Environmental Impact Assessment of the Agarak Mine on the Water Quality of the Aras River: Validation of Physicochemical Results Using Biological Indices

Document Type : Research Paper

Authors

• Nadia Hassanloo ¹
• Pardis Alipour ¹
• Ali Moridi ²
• Reza Khalili ³

¹ Master Student, Department of Civil Engineering, Faculty of Civil and Environmental Engineering, Shahid Beheshti University, Tehran, Iran.

² Civil, Water and Environmental Engineering Faculty, Shahid Beheshti University

³ Ph.D. Student, Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran

Abstract

Keywords

• Aras River
• Agarak Mine
• Biological Index
• IRWQIsc
• NSFWQI

Main Subjects

• هیدرولوژی

EXTENDED ABSTRACT

Introduction

Rivers play a crucial role in supplying water for various activities, including agriculture, industry, drinking water, and electricity generation. Awareness of water quality is a critical need in water resource planning and development. Given the diversity of water pollutants, it is not feasible to provide a single standard for assessing water quality, and therefore, various indices have been developed to evaluate water quality.One of the most widely used and simple water quality indices worldwide is the NSFWQI (National Sanitation Foundation Water Quality Index), which was first introduced in the 1970s with the support of the U.S. National Sanitation Foundation. This index evaluates nine parameters—pH, DO (Dissolved Oxygen), TDS (Total Dissolved Solids), nitrate, temperature, phosphorus, BOD (Biochemical Oxygen Demand), turbidity, and fecal coliform—using a weighting factor. In Iran, considering the climatic conditions and water resource challenges, the Iran Surface Water Quality Index (IRWQI_SC) has been developed, which is an integrated index derived from NSFWQI and BCEWQI (British Columbia Water Quality Index) that provides a quantitative assessment of water quality.Another important method for estimating water quality is the assessment of biological indices. These methods are diverse and involve the direct study of plants and animals that inhabit the natural environment to estimate water quality. Benthic organisms, particularly macroinvertebrates, accurately and sensitively reflect the water quality conditions in any given area within aquatic ecosystems. They can be used in the assessment of aquatic ecosystems and to determine trends in water quality changes.

Methodology

In this study, parameters including EC, pH, turbidity, water temperature, dissolved oxygen, nitrate, total phosphate, fecal coliform, and BOD5 were measured at six stations using a portable Hack multi-parameter device. The selected stations were located along the Aras River within East Azerbaijan Province. Sampling was conducted in the autumn of 2022. After collecting the samples, they were placed in ice-containing containers and transported to the laboratory. For macroinvertebrate sampling, a Surber sampler with an area of 0.09 square meters was used. At each station, three separate macroinvertebrate samples were sieved using a 0.5 mm mesh sieve, and the contents of the sieves were separately preserved in containers with 96% alcohol and Rose Bengal (at a concentration of 1:1000). The samples were then transferred to the laboratory for sorting and identification. In the laboratory, each sample was again sieved using a 0.5 mm mesh sieve, and the macroinvertebrates were separated. The coordinates of each station and its elevation above sea level were recorded using a GPS device. Subsequently, the water quality indices IRWQIsc and NSFWQI, along with the biological indices BMWP, ASPT, FBI, and Shannon-Wiener, were measured.

Results and Discussion

In this study, to assess the water quality and biological status of the Aras River, water quality parameters were collected during the autumn from six stations along the river. These were evaluated using Pearson's correlation coefficient and the water quality indices IRWQI_SC and NSFWQI, as well as the biological indices BMWP, ASPT, FBI, and Shannon-Wiener. The results from the IRWQI_SC index indicated relatively poor water quality across all stations, while the NSFWQI index suggested moderate quality for the river. Moreover, the biological indices BMWP, ASPT, FBI, and Shannon-Wiener pointed to pollution at the station downstream of Agarak and a decrease in water quality at this station compared to others. The findings from the biological assessments revealed the presence of an environmental pollutant source in the Agarak area, which has led to changes in the macroinvertebrate community and ecological conditions in the area downstream of Agarak.

Author Contributions

Ali Moridi and Reza Khalili conceived of the presented idea, developed the theory and performed the computations.and carried out the experiment. Nadia Hassanloo verified analytical methods and performed the computations. Pardis Alipour investigated and supervised the findings of this work. All authors discussed the results and contributed to the final manuscript, but Ali Moridi worte the final version of manuscript. All authors have read and agreed to the published version of the manuscript. All authors contributed according their name place to the conceptualization of the article and writing of the original and subsequent drafts.

Data Availability Statement

Data is available on reasonable request from the authors.

Acknowledgements

The authors would like to thank all participants of the present study.

Ethical considerations

The authors avoided data fabrication, falsification, plagiarism, and misconduct.

Conflict of interest

The author declares no conflict of interest.