HCH isomers change in Pyrenean freshwater ecosystems triggered by the transfer operation of Bailín landfill: The case of Sabocos tarn

Abstract This study reports major hexachlorocyclohexane (HCH) isomers percentage changes in Sabacos tarn water mass, a glacial lake located in the Spanish Pyrenees. This chief fluctuation is due to the transference of 180,000 m3 of soil and debris containing 30,000 to 80,000 t of HCH solid waste from the original unlined landfill to a secure cell in 2014, both located in Bailin (Huesca, Spain), at a distance of 24.50 km from Sabocos. A strong shift of HCH isomers percentages in the water body of Sabocos was recorded in water samples encompassing a timespan before, during and after the transfer operation, together with a significant net increase of the total isomers content. Lindane (γ-HCH) was the most abundant isomer in Sabocos water before the Bailin transfer operation, whereas α-HCH isomer recorded highest values after the waste relocation. These results suggest the relevance of local airborne transport, even to areas located in non-prevalent wind directions favored by thermal and topographically induced breeze regimes as in the case of Bailin and Sabocos tarn. Thus, a better understanding of local airborne spreading mechanisms is essential to prevent future pollution episodes and for the design and management of remediation operations in areas affected by HCH worldwide, or other waste products of comparable characteristics.