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

Title and Keywords: • Revised title to "Heavy Metal Release Patterns and Contamination Assessment from Cigarette Butts in Coastal Waters: A Study in Prigi Bay, Indonesia" to better reflect study scope • Updated keywords to avoid duplication with title terms and improve discoverability Abstract • Added structured format with clear background, objectives, methods, results, and conclusions • Incorporated specific quantitative data (percentages, ranges, pollution values) • Improved sentence structure and eliminated repetitive content Introduction: • Enhanced narrative flow with improved transitions between paragraphs • Added explicit literature gap identification and study innovation highlights • Incorporated justification for representative heavy metal selection from different release rate categories • Strengthened connection between research problem and study objectives Materials and Methods: • Added appropriate references • Clarified EP calculation methodology and interpretation limitations • Enhanced methodological descriptions with proper citation support Results and Discussion: • Extensively revised sentence structure by breaking complex sentences into shorter, clearer segments • Incorporated quantitative data directly in text (percentages, ranges, concentration values) • Eliminated redundant information and improved paragraph transitions • Added statistical notation to figures where appropriate • Enhanced discussion of empirical findings with reduced reliance on general literature • Strengthened interpretation of metal-specific leaching patterns and spatial distribution results Conclusion: • Condensed content while maintaining essential findings • Added explicit recommendations for policy implementation and future research • Clarified knowledge contributions and study innovations Overall Improvements: • Consistent scientific formatting for statistical data and percentages • Improved readability through simplified language and clearer structure • Enhanced coherence and logical flow throughout manuscript • Comprehensive response to all reviewer feedback while maintaining scientific rigor . 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. .