Untargeted characterisation of dissolved organic matter contributions to rivers from anthropogenic point sources using direct‐infusion and high‐performance liquid chromatography/Orbitrap mass spectrometry

Abstract

Rationale Anthropogenic organic inputs to freshwaters can exert detrimental effects on aquatic ecosystems, raising growing concern for both environmental conservation and water security. Current regulation by the EU water framework directive (European Union, 2000/60/EC) relates to organic pollution by monitoring selected micropollutants; however, aquatic ecosystem responses require a comprehensive understanding of dissolved organic matter (DOM) composition. The introduction of high‐resolution mass spectrometry (HRMS) is set to greatly increase our understanding of the composition of DOM of both natural and anthropogenic origin derived from diffuse and point sources. Methods DOM was extracted from riverine and treated sewage effluent using solid‐phase extraction (SPE) and analysed using dissolved organic carbon analysis, direct‐infusion high‐resolution mass spectrometry (DI‐HRMS) and high‐performance liquid chromatography (HPLC)/HRMS. The data obtained were analysed using univariate and multivariate statistics to demonstrate differences in background DOM, anthropogenic inputs and in‐river mixing. Compound identifications were achieved based on MS2 spectra searched against on‐line databases. Results DI‐HRMS spectra showed the highly complex nature of all DOM SPE extracts. Classification and visualisation of extracts containing many thousands of individual compounds were achieved using principal component analysis (PCA) and hierarchical cluster analysis. Kruskal‐Wallis analyses highlighted significant discriminating ions originating from the sewage treatment works for more in‐depth investigation by HPLC/HRMS. The generation of MS2 spectra in HPLC/HRMS provided the basis for identification of anthropogenic compounds including; pharmaceuticals, illicit drugs, metabolites and oligomers, although many thousands of compounds remain unidentified. Conclusions This new approach enables comprehensive analysis of DOM in extracts without any preconceived ideas of the compounds which may be present. This approach has the potential to be used as a high throughput, qualitative, screening method to determine if the composition of point sources differs from that of the receiving water bodies, providing a new approach to the identification of hitherto unrecognised organic contribution to water bodies.

High-throughput wastewater analysis for substance use assessment in central New York during the COVID-19 pandemic

“…Piperine is a natural alkaloid in black pepper that possesses important therapeutic properties 96 and has been proposed as a potential inhibitor of SARS-CoV-2 RNAdependent RNA polymerase on the basis of molecular docking simulations. 97 Only two previous studies reported the occurrence of piperine in wastewater 98 or wastewater-impacted surface waters, 99 but neither of them quantied its actual concentration. Like other 26 substances identied by suspect screening, piperine was ubiquitously present in wastewater sampled from the studied sewersheds (i.e., 100% detection frequency) based on a retrospective screening.…”

Mathematical chromatography deciphers the molecular fingerprints of dissolved organic matter

“…There is an increasing interest in such compounds that exist as part of DOM. 45 Since the relevant molecular formulas are known, our approach could be modified to target specific formulas and isomers. A PARAFAC model would describe their dynamics well if these specific compounds behave like the remainder of DOM.…”

Tracing Carbon and Nitrogen Microbial Assimilation in Suspended Particles in Freshwaters

“…Although treated and untreated sewage discharges led to an increase the bioavailability of both dissolved organic and inorganic nitrogen and phosphorus in freshwaters (Yates et al 2019) stimulating bacterioplankton growth, the discharge of potentially harmful compounds that escape conventional treatment could explain the negative impact on microbial diversity (Chonova et al 2018;Hagberg et al 2021). In the same study reach, Pemberton et al (2020) reported changes in the chemical composition of DOM due to STW effluent, highlighting the presence of pharmaceuticals, illicit drugs, and flame retardants. Future studies are needed to assess the impact of these pollutants on the structure and functioning of aquatic microorganism communities.…”