نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه مهندسی محیطزیست، پژوهشکده محیطزیست، جهاد دانشگاهی، رشت، ایران
2 مرکز ملی مطالعات و تحقیقات دریای خزر، موسسه تحقیقات آب، تهران، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The Caspian Sea as the largest lake in the world is very important from the different aspects of economic, social, tourist, and environmental. In this regard, monitoring the water quality of the southern shores of the Caspian Sea has a special importance in order to study it according to national and international standards and control the possible pollution of the coastal strip of Iran. Therefore, the National Research Center of Caspian Sea was analyzed and checked the quality of water in terms of amount heavy metal by establishing 14 stations in the coastal strip from Miankala to Astara. In this study, the concentration of heavy and dangerous metallic and non-metallic elements in depth 1 and 7 meters from Farah Abad station to Lisar and at two depths of 1 and 4 meters in Miankala and Astara stations were measured by ICP-MS method and heavy metal evaluation index, pollution degree index, heavy metal pollution index and Spearman's correlation coefficient were calculated according to the concentration data. The obtained results show that the average concentration of heavy and dangerous metals B(2.37ppm), Ba(24.9ppb) and Zn(18.3ppb) at a depth of one meter and B(2.44ppm), Zn(26.5ppb) and As(17.5ppb) at a depth of seven meters are the highest concentrations recorded in the monitoring stations. According to the data, the highest value of the HEI(1.58), the Cd(-5.96) and the HPI(68.49) of heavy metals were obtained at depth of seven meters in Farah-Abad station and one meter Faridoonkanar and Miankale station, respectively.
کلیدواژهها [English]
Analysis of heavy metal indexes in the water of the southern shores of the Caspian Sea (monitoring year 1400)
EXTENDED ABSTRACT
Coastal areas are considered as important and sensitive regions due to their abundant water resources, unique ecological and biological resources, economic activities, social interactions, and tourism. However, due to population growth and improper exploitation, significant environmental damages have been inflicted upon these areas. One of the most pressing global issues is environmental pollution by heavy and hazardous metals. Heavy metals are considered persistent and enduring pollutants in the environment, as they accumulate in food chains or organisms and have various adverse effects. Assessing different indexes of water pollution is a simple and practical method to examine water quality, analyze its qualitative changes, and identify sensitive areas. Evaluation indexes for heavy metals, such as the Heavy Metal Evaluation Index (HEI), Heavy Metal Pollution Index (HPI), and Contamination degree (Cd), are utilized in various studies for classifying water pollution in terms of heavy metals.
The Caspian Sea, as the largest enclosed water body on Earth, possesses unique natural conditions and plays a significant geopolitical role in the region. Therefore, due to the importance of coastal protection, water resource management, pollutant control, and the examination of environmental changes and their causes, this article presents the results of the analysis of heavy metal and toxic parameters in the water of the Caspian Sea during the monitoring of the year 1400. Additionally, the results were analyzed using statistical methods and calculated various indexes for heavy metals at the sampling stations.
The sampling in this monitoring was conducted using a water sampling device at depths of one meter and seven meters. However, in the Astara and Miankaleh stations, due to coastal conditions, sampling was carried out at depths of one meter and four meters. The sampling stations from east to west in the Caspian Sea are: Miankaleh, Farahabad, Larim, Fereydunkenar, Mahmudabad, Sisangan, Namakabroud, Tonekabon, Ramsar, Dastak, Bandar-e Anzali, Rezvanshahr, Lisar, and Astara. For sampling at each station, the sampling container was rinsed with water from the same location, and then 1000 milliliters of water were collected from an approximate depth of 35 centimeters. The samples were sent to the laboratories in cooling chambers on the same day, according to the relevant standards.
In this monitoring, the concentrations of heavy elements such as molybdenum (Mo), mercury (Hg), copper (Cu), selenium (Se), bromine (Br), strontium (Sr), silicon (Si), arsenic (As), boron (B), aluminum (Al), barium (Ba), uranium (U), rubidium (Rb), lead (Pb), nickel (Ni), zinc (Zn), cobalt (Co), cadmium (Cd), and chromium (Cr) were measured using the inductively coupled plasma method, and their composition was determined by mass spectrometry, following the standard method number 3125. This monitoring was carried out in Mehr 1400, with three replicates for each station's sampling, and the average of the results was reported.
In this study, the concentrations of various heavy and hazardous metals were assessed, and some of them, such as arsenic, boron, nickel, and copper, were found to exceed the standard limits in the Caspian Sea. Furthermore, based on the obtained concentrations at a depth of one meter, the Heavy Metal Evaluation Index (HEI) indicated that the Astara station (53.1) had the highest value, indicating a moderate impact of heavy metals, while Tonekabon had the lowest value (0.46), indicating relatively clean water in terms of heavy metals. In addition, the pollution degree index value (Cd) of all stations is less than one, so they are in the category of low pollution.In this project, based on the performed statistical analysis, at a depth of one meter, significant correlations were found at a 95% confidence level between copper and lead, the Heavy Metal Evaluation Index and the Heavy Metal Pollution Index, molybdenum and barium, aluminum and lead, nickel and the Heavy Metal Evaluation Index. The positive and negative coefficients in the correlation relationships indicate a direct and inverse relationship between these parameters, respectively. At a depth of seven meters, significant correlations were found at a 99% confidence level between copper and molybdenum, nickel and lead. Moreover, a significant correlation at a 95% confidence level was observed between nickel and copper, and also between molybdenum and selenium