shahab ahmadi doabi; Majid Afyuni; Mahin Karami
Abstract
Introduction: Atmospheric dust is an important source of heavy metals, particularly in urban environments. Heavy metals can easily attach to dust particles and be distributed in large areas. Therefore, assessing the extent of heavy metals pollution present in nuisance dust is important for establishing ...
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Introduction: Atmospheric dust is an important source of heavy metals, particularly in urban environments. Heavy metals can easily attach to dust particles and be distributed in large areas. Therefore, assessing the extent of heavy metals pollution present in nuisance dust is important for establishing pollution control strategies and evaluating the results of previous measurements. Heavy metals contamination in atmospheric dust of Kermanshah provine has not been previously investigated. The main objective of this initial study was to determine the concentrations of heavy metals in atmospheric dust samples that were collected from Kermanshah province and to assess their contamination level. The results can provide a baseline for use in future environmental impact assessments and to guide pollution mitigation targets.
Materials and Methods: Dust samples were collected from 49 sites across the province, during the summer 2013. Dust sampling sites were selected in different urban (35 site) and suburban (14 site) locations in Kermanshah, Songhor, Gilangharb, Ghasre-Shirin, Sahneh, Sarpolzahab, Kangavar, Paveh and Javanrood cities. Dust collectors were installed on the roof of buildings about 3–4 m above the ground level. Each collection tray consisted of a circular plastic surface (320 mm in diameter, 120 mm depth) that was fixed on holders with 33 cm height and covered with a 2 mm PVC mesh on top to form a rough area for trapping saltant particles. The dust samples were analyzed for their Zn, Cu, Ni, Cr, Mn and Fe concentrations using an Atomic Absorption Spectrophotometer. In the present study, geo-accumulation index (Igeo), enrichment factor (EF), pollution index (PI) and integrated pollution index (IPI) were calculated to assess the heavy metal contamination level in the atmospheric dust.
Results and Discussion: The results showed that except for Fe and Mn, all heavy metal concentrations of atmospheric dust in Kermanshah provine were higher than in the background soils of world, showing that these heavy metals are likely from anthropogenic sources. The order of mean Igeo values was Ni> Zn> Cu> Cr> Mn> Fe, similar to the order of their EFs and PIs, which can also be seen as the decreasing order of their overall contamination degrees in atmospheric dust of Kermanshah province. The mean Igeo for Ni points to moderately to strongly pollution. 59% of calculated Igeo for Ni falls into class 2 (moderately polluted) and 37% into class 3 (moderately to strongly polluted), while according to the Igeo values for Mn (98%) and Fe (100%), they were practically unpolluted (class 0). The maximum EFs of Zn, Cu and Ni were higher than 10, which show that Zn, Cu and Ni in atmospheric dusts mainly originate from anthropogenic sources. It seems that EFs can also be an effective tool to differentiate the natural origins from anthropogenic sources. The mean EF (11.2) and 94% of Ni EFs were in the range of 5–20 indicating that Ni was a main contaminant in studied samples. Mn had 41% EFs less than 2 and 59% EFs in the range of 2–5, with mean EF less than 2, indicating minimal enrichment. The analytical results of heavy metals Igeo are same as the analytical results of EFs. The PIs of Zn, Cu and Ni were in the ranges of 2.1 to 11.3, 1.7 to 18.3 and 3.3 to 13.6, with an average of 3.8, 3.3 and 6.9, respectively. These data indicate that Zn, Cu and Ni may cause serious pollution in atmospheric dust of Kermanshah. The IPIs of atmospheric dust samples vary from 1.9 to 6.2 with mean value of 2.9, indicating that all studied samples were polluted by heavy metals.
Conclusion: The concentrations of heavy metals that were investigated in this study were compared with the reported data of other cities and with the background values of elements in the world soils. The concentrations of Zn, Cu, Ni and Cr in urban dust samples, and Fe and Mn in suburban dust samples were higher than their respective values in the world soils. The results indicate that atmospheric dusts in Kermanshah provin have elevated metal concentrations in general. The calculated values of Igeo and EF of heavy metals revealed the order of Igeo and EF as Ni> Zn> Cu> Cr> Mn> Fe. The high Igeo and EF for Ni, Zn and Cu in atmospheric dusts indicated that there was a considerable Ni, Zn and Cu pollution (Especially nickel), which possibly originate from traffic and industrial activities. The Igeo and EF of Mn and Fe were low. The results of PI also supported Zn, Cu and Ni serious pollution in atmospheric dust. Similarly, IPI results confirmed atmospheric dust samples pollution by heavy metals. These findings indicated that more attention should be paid to heavy metal contamination of atmospheric dusts in Kermanshah, especially in case of Ni.
shahab ahmadi doabi; Majid Afyuni; Mahin Karami; Safura Merati Fashi
Abstract
Introduction: Zinc (Zn) is an essential trace element for plants as well as for animals and humans. On the other hand, Zn is a heavy metal and its high concentration can cause some environmental problems. There are significant relationships between soils, plants and humans Zn status in a certain agro-ecosystem.Therefore, ...
