NMR-based metabolomics of sub-lethal organophosphate ester exposures to Daphnia magna

Session: Poster session

Vera Kovacevic, University of Toronto, [email protected]
Andre Simpson, University of Toronto Scarborough, [email protected]
Myrna Simpson, University of Toronto Scarborough, [email protected]

Abstract

Organophosphate esters (OPEs) are a class of emerging contaminants that have various chemical structures and sorption affinities for dissolved organic matter (DOM). It is predicted that hydrophobic OPEs will sorb to high levels of DOM and consequently their bioavailability and toxicity may be lowered. ¹H nuclear magnetic resonance (NMR)-based metabolomics was used to evaluate how two concentrations of DOM (1 and 5 mg organic carbon/L) alter the metabolic response of Daphnia magna exposed to sub-lethal concentrations of three individual OPEs with varying hydrophobicity. As expected, both DOM concentrations did not substantially alter the metabolic profile of D. magna exposed to the hydrophilic contaminant tris(2-chloroethyl) phosphate (TCEP). Similarly, DOM also did not mitigate the metabolic changes due to exposure of the hydrophobic contaminant tris(2-butoxyethyl) phosphate (TBOEP). The addition of low and high DOC concentrations enhanced the D. magna metabolic response to the most hydrophobic contaminant triphenyl phosphate (TPhP), which is likely due to synergistic impacts of both DOM and TPhP exposure. Our results show that DOM-OPE interactions cannot be predicted based on contaminant hydrophobicity. Therefore, since DOM is ubiquitous in the environment, how DOM alters sub-lethal toxicity should be considered when evaluating the toxicity of emerging contaminants in freshwater ecosystems.

1. Keyword
environmental contaminants

2. Keyword
zooplankton

3. Keyword
dissolved organic matter

4. Additional Keyword
metabolomics

5. Additional Keyword
NMR spectroscopy