Dissolved organic matter in lakes is more than the only sum of its parts.
Simulating vertical and lateral mixing in Lake Geneva, Thibault showed that the decay of DOM is faster when different DOM pools get mixed. This non-conservative patterns of decay are not related to the original composition of those pools, but instead to which microbial activities are activated.
A great work from the PhD candidate Thibault Masset ( LCME, University of Savoies-Mont-Blanc) about PCB transfers to lake fish.
Masset T, Frossard V, Perga ME, Cottin N, Piot C, Cachera S, Naffrechoux E (2019) Trophic position and individual feeding habits as drivers of differential PCB bioaccumulation in fish populations. Science of The Total Environment,674, 472-481.