Impact of cigarette butts on microbial diversity and dissolved trace metals in coastal marine sediment

Cigarette butts are the most common plastic form of litter found in the marine coast, threatening the quality of the seawater and marine life. However, the impact of cigarette butts known to contain toxic chemicals has been investigated to date in very few marine species. This study aimed to evaluate the effects of cigarette filters (smoked or unsmoked) on the microbial diversity inhabiting coastal sediments by high-throughput sequencing of the 16S rRNA genes. Both bacterial structure and metals distribution were impacted by cigarette filter addition in laboratory sediment experiments, compared to control sediment incubations without filter. Both smoked and unsmoked cigarette filters decreased pH and dissolved Cd, Mo and V concentrations in marine sediment incubations, while they increased dissolved Fe, Mn, Zn levels in the surrounding environment. Smoked filters dramatically decreased the relative abundance of the phyla Bacteroidetes and Cyanobacteria, while the members of the phyla Gammaproteobacteria, Firmicutes and Thermotogae were enriched by smoked filters in marine sediments. Bacterial taxa associated with deep marine environments or hydrothermal seep fields were selected by smoked cigarette filters. This study demonstrated for the first time the microbial community changes and impacts from toxic cigarette filters in coastal marine sediments