Cigarette butt decomposition and associated chemical changes assessed by 13C CPMAS NMR

Cigarette butts (CBs) are the most common type of litter on earth, with an estd. 4.5 trillion discarded annually. Apart from being unsightly, CBs pose a serious threat to living organisms and ecosystem health when discarded in the environment because they are toxic to microbes, insects, fish and mammals. In spite of the CB toxic hazard, no studies have addressed the effects of environmental conditions on CB decompn. rate. In this study we investigate the interactive effects of substrate fertility and N transfer dynamics on CB decompn. rate and carbon quality changes. We carried out an expt. using smoked CBs and wood sticks, used as a slow decompg. std. org. substrate, incubated in both lab. and field conditions for two years. CB carbon quality changes during decompn. was assessed by 13C CPMAS NMR. Our expt. confirmed the low degrdn. rate of CBs which, on av., lost only 37.8% of their initial mass after two years of decompn. Although a net N transfer occurred from soil to CBs, contrary to our hypothesis, mass loss in the medium-term (two years) was unaffected by N availability in the surrounding substrate. The opposite held for wood sticks, in agreement with the model that N-rich substrates promote the decompn. of other N-poor natural org. materials with a high C/N ratio. As regards CB chem. quality, after two years of decompn. 13C NMR spectroscopy highlighted very small changes in C quality that are likely to reflect a limited microbial attack. [on SciFinder(R)]