Iranian Journal of

Results: The mean concentration of heavy metals was as follow: Pb (251.20), Ni (94.6), Cu (75.80), Zn (132.84), Cd (0.69), V (4.97) and Cr (141.48) (mg/kg). The average value of enrichment factor in the soil samples decreased as Pb>Ni>Cu>Cr>Zn>Cd>V. Nemrow integrated pollution index (NIPI) indicated high level of pollution for the studied heavy metals except V. The Potential ecological risk of the studied heavy metals showed a low potential ecological risk for V, Cd, Zn and Cr; Cu showed a moderate risk and Ni and Pb indicated a considerable ecological risk. The mean value of the risk index indicated that 27 (55.10%) of the soil samples with a moderate risk, 21 (42.85%) with a considerable risk and one sample (2.05%) with a high ecological risk.
Conclusion: The obtained results from the enrichment factor, Potential ecological risk, and risk index indicated that the main source of heavy metals in the study area were anthropogenic sources such as oil drilling activities.
 

Background and Objective: Heavy metals are the most frequent pollutants of urban soils. In general, human health and especially children are directly at risk if the soil is being accidentally ingested orally or nasally. Therefore, this study was conducted to assess potential ecological risk index (RI) of Pb, Cd, Cr and Cu in surface soils of urban parks in Tehran City in 2016.
Materials and Methods: A total of 60 surface soil samples were collected from Mellat, Laleh, Velayat, Ekbatan and Pirouzi parks. The heavy metals contents in samples were determined using ICP-OES after acid digestion of soil samples. Also, RI of heavy metals was determined. All statistical analyses were performed according to the Shapiro-Wilk test, One-Way ANOVA, One Sample T-Test and Pearson Correlation Coefficient.
Results: The lowest and highest contents of the metals (mg/kg) with an average of 0.52 ± 0.25 and 153.81 ± 31.83 were related to Cd and Pb, respectively. Pb and Cu were higher than MPL. Also, the highest surface soil contamination was related to Velayat Park located at the south of Tehran. The value of RI was 99.16 and therefore the soil contamination was categorized in low ecological risk.
Conclusion: Although the value of RI categorized as low ecological risk, due to mean concentrations of Pb and Cu were higher than MPL, control of soil-contamination sources, periodic monitoring of surface soil in the urban parks where citizens spend most of their free time. Additionally, it should be avoided to construct urban parks close to the regions with high traffic intensity.
 

Background and Objective: Heavy metals contaminations are readily bioaccumulated in aquatic systems and lead to increased concentrations in food chains, posing a serious threat to human health, water-related organisms and aquatic ecosystems. The purpose of the present study was to determine the concentration of heavy metals in surface sediments of CheshmehKile River, to evaluate environmental and ecological risk and to determine the degree of contamination of the elements studied.
Materials and Methods: In this study, 25 samples of surface sediment were collected from the CheshmehKile River. The heavy metals content of the samples was measured by inductively coupled plasma-optical emission spectrometry. According to the content of heavy metals in sediment samples, environmental and ecological risk indices were calculated. Also, river contamination was evaluated by comparing the elements studied values with the sediment quality guidelines values.
Results: The mean concentration of chromium, manganese, iron, cobalt, nickel, zinc and arsenic were 41.27, 356.35, 16756.32, 9.17, 11.87, 41.24 and 24.60 µg/g, respectively. Based on the values of the CF and I_geo indices, all of the elements, with the exception of arsenic, showed a low degree of contamination. The indices of Eⁱ_r and RI also showed the lowest ecological risk at all stations.
Conclusion: The results of this study showed that the surface sediments of CheshmeKile River in Mazandaran province were somewhat contaminated with arsenic. However, fortunately, the river sediments were of good quality from the point of view of the content of chromium, manganese, iron, cobalt, nickel and zinc.

