Effect‐directed analysis of sediment‐associated algal toxicants at selected hot spots in the River Elbe basin with a special focus on bioaccessibility

Abstract

Benthic algae are the dominant primary producers in many rivers and may be at risk of being affected by sediment-associated toxicants. Toxicity as well as bioaccessibility should be considered for the identification of major toxicants affecting benthic algae. Thus, effect-directed analysis (EDA) combining biotesting, fractionation, and chemical analysis was combined with both exhaustive and bioaccessibility-directed extraction to identify the major toxicants in sediments at three industrial sites in the Elbe River basin (Bitterfeld, Most, and Prelouc). Exhaustive accelerated solvent extraction was used together with bioaccessibility-directed extraction with TENAX in aqueous suspension. Growth inhibition of the green alga Scenedesmus vacuolatus identified polycyclic aromatic compounds as important algal toxicants at all three sites, while in Bitterfeld and Prelouc additional toxicants, such as N-phenyl-2-naphthylamine and 7H-benzo[de]anthracen-7-one, played an important role. Confirmation of the identified compounds was based on the index of confirmation quality (ICQ) comparing the effect of an artificial mixture to that of the original sample. The results suggest a successful confirmation of identified toxicants for most fractions with ICQ values between 0.5 and 2. The bioaccessibility of toxicants decreased in the order Prelouc > Bitterfeld > Most as determined by the investigation of TENAX samples. Similar total concentrations of toxicants in Prelouc and Most sediment result in bioaccessible concentrations in Prelouc that exceed those in Most by a factor of 10 to 20. The extraction with TENAX with a subsequent EDA proved to be a powerful tool for prioritizing contaminants and contaminated sites with respect to the hazard of sediment-associated toxicants to green algae.

Identification strategy for unknown pollutants using high-resolution mass spectrometry: Androgen-disrupting compounds identified through effect-directed analysis

“…Only one study has reported benzanthrone levels in sediment from the river Elbe basin at several locations. Benzanthrone was found to be present in one sediment fraction with high algal toxicity at a concentration of 1.2 μg/g dw [7]. …”

“…In the past few years, this aspect of EDA has been lacking due to the immense number of compounds present in the complex samples, even after extensive fractionation. A common approach is target analysis of certain compound groups, based on prior structure-toxicity knowledge [5, 7, 8]. This excludes the possibility to identify compounds with unknown modes of action, or the identification of emerging pollutants.…”

Bioassay-directed identification of organic toxicants in water and sediment of Tai Lake, China

“…Once suspect key toxicants have been identified, confirmation of putative causative agents is essential. Spiking of suspect toxicants has been used as a approach for confirming the suspect toxicants (Bandow et al, 2009;Schwab et al, 2009). Moreover, the presence of synergists or antagonists can modulate toxic potencies of some classes of pollutants and also needs to be considered as a confirmation approach.…”

Effect-Directed Analysis of Complex Environmental Contamination

“…Separation techniques based on classical NP-phases such as alumina [132][133][134][135][136][137] or silica [133,138,139] have been used frequently in EDA. Popular columns for primary fractionation include aminopropyl silica [141-145], cyanopropyl silica [18,140,[146][147][148][149][150][151][152][153][154][155][156][157][158], and cyano-amino-bonded silica [159][160][161][162][163]. Popular columns for primary fractionation include aminopropyl silica [141-145], cyanopropyl silica [18,140,[146][147][148][149][150][151][152][153][154][155][156][157][158], and cyano-amino-bonded silica [159][160][161][162][163].…”