Occurrence of drug target residues within decantation tank sediments: a good clue to assess their historical excretion?

Abstract

This study investigated the potential of sediments accumulated in sewer systems to record human activities through the occurrence of drug target residues (DTR). The installation studied is 17 m deep underground decantation tank that traps the coarse fractions of a unitary sewer system (northern part of Orléans, France), collecting both stormwater and wastewater. The sediments deposited in this tank could constitute a nonesuch opportunity to study the historical evolution of illicit and licit drug consumption in the catchment, however, the deposition processes and the record of DTRs remain largely unknown at present. Five cores were acquired from 2015 to 2017. One hundred fifty-two sediment samples were extracted using a mixture of ultra-pure water:methanol (1:1) prior to analysis of the extracts by high-pressure liquid chromatography coupled to tandem mass spectrometry. Several classical sedimentological analyses such as total organic carbon, facies description and granulometry were also performed on these samples, in order to understand the most important factors (e.g., physico-chemical properties of the DTRs, solid type, assumed load in wastewater) impacting their deposition.The key role of the speciation of DTRs was highlighted by the higher contents in neutral and anionic DTRs in organic layers, whereas only cationic DTRs were found in mineral layers. The considerable modifications in the sediments’ properties, generated by distinct origins (i.e., stormwater or wastewater), are therefore the most important drivers that must be taken into account when back-calculating the historical patterns of drug consumption from their DTR concentrations in decantation tank sediments. Further research remains necessary to fully understand the deposition process, but this study provides new clues explaining these temporal evolutions.

Trace organic contaminants within solid matrices along an anthropized watercourse: Organo-mineral controls on their spatial distribution

“…Yet, contrary to hydrophobic contaminants, for which it is considered that the role of mineral surfaces in their adsorption can be neglected (Mader et al, 1997), it is possible that for more hydrophilic compounds, such as those investigated below, mineral surfaces, which are also hydrophilic, may play a more important role (Schaffer et al, 2012;Scheytt et al, 2005), in particular clay minerals (Droge and Goss, 2013a;Thiebault, 2020). Due to their cation exchange capacity (which is the same as that of organic matter, Droge and Goss, 2013b) and high specific surface area, clay minerals are considered as favourable for the sorption of TrOCs, and especially cationic ones (Dordio et al, 2017;Thiebault et al, 2021b). Therefore, the objective of this paper is to try to go beyond TOC alone to understand the factors controlling the spatial dynamic of TrOC sedimentary occurrences within an anthropized catchment.…”

“…mineralogy is the frequent detection of very hydrophilic TrOCs in sediments (e.g. ACM, ATE), despite their high water solubility and theoretical low susceptibility to sorption(López-García et al, 2021;Thiebault et al, 2021b).…”