Fate and Effects of Quaternary Ammonium Compounds in Soil -The role of microaggregation
Final Report Abstract
Quaternary alkylammonium compounds (QAAC) are cationic organic compounds used as surfactant and disinfectants in numerous applications, amongst others, in agriculture. The risks of co-selection for antibiotic resistance associated with this groups of compounds would entail risks for humans and environment. Available sorption studies with clay minerals indicated that soils could act as potential (final) sink with an accumulation potential for QAACs, however little data on concentration and degradation were available. It was the mission of the project, to understand the fate of QAACs in real soils and specifically address the role of soil microaggregation. We documented the exponential increase of QAAC concentrations in a chronosequence of wastewater irrigated soils in the Mezquital Valley of Mexico. Subsequently, in cooperation with the Hessian State Agency for Nature Conservation, Environment and Geology a total of 65 soil samples from different land uses (arable land, grassland, forest, vineyard) and area types (agglomeration, rural) were analyzed QAACs. Jansen et al. 2023 documented an almost ubiquitous presence of QAACs in 97% of soils of Hesse that were analysed. The highest concentrations were found in floodplain soils, which were influenced by the deposition of suspended solids during floods and concentrations reached up to 5.5 mg kg-1. The occurrence of QAACs in forest soils suggests a possible input via atmospheric deposition. High concentrations of long-chain dialkylammonium compounds (DADMACs) indicate low degradability and accumulation over time. To study dissipation of QAACs in natural soils, four soil pairs with different clay contents were formed from eight of the arable soil samples. Within each pair, one soil was contaminated with QAAC (>100 µg kg-1) and one was uncontaminated (<5 µg kg-1), hypothetically leading to better microbial adaptation and thus faster dissipation. Here we found that contrary to our hypothesis several QAACs correlated positively with a slower degradation. This slow degradation was likely also supported by occlusion within microaggregates based on our findings. We demonstrated that soil solutes influence the characteristic property of QAACs to form micelles and results indicated that in natural environments and in the presence of dissolved organic matter, critical micelle concentration of BAC homologues is lowered. Also we found that the QAAC molecules at environmentally relevant concentrations are able to interfere with the stability of aggregates mirroring effects known from studies on the molecular scale. Overall, we have been able to show that QAACs are present in soils, have the potential to accumulate, are likely to be transported attached to particles and may affect aggregate stability of soil aggregates. Further research concerning the risk of dissemination of antimicrobial resistance is needed.
Publications
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Smectite clay minerals reduce the acute toxicity of quaternary alkylammonium compounds towards potentially pathogenic bacterial taxa present in manure and soil. Scientific Reports, 10(1).
Heyde, Benjamin Justus; Glaeser, Stefanie P.; Bisping, Linda; Kirchberg, Kristin; Ellinghaus, Rüdiger; Siemens, Jan & Mulder, Ines
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Soil water solutes reduce the critical micelle concentration of quaternary ammonium compounds. Environmental Science and Pollution Research, 27(36), 45311-45323.
Mulder, Ines; Schmittdiel, Malte; Frei, Henning; Hofmann, Laura; Gerbig, Dennis & Siemens, Jan
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Quaternary alkylammonium disinfectant concentrations in soils rise exponentially after long-term wastewater irrigation. Environmental Research Letters, 16(6), 064002.
Heyde, Benjamin Justus; Anders, Anja; Siebe, Christina; Siemens, Jan & Mulder, Ines
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Biosolids for safe land application: does wastewater treatment plant size matters when considering antibiotics, pollutants, microbiome, mobile genetic elements and associated resistance genes?. Environmental Microbiology, 24(3), 1573-1589.
Wolters, Birgit; Hauschild, Kristin; Blau, Khald; Mulder, Ines; Heyde, Benjamin Justus; Sørensen, Søren J.; Siemens, Jan; Jechalke, Sven; Smalla, Kornelia & Nesme, Joseph
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Widespread occurrence of quaternary alkylammonium disinfectants in soils of Hesse, Germany. Science of The Total Environment, 857, 159228.
Jansen, Kai; Mohr, Christian; Lügger, Katrin; Heller, Christian; Siemens, Jan & Mulder, Ines
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“Quartäre Alkylammoniumverbindungen in hessischen Böden” in Boden und Altlasten – Nachrichten aus Hessen, Ausgabe 2023, Hessisches Landesamt für Naturschutz, Umwelt und Geologie, Wiesbaden
Jansen, Kai, Christian Mohr, Katrin Lügger, Christian Heller, Jan Siemens & Ines Mulder
