Clay mineralogy and heavy metal geochemistry of the Tigris River sediments in selected area of northern Iraq

Abstract

Thirteen samples of sediment were collected from the Tigris River between Hammam Al-Aleel and Fat'ha area, northern Iraq to determine the texture of these sediments, clay mineral assemblages and concentrations of some heavy metals. The grain size analysis of the samples revealed that the silt fraction is the most dominant type in the studied samples, and the size decreases down-stream in accordance with the river's morphology and gradient. The clay fraction was examined by employing XRD to recognize the clay mineral types. It was found that montimorillonite is the most dominant mineral, in addition to illite, palygoriskite, kaolinite and chlorite. The heavy metal elements were determined by Atomic Adsorption Spectrum (AAS) instrument and they included Zinc (Zn), Copper (Cu), Cobalt (Co), Cadmium (Cd) and Lead (Pb) in the clay fraction. However, due to human activities like fertilization of soil and industrial water, such elements as Pb (163 ppm), Zn (121 ppm), Co (33 ppm) were higher than the normal concentration, while the concentration of Cu (42 ppm) was lower than the normal.