Polyaromatic hydrocarbon concentrations and patterns in sediments and surface water of the Mansfeld region, Saxony-Anhalt, Germany

The composition and spatial distribution of polyaromatic hydrocarbons (PAHs) and their relation to potential pollution sources were investigated in the Bose Sieben Creek, Saxony-Anhalt, Germany, using two techniques: semipermeable membrane devices (SPMDs) and sediment analysis. SPMD is an integrative device that passively samples hydrophobic chemicals of low to moderate molecular weight (<600 Da) in water. SPMDs were placed in water for 34 days at three sites where sediments were also sampled. Fifteen PAHs were determined in SPMDs and in sediment samples to evaluate the concentration levels and specific PAH patterns. Time-weighted average aqueous PAH concentrations were estimated from the PAH amount accumulated in SPMDs during the deployment period using previously reported sampling rates. Sediment-water partition coefficients were used to estimate PAH concentrations in pore water from sediments. Calculated pore water concentrations were, on average, almost three orders of magnitude higher than those calculated from SPMDs. Thus, in addition to contamination from other sources, the water concentration at the sampling sites might be elevated due to contaminant mobilization from historically contaminated sediments. Relative PAH patterns from SPMDS and sediment were compared using principal component analysis, and were correlated with the PAH patterns from different potential contamination sources, including Theisen sludge, one of the by-products of the smelting process for copper production in the region in the past, which is likely to be the main contamination source of PAHs. Moreover, three origin indices (concentration ratios of PAH isomer pairs) were used to evaluate the suitability of these compounds as tracers to distinguish between the contamination arising from different sources. The evaluation of contaminant patterns permits the conclusion that the PAHs are of pyrolytic, industrial origin, possibly including contamination by Theisen sludge, and rules out a petrogenic source for the hydrocarbons.