How to Extract Microplastics from Heterogeneous and Cohesive Marsh Substrate

Microplastics are an emerging issue since they were recently discovered in some of the most remote places on Earth. While identifying the type of plastic and counting the number of particles is a relatively straight forward approach, the hazard potential for health and environment, resulting from chemical additives are little understood. What is known is that acidic conditions, like it is the case in stomachs, lead to leaching and solution of these compounds. The frequently investigated aquatic or beach environments are chemically pretty inert. Marsh soils – rich in organic matter, organic acids, contaminants, endobenthic organism and microbial communities – act as natural chemical and biological reactors and must, thus, be expected to chemically interact with microplastics as both a source or sink for plastic-carried contaminants. Our study focuses, consequently, on the challenging marsh substrate. The first goal is to develop a two-step extraction procedure, since marsh sediment composition – clay-rich and organic-rich – has a highly heterogeneous and also cohesive nature. As a first important step to solve this technical issue to separate microplastic particles from marsh sediment, we developed an elutriation column, which allows for separating fine and light from coarse and heavy material. Various combinations of density fluids were tested in the attempt to separate denser-than-water microplastics from sand particles during this approach. In a repetitive second step, the output sample from the elutriation column will be placed into the density separator so that the microplastic particles of various density are separated from the suspended clay particles – after the organic matter got dissolved by using a temperature-controlled Fenton’s solution. The long-term goal is to provide a universal method to accurately evaluate the level of hazardous potential within a desired area.