Distribution and Seasonal Variation of Heavy Metal in Surface Sediments from Arvand River, Persian Gulf

Abstract

Distribution and seasonal variation of heavy metals copper (Cu), nickel (Ni), cadmium (Cd), cobalt (Co), lead (Pb) and mercury (Hg) were measured in the surface sediments samples taken from Arvand river in the northeast Persian Gulf. Concentration of heavy metals varied depending on different season and sampling sites. The concentration order of heavy metals in sediment were Ni > Cu > Co > Pb > Cd > Hg. There was significant difference (p<0.05) in metals levels between different seasons and stations. The highest concentration of Ni, Cu, Cd, Pb and Hg was detected in S3 in July and the highest concentration of Co was detected in S3 in April. The percentage of mercury associated with different fractions in the sediment from was in the order of residual > organic matter > easily and exchangeable > acid reduction. Igeo values calculated for Cu (4.5) and Ni (3.6) showed higher values in the July month in the upstream region of the river than in the other seasons. BAFs of Ni were extremely higher than other metals followed by Cu, Co, Pb, Cd and Hg, respectively. These results indicate that Ni and Cu are more easily available than other elements. The analysed heavy metals were found in sediment samples at mean concentration in the sediment quality guideline proposed by NOAA and ROPME, except for Ni concentration in some cases.