Occurrence and assessment of emerging contaminants adsorbed onto microplastic debris in the Macaronesia region

Abstract

The occurrence and accumulation of microplastics in the aquatic environment has becomes a global problem. These microplastics can adsorb on their superficies other hydrophobic organic chemicals surrounding and act as vectors for the transport of these contaminants and transfer to organisms. This study presents the first coordinated comprehensive three-year spatial-temporal assessment of the occurrence and distribution of emerging contaminants adsorbed on microplastic debris collected from 32 beaches across of Macaronesia (Canary Islands, Madeira, Azores, and Cabo Verde). Two types of microplastic debris (pellets and fragments) were analysed for 34 contaminants using previously established analytical procedures. These included twelve UV filters (UVFs) and UV stabilizers (UVSs) commonly added to personal care products; thirteen steroid hormones and nine pharmaceutical compounds. Concentrations were typically in the nanograms per gram range, obtaining highest concentrations for UV compounds, followed by hormones and, in much lower concentration, pharmaceuticals, possibly due to their hydrophilic nature. The most frequently detected compounds of each family were octocrylene (UVFs), levonorgestrel (hormones) and caffeine (pharmaceuticals) found in 69.12 %, 36.65 % and 29.89 % of the samples, respectively. This study presents a unique multi-archipelago dataset revealing unexpected contamination patterns including significant high concentrations of UV compound even on uninhabited and protected beaches such as Achados Beach (Santa Luzia, Cabo Verde), suggesting the influence of long-range oceanic transport. The findings underscore the ecological risks posed by key pollutants like octocrylene associated with plastics in insular ecosystems. This baseline data is crucial to inform mitigation strategies, including the regulation of UV filters in coastal and marine environments.