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A major goal of ecotoxicology is the prediction of adverse outcomes for populations from sensitive and early physiological responses. A snapshot of the physiological state of an organism can be provided by metabolic fingerprints. However, to inform chemical risk assessment, multivariate metabolic fingerprints need to be converted to readable end points suitable for effect estimation and comparison. The concentration- and time-dependent responsiveness of metabolic fingerprints to the PS-II inhibitor isoproturon was investigated by use of a Myriophyllum spicatum bioassay. Hydrophilic and lipophilic leaf extracts were analyzed with gas chromatography-mass spectrometry (GC-MS) and preprocessed with XCMS. Metabolic changes were aggregated in the quantitative metabolic effect level index (MELI), allowing effect estimation from Hill-based concentration-response models. Hereby, the most sensitive response on the concentration scale was revealed by the hydrophilic MELI, followed by photosynthetic efficiency and, 1 order of magnitude higher, by the lipophilic MELI and shoot length change. In the hydrophilic MELI, 50% change compares to 30% inhibition of photosynthetic efficiency and 10% inhibition of dry weight change, indicating effect development on different response levels. In conclusion, aggregated metabolic fingerprints provide quantitative estimates and span a broad response spectrum, potentially valuable for establishing adverse outcome pathways of chemicals in environmental risk assessment. [ABSTRACT FROM AUTHOR]

The difference between the molar concentrations of simultaneously extracted metals (SEM) and acid volatile sulfides (AVS) is widely used to predict metal availability toward invertebrates in hypoxic sediments. However, this model is poorly investigated for macrophytes. The present study evaluates metal accumulation in roots and stems of the macrophyte Myriophyllum aquaticum during a 54 day lab experiment. The macrophytes, rooting in metal contaminated, hypoxic, and sulfide rich field sediments were exposed to surface water with 40% or 90% oxygen. High oxygen concentrations in the 90% treatment resulted in dissolution of the metal-sulfide complexes and a gradual increase in labile metal concentrations during the experiment. However, the general trend of increasing availability in the sediment with time was not translated in rising M. aquaticum metal concentrations. Processes at the root-sediment interface, e.g., radial oxygen loss (ROL) or the release of organic compounds by plant roots and their effect on metal availability in the rhizosphere may be of larger importance for metal accumulation than the bulk metal mobility predicted by the SEM-AVS model. [ABSTRACT FROM AUTHOR]

Investigates the 2,4,6-trinitrotoluene (TNT) transformation process in sediment-free aquatic phytoremediation systems of Myriophyllum aquaticum. Extraction of the oxidized TNT metabolites; Isolation of six compounds unique from the reduction products of TNT; Evidence of oxidative transformations, methyl oxidation and/or aromatic hydroxylation.