جستجوی مقالات مرتبط با کلیدواژه « pollution indices » در نشریات گروه « آب و خاک »

Although the exploitation of mineral resources is very useful for the country, it has a negative impact on human and plant life with its destructive effects. These destructive effects appear as pollution in the soil, which can lead to the imbalance of ecosystems and ultimately endanger human health. In addition, economic development and the expansion of industrial areas, especially coal mining mines, cause heavy metal contamination of the soil to become more severe and cause the destruction of soil resources and the deterioration of ecosystems in different regions of the world. The present study was conducted to investigate the contamination of the two elements Pb and Zn in the surface soil of the Komarzd mining area in Mazandaran province (Iran) due to coal mining.

Komarzd mines in Mazandaran province are one of the largest and oldest coal-producing areas in the central Alborz coal field. Komarzd mines are located 48 km from the southern district of Qaemshahr and 25 km from Alasht. Four indices, including CF, mCF, RI, and Igeo were calculated for 110 samples from surface soil prepared at a depth of 5-15 cm. After separating the rubble, the collected soils were kept in closed plastic bags with a unique code, and a GPS device recorded their location. The samples prepared in a dry environment were transferred to the laboratory. The ICP-MS method at 75 microns was used to analyze and measure the concentration of heavy elements in the collected samples. According to the presence of different elements measured in the region's soil and the compounds in it, two metals Zn and Pb were selected for evaluation and analysis. Sampling was randomly selected based on saved points and drilling tunnels. PCA statistical test is a type of multivariate analysis widely used in sediment, water, and soil pollution studies. Varimax Rotation is one of the most common types of PCA tests to interpret the results and contamination components of the method. This statistical method can be calculated using R and SPSS softwares.

The results showed that the ordinary kriging model is the most suitable model to show the region's concentration distribution of the two metals, PB and Zn. Also, the statistical status of the elements showed that the lowest amount of Zn for the Igeo index is equal to -0.53 and the highest value for the CF index is equal to 0.72. The amount of Pb concentration measured based on Igeo, CF, mCF, and RI indices equals 0.08, 1.03, and 213 mg/kg, respectively (RI<CF<Igeo). The results of the CF and mCF showed that the region has a low or moderate pollution status in terms of the concentration of the two determining elements; in other words, the value of this factor for Zn is less than 1 (CF<1) and the amount for Pb is (3 > CF> 1). The Igeo index showed that Zn with a concentration lower than zero is not polluted, but Pb with a value (0< Igo <1) has a non-polluted to slightly polluted state. The RI also showed that the concentration of the two elements is less than 150 mg/kg, so this index is also in the low-risk category of contamination (RI ≤ 150). By evaluating the graphs obtained from the PCA analysis, it was found that the two elements Zn and Pb in the correlation analysis graph have a good correlation and distribution, and the changes in the two axes show 47.9% and 24%, respectively, for the Igeo. This indicates the presence of environmental factors in the distribution of this element in the environment. The CF also showed that their distribution in region three negatively correlated with environmental factors. Its value for the two axes is 32.5 and 21.9 %, respectively. The correlation of the Zn element is less than -0.5, but the Pb element is more than -0.5. In general, the value of this variable is 8 and 20, respectively, based on the diagram of two minimum and maximum values. The mCF and RI indices showed that environmental factors influence the distribution of the two elements PB and Zn, and among the two elements, the distribution of the Pb element in the mCF and RI, results of 32.8 and 34.4 has the most influence from the distribution of the drilling tunnel and had environmental factors and has a lower correlation than Zn. The effect percentage of these two elements is 32.8 and 23.2%, respectively, and the two elements Zn and Pb have a good correlation and distribution with environmental changes and human factors.

