Use of semipermeable membrane devices (SPMDs) - Determination of bioavailable, organic, waterborne contaminants in the industrial region of Bitterfeld, Saxony-Anhalt, Germany

Triolein-containing semipermeable membrane devices (SPMDs) were employed as passive samplers to provide data on the bioavailable fraction of organic, waterborne, organochlorine pesticides (OCPs), polychlorinated biphenyls (PC Bs) and poly nuclear aromatic hydrocarbons (PAHs) in streams flowing throug h a highly polluted industrial area of Bitterfeld in Saxony-Anhalt, Germany . The contamination of the region with organic pollutants originates in was tewater effluents from the chemical industry, from over one-hundred years o f lignite exploitation, and from chemical waste dumps. The main objective w as to characterise time-integrated levels of dissolved contaminants, to use them for identification of spatial trends of contamination, and their rela tionship to potential pollution sources. SPMDs were deployed for 43 days in the summer of 1998 at four sampling sites. The total concentration of poll utants at sampling sites was found to range from a low of 0.8 mug/SPMD to 2 5 mug/ SPMD for PAHs, and from 0.4 mug/SPMD to 22 mug/SPMD for OCPs, respec tively. None of the selected PCB congeners was present at quantifiable leve ls at any sampling site. A point source of water pollution with OCPs and PA Hs was identified in the river system considering the total contaminant con centrations and the distribution of individual compounds accumulated by SPM Ds at different sampling sites. SPMD-data was also used to estimate average ambient water concentrations of the contaminants at each field site and co mpared with concentrations measured in bulk water extracts. The truly disso lved or bioavailable portion of contaminants at different sampling sites ra nged from 4% to 86% for the PAHs, and from 8% to 18% for the OCPs included in the estimation. The fraction of individual compounds found in the freely dissolved form can be attributed to the range of their hydrophobicity. In comparison with liquid/liquid extraction of water samples, the SPMD method is more suitable for an assessment of the background concentrations of hydr ophobic organic contaminants because of substantially lower method quantifi cation limits. Moreover, contaminant residues sequestered by the SPMDs repr esent an estimation of the dissolved or readily bioavailable concentration of hydrophobic contaminants in water, which is not provided by most analyti cal approaches.