Assessment of trace elements contamination in surface sediments of the Bakhtegan lake, Iran

Concentrations of elements (As, Co, Cu, Ni, Mo, Pb, V, Cd, Cr and Zn) are studied in the surface sediments of Bakhtegan Lake, northwest of Nyriz City, Iran, to assess metal contamination. The average abundance order of trace elements content in Bakhtegan Lake sediments is Cr>Ni> V> Zn> Cu> Co> As> Pb> Mo>Cd. The comparison of trace elements concentration in Bakhtegan Lake sediments with toxicological reference values, reveal that the average concentration of As, Cr and Ni in the present sediments is higher than threshold effective level (TEL). Ni shows higher concentration than toxic effect threshold (TET) and probable effective level (PEL) values. The results of contamination factor (CF) based on background value reveal that Cr, Cu, Zn, V, Co, Pb, Mo, As and Ni have moderate and Cd has considerable contamination factor. The application of modified degree of contamination values (mCd) based on background and mean shale values indicate low and very low degree of contamination in sediment samples, respectively. The calculated EF values indicate that Cd in Bakhtegan Lake sediments is enriched compared to the background value. The strong association of Cr, Ni, Zn, Co, Cu, Pb, and V in sediments and high loading of these trace elements with clay, Mn and Fe (PC1) agree with the measured correlation coefficients indicating that Mn and Fe hydroxides and clay content play a significant role in the distribution and sorption of trace elements in sediments. The results of PCA for As and Cd indicate that these elements are influenced by anthropogenic activities.