As part of BLUEISLANDS activities, marine litter surveys and sand samples collection were conducted on beaches of 8 islands of the Mediterranean Sea
In 2017, as part of BLUEISLANDS activities, 147 marine litter surveys were conducted on 24 beaches of 8 islands of the Mediterranean Sea. The results have shown that, on average, the accumulation rate of marine litter was of 0.08 items/m2/day during the low season and of 0.25 item/m2/day during the high season. This represents an average increase of +205% during the high season. Depending on the type of beach considered, this increase goes from +309% for the touristic beaches (low season: 0.09 item/m2/day, high season: 0.35 item/m2/day), to +327% for the beaches mainly used by locals (low season: 0.05 item/m2/day, high season: 0.21 item/m2/day) and to 68% for the remote beaches (low season: 0.11 item/m2/day, high season: 0.18 item/m2/day).
These results clearly show the seasonal variations of the “visible” marine litter (plastic bottles, cigarette butts or even small pieces of plastic of less than 5mm). But what about the very small particles which cannot be seen with the naked eye?
To address this specific point, while the marine litter surveys were conducted, sand samples were collected at the same time for further analysis at the ICTA-UAB (Barcelona, Spain). For each beach, 4 campaigns of sampling (2 during the low season and 2 during the high season) were implemented. For each campaign, 5 samples of 1 litter of sand were collected and stored into clean glass jars to avoid any contamination from airborne particles. These samples were then processed in the laboratory. The microplastic were extracted from the sediment by density separation: pure water saturated with salt (NaCl) was added to a known amount of sand to make the microplastics float. This solution with the microplastics was then filtered and the filters analysed under microscope to count and characterize the particles found.
The results obtained from the 1st campaign (low season) for the 3 types of beach of 6 islands are presented here. Despite differences between beaches and islands, all the samples analysed were contaminated with microplastics (fibres, microbeads, foams...). The lowest concentrations were found in Cyprus (16.8 microplastics /kg of dry sand, ±10.2) and the highest in Malta (568.8 microplastics /kg of dry sand, ±239.1). Ongoing analysis will reveal if the concentrations significantly change during the high touristic season. Moreover, it will be tested if the characteristic of the sand (grain size, presence of seashell debris...) has an impact on its capacity to retain the microplastics.