Cigarette butts (CBs) are the most common form of litter worldwide and a persistent source of plastic and chemical pollution in aquatic environments. Despite their potential environmental burden, the accumulation dynamics of CBs as aquatic biome pollution are poorly described. We conducted a longitudinal field study of runoff-contributing surfaces near stormwater inlets that flow into the Kendall-Frost Marsh Reserve (San Diego, California) to characterize CB accumulation dynamics. Using a stratified random sample of 29 inlets, CBs were counted and removed in six rounds from January to August 2025. We analyzed counts using mixed-effects negative binomial regression and a first-order accumulation model. Surveys yielded 355–1406 CBs per round, with strong temporal correlations (r = 0.77–0.95, p < 0.001). The accumulation model fit well (adjusted R2 = 0.988), estimating a daily input rate of 79.7 CBs, an annual input of 29,073 CBs (0.44/m2), and a steady-state observable storage of 1503 CBs (0.02/m2). Results indicate the accumulation of countable CBs near storm drains rapidly establishes an equilibrium following removal, with an unknown number of uncountable CBs and fragments remaining in the environment. Effective mitigation of CB contamination of aquatic biomes must involve source reduction.
Matt et al. (Wed,) studied this question.