Spatial distribution and heavy metal leaching assessment of cigarette butts in coastal environments: Evidence from Prigi Bay, Indonesia

Cigarette butts are commonly found as marine litter worldwide and these small but persistent waste items contain toxic components including heavy metals. They pose environmental risks through metal leaching into coastal ecosystems, yet their contribution to marine pollution remains poorly understood. This study aims to investigate the spatial distribution and heavy metal leaching patterns of cigarette butts and evaluate their contamination potential in coastal environments. Cigarette butts were collected from four beaches in Prigi Bay and subjected to seawater leaching experiments over 1, 7, and 30 days, followed by heavy metal analysis using ICP-OES. A total of 608 cigarette butts were collected, with Prigi Beach showing the highest abundance (37 %), followed by Cengkrong (31 %), Mutiara (20 %), and Karanggongso (12 %) beaches with significant differences among sites (χ² = 85.91, p < 0.05). Cigarette butts were predominantly distributed in backshore zones compared to foreshore zones across all beaches. Whole cigarette butts (WCBs) dominated with abundance ranging 7–29 % compared to decayed cigarette butts (DCBs) at 5–9 %. Leaching experiments revealed distinct heavy metal release patterns: Cd demonstrated rapid early release, Fe exhibited delayed peaks on day 7, and Zn increased progressively over time. Estimated pollution values ranged 0.0448–0.1906 µg/m² for Fe and 0.0189–0.0804 µg/m² for Zn, with Prigi and Mutiara Beaches showing highest contamination potential. This study provides the first quantitative assessment of cigarette butt contamination in Indonesian coastal waters. The findings emphasize cigarette butts as persistent heavy metal sources, contributing essential data for targeted coastal waste management strategies.