monitoring of heavy metals in water, sediment and phragmites australis of aras river along the iranian-armenian border

Background: aras river is the main source of drinking water supply in northwestern provinces of iran. the present study aimed to determine the concentration of heavy metals in the river on the border between iran and armenia.methods: three samples were taken from the aras river water, the river bottom sediments and the root of phragmites australis. in water sampling, the concentration of hg, mo, cu, c o, b, cd, ni, zn, pb, al, mn, cr, and fe was noticed while in sediment sampling, to measure the concentration of cu and mo. in samples taken from the plant root, the concentration of cu was only analyzed. the water sampling was performed at 11 stations along the river course during four seasons fall, winter, spring and summer 2011.results: the highest and lowest concentrations respectively belonged to al (2600 ppb) and cd (0.4 ppb). parameters including b, cu, mo and al were all higher than the standard limits. the results obtained from sediment and root sampling indicated that the concentration of cu exceeds the standard.conclusion: poor quality of aras river reveals to the necessity of implementing mitigation measures to improve the water quality of the river.