Hamidreza Pakzad; Hashem Bagheri; Farzaneh Teymouri
Volume 15, Issue 4 , January 2018, , Pages 125-140
Irankuh Pb-Zn mine is located in 20 km SW of Isfahan in the Zayandehrud river drainage basin. Shale and carbonate are host rocks of the ore deposits. High concentration of Pb and Zn formed ore complex in these rocks. Weathering and erosion of the host rocks of ore deposits, waste water ...
Irankuh Pb-Zn mine is located in 20 km SW of Isfahan in the Zayandehrud river drainage basin. Shale and carbonate are host rocks of the ore deposits. High concentration of Pb and Zn formed ore complex in these rocks. Weathering and erosion of the host rocks of ore deposits, waste water and waste material arising from mining have made potential for pollution of running water, ground water and agriculture soils by the heavy metals. The main objectives of this investigation were to study the total concentration of Zn, Pb, Ni,Cu, Co, Ag, and Cd in the shale deposits of the mine and physicochemical factors on their distribution and pollution.
Materials and methods:
For measuring heavy metals values, twenty samples were taken from the shale deposits. For distinguishing the shale forming minerals, thin sections were prepared and studied by polarizing microscope. The rock forming clay minerals, after preliminary treatments (heating at 550oc, ethylene glycol solvation), were detected by XRD. Organic carbon, calcium carbonate and Eh/pH of the shales were measured. Heavy metals values in the sample were measured by AAS after mineralization. Correlation coefficient of organic carbon and Mn with metals and also metals-metals were calculated. For comparison of the heavy metal concentration relative to their natural amount (in shale), enrichment factor was applied.
Results and discussion:
The dark grey to olive colored shales in the studied area consist of clay to fine silt size. Quartz, biotite, muscovite, feldspar and clay minerals are the non-opaque minerals of the shales. The clay minerals are illit (60-70%), kaolinite (9-27%) and chlorite (7-22%) respectively. Sphalerite, pyrite and galena are the main opaque minerals of the mine. The mean OC content of the shale is about 2% (0.35-5.5%) and less than 1% calcium carbonate. The pH of the samples is nearly neutral (6.8-7.8) and they have an oxidizing to nearly reducing Eh (18 to -100 v).
The average concentration of heavy metals in the shales are Zn=128.05>Pb=42.55> Ni=35.24> Cu=24.18> Co=7.4> Ag=3.33> Cd=0.79 in ppm, respectively. Highly positive correlation between Ag-Pb-Cd, Cd-Zn-Pb and Co-Ni-Mn and also positive correlation between Zn with organic carbon show geochemical convenient conditions for concentration of the metals. The calculated enrichment factor has revealed extremely high enrichment for Ag and average for Cd. Other elements are depleted in the sediments. Due to relative high concentration of the metals and their extent of the shales in the study area, activation of the heavy metals in suitable conditions can be a potential source for environmental contamination in the groundwater and runoff water of the basin.
Hamid Reza Pakzad; Mehrdad Pasandi; Ardeshir Romiani; Mahdi Kamal
Volume 12, Issue 2 , July 2014
The Anzali wetland is highly important for the particular ecologic, economic and social conditions. Several rivers discharge to Anzali wetland after passing through surrounding forests, towns and villages. Sampling of the sediments of Anzali wetland was carried out at 22 sampling points located in the ...
The Anzali wetland is highly important for the particular ecologic, economic and social conditions. Several rivers discharge to Anzali wetland after passing through surrounding forests, towns and villages. Sampling of the sediments of Anzali wetland was carried out at 22 sampling points located in the inflowing rivers and the canals connecting the wetland to the Caspian Sea in order to determine the heavy metals concentrations and also physicochemical properties influencing concentration of these elements. The major clay minerals of these sediments are montmorillonite, chlorite and kaolinite in their order of abundances. The result showed that the concentration of Cr, Cu and Ni increased in the samples with higher amount of clay and the Zn concentration increases in the samples containing montmorillonite and illite. Increases of the Cr and Cu concentrations and decreases in the Ni concentration conform to increase in the amount of TOC. The Ni concentration was higher in the samples with higher Fe and Mn concentration. The amount of calcium carbonate is positively correlated with the Sr concentration. According to the enrichment factor, Cu and Zn showed average enrichment in just one sample. Ni, Sr and Cr were depleted in the fine-gained sediments of Anzali wetland.