Background and Objective: Considering the toxicity, health and ecological hazards of heavy metals in the environment and the impact on organisms, it looks essential to measure and evaluate their concentrations at the various levels in indigineous ecological strctures. The present study evaluated the concentration of Lead, Nickel, Copper and Zinc and their ecological risk assessment in surface sediments of Sezar River in Lorestan province.
Materials and Methods: 16 stations along the Sezar River were selected for sampling. After preparation and acid digestion of the samples, the concentrations of these metals were determined by Atomic absorbtion.
Results: The average total concentration of the detected metals Ni, Zn, Cu and Pb in the sediment was 71.84 > 40.56> 7.75 > 5.61 mg/kg, respectively. In addition, the evaluation of the Potential acute toxicity, ecological risk, and Pollution Load Index represented a low pollution in the sediments. The environmental risk of the metals in the sediment was evaluated as: Ni> Pb> Cu> Zn. The findings showed that among metals, the contamination factor and modified hazard quotient (mHQ) for nickel was moderate and in the mediun to severe pollution level to the contamination, respectively.
Conclusion: According to the results, it can be concluded that Potential acute toxicity, pollution and ecological risk in the region for investigated metals were low. However, a rapid expansion of various human activities in the area and the pollution of nickel in the river along with the probability of its biological effects require continuous monitoring of the river in order to assess the health risk and its ecological risk.
 

Background and Objective: This study conducted to assess ecological risk of an important group of pollutants called polycyclic aromatic hydrocarbons (PAHs) in offshore sediment of the Persian Gulf deposits in Bushehr province. The aim of this study was to model the toxicity of PAHs for aquatic organisms in the study area.
Materials and Methods: In the first step of the applied risk assessment model in this study, the unit of toxicity for each PAH and solubility were calculated by Quantitative Structure-Activity Relationships (QSAR) model. In the second step, the pore water concentration of all compounds in sediment was calculated as an available fraction. Finally, the proposed model was used to evaluate the offshore sediments of the Persian Gulf. Sediments in 19 stations and 7 transects were studied to assess the ecological risk of 21 PAHs. The extraction and clean up method was based on pressurized liquid extraction (PLE) with packed clean up cell. Compounds were analyzed by GC-MS.
Results: The toxicity and solubility of PAHs were modeled. The Pearson correlation for the predicted and measured data was more than 0.93. The amount of total toxicity was introduced as a risk index. The maximum and minimum total toxicity values for the sediments were found as 0.018 and 0.147, respectively. The results from this study indicated that although the concentration of PAHs in the sediments may not cause significant concern in the study area, they may affect benthic organism at the sub-lethal levels. According to the applied risk assessment model for 21 unsubstituted PAHs, the offshore sediments of Bushehr are in low-risk range.
Conclusion: The result of this study indicated a low risk of the sediments. The hazard index decreased as the distance from coastal and oil and gas industry increased, indicating the high impact of anthropogenic activities on the contamination of the study area.
 

Background and Objective: Application of sewage sludge contaminated with heavy metals may cause health and ecological concern. Ecological risk and heavy metals content of sewage sludge from wastewater treatment plants of East Azerbaijan province were evaluated in the present study.
Materials and Methods: Nine composite samples were taken and analyzed for heavy metals. The geo-accumulation index (Igeo), contamination factor(CF) , and potential ecological risk index were calculated.
Results: Variation of the heavy metals concentrations were in the following order: Zn>Cu>Pb>Cr>Ni>As>Hg>Cd. The contents of some heavy metals were several order of magnitude higher than the crustal average (CA) values. Considering the Maximum Permissible Standards (MPS) and the Muller's index, the Cd, Cu, and Zn pollution were found to be in the moderate range, whereas As and Pb were in strongly polluted category; and Hg was in extremely polluted category. Considering MPS, the single-factor pollution index (PI) and the Nemerow’s synthetic pollution index (PN) were lower than 1 and 0.7 respectively. This indicated that the sludges were unpolluted with most heavy metals and could be safely applied for agricultural uses. However, a high potential ecological risk for As and Cd; very high risk for Pb; and extremely high risk for Hg were calculated when considering the CA values. There were significant differences between the levels of heavy metals and MPS (p <0.05).
Conclusion: Although the metal concentrations were below the MPS according to the US EPA regulations, sludge samples showed a high degree of potential ecological risk for the environment in comparision with the CA values,. Periodic monitoring of sludge quality are strongly recommended.  

