نوع مقاله : مقاله پژوهشی
نویسندگان
گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشکدگان کشاورزی و منابع طبیعی، دانشگاه تهران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Soil contamination with heavy metals, particularly cadmium (Cd), is one of the serious environmental challenges that has significant negative impacts on ecosystems and human health. This study evaluates the ecological and environmental risks of cadmium in a section of the agricultural lands in the Shahr-e Rey region of Tehran Province. In this regard, soil sampling was conducted from 41 points at a depth of 0 to 20 cm, and the total concentration of cadmium was measured using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) after digesting the samples with aqua regia, in accordance with the EPA 3050B standard. The results showed that the average cadmium concentration was 0.79 mg/kg, with a range of 0.17 to 2.05 mg/kg, which is below the permissible limits set by the Environmental Protection Agency of Iran. To assess contamination, environmental indices including the Geo-accumulation Index (Igeo), Contamination Factor (CF), Enrichment Factor (EF), and Ecological Risk Index (ER) were calculated. The Geo-accumulation Index ranged from -0.82 to 2.77, the Ecological Risk Index ranged from 25.50 to 307.50, the Enrichment Factor ranged from 0.69 to 8.57, and the Contamination Factor ranged from 0.85 to 10.25. These indices indicate moderate to relatively high pollution levels in most of the soil samples for cadmium in the studied region. The analysis of these four indices, along with field visits to the area, confirms that human activities have a significant impact on increasing the concentration of this heavy metal in the region's topsoil. This study emphasizes the necessity of proper irrigation and fertilization management to prevent the accumulation of heavy metals. Furthermore, the results clearly demonstrate the influence of industrial and agricultural activities on the increased concentration of cadmium in the region's soils, which could have serious consequences for human health and the environment. Based on the findings, urgent measures are essential to reduce contamination and protect soil resources.
کلیدواژهها [English]
EXTENDED ABSTRACT
Soil, as a non-renewable resource, plays a vital role in agricultural production and meeting human food needs. However, soil contamination with heavy metals, particularly cadmium (Cd), poses a serious environmental challenge with significant negative impacts on ecosystems and human health. Cadmium, as a toxic element, enters soils through human activities such as agriculture, industry, and urbanization, and high concentrations can cause major changes in the physical and chemical properties of soil. This pollution not only threatens human health but also adversely affects the quality and yield of agricultural products. Prolonged exposure to cadmium can lead to severe health issues, including damage to the kidneys and lungs. Therefore, accurate assessment of cadmium concentrations in soil and the use of various indices such as contamination factor (CF), enrichment factor (EF), geoaccumulation index (Igeo), and ecological risk assessment (ER) are essential for better understanding the pollution status. Recent studies have shown that high concentrations of cadmium in certain areas, especially near industrial sites and agricultural regions, are due to improper use of chemical fertilizers and urban wastewater. Continuous assessment of soil pollution status and the implementation of necessary measures to reduce it are crucial for protecting the environment and public health. This research investigates cadmium pollution in the soils of Shahr-e Rey County in Tehran Province and evaluates pollution levels using scientific methods. The results of this study can aid in better management of soil and water resources, contributing to ecosystem preservation and improving the quality of life for local residents.
This study focuses on investigating soil contamination in Shahr-e Rey County, Tehran Province, with an emphasis on cadmium (Cd) concentration and its influencing factors. Shahr-e Rey County is recognized as one of the important agricultural areas in Tehran Province. The study area covers approximately 5,500 hectares. In this research, 41 soil samples were collected from a depth of 0 to 20 centimeters, and various physical and chemical properties of the soil including texture, organic carbon (OC), acidity (pH), electrical conductivity (EC), available phosphorus, and lime content were measured using standard soil analysis methods. Subsequently, total cadmium concentration was determined. Environmental indices including geoaccumulation index (Igeo), contamination factor (CF), enrichment factor (EF), and ecological risk assessment (ER) were calculated. Finally, a spatial variability map of cadmium was created using the nearest neighbor interpolation method. The accuracy of the spatial modeling was validated using metrics such as root mean square error (RMSE) and coefficient of determination (R²) along with leave-one-out cross-validation (LOOCV).
In this study, cadmium (Cd) concentration in soil samples was examined. The concentration range of cadmium varied from 0.17 to 2.05 mg/kg. The maximum concentration found was 2.05 mg/kg, significantly exceeding national and international permissible limits. The average cadmium concentration was reported at 0.79 mg/kg, indicating considerable soil pollution in the area that could negatively impact plant health and living organisms. The ecological risk index (ER) revealed that approximately 7% of samples fell into the low-risk category, 17% into moderate risk, 56% into significant risk, and 20% into high-risk categories, indicating substantial environmental hazards. The geoaccumulation index (Igeo) averaged 1.20. Based on the classification of this index, approximately 10% of the samples fell into the unpolluted class, 24% into the unpolluted to slightly polluted class, 51% into the moderately polluted class, and 15% into the moderately to severely polluted class. The enrichment factor (EF) had an average of 3.29, with about 22% of the samples classified as having minimal enrichment, 63% as having moderate enrichment, and 15% as having high enrichment. The contamination factor (CF) also showed an average of 3.94, with around 5% of the samples in the low pollution class, 29% in the moderate pollution class, 51% in the high pollution class, and 15% in the very high pollution class.The cadmium distribution map created using the nearest neighbor method showed significant accumulation particularly in the northwestern and central areas influenced by industrial activities and irrigation with wastewater. These findings underscore the need for management measures to mitigate pollution risks.Furthermore, validation of the nearest neighbor method using LOOCV resulted in a coefficient of determination R2=0.42 and root mean square error RMSE=0.35 Overall, increased cadmium concentrations in surface soils can be attributed to human activities such as wastewater irrigation practices, pesticide use, chemical fertilizers application, as well as proximity to Iranol Oil Refinery.
Geochemical analysis focusing on indices such as geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (CF), and ecological risk assessment (ER) indicates relatively severe cadmium pollution in agricultural soils resulting from human activities including agriculture, industry, and wastewater usage. The results highlight significant levels of cadmium pollution in the region's soil necessitating careful management of water and soil resources. Additionally, impacts from human activities such as industrial wastewater discharge on soil contamination were evaluated. Given Shahr-e Rey County's proximity to Tehran metropolis and extensive industrial activities, pollution from these sources could pose serious environmental health risks. Therefore, precise planning for water and soil resource management is essential to preserve regional ecosystems while enhancing residents' quality of life.
Conceptualization, Sh.R.S., A.K. and F.S.; methodology, Sh.R.S. and A.K.; software, Sh.R.S. and A.K.; validation, Sh.R.S. and A.K.; formal analysis, Sh.R.S. and A.K.; investigation, Sh.R.S. and A.K.; resources, A.K.; data curation, Sh.R.S. and A.K.; writing—original draft preparation, Sh.R.S. and A.K.; writing—review and editing, Sh.R.S., A.K. and F.S.; visualization, Sh.R.S. and A.K.; supervision, A.K.; project administration, A.K.; funding acquisition, A.K. All authors have read and agreed to the published version of the manuscript. All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts.
Data is available on reasonable request from the authors.
The authors would like to thank the reviewers and editor for their critical comments that helped to improve the paper. The authors gratefully acknowledge the support and facilities provided by the Department of Soil Science, University of Tehran, Iran.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
The authors declare no conflict of interest.
)