Suspended particulate matter serves as a means of transport for nutrients and pollutants, nourishing sediments, floodplains, and the ocean. It acts as key microscopic bioreactors and is under pressure from climate change. For this reason, an understanding of how SPM forms and assembles, what local and seasonal dynamics it is subject to, and of the underlying physico-chemical principles at work is of importance to many disciplines. SPM is usually reported as a pure sum parameter, but it is highly complex: it is a mixture of minerals and organic matter from the molecular to the organism level. With this review, the EDGE team provides a holistic view on this topic bringing together the views of different disciplines and identifying which substances contribute to flocculation. They show that phyllosilicates, iron oxides/(oxy)hydroxides & microbial exopolymers are key as they enhance physicochemical surface heterogeneities.
