Abstract:

Within this thesis rapid approaches to screening for the presence of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/PCDFs) and polychlorinated biphenyls (PCBs) in street dust and wipe samples were validated and applied in environmental monitoring or as part of governmental inspection programs. Generally, instrumental analysis was based on gas chromatography coupled to high resolution mass spectrometry (GC/HRMS) and quantification was based on isotope dilution analysis. Street dust samples were collected using a natural bristle brush and stainless steel scoops. Mass recovery of fine-particle sea sand (a dust surrogate) on asphalt and concrete surfaces was used as a criterion for the effectiveness of sampling. Better mass recoveries of the dust surrogate were achieved on concrete than on asphalt surfaces. A wipe sampling method based on solvent wetted cotton wipes was evaluated for the investigation of transfer efficiencies during the sampling of PCBs and PCDD/PCDFs in particulate films (PFs) and oily liquid films (OFs). For PFs sufficient transfer efficiencies of low concentrated PCB and PCDD/PCDF congeners in 1g/m2 spiking surrogate were achieved after the first wipe using n-hexane as wetting solvent. Transfer efficiencies for oily liquid films (OFs) were highest in the first wipe if n-hexane and n-heptane were used as compared to toluene. The spiking experiments of OFs showed a log-linear correlation between the number of wiping procedures and transfer efficiency which indicates that transfer efficiencies were constant in subsequent wipes. For the extraction of PCBs and PCDD/PCDFs from street dust samples an extraction temperature optimization for a pressurized liquid extraction (PLE) method was developed and compared with Soxhlet extraction for the analysis of PCBs in real street dust samples. Toluene was used as the extraction solvent in both cases. During this study, a combination of toluene and PLE achieved better extraction efficiencies than Soxhlet extraction. Finally, the performance of the PLE method was evaluated by analysing NIST (National Institute for Standards and Technology) Standard Reference Material 1649a for PCB and PCDD/PCDF concentrations. This demonstrated that the accuracy of the PLE method for the determination of both substance classes was satisfactory. Additionally, for wipe sample extraction it could be successfully demonstrated that PLE is a suitable tool. The feasibility of the wipe sampling method was demonstrated on various impervious surfaces of different origin, and concentration levels of PCBs (PCB6: 0.0062 (exterior window surface of a resident house) – 1408 µg/m2 (working area of transformer recycling); dl-PCBs: 0.00072 (exterior window surface of a resident house) – 34 ng/m2 (working area of transformer recycling)) and PCDD/PCDFs (0.00045 (exterior window surface of a resident house) – 1614 ng/m2 (accidental heavy fires)) in wipe samples were discussed. Street dust samples were taken from rural, urban, industrial and industrially influenced urban areas. PCB6 concentrations ranged from 5090±2200 µg/kg (average±standard error of mean) in dusts from industrial premises to 29±8.7 µg/kg in rural areas. Concentration ranges were for dioxin-like PCB toxicity equivalents (dl-PCB TEQ) from 362±164 ng/kg (industrial premises) to 6.5±1.8 ng/kg (rural areas), and for PCDD/PCDF TEQ from 503±448 ng/kg to 2.4±0.13 ng/kg. Area concentrations of PCB6 (0.040 µg/m2 – 22 µg/m2), dl-PCB TEQ (0.0038 ng/m2 – 2.6 ng/m2) and PCDD/PCDF TEQs (14 pg/m2 – 1980 pg/m2) were estimated. Furthermore, particle size related concentrations of PCBs and PCDD/PCDFs in street dusts were analysed showing throughout almost all samples a distinctive trend of increasing concentrations with decreasing particle sizes. Characterization of homologue patterns of PCBs and PCDDs/PCDFs in street dusts was performed showing a dependence of homologue patterns on different area types, especially for PCBs. It could be demonstrated that the analysis of concentrations in combination with specific homologue patterns of PCBs and PCDDs/PCDFs in street dust samples enables allocation of potential emission sources. However it could not be clearly pointed out that a correlation between sampling site category and concentration exists. For future research a more significant differentiation between sampling site category and concentration may be possible with a higher number of sampling points in a follow-up study. Dusts with origin from industrial sites exhibit concentrations that can even be regarded as secondary sources for the distribution of POPs causing transfer and redeposition into their neighbourhood in the form of hot spots. NRW as an industrial federal state of Germany is affected by a significant number of recycling facilities that deal with, e.g., the recycling of transformers. Revision of regulation EC 850/2004 in order to minimize the threshold value for POPs in waste materials or as in this case in industrial dusts enables discharge of hazardous and highly contaminated materials at an earlier stage and reduces the potential for emission into the environment.