Microplastics contamination in an artificially ventilated Lake (Lake Hallwil, Switzerland)

Plastics are omnipresent in our daily lives, and this has a profound yet poorly understood impact on our health and environment. Since the 1950s, plastics consumption has strongly increased across the globe. Large amounts of this plastic is not recycled and is disposed into the environment. Through fluvial systems, plastics are transported and are deposited in reservoirs such as lakes and oceans where the plastics accumulate in the sedimentary systems. Thus, sediments which contain these plastic fragments can be used to assess their fate pathways, mass loads and accumulation rates in different environmental systems. This study aims to assess the plastics contamination in lake sediments, particularly for the microplastic size fraction (< 1mm) within an artificially ventilated lake, Lake Hallwil, Switzerland. We aim to understand plastics temporal deposition and understand accumulation areas. For this purpose, we retrieved short gravity sediment cores to study the temporal deposition history of plastics.  In addition, surface sediment samples have been taken from different locations within the lake basin for the geographical distribution of plastics. In order to quantify microplastics in sediments, the particles must be extracted from the lake sediments before further identification and characterization.

In this contribution, we present (1) the workflow to separate microplastic particles from the sediments and (2) the first data for the temporal evolution and the geographical distribution of the microplastic contamination recorded in lake sediments.

Using these first results, we plan to further expand the study to better understand the pathways of microplastics into lakes to assess specific release scenarios and mass concentrations of plastics from urban to natural areas surrounding Lake Hallwil, and compare these results to other lake systems.