Contenido, distribución y transporte de α, β, γ y δ- hexaclorociclohexano en suelos afectados por vertidos de productos fitosanitario

Approximately 1000 tonnes of pesticide residues were spilled in 1960 in Torneiros (Pontevedra, Spain). Soils were sampled at intervals of 50 meters between the point of discharge and a nearby river. Soil samples were characterized and hexachlorocyclohexane soil contents were determined. The highest concentrations were found in soil surface layers from the spill area, especially α and β-hexachlorocyclohexane (25120 and 15120 μg kg-1, respectively) followed by γ -HCH. In all soils the concentration of many of the isomers is about five times higher than the maximum allowed by the current legislation. It has established close, and highly significant, negative correlation between α + β + γ+ δ- HCH content and spill zone distance, as well as HCH (all isomers and each of them) content and depth. Each of the isomers content are positively correlated with pH and organic matter content, which indicates that their stability increases in conditions close to neutrality, and reflects the isomers lipophilicity especially β and δ -HCH. α -HCH/γ -HCH ratio in soils decreases with depth and distance to landfill area and is higher than the commercial mixture, which indicates lindane degradation. Hexachlorocyclohexane high concentrations, especially in the surface layer along the study area, confirm the transport from the spill zone.