Spatiotemporal trends and index-based assessment of beach litter abundance and pollution status on Shantou beaches, China.

Beaches are crucial for coastal tourism, but their condition is increasingly degraded by recreational activities and beachgoers. Litter, a growing issue in coastal and marine environments, poses a significant environmental threat. In China, research on litter abundance and pollution levels, particularly in coastal areas, remains limited. This study investigates the spatiotemporal distribution and composition of litter on 10 popular beaches in Shantou, using pollution indices to assess beach quality. Litter was collected from a 30 × 20 m area during winter (December and January), spring (March and April), summer (June, July, and August), and autumn (October and November), and classified into seven categories. The results show that litter density was highest in summer than other seasons, with plastic being the predominant litter type throughout the year. Seasonal assessments indicated that winter was the cleanest season (mean CCI 0.95), while summer had poorest conditions, with 40 % of beaches classified as "dirty" (mean CCI 8.0). Hazardous items and plastic pollution were minimal in winter (mean HII 0.03, PAI 0.45) but peaked in summer, with 10 % of sites classified as high-risk (HII category III) and plastic accumulation was significant (mean PAI 3.94). CEI results showed that all sites were classified as "extremely dirty" during summer (mean CEI 84.47). These findings suggest that beach litter in Shantou is mainly generated by recreational and tourism activities, with additional litter transported by ocean currents and deposited on the shore.