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Introduction: Zinc (Zn) is an essential trace element for plants as well as for animals and humans. On the other hand, Zn is a heavy metal and its high concentration can cause some environmental problems. There are significant relationships between soils, plants and humans Zn status in a certain agro-ecosystem.Therefore, mass flux assessment of Zn in agro-ecosystem is important regarding to plant and human nutrition in one hand and environmental quality on the other hand. Therefore, assessing the Zn accumulation trend in agricultural soils is essential to prevent Zn deficiency as well as soil pollution by Zn.
Materials and Methods: This investigation was conducted in order to model Zn accumulation rate in agricultural soils of Kermanshah province using inputs and outputs fluxes mass balance. Mass Flux Assessment (MFA) model were applied for the modeling accumulation rate of Zn uses a random method of element balance with the combination of Latin Hyporcube method and Mont-Carlo simulation, in several agricultural ecosystems of some townships (Kermanshah, Songhor, Gilanegharb, Ghasreshrin, Shaneh, Sarpolezahab, Kangavar, Paveh and Javanrood). In this study, mass flux assessments were done at both provincial and township scales. Various routes of Zn considered in this study were livestock manure, mineral fertilizers, pesticides, atmosphere deposition, municipal waste compost (input) and uptake by plant (output). Agricultural information, including crop type, crop area and yield, kind and number of livestock, application rates of mineral fertilizers, compost, pesticides and atmospheric deposition rates and also a metal concentration in the plants, livestock manure, mineral fertilizers, compost and dust was used to quantify Zn fluxes and Zn accumulation rate. Given that the other sources of Zn input such as sewage sludge and output such as leaching are not important fluxes in the study area, the calculations performed here presented a good estimation of the average net effects of the dominating Zn inputs and outputs of the Zn status in agricultural soils of the study region.
Results and Discussion: The results showed that the maximum and minimum of the Zn accumulation rate were seen in agricultural soils of Paveh (1172 g ha-1yr-1 in average) and Kermanshah (-26 g ha-1yr-1 in average)respectively. The average net flux of Zn accumulation rate for Kermanshah province was also 1538 g ha-1yr-1. The negative Zn accumulation rate of Kermanshah soils implies depletion of this element that is due to higher uptake of Zn by plants, especially crops with high performance such as maize and sugar beet. The calculated accumulation rates were less than the critical accumulation rate (calculated for the next 200 years in the study area). The results showed the high range (difference between the simulated maximum and minimum) of the Zn accumulation rate in Paveh was 1307 g ha-1yr-1, and the lowest in Songhor was 175 g ha-1yr-1. The major part of the uncertainty in the Zn balance resulted from manure source. According to the calculated SRCAP (Standardized Regression Coefficients Aggregated in Percent) values, Zn input with manure and then Zn output with crop removal were the main sources of Zn net flux uncertainty at township and province 9 levels. The uncertainty associated with livestock manure fluxes explained 67-94% of the total uncertainty. This large contribution was mainly due to large uncertainty in the numbers of dominant livestock, in particular cattle and poultry, and in the Zn:P concentration ratios of their manures. The influence of crop removal on Zn net fluxes uncertainty ranged from 3-29% among the townships. Differences in contributions of individual crops to the total cultivated area and in the Zn concentration of dominant crops as well as uncertain crops yield data were the main reasons for this large variation among townships.
Conclusion:The most important routes of Zn entry into the agricultural soils were livestock manures (69-93%) and atmosphere deposition (9-28%) in township level, while in provincial scale, they were compost (61%), livestock manures (33%), and atmosphere deposition (5%) respectively. The uncertainty analysis results indicated that livestock manure was the most effective rout on Zn accumulations rate uncertainty (79% in province scale and 67-94% in township scale). The results also indicated that current agricultural management generally leads to accumulation of Zn in soils of the study area (with exception for Kermanshah township soils). This can cause some difficulties such as soil contamination or soil fertility loss by nutritional elements imbalance in future.