Quantitative assessment and spatial distribution of macroplastic and cigarette butt contamination in Bushehr's stormwater system near the sensitive Persian Gulf coast.

In recent years, the rise of plastic production and its widespread pollution have become major global environmental challenges. The presence of microplastics in ecosystems leads to their accumulation in living organisms, which is ultimately transferred to humans through the food chain, posing a serious threat to public health. Cigarette butts (CBs), made of cellulose acetate filters, can take up to a decade to decompose, releasing toxic chemicals and heavy metals. This study analyzed the spatial distribution of macroplastics and CBs in Bushehr's stormwater collection system. Sampling across seven urban stations (using population-proportional random selection) quantified macroplastic count, color, type, and source, alongside CB abundance. Pollution intensity was evaluated using the Clean Environment Index (CEI) and Cigarette Butt Pollution Index (CBPI). The results indicated high levels of macroplastic and CB contamination across all stations. CBPI values ranged from 20.0 to 279.9, with a mean of 111.43, placing all stations in the "extremely" pollution category. The most common items were cups and bags (mainly polyethylene and polypropylene), whose low density facilitates transport through open stormwater channels. Most macroplastics measured 1-5 cm in size, increasing the risk of fragmentation. These findings highlight anthropogenic drivers of pollution and the urgent need for targeted waste management and stormwater interventions to protect the Persian Gulf ecosystem.