Zacharias Steinmetz

I combine environmental chemistry, analytics, ecotoxicology, and soil science to unravel the complexities of anthropogenic pollutants in the environment, scrutinizing their fate and effects from source to sink.

My research focuses on the impact of agriculture on land and water.

main research interests

Investigating the sources, sinks, and pathways of plastics and other anthropogenic pollutants in agroecosystems
Developing novel methods for characterizing and quantifying synthetic polymers in heterogeneous matrices, for example, using pyrolysis-gas chromatography/mass spectrometry (Pyrolysis-GC/MS) and Fourier-transform infrared spectroscopy (FTIR) in combination with advanced data science applications
Elucidating the indirect effects of anthropogenic pollutants on ecosystem functions using biomarkers.

selected publications

2021

ANCHAM

Microplastic Spectral Classification Needs an Open Source Community: Open Specy to the Rescue!

Win Cowger, Zacharias Steinmetz, Andrew Gray, Keenan Munno, Jennifer Lynch, Hannah Hapich, Sebastian Primpke, Hannah De Frond, Chelsea Rochman, and Orestis Herodotou

Analytical Chemistry 93(21), 7543–7548, 2021

Abstract DOI Request PDF Code

Microplastic pollution research has suffered from inadequate data and tools for spectral (Raman and infrared) classification. Spectral matching tools often are not accurate for microplastics identification and are cost-prohibitive. Lack of accuracy stems from the diversity of microplastic pollutants, which are not represented in spectral libraries. Here, we propose a viable software solution: Open Specy. Open Specy is on the web (www.openspecy.org) and in an R package. Open Specy is free and allows users to view, process, identify, and share their spectra to a community library. Users can upload and process their spectra using smoothing (Savitzky–Golay filter) and polynomial baseline correction techniques (IModPolyFit). The processed spectrum can be downloaded to be used in other applications or identified using an onboard reference library and correlation-based matching criteria. Open Specy’s data sharing and session log features ensure reproducible results. Open Specy houses a growing library of reference spectra, which increasingly represents the diversity of microplastics as a contaminant suite. We compared the functionality and accuracy of Open Specy for microplastic identification to commonly used spectral analysis software. We found that Open Specy was the only open source software and the only software with a community library, and Open Specy had comparable accuracy to popular software (OMNIC Picta and KnowItAll). Future developments will enhance spectral identification accuracy as the reference library and functionality grows through community-contributed spectra and community-developed code. Open Specy can also be used for applications beyond microplastic analysis. Open Specy’s source code is open source (CC-BY-4.0, attribution only) (https://github.com/wincowgerDEV/OpenSpecy).

2020

JAAP

A simple method for the selective quantification of polyethylene, polypropylene, and polystyrene plastic debris in soil by pyrolysis-gas chromatography/mass spectrometry

Zacharias Steinmetz, Aaron Kintzi, Katherine Muñoz, and Gabriele E. Schaumann

Journal of Analytical and Applied Pyrolysis 147, 104803, 2020

Abstract DOI Request PDF Data

The lack of adequate analytical methods for the quantification of plastic debris in soil challenges a better understanding of their occurrence and fate in the terrestrial environment. With this proof-of-principle study, we developed a simple and fast method for the selective quantification of the three most environmentally relevant polymers polyethylene (PE), polypropylene (PP), and polystyrene (PS) in soil using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). In order to facilitate the preparation of calibration series and to better account for the heterogeneity of soil matrix, polymers were dissolved in 1,2,4-trichlorobenzene (TCB) at 120 °C. Thereby, liquid sample aliquots from up to 4 g of solid sample became amenable to pyrolysis without further preparation. To evaluate the performance of this approach, three reference soils with 1.73–5.16% organic carbon (C_org) were spiked at 50 and 250 μg g⁻¹ of each polymer and extracted with TCB. Prior cleanup steps with methanol, flocculation with KAl(SO₄)₂, or Fenton digestion were tested for their suitability to reduce potentially interfering C_org. Calibration curves responded linearly (adj. R² > 0.996) with instrumental detection limits of 1–86 ng corresponding to method detection limits of 1–86 μg g⁻¹. The measurement repeatability was 3.2–7.2% relative standard deviation. Recoveries of 70–128% were achieved for plastic contents of 250 μg g⁻¹ extracted with TCB without prior cleanup from soils with less than 2.5% C_org. A higher C_org particularly interfered with the quantification of PE. The addition of non-target polymers (polyethylene terephthalate, polyvinyl chloride, poly(methyl methacrylate), and tire wear particles) did not interfere with the quantification of the analytes highlighting the selectivity of the method. Further research is needed to determine low plastic contents in soils exceeding 2.5% C_org. With 1–3 h processing time per sample, our method has the potential for routine analyses and screening studies of agricultural systems to be complemented with microspectroscopic techniques for additional information on particle shapes and sizes.