Background and Objective: Landfills as municipal solid waste are considered as the source of pollution. The present study aimed to assess the ecological risk of heavy metals in Tehran landfill soil and the adjacent residential area.
Materials and Methods: Having consulted with the specialists and considered the waste processing facilities, 12 sampling points were selected and sampled in four seasons. Soil samples were digested using HNO₃: HClO₄: HCl: HF. The levels of metals were measured using ICP-OES which further applied for the calculation of ecological risk. Kolmogorov-Smirnov, Kruskal-Wallis, and Pearson correlation coefficient analyses were run to determine the significant differences between metals concentrations in various seasons and sampling points. 
Results: Metal concentration showed to follow theorder: Al > Fe > Mn > Zn > Cr > Pb > Cu >Ni > Co > As > Cd. Kruskal-Wallis results and pairwise comparison showed a statistically significant difference between metal concentrations across sampling points and seasons, especially in rainy seasons. Pearson correlation coefficient displayed a strong relationship between the mean concentrations of Cu - Pb, Cu - Zn, and Pb - Zn with obtained values of 0.932, 0.874, and 0.883, respectively. Cu exhibited the highest contamination factor at the compost and fermentation sites (13.2 and 9.89, respectively). The geo-accumulation index proved the anthropogenic sources of pollution. The potential ecological risk index (ERI) for the sampling sites ranged from 67.3 to 154, with the order of Cd > Cu > Pb > Ni > As > Cr > Zn > Co > Mn. 
Conclusion: Due to the obtained moderate to severe ecological risk and exceeded background concentrations of heavy metals, it can be concluded that metal changes and soil pollution are both affected by landfill activities.

Background and Objective: Due to the importance of Mordab river, the concentration and distribution of heavy metals in sediments and part of Caspian sea coast, mostly affected by the Mordab river, were evaluated. Additionally, considering the possibility of heavy metals release from sediments to water column and transfer to crops, the health risk of rice consumption in the region was assessed.
Materials and Methods: 21 sediments samples and 4 rice samples from paddy fields along the Mordab River were collected. Heavy metal contents of the samples were measured using ICP-MS. Data analysis was performed using enrichment factor (EF), ecological risk index (RI), health risk index, principal component analysis (PCA) and Mann-Whitney test.
Results: The maximum concentrations of elements was higher in coastal sediments than the Mordab River. The results showed low to moderate risk of elements in most stations except for two coastal stations which exhibited considerable risk of contamination with regard to Cr. Principal component analysis categorized the elements into three components of different origin. Moreover, the estimation of weekly intake of elements through rice consumption were less than their permissible concentration set by World Health Organization.
Conclusion: The concentration of chromium in sediments, especially coastal sediments, is high, which may be partly due to the concentration of heavy minerals (chromium) in this fraction. Therefore, the origin of elements, particularly chromium, should be determined through sequential extraction methods. On the other hand, despite the pollution of river sediments and high consumption of rice among the residents of the study area, there is no danger to rice consumers in terms of heavy metals.

Background and Objective: Soils and sediments contamination with trace and toxic elements lead to potential ecological risk and adverse effects on human health and so have been the cause of increasing concern worldwide. Therefore, this study was carried out to potential ecological risk assessment of As, Cd, Ni and V in surface sediments of Khazar Abad, southern parts of Caspian Sea in 2019.
Materials and Methods: In this descriptive cross-sectional study, a total of 36 surface sediment samples were collected from 12 sampling sites. After samples preparation, the elemental contents were determined using ICP-OES. Also, potential ecological risk factor (Eⁱ_r) and cumulative potential ecological risk index (RI) were calculated. All statistical analyses were performed by SPSS software.
Results: Based on the results obtained, the mean contents of As, Cd, Ni and V in analyzed samples were found to be 12.7, 0.191, 35.0, and 31.9 mg/kg, respectively. The computed values of Eⁱ_r  showed that factor values were decreased in the order Cd > As > Ni > V. Additionally, the mean values of RI with 53.7 indicated that all the examined elements have the "low potential ecological risk".
Conclusion: Accordingly, although the examined elements have shown a low potential ecological risk, cadmium with 46.4% and arsenic with 45.4% mean values of RI can cause for concern. Therefore, source identification and management of organic and inorganic pollutants and also periodic monitoring of water and sediments as the sink of environmental pollution are recommended.

