Steve Utecht, MSc (Doctoral candidate)

Objective of research: Microplastic in fluvial sediments

Fig.1: Examples of environmental-sampled microplastics < 630 µm

The focus of my research is to generate a better understanding about the deposition of microplastics in river sediments. In particular, deeper sediment layers have been barley studied in the past. In order to understand the deposition of microplastic, a number of different factors have to be considered. Anthropogenic influences such as population density, sewage treatment plants, or catchment properties significantly determine whether and in what quantity rivers carry microplastic. However, no information can be derived here considering spatial distribution of microplastic within the sediments. Hydraulic properties (i.e. discharge and flow velocity), material properties and shape of the plastic as well as the degree of degradation (i.e. density, fragmentation, etc.) can influence the behaviour of the particles in the water column and thus strongly influences depositional processes. It is also unclear, to what extent morphological characteristics of the sediments (i.e. bulk density, porosity, content of organic matter, etc.) and relief-forming processes (i.e. formation of flow resistances, morphology of the waterbed, etc.) influence the deposition. Coming from a small scale perspective, the complex interaction of the aforementioned factors can lead to completely different deposition results.


Microplastic-related field and laboratory analyses

  • Development of a sampling technique for deep-resolved sediment samples
  • Density separation, degradation of organic matter from the sample matrix and sieving for the fractionation of the matrix
  • Spectroscopic identification (Raman microspectroscopy and IR spectroscopy)
  • Fluorescence staining
  • Nutrient content determination: Carbon (C), Phosphorus (P) and Nitrogen (N)
  • Determination of total organic carbon (TOC)
  • Grain size analysis (Mastersizer)


Topic: Master thesis

Title: Microplastic detection at the effluent of a municipal wastewater treatment plant with Raman spectroscopy



[in prep] How the Nile Red staining-assisted fluorescence microscopy quantitatively and qualitatively affects microplastic detections from natural systems

[in prep] Despotional depth distribution patterns of microplastic in a gravel-based riffle structure

[in prep] Review: Global microplastic abundance in riverbed sediments


Gallery: Tools for microplastic analysis

Set up
Set up of freeze core extraction
Depth control of the freezing lance
Freeze core
Freeze core
Sediment Cube Sample (SCS) cut from the freeze core for laboratory analysis
Sieve cascade
Sieve cascade for particle fractionation (>25 µm, > 75 µm, > 125 µm, > 250 µm)
Sample vessels
Sample vessels
Confocal Raman spectroscopy
Confocal Raman spectroscopy


Gravitational settling of particles (< 25 µm)

Fig.2: The numbers represent the days after a image was taken