The effects of cigarette butts on soil microbial activity

Abstract

This work investigated the impact cigarette butts (CB) and cigarette filters (CF) might have on soil microbial activity and heavy metal availability when the butts are discarded in the environment. The research examined and measured changes in soil respiration, enzyme activity and microbial growth following the addition of burnt CB and unburnt CF CB and CF extracts. Few studies have been conducted to assess their potential influence on soil microbial diversity and activity. The soil was incubated with burnt CB and unburnt CF placed on the soil surfaces, with amendments of CB and CF extracts together with no treatment control soil. Soil respiration, together with the activities of arginase and urease were periodically measured to determine the effect of these potential pollutants. Moreover, these CB and CF extracts were used to produce A. chroococcum soil pastes to determine whether these affected the growth of this organism and whether these organisms could be used as a bioindicator for CB pollution. Microbial culture plates were prepared from soil and exposed to CB and CF extracts to determine the effect of these pollutants on microbial population. No clear conclusions could be drawn from the enzyme assays as the minor changes observed in activity between treatment and control were not statistically significant. Soil respiration was affected on the first day of monitoring, where the rate of respiration decreased significantly in the soil treated with the CF extract but registered a slight increase in the soil treated with the CB extract. Probably due to the organics released from the CB. A. chroococcum was affected by the CB extract, especially on increasing the concentration. There was a change in the microorganism growing on the media plates treated with the CB extract when compared with the no treatment plate. Even though the CF treatment resulted in a change in microbial growth, the difference was minimal when compared with that caused by the CB extract. This work has thus shown that the effect of potential pollutants in soil could be very complex.