PARENT SESSION
75 - Pollution of Alpine Environments
8:00 AM to 6:30 PM, Wednesday, 15 May 2002
Exhibition Area

(75-07) Temporal trends of PCB levels in sediment cores from four remote lakes in Chile .

Pozo, Karla^*,1, Barra, Ricardo², Urrutia, Roberto², Di Guardo, Antonio³, Focardi, Silvano¹, ¹ University of Siena, Department of Environmental Sciences, Siena, Italy² EULA, Center, University of Conception, Chile, Conception, Chile³ DBSF, University of Insubria, Varese, Italy

ABSTRACT- It is well known that PCBs and other POPs (Persistent Organic Pollutants) can reach polar regions by means of long- range atmospheric transport (LRAT). It is not clear whether this phenomenon is occurring in the continental Southern Hemisphere and little information is available about the general distribution of these pollutants in remote areas of South America. Sediment cores from four Chilean lakes were sampled at various altitudinal and latitudinal gradients along the Andes and analysed to confirm the distribution of PCBs. Levels of air-borne PCBs bound in sediment can be used to reconstruct the historical trends of PCB deposition in such remote areas. The lakes chosen were selected on the basis of altitudinal differences and their distance from local pollution sources. Sediment cores of Chungara Lake (4520 m a.s.l., 18 degrees SL), Laja Lake (1320 m a.s.l., 37 degrees SL), Castor Lake (750 m a.s.l., 45 degrees SL) and Venus Lake (600 m a.s.l., 47 degrees SL) were obtained using a gravity corer. Core samples, cut into one cm slices, were analysed for PCBs using HRGC-ECD gas chromatography. Sedimentation rates (210 Pb) and Total Organic Carbon (TOC) were also measured. PCBs were detected in all lakes and in some cases well exceeding background concentration ranges of low altitude lakes. The results provide information on the historical circulation of PCBs in this part of the Southern Hemisphere. Data can be used to identify distant sources and to define the background load of PCBs in Chile. Results are discussed in terms of LRAT in the Southern Hemisphere. Research funded by FONDECYT N 1010640.

Key words: Sediment, PCBs, Atmospheric deposition, lake