Monitoring the quality of groundwater around the landfill is very important for environmental health. Due to the increase in the population and their living standards and technological advances, the amount of solid wastes from human and industrial activities are increasing. The aim of this study was to investigate the amount of heavy metals e.g. lead, cadmium, copper, and zinc in water wells near Azadshahr (in Golestan province) Landfill.
Material and methods:
In this research, to investigate the concentration of heavy metals in groundwater resources around the landfill site of Azadshahr city, sampling of water was carried out from seven deep wells around the landfill site in spring and summer of 2016. Sampling was carried out in accordance with standard methods. Samples were immediately transferred to the water and wastewater laboratory of the School of Public Health in Gorgan University of Medical Sciences, in glass bottles surrounded by ice. After preparation of the standard solution of each heavy element, the concentration of lead, cadmium, copper and zinc elements was read in micrograms per liter using the metrological polarogram. After determining the concentration of the above parameters, statistical analysis and drawing of the corresponding graphs were performed by Excel and SPSS software to analyze the results and compare the concentrations in downstream and upstream.
Results and discussion:
The results showed that the amount of lead in the wells around the landfill was 3.1± 2.1 μg/l and cadmium content was 1.1± 0.37 μg/l, which was not statistically different between spring and summer. According to the standard of 1053 countries, the maximum lead and cadmium levels for drinking water are 10 and 3 μg.l, respectively, which demonstrates that our calculations are within the allowable range. The copper content of wells around landfill was 5.22 ± 5.21 μg/l and there was no statistical difference between spring and summer. Also, according to the standard of 1053 countries and WHO, the maximum allowable amount of copper for drinking water is 2 and 1 mg.l, respectively. So, the copper content of the studied water was within the allowable range. Although there was no statistically significant difference between upstream and downstream copper, its content in downstream wells was about 1.27 times more than that of upstream wells. This may be due to the organic matter penetration into the groundwater. The amount of zink in the wells around the landfill was 23.1 ± 5.31 μg/l, which was not statistically different between spring and summer. According to the standard of 1053 countries, the maximum allowable amount of zink for drinking water is 3 mg/l. Although there was no statistically significant difference between the upstream and downstream waters, its value in the downstream wells was about 1.16 times higher than that of the upstream wells, which can still be due to infiltration organic substances leach into the groundwater.
The results of this study showed that the concentration of chemical parameters of water wells around the landfill was below the drinking water standard of the country. Also, the concentration of all elements in downstream wells was calculated more than the upstream wells. Since the Azadshahr is an agricultural area, the groundwater pollution that is used in agriculture can transfer heavy metals to humans through agricultural products and, therefore, strict measures should be taken to prevent groundwater contamination in the area.