When studying microplastics, there is a risk of results being “polluted”, which is why it is important for the research to be “plastic-free”. A study carried out at the University of Pisa and published in the journal “Science of the Total Environment” focused on this particular aspect in relation to groundwater studies.
"The study of microplastics in groundwater is a relatively new topic. In order to avoid possible contamination, at the beginning of the research we defined a sampling and sample treatment protocol that was completely “plastic-free”, as the scientific community would expect," says Professor Stefano Viaroli of the University of Pisa. "However, when we arrived on site, we found wells and piezometers with PVC linings and pipes, and so we wondered if and to what extent these plastic elements could affect the water quality and the overall results.”
In fact, groundwater sampling relies on existing monitoring wells and water wells, often constructed with PVC linings or pipes, which are convenient in terms of quality/price but, as in this case, have problematic aspects.
The research team therefore undertook a thorough review of existing studies, although the characteristics of these wells are often insufficiently detailed in various studies. Preliminary results showed that if PVC makes up more than 6% of the total concentration of microplastics in water samples, it is likely that PVC linings and pipes are a local source of pollution, invalidating the analytical results. In actual fact, this phenomenon does not currently raise environmental alarms, although future studies in physics or material science will need to define the ageing rates and processes of PVC with a quantification of the possible release of microplastics
“Wells, as direct access to the aquifer, can be a preferred channel for contamination, both of microplastics and of any other contaminants from the surface. For this reason,” concludes Viaroli, “it is important that they are properly protected and are sampled with particular care, in order to obtain more meaningful data on the real state of the entire aquifer and not just on a single point”.
The work, published in the journal “Science of The Total Environment”, is part of SPONGE, a Postdoctoral Fellowship funded by the European Commission under the Marie Skłodowska-Curie Actions and coordinated by the University of Pisa, which started in 2022 and aims to study microplastics and other emerging pollutants in urban aquifers.
The research involved lecturers from the Departments of Earth Sciences, Chemistry and Industrial Chemistry and from the Centre for Instrument Sharing (CISUP) of the University of Pisa: Stefano Viaroli, Roberto Giannecchini, Riccardo Petrini, Viviana Re and Valter Castelvetro. Lecturers from the Eastern Institute of Technology (China), Southern University of Science and Technology (SUSTech) (China) and Kangwon National University (South Korea) also collaborated.