Background and Objective: Among the emerging contaminants, microplastics threaten public health. This study aimed to determine microplastic and mesoplastics in soil of residential areas adjacent to Tehran Landfill and assess its ecological risk.
Materials and Methods: The present descriptive cross-sectional study was conducted on 20 shallow and deep soil samples from residential areas near the Tehran landfill in July 2021. The microplastics were floated in NaCl and ZnCl₂ solutions, and the mesoplastics were separated manually. The identification of physical and chemical properties of polymers was performed by stereomicroscope and FTIR analysis, respectively.
Results: The average amount of micro-plastics in shallow and deep soils estimated 76±34.98 and 24.7±19.79 particles/kg_soil, respectively. The average amount of mesoplastics obtained 5.25±2.91 and 3.55±1.09 particles/kg_soil, in shallow and deep soils, respectively. Paired-samples T-test showed significant differences between shallow and deep soil in terms of plastic particles (p<0.001). The most abundant microplastic particles were the fragment-shaped with the particle size of 0.1-0.5 mm and LDPE polymer types with the percentage of 37.75, 44.64, and 46.15, respectively. Mesoplastic particles, the 0.5-1 cm film-shaped particles and LDPE polymer types with the percentage of 62.76, 61.46, and 50.7 were found as the most prevalent. Microplastics and mesoplastics' potential ecological risks value in all sampling points was less than 150, indicating low ecological risk.
Conclusion: Despite the low PERI of microplastics and soil mesoplastics in residential areas, the E_rⁱ index for LDPE was high. Thus, Ecological risk is probable if control measures are not taken against plastic pollution.
 

Background and Objective: Water resources deficiency has caused the use of effluents to be considered as a source for re-use in the form of haloculture projects. An attempt has been made to investigate the possibility of using effluent produced by sugarcane production companies in the implementation of haloculture projects, from the viewpoint of the most used pesticides.
Materials and Methods: Ten water, four sediment, two plant, and two fish samples were analyzed using gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) to determine the concentration of pesticides. In order to assess the ecological risk, toxic unit (TU) and risk quotient (RQ) were calculated.
Results: Glyphosate and Ametryn in all liquid, solid, and biological samples had concentrations below the detection limit. 2.4.D, Metribuzin, and Atrazine had detectable concentrations in the samples. However, their concentrations are lower than the standard values. Metribuzin and Atrazine had high concentrations in the stems and leaves of reeds in the region, which may indicate the role of these plants in the remediation of water and sediment from these compounds.
Conclusion: Using effluent from Amirkabir and Mirzakouchak Khan agro-industrial complexes to implement the haloculture project does not pose a particular problem from the viewpoint of contamination with the studied pesticides. This is confirmed due to the small concentrations of the studied compounds in the liver and below the detection limit in the muscles. However, it is necessary to carry out more studies to evaluate the quality of effluent in terms of the other types of pollution.
 

Background and Objective: One of the significant challenges in mining areas is the pollution of the environment by heavy metals. Therefore, it is crucial to assess the pollution risk associated with mining wastes and take action to mitigate their environmental impact. The current study assessed the risk potential of recently deposited tailings in the Songun copper mining area.
Materials and Methods: Based on the conditions of tailings, 26 samples were randomly selected from the recently deposited mine wastes. Twenty-two thin and thin polished sections were prepared for lithology and mineralogy studies. Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) was employed to analyze all 26 samples, while X-ray diffraction method (XRD) was used to analyze a subset of 10 samples.
Results: Sulfide minerals, as the main source of environmental pollution, remain intact and unaffected in the tailings. However, the majority of potentially toxic elements (PTEs) exhibit higher concentrations in the waste composition than the standard levels, resulting in a total ecological risk index of 49.93. Geochemical indicators highlight significant pollution levels for elements such as lead (Pb), arsenic (As), and copper (Cu). The values of the non-carcinogenic risk index for children (except As and Fe) and adults are lower than 1, indicating a non-significant non-carcinogenic health risk. However, the carcinogenicity index also indicates a significant carcinogenic risk in the case of long exposure to wastes, particularly for children.
Conclusion: Therefore, wastes pose a significant environmental risk potential, and due to this risk, proper management of their storage is necessary to prevent the release of PTEs into the environment.