Assessing landfill leachate heavy metal effect on the surface water quality: A case of Gheshlagh River, Sanandaj City, Iran

Pollution resulted from the leachate of the Sanandaj City landfill into Gheshlagh River is an important environmental and health issue, which has endangered the river. Having a population of more than 400,000 and four municipality districts, the solid waste generation rate is approximately more than 300 tons/day in Sanandaj City. The wastes generated are disposed of at the Sanandaj City landfill with an area of approximately 35 hectares located on the off-road at the Sanandaj-Kamyaran highway. The leachate formed is discharged into the Gheshlagh River through seasonal Kilak River during the succulence (winter and spring) seasons due to the un-sanitary conditions of the landfill. In this study, we investigated the effects of the heavy metals (mercury [Hg], lead [Pb], zinc [Zn], and copper [Cu]) existing in the leachate on the Gheshlagh River and its autopurification capacity. For this purpose, we selected five stations and performed random sampling during two above-mentioned seasons and analyzed the samples. The data were analyzed using one-way analysis of variance and t-test. In general, our results showed that the concentration of the measured elements was more at the leachate confluence station compared with the control station. The mean concentration of the heavy metals in different sampling times and stations was observed in the order of Cu > Zn > Pb > Hg. However, the autopurification of the river resulted in statistical insignificancy of the data, except for Hg.