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1G - Long-range transport of pollutants (chemicals) (WE13/10) Temperature dependence of the accumulation of organochlorine compound in soils, sediments and mosses from the Andean mountains. Grimalt, Joan1, Borghini, Francesca2, Sanchez-Hernandez, Juan Carlos3, Barra, Ricardo4, Focardi, Silvano2, 1 Department of Environmental Chemistry (ICER-CSIC), Barcelona, Catalonia, Spain2 Department of Environmental Sciences, University of Siena, Siena, Siena, Italy3 Department of Environmental Sciences, University of Castilla- La Mancha, Toledo, Castilla-La Mancha, Spain4 EULA-Chile Environmental Sciences Center, University of Concepción, Concepcion, Concepcion, Chile ABSTRACT- Organochlorine compounds (OC), namely pentachlorobenzene, hexachlorobenzene, hexachlorocyclohexanes, polychlorobiphenyls (PCBs) and DDTs, have been studied in lake soils, sediments and mosses distributed over three altitude gradients of the Andean mountains at 18°S, 37°S and 45°S. Concentrations of most OC in soils exhibited a significant correlation with total organic content (TOC) but no correlation was observed for OC in sediments. Log transformed TOC normalized concentrations of OC in soils showed a significant linear dependence from reciprocal of temperature independently of the origin of the compounds, e.g. industrial, agricultural or mixed. In the context of the samples selected for study this dependence is related to altitude. Thus, the samples situated at higher elevation showed higher concentrations. Similar temperature-concentration dependences were observed in sediments but only for the more hydrophobic compounds, e.g. PCB congeners #138, #158/160 and #180. Mosses also exhibited the same temperature-dependent distribution. The phase transfer enthalpies calculated from the soil values exhibited similar but slightly higher values than those determined in laboratory experiments. The difference pointed to retention mechanisms other than linear adsorption for the accumulation of OC in these high mountain areas. In contrast, the air-moss phase change enthalpies showed lower values at lower OC volatility. This feature, together with the lower range of concentration of these compounds, is probably due to moss difficulties for the incorporation of the less volatile compounds. Key words: soil, Organochlorine compounds, mosses, Andean mountains |
