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Ecosystems at risk in Antarctica due to microplastics

Microplastics are nowadays found even in the most remote regions of the planet, from the deepest ocean floors to the North and South poles. Most evidence comes from aquatic ecosystems, and although there is increasing evidence that plastic pollution is affecting also plants and soil, it is still unclear the extent to which plastics have actually entered terrestrial food webs. Unexpectedly, new evidence has emerged just from a remote Antarctic island, where microplastics appear now to be an integral part of the soil food web.
In February 2016, a large piece of polystyrene foam – used for home insulation, packaging and other purposes was found on King George Island (South Shetland Islands), off the coast of Antarctica. The foam was covered by moss, lichens, microscopic algae and miniscule six-legged creatures known as Antarctic springtails (Cryptopygus antarcticus). Collembolans is a group of millimetric to submillimetric arthropods very close to insects. This species is central to Antarctic soil food webs and is an excellent model of soil animals that are very abundant throughout the world. In Figure 1 it is possible to appreciate the King George Island coast, the found plastic piece and a detail of it.
The question was: do soil animals also ingest fragments of plastic? This question was difficult to answer because it is technically very challenging to detect tiny fragments of plastics in the gut of millimetric animals. In order to overcome the problem, a new approach based on infrared imaging of the pre-digested arthropods was developed. Specifically, collembolans underwent enzymatic digestion followed by hydrogen peroxide treatment. By this approach, that saves the springtail skeleton, most of the organic matter content was removed from the collembolan's body, thus reducing its optical density for infrared (IR) transmission measurements that would otherwise be characterized by strong IR absorption bands of the organic matrix. In Figure 1, the optical images of the pristine and pre-digested collembolanare shown, for highlighting the digestion effects. Collembolans were then chemically characterized by FTIR imaging, and polystyrene was identified in the animal gut by spectral comparison with the FTIR spectrum of the plastic piece from where the animal were collected on King George Island.
 

Figure 1.    Left. A photo of the King George Island coast is shown. The picture of the PS fragment disposal site and a detail of its structure are also shown. Right. From left to right are shown the optical image of one pristine collembolan, the optical image of the pre-digested collembolan and finally the RGB FTIR hyperspectral image showing spectral regions of lipids (blue, 3000–2800 cm−1), proteins (green,1700–1500 cm−1 ) and PS (red peak, at 1490 cm−1). 

 

Microplastics can alter the metabolism of these invertebrates but can also transport contaminants and pathogens. Overall, microplastics could disrupt fluxes of energy and matter in the food web. Collembolans are minute animals but their abundance in soil can range from several tens to hundreds of thousands individuals per m2. These high numbers mean that collembolans may transport and thoroughly redistribute fragments of microplastics horizontally and vertically through the entire soil profile. Future studies will have to understand the impact of microplastics relative to other environmental pressures such as chemical pollution and climate change but it is clear that microplastics have already deeply penetrated the soil food web with potential negative impacts on plant and soil interactions.
The study was coordinated by a team of researchers of the University of Siena in collaboration with the SISSI beamline of Elettra, where the FTIR analysis was perfomed, and the University College Dublin. The research was conducted within the Italian national Antarctic research program (PNRA), with the support of the Brazilian Antarctic program (PROANTAR), the Chilean Antarctic Institute (INACH), and the European consortium CERIC-ERIC.
 

This research was conducted by the following research team:

Bergami Elisa1, Rota Emilia1, Caruso Tancredi2, Birarda Giovanni3, Vaccari Lisa3and Corsi Ilaria1

 

1 Department of Physical, Earth and Environmental Sciences, University of Siena, Siena 53100, Italy
2 School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
3 SISSI-Chemical and Life Science branch, Elettra–Sincrotrone Trieste, S.S. 14 Km 163.5, 34149 Basovizza,Trieste, Italy


Contact persons:

Elisa Bergami, email: elisa.bergami@unisi.it
Giovanni Birarda, email: giovanni.birarda@elettra.eu

 

Reference

Bergami Elisa, Rota Emilia, Caruso Tancredi, Birarda Giovanni, Vaccari Lisa and Corsi Ilaria “Plastics everywhere: first evidence of polystyrene fragments inside the common Antarctic collembolan Cryptopygus antarcticus” Biol. Lett.16: 20200093, 2020, DOI: 10.1098/rsbl.2020.0093



Last Updated on Tuesday, 14 July 2020 15:33