Disentangling Mechanisms in Natural Toxin Sorption to Soil Organic Carbon

Natural toxins are multifunctional, often ionizable organic compounds increasingly detected in the environment. Surprisingly little is known about their interactions with soil carbon, although sorption largely controls transport, bioavailability, and dissipation. For a set of 117 natural from 36 compound classes pH-dependent carbon–water distribution coefficient (Doc) was quantified using column chromatography approach under changing conditions regards to pH, ionic strength, major inorganic cation solution. could be assigned groups either hydrophobic partitioning or specific (complexation reactions, exchange) as dominating mechanisms. The complex interplay equally influenced by sorbate, sorbent, solution characteristics. High variability particularly observed presence Ca2+ resulting Doc being enhanced factor 10 when pH increased 4.5 6. Sorbates following this trend contain functional able form ternary complexes via aromatic moieties adjacent protonated N presumably stabilizing exchange reactions. Although stronger than predicted, investigated were highly mobile all considered conditions.