Previous studies on microplastics (MPs) distribution have predominantly focused on water bodies within specific regions, with limited emphasis on the contributions of MPs directly discharged from functional zones surrounding isolated island. This study addressed this gap by investigating the occurrence and distribution of MPs in water and sediment directly discharged into the adjacent coast of Hainan Island, a geographically isolated and ecologically sensitive region in the South China Sea. Based on the sampling from 40 typical sewage outlets (affiliated to five functional zones, i.e., wastewater treatment plants (WWTP), industrial area (ID), residential area (RA), aquaculture area (QA), estuary (EST)) around the Hainan Island, we analyzed the MPs abundance and composition in water and sediment. Our findings revealed significant contributions of land-derived MPs, with an average abundance of 15,900 items/m