An historical record of toxaphene and its congeners in a remote lake in western Europe

Historical trends in the concentrations of toxaphene, its component homologue groups, and individual chlorobornane congeners were determined in a dated sediment core from a mountain fake, Lochnagar, in Scotland, U.K., representing the first such profiles outside of North America. The profile of total toxaphene showed a bimodal distribution with maxima in the mid-1970s and early 1990s unlike the unimodal PCB profile (maximum 1973) in the same core. The earlier toxaphene peak shows agreement with the U.S. source curve and therefore may correspond to modeled global patterns while the later peak may be due to long-range transport from eastern and southern Europe or from still lower latitudes. Sediment toxaphene concentrations (14 ng/g dry wt (dw) at surface; 40 ng/g dw at maximum) and accumulation rates (surface 0.42 ng cm(-2) yr(-1); maximum 1.6 ng cm(-2) yr(-1)) were considerably higher than levels in untreated sites in the Great Lakes region and the Canadian Arctic and are equivalent to those reported for the Great takes themselves where there have been additional riverine inputs. Two toxaphene congeners, B6-923 and B7-1001, accounted far most of the hexa- and heptachlorobornanes, respectively. B6-923 and B7-1001 abundance ratios (relative to the sum of 12 chlorobornane congeners) had doubling times of 17 +/- 3 and 12 +/- 3 yr, respectively. Given the remoteness of the site from areas of toxaphene production and usage, the high sediment levels raise concerns over toxaphene levels in areas of Europe closer to sources, especially where sites are fished for human consumption. Further European data are needed for comparison.