evaluation of heavy metal pollution in anzali wetland, guilan, iran

background: evaluation of heavy metals as toxic pollutants in environment has a significant importance in environmental pollution studies. surficial sediments of water resources have a high potential in releasing heavy metals to the upper water environment, hence sediment analysis presents guidelines to the authorities for monitoring the environmental systems. methods: in this study, total and fractional concentration of eight heavy metals (v, ni, cr, cd, zn, as, fe, and pb) were investigated along different sites of anzali wetland in iran using bulk elemental analysis and sequential chemical extraction techniques respectively. geoaccumulation index (igeo) and pollution index (ipoll) were computed and compared in different sites of the wetland, too. results: total concentration of metals in sediment samples found to be in this order: fe>as>cr>zn>ni>v>pb>cd. the speciation data revealed that most metals were bonded in lithogenous fractions that means no pollution. igeo results indicated that the wetland is moderately to highly polluted for cd and as and ipoll results showed that the wetland is moderately polluted for pb and cd were applied to metals also to investigate on igeo and ipoll results. for v, ni, cr, zn and fe, cluster analysis confirmed both indices but for as and pb it confirmed igeo results. conclusion: the results of the present study showed that the anzali wetland is threatened by pollutants related to rivers entering it. so to preserve the environment of the anzali wetland from deterioration, the main act is to prevent the discharge of wastewater to rivers entering it.