Microplastic pollution on sandy beaches of Puerto Rico

Caribbean islands, including Puerto Rico, are biodiversity hotspots threatened by microplastics (<5 mm). Little is known about the extent of microplastic pollution in coastal sandy beaches of Puerto Rico. Sand from six northern beaches was collected in the high tide line to determine microplastic abundance (0.3-4.75 mm). Península La Esperanza, the most polluted beach, exhibited higher average abundance (17 items/kg dw) and diversity. High urbanization, industrial/port activities, and riverine input are likely sources of plastic debris on this beach. The other beaches showed lower and similar average abundance (3 to 7 items/kg dw) despite having distinct potential point and non-point sources. Overall, fibers (40%), fragments (28%) and foams (27%) predominated (n = 102 particles). Results showed comparable levels to other world beaches, some classified as highly contaminated, but only when transforming units to items/m². Preliminary ATR-FTIR analysis identified mainly polyethylene. It is imperative to have plastics source reduction through waste management.