According to the measurements and the results of four indices, the area is uncontaminated or has low contamination in terms of the concentration of two elements, PB and Zn. Therefore, mineral tailings and coal exploitation do not significantly affect the distribution of the mentioned elements. To improve the research results, other indices can be used to determine the role of environmental factors. Also, considering the agricultural lands and water resources of Talar River, it is better to use other elements that directly affect human health and analyze the region's conditions in terms of environmental pollution to achieve better results and accuracy. One of the main disadvantages of measuring the sources of pollution is the many problems in laboratory work and the preparation of laboratory materials. Still, with this research, it is possible to determine the existing doubts in the field of soil pollution for residents and show the impact of mining on the spread of pollutants. A suggestion to improve this research is to consider elements other than Pb and Zn in different environments such as water sources; In general, for a more detailed investigation, other elements that play a role in human health should be investigated.

The aim of this study was to investigate the origin and potential ecological risk of heavy metals (arsenic (As), cadmium (Cd), lead (Pb), nickel (Ni), zinc (Zn) and Cu (copper) in different land uses in West of Arak, Markazi Province. A total of 235 Surface soil samples were taken from the depth of 0-5 cm including 160, 46 and 29 samples from agricultural, rangeland and industrial land uses, respectively. The ranges of As, Pb, Zn, Ni, Cd and Cu in studied soils were 55.7–357.2, 6.8–256, 13.2–858, 26.7–172, 0.1–3.65 and 5.1–34.1 mg/kg, respectively. Comparison of the mean concentration of heavy metals in different land uses indicative of the same influence of land use to metal accumulations of As, Pb, Zn and Cu, but in the case of Ni and Cd showed that a differential influence of land use the distribution of these metals in the soil. When the average amount of crust was used as a reference background, the Cf values of As in all land uses were higher than other metals, indicating high level of pollution of soils in this region. The index of PLI in land uses comprised, industrial (3) > rangeland (2.4) > agriculture (2.39), indicating the pollution and gradual destruction of soil. The mean PER based on reference and local GB showed very high and low pollution level in all land uses, respectively. Principal component analysis (PCA) showed that Pb and Zn originated from common anthropogenic sources related to industrialization and mining, whereas Cu and Ni are probably in associated with geological sources. Cd was mainly derived from the input of agricultural and industrial activities, and As should be attributed to natural resources, emissions from local industries, mining, herbicides and the use of poultry manure and atmospheric dust.

Heavy metal (HM) contamination and accumulation in soil and water is a serious problem throghout the world due to the toxicity, abundant sources, non-biodegradable nature, and accumulative behavior of HMs in environment. A comprehensive understanding of the HM pollution in soil is essential in order to make informed decisions on the approaches to reduce contamination, minimize human exposure, and protect populations from the risk. Pollution indices widely considered as useful tools for evaluation of the degree of contamination. In this paper, geo-accumlation Index (Igeo), enrichment factor (EF); single pollution index (PI), contamination factor (Cf), eological risk factor (Eri), sum of pollution index (PIsum), Nemerow pollution index (PINemerow), pollution load index (PLI), vector modulus of pollution index (PIVector), background enrichment factor (PIN), multi-element contamination (MEC), contamination security index (CSI), the probability of toxicity (MERMQ), degree of contamination (Cdeg), modified degree of contamination (mCd), potential ecological risk (RI), exposure factor (ExF) were suggested to address the degree of HM pollution in soil. Finally, a method was proposed for non-dimensionalisation of the above-mentioned indices as well as for calculation of an integrated soil contamination index derived from the sum of the weighted-average scores of all individual indicators. Using these indicators is useful in quantitative evaluation and digital mapping of soil pollution for management purposes.

