Abstract
This work was designed to investigate the removal efficiency as well as the ratios of toluene and xylene transported from air to root zone via the stem and by direct diffusion from the air into the medium. Indoor plants (Schefflera actinophylla and Ficus benghalensis) were placed in a sealed test chamber. Shoot or root zone were sealed with a Teflon bag, and gaseous toluene and xylene were exposed. Removal efficiency of toluene and total xylene (m, p, o) was 13.3 and 7.0 μg·m−3·m−2 leaf area over a 24-h period in S. actinophylla, and was 13.0 and 7.3 μg·m−3·m−2 leaf area in F. benghalensis. Gaseous toluene and xylene in a chamber were absorbed through leaf and transported via the stem, and finally reached to root zone, and also transported by direct diffusion from the air into the medium. Toluene and xylene transported via the stem was decreased with time after exposure. Xylene transported via the stem was higher than that by direct diffusion from the air into the medium over a 24-h period. The ratios of toluene transported via the stem versus direct diffusion from the air into the medium were 46.3 and 53.7 % in S. actinophylla, and 46.9 and 53.1 % in F. benghalensis, for an average of 47 and 53 % for both species. The ratios of m,p-xylene transported over 3 to 9 h via the stem versus direct diffusion from the air into the medium was 58.5 and 41.5 % in S. actinophylla, and 60.7 and 39.3 % in F. benghalensis, for an average of 60 and 40 % for both species, whereas the ratios of o-xylene transported via the stem versus direct diffusion from the air into the medium were 61 and 39 %. Both S. actinophylla and F. benghalensis removed toluene and xylene from the air. The ratios of toluene and xylene transported from air to root zone via the stem were 47 and 60 %, respectively. This result suggests that root zone is a significant contributor to gaseous toluene and xylene removal, and transported via the stem plays an important role in this process.
Highlights
The quality of the indoor environment has become a major health consideration in the developed world; a situation exasperated by urban-dweller generally spending 80–90 % of their time in indoors (Krzyanowski 1999; Wang et al 2007)
Three potted plants were exposed for 24 h in a sealed chamber (1.0 m3) at a light intensity of 20 ± 2 μmol·m−2·s−1
Gaseous toluene and xylene were removed by indoor potted plants, S. actinophylla and F. benghalensis in the sealed chamber (Fig. 2)
Summary
The quality of the indoor environment has become a major health consideration in the developed world; a situation exasperated by urban-dweller generally spending 80–90 % of their time in indoors (Krzyanowski 1999; Wang et al 2007). The quality of indoor air is of particular concern, with over 200 volatile organic compounds (VOCs) having been detected as contaminants (Kostiainen, 1995). Each compound is likely to be present in very low concentrations, the mixture can produce additive and possibly synergistic effects (Weschler and Shields 1997; World Health Organization 2000). Indoor air is almost 5–10 times more polluted compared to the outdoor environment (Brown et al 1994; Environment Australia 2003). VOCs such as toluene and xylene are highly toxic and are thought to be significant contributors to reduce indoor air quality (IAQ)-associated health problems and contributing to sick-building syndrome and/or building-related illness (Abbritti and Muzi 1995; Wallace 2001; Orwell et al 2006; Tsai et al 2012).
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