Aggregation in experimental studies with microparticles: Experimental settings change particle size distribution during exposure.

The ubiquitous occurrence of microplastics is raising broad concerns and motivating effect studies. In these studies, however, particle behaviour in the water and aggregation are rarely considered leading to contradictory results reported by different studies. Using an environmentally relevant experimental setup with Daphnia magna as a test organism, we investigated how experimental conditions affect particle aggregation and the aggregate heterogeneity in terms of the particle size distribution.

Ecotoxicological assessment of suspended solids: The importance of biofilm and particle aggregation.

Assessment of microplastic impacts in biota is challenging due to the complex behavior of the test particles and their interactions with other particulates, including microorganisms, in the environment. To disentangle responses to microplastic exposure from those to other suspended solids, both microplastic and natural particles must be present in the test system. We evaluated how microplastic, non-plastic particles, and biofilms interacted in their effects on survivorship using acute toxicity assay with Daphnia magna.