Microplastics in Sand: Green Protocol for Expert Citizen Science over Large Geographical Areas

Microplastics (MPs) pollution assessment must not pollute. Inspired by this catch phrase, we critically evaluated the environmental impact, safety, and effectiveness of various analytical strategies currently used to assess MPs contamination on sand. Density separation enables the isolation of MPs from sand. We highlighted the major drawbacks of using the standard high-density solutions. As we recognized there is room for greenness improvement in this hot research field, we considered 21 reagents able to provide high-density media. We aimed to put forward the green MPs determination protocol to be used in subsequent expert citizen science national campaign. The analytical workflow was optimized studying MPs contamination of composite sand specimens representatively sampled from a large beach-dune complex WWF oasis exposed to the effect of tourism in Venice (Italy). MPs have been quantified and characterized. We suggest calcium nitrate as the best trade-off reagent providing both greenness/safety and efficacy. Calcium nitrate can be upcycled from industrial waste streams according to the circular economy vision. Additionally, we critically reviewed all other critical steps of the MPs isolation to put forward a preeminent green, simple, reliable, and logical approach to the analysis of MPs in sand for expert citizen science campaigns.