Heavy metals are considered as serious pollutants due to their toxicity, persistence in natural conditions and ability to enter and accumulate in the food chain. Therefore, this study was carried to assess the potential ecological risk and identify the source of heavy metals including lead, arsenic, cadmium and zinc in the surface water and sediments from Gheshlagh river, Sanandaj. For this purpose, 16 samples of surface water and sediment were collected. Then, concentrations of arsenic, lead, cadmium and zinc were determined by atomic absorption spectrometry. Moreover, potential ecological risk index (PERI) and enrichment factor (EF) were utilized to assess the ecological risk, and heavy metals pollution index (HPI) was used to survey the effects of heavy metals on human health. Multivariate analyses such as correlation analysis, principal component analysis (PCA) and EF were used to identify human resource potential of arsenic, lead, cadmium and zinc. The results showed that the average concentration of a group of elements, including Pb, Cd and Zn, was higher than background levels, whereas average concentration of As was significantly lower than the background levels. Enrichment of the studied heavy metals was obtained as Pb> Zn> Cd> As in Gheshlagh river.  The results of PERI showed a low risk for Pb, As and Zn and a moderate risk for Cd in the samples under the influence of road traffic. Considering the results of EF and PCA, it can be concluded that the concentration of As has been mostly affected by the geological structure. Pb and Cd concentrations in four sampling areas were equally affected by agriculture and road traffic. It was also found that the concentration of Zn is influenced by residential wastewater.

Irankuh Pb-Zn mine is located 20 km Southwest of Isfahan in the Zayandehrud River drainage basin. Shale and carbonate are the host rocks of the ore deposits formed from high concentrations of Pb and Zn. Weathering and erosion of the host rocks of ore deposits, waste water and waste materials arising from mining have a potential for heavy metal pollution of running water, ground water and agricultural soils. The main objectives of this investigation were to study the total concentration of Zn, Pb, Ni, Cu, Co, Ag, and Cd in the shale deposits of the mine, and the physicochemical factors on their distribution and pollution. For measuring heavy metal values, twenty samples were taken from the shale deposits. For distinguishing the shale-forming minerals, thin sections were prepared and studied with a polarizing microscope. The rock forming clay minerals, after preliminary treatments (heating at 550oc, ethylene glycol solvation), were detected by XRD and the organic carbon, calcium carbonate and Eh/pH of the shales were then measured. Heavy metal values in the sample were measured by AAS after mineralization. The correlation coefficient of organic carbon and manganese with metals and also metals-metals were calculated. For comparison of the heavy metal concentration relative to their natural amount (in shale), the enrichment factor was applied. The dark grey to olive-coloured shales in the studied area consisted of clay to fine silt size. Quartz, biotite, muscovite, feldspar and clay minerals comprise the non-opaque minerals of the shales while the clay minerals are illit (60-70%), kaolinite (9-27%) and chlorite (7-22%), respectively. Sphalerite, pyrite and galena are the main opaque minerals in the mine. The mean OC content of the shale is about 2% (0.35-5.5%) with less than 1% calcium carbonate. The pH of the samples is nearly neutral (6.8-7.8) and they have an oxidizing to nearly reducing Eh (18 to -100 v). The average concentration of heavy metals in the shales were Zn=128.05>Pb=42.55> Ni=35.24> Cu=24.18> Co=7.4> Ag=3.33> Cd=0.79 in ppm, respectively. A highly positive correlation between Ag-Pb-Cd, Cd-Zn-Pb and Co-Ni-Mn and also a positive correlation between Zn with organic carbon demonstrate geochemical convenient conditions for concentration of the metals. The calculated enrichment factor has revealed extremely high enrichment for Ag and average for Cd. Other elements are depleted in the sediments. Due to the relative high concentration of the metals and extent of the shales in the study area, activation of the heavy metals under suitable conditions can be a potential source for environmental contamination in the groundwater and runoff water of the basin.

In this study, the distribution of heavy metals (As, Cr, Ni, V, Mn, Fe, Zn, Pb) and sulfur in soil samples collected around the petrochemical complex and petroleum refinery at Abadan has been investigated. For this purpose, 22 surface soil samples were taking into consideration the prevailing wind direction (NW-SE). Sample number 22 is a control sample and was collected from a rural area. After preparation in the laboratory, the samples were analyzed using the ICP-OES method to assess concentrations of different elements. Also, the pH and organic matter content of samples were measured using standard methods. Pollution levels in the soil samples were investigated using different indices, including enrichment factor, contamination factor, contamination degree, saturation degree of metals and Potential acute toxicity. The mean concentrations of elements in the samples were compared to the mean concentration of these metals in the upper crust, soil worldwide, and EPA standards. The results of calculating the geochemical indices indicated that soil samples are more contaminated with S, Pb and Zn. The statistical analysis showed that nickel, vanadium, iron, manganese may be mainly derived from geogenic sources. Lead and zinc may originate from traffic and vehicle emissions as well as the petrochemical complex and petroleum refinery activities. As and Cr have both a geogenic and an anthropogenic origin. High concentrations of sulfur in the study area originated from the petrochemical complex and petroleum refinery activities.

Ahvaz as the focal point of south western of Iran has impressed by Middle East Dust (MED) storms which has originated from Iraq, Saudi Arabia, Jordan, Syria and also Africa. The main objective of this study was to evaluate heavy metals contents of PM10during normal and dust event days in Ahvaz. High volume sampler device was selected to take sample at a high traffic area of the city. Result showed that during dust event days, the average concentrations of PM10were 300 and 278 μgm-3in the spring and summer, while during normal days, the corresponding values were 145 and 126, respectively. Findings of enrichment factors indicated that Al with low enrichment factor had crustal origin, whereas Pb and Zn with high EF had anthropogenic sources such as transportation as well as industrial emissions. In present study, the concentrations of PM10were higher than the standard values.