Soil is a hardly renewable natural resource. Although soil degradation, caused by either human activities and natural processes is a relatively slow procedure, but its effects are long lasting and most often, irreversible in the time scale of man's life. Among the most significant soil contaminants resulting from both natural and human sources, heavy metals are more important due to their long- term toxicity effects. For evaluating soil's enrichment rate by heavy metals, a wide and full study of soils background values, including total and available fractions of heavy metal contents should be done. Zanjan province has some great mines and concentrating industries of lead and zinc especially in Angoran, Mahneshan. Unfortunately produced waste materials of these industries spread over the adjacent areas. Investigations showed that accumulation of some heavy metals in vegetables and crops planted in this region had occurred. Therefore, performing some investigations in these polluted areas and assessing pollution rate and heavy metals distribution in arable lands had prime importance. Our goals were: 1) determining the total and available amounts of Cu, Pb, Zn and Cd in the soils of arable lands in polluted areas of Zanjan city, 2) producing the distribution map for the metals mentioned above and 3) calculating pollution indices in the soils.
The study area was in south west of Zanjan city. For soil sampling, a 1 Km by 1 Km grid defined in ArcGIS software on landuse layer and totally 144 points that placed on agricultural lands, due to our goals, were sampled. For sampling, in a 5m radius around the point we collected some subsamples from depth of 0 - 15 cm, and after mixing the subsamples, finally a 1Kg soil sample prepared and sent to the laboratory. Sampled soils were air dried and were passed through a 2mm sieve. Soils organic matter (OM) content and texture were determined by Walkely-Black and Bouyoucos hydrometer methods, respectively. Soils pH were determined by glass/calomel electrode in saturation paste, EC by EC-meter in saturation paste extract, and calcium carbonate equivalent (lime) by reverse titration method. Total and available amounts of Zn, Cu, Cd and Pb were extracted by Aqua- Regia method (wet oxidation by chloridric acid and nitric acid with the 3:1 ratio) and by DTPA extracting solution, respectively. After extracting and filtering liquid samples, metal concentrations were measured by atomic adsorption method using GBC avanta P. Statistical analysis by SPSS and indices calculation by Excel were performed, and distribution maps were prepared by Inverse Distance Weighting method in ArcGIS software. For evaluating pollution rate, Geoaccumulation index, Enrichment factor and Availability Ratio indices were calculated and interpreted.
The textures of soil samples were loam, clay loam and sandy loam. The OM contents of almost soils were less than 2 percent. Lime was less than 25 percent and acidity of soils were neutral to slightly alkaline. Soils salinity were less than 2 dS/m except a few samples. Accordingly, these soils were suitable for agriculture and there were no limitation due to evaluated properties. Median values for the total concentrations of Cd, Cu, Pb and Zn (extracted by Aqua Regia) were 0.5, 22.5, 14 and 82.3 mg/Kg of soils, respectively, and for available fraction (extracted by DTPA) were 0.1, 0.9, 1.6 and 3.2 mg/Kg of soils that were much lower than measured total values. According to 90th percentile of geoaccumulation index, at least 10 percent of samples had been polluted with Zn, Pb and Cd. Enrichment factor revealed no long term pollution. Availability ratios of Pb and Zn were relatively high, showing there exists unique and recent pollution source for them. All pollution indices showed positive correlations with OM content of soils (except for availability ratios of Cd, which had negative correlation). Therefore, OM content of soils were respect to control these indices. Geoaccumulation index of Zn, Cd and Pb, and availability ratios of Zn and Pb showed negative correlations with soil pH. Therefore, in some seasons of the year, their availabilities will increase in soil.
The results showed that Cu content in soils were not in the critical limit but Cd, Pb and Zn content in soils were greater than standard levels and reclamation procedures for remedy of these soils must be done. The high values of the heavy metals in available fraction inthe soils increased the risk of bioaccumulation in microbial and biotic tissues. In areas where there are high content of available form of heavy metals in soils, it could be an index of new contamination in soils by heavy metals. According to geoaccumulation index of Cd, Zn and Pb, there are some contaminated points around waste depositition areas near Zanjan city. These points are in the direction that wind could effectively transport the particles of wastes to urban area. Enrichment factor (EF) showed that at least there were a few points polluted by Cd, Zn and Cu, although EF values were generally low. The leaked wastes of Zinc and lead industries had been spread in deposited areas caused difficulties in determining background values for the selected metals.