Impact of contaminants on aquatic systems and inundated sites with respect to flood events - In vitro biotests, chemical target analysis and fractionation methods

Abstract

Scope of the present study is the development and application of aquatic in vitro bioassays and methods of effect-directed analysis (EDA). It aims at investigating contamination of suspended particulate matter (SPM) and pollution of inundated sites and riparian aquifer, respectively. In the first part of this study, SPM was sampled during flood events and toxicological activities were determined. The second part of the study dealt with possible conflict of interests between flood management (operation of retention basins) and drinking water supply (sustainment of water protection areas). Cytotoxic potencies were determined with the Neutral Red retention assay and dioxin-like and aryl hydrocarbon receptor mediated activities with the 7 ethoxyresorufin-o deethylase (EROD) assay, both using RTL W1 cells derived from rainbow trout (Oncorhynchus mykiss). Both bioassays indicated elevated potencies assoviated with SPM sampled during flood events. Highly active samples were fractionated in order to determine effective compounds. Strongly persistent compounds had an only minor contribution to total biological effects, whereas less persistent substances caused the bulk of biological activity. Chemical analysis showed that compounds analyzed with priority are not capable of adequately explaining the biological effects measured. Non-priority and a priori unknown compounds were mainly effective. The second part of the study aimed to investigate impacts of river contaminants to inundated sites and aquifer in flood events. For this end, the biotest battery was extended with the Ames Fluctuation assay and the bacterial tester strains TA98 and TA100 (Salmonella typhimurium) to detect mutagenic activity, as well as the Yeast Estrogen Screen (YES) assay with bakery yeast (Saccharomyces cerevisiae) to determine endocrine activity. Further, a recently developed method of effect-directed analysis (EDA) was used to separate more polar compounds in SPM and soil. Less persistent compounds were shown to be highly active. However, more polar compounds caused the highest effects. In accordance to findings of the first part of the study, chemical analysis showed that priority compounds only made a minor contribution to biological effects. River contaminant infiltration in the aquifer was assessed following a flood event with a recurrence interval of ten years by measurement of a tracer compound and hormonal activity. Both parameters indicated contamination of the aquifer following the flood. Water that was sampled in the hinterland showed delayed effects and, thus, indicated mass transport in groundwater layers over elevated distances. The findings of this study document high contamination of flood SPM that may be deposited at inundated sites. In particular, increased biological effects and chemical loads of more polar compounds indicate an increased impact of contaminant transfer through soil and aquifer contamination. Furthermore, infiltration and increased toxicological effects indicate a general risk of groundwater contamination in consequence of flood events. The results of the present study directly contribute to a manual assisting stakeholders and operators of retention basins and waterworks to a priori avoid potential conflict of interests and, thus, could directly be implemented in practical work.