Screening, quantitative analysis and toxicology of organic compounds in sediments and suspended particulate matter of the Saar and the Rhine (Germany)

Abstract

River sediments and suspended particulate matter (SPM) are sinks as well as secondary sources for nonpolar organic compounds that might pose a risk to aquatic ecosystems’ goods and services. Sources of these pollutants are for example wastewater treatment plants effluents or direct discharges as well as dry and wet atmospheric deposition. Surface run-off of contaminated soils and dust from streets are other important origins. The particularly bound substances with different physical and chemical properties are constrained to partitioning processes between the solids and the water phase. Hence, they might get bioavailable and thus pose an ecotoxicological risk for water organisms. During flood events, contaminated sediments could be remobilized and transported to riparian lands. Consequently, there are concerns regarding risks for terrestrial ecosystems’ goods and services. In the first part of this thesis, sediments and SPM samples of the Saar and the Rhine were investigated regarding organic compounds using target, suspect and nontarget screening analysis with gas chromatography – mass spectrometry (GC-MS). Sediment core and suspended particulate matter samples were collected at representative sampling sites along the both rivers. This study was conducted, among other things, to improve information regarding nonprioritized organic compounds in sediments and suspended particulate matter of the Saar and the Rhine. In the second part, the extractability and potential toxicity of particularly bound organic compounds was investigated. Sediment samples from the Saar as well as the Elbe and the Bilina in Czech Republic was extracted with different exhaustive and biomimetic extraction approaches. Soxhlet, ultrasonic and accelerated solvent extraction as well as membrane dialysis extraction were used as exhaustive methods. Extractions with Tenax®-TA as well as mixtures of water with methanol or 2-hydroxypropyl-β-cyclodextrin were applied as biomimetic approaches. The main objective of these investigations was the generation of comprehensive knowledge concerning the relationship between the physical-chemical properties of compounds and sediments as well as extractability and resulting toxicity. Recommendations for the integrated risk assessment of sediments including exhaustive extraction as well as biomimetic methods and dosing were compiled. In the third part, potentially adverse effects of contaminated sediments and SPM for riparian lands were investigated. A main aim was the investigation of two exposition pathways in the contact tests – native sediment versus acetonic extract. Effect-directed analysis was used to examine selected soil and SPM samples regarding effect potentials in vitro and to unravel responsible compound classes or substances, respectively.