The plastics footprint of the anthropocene: Microplastics in the environment
Since the middle of last century global production of plastics was accompanied by an accumulation of plastic litter in the marine environment. Being dispersed by currents and wind, persistent plastics are mostly not degraded but fragmented leading to an increasing amount of small plastic particles, so called “micro-plastics”, in the marine environment. Due to their small size, micro-plastics have the potential of being ingested by benthic and planktonic organisms and thus of entering marine food webs. For reliable evaluation and assessment of food web effects, a detailed quantitative and qualitative monitoring of micro-plastics in the marine environment is highly required. Due to the methodology currently used, the scarce data on micro-plastics concentrations is mostly biased towards larger particles. Therefore, reliable data on concentrations of micro-plastics in marine systems are still lacking but of utmost importance. Fourier Transform infrared (FT-IR) spectroscopy offers the possibility of proper identification of plastic particles in environmental samples. However, standard FT-IR still requires time- and labour-consuming pre-sorting of particles by hand. Hence, small or less abundant micro-plastics are potentially overlooked. A highly promising FT-IR extension (FT-IR Imaging) allows for detailed and unbiased high throughput analysis of total micro-plastics in a given sample without prior pre-sorting by hand. Within the framework of the several basic and contract research projects, we developed a standardized analysis procedure based on FT-IR Imaging for the analysis of microplastics in different sample types (e.g. sediment, plankton & biota) from different marine regions from coastal to polar waters. Since for a definition of sources & sinks of microplastics, holistic approaches across ecosystems are needed, in the near future, also estuaries, rivers and sewage treatment plants, will be analyzed for the presence of microplastics.
Chemical image of an extracted sediment sample containing microplastics. A: Overview of the whole sample filter. B: Detail of the filter with a PMMA particle (B: red square; C: red spectrum,) and a PP particle (B: blue square; C: blue spectrum). C: Spectra in black are reference spectra. The color bar represents the intensity of the integrated band region. The length of a red FPA field is 170 µm.