| Summary: | 碩士 === 國立臺灣大學 === 園藝暨景觀學系 === 101 === Benzene is one of the common indoor volatile organic compounds and has been classified as a human carcinogen. Many indoor plants can remove benzene, althouth with various efficiency. This study aimed to compare benzene removal rates of Cordyline terminalis L. ‘Baby Doll’, Asplenium nidus L., and Aglaonema Schott ‘Silver Queen’. Results showed that Cordyline terminalis L. ‘Baby Doll’ had higher efficiency to remova benzene and thus Cordyline was selected for further studies including effect of light intensity, initial benzene concentration, and growing media on benzene removal rate. Carbon dioxide concentrations during experiments were also measured to clarify the effect of benzene on plant photosynthesis.
Potted plants of Cordyline terminalis ‘Baby Doll’, Asplenium nidus, or Aglaonema ‘Silver Queen’ plants were placed in chambers containing an initial 5 μL‧L-1 benzene. Benzene removal rate of each plant species were 24.8, 18.1, and 24.9 μg‧h-1, respectively. A higher CO2 removal rate during lighting period of day 1 was measured for Asplenium nidus.
Potted Cordyline, with root-zone wrapped Cordyline’ potted plants were placed under light intensity of 20, 40, 60, 80, and 100 μmol‧m-2‧s-1 PPF in chambers containing an initial 5 μL‧L-1 benzene. Plants under 80 and 100 μmol‧m-2‧s-1 PPF had higher benzene removal rate per leaf area than those under 20 and 40 μmol‧m-2‧s-1. Carbon dioxide removal rate during lighting period of day 1 increased linearly as light intensity increased. From day 2, carbon dioxide concentration in each treatments decreased with increasing light intensity. Net photosynthesis rate increased with increasing light intensity.
Potted plants of Cordyline were placed within chambers containing 5, 10, 15, 20, and 25 μL‧L-1 benzene. Results show that benzene removal rate increased linearly with increasing initial benzene concentration. Initial benzene concentration did not affect CO2 uptake and evolution. Benzene concentration did not alter leaf Fv/Fm, ranged between 0.79 and 0.81.
Potted plants of Cordyline exposed to an initial 5 μL‧L-1 benzene exhibited increased benzene removal rate after 61 or 123 h induction period for unwrapped-root zone and wrapped-root zone treatments, respectively. Plants with root-zone wrapped had lower benzene removal rate than those without wrapping during and after induction period. Root zone wrapping did not affect CO2 uptake and evolution of Cordyline.
When exposed to an initial 5 μL‧L-1 benzene in the chamber, Cordyline plants grown with bark-based medium had lower benzene removal rate than those grown with peat-based medium. Sterilized root zone showed consistently lower benzene removal rate than whole plant and non-sterilized root zone, whereas the benzene removal rate did not differ between the whole plant and non-sterilized root zone. Carbon dioxide decreased during light period and increased during dark period when the chamber was placed with whole plant. CO2 concentration increased in the chamber when placed with non-sterilized root zone during dark period of day 2, and CO2 did not decrease until the ninth hour of next lighting period. CO2 concentration did not increase in the chamber until 36 h after placing sterilized root zone.
Benzene concentration did not decrease during 48 h after placing sterilized medium or sterilized medium with roots when exposed to an initial 5 μL‧L-1 benzene in the chamber. After 48 h, benzene removal rate ranged beween 14.2 and 15.2 μg‧h-1 for both treatments. Average CO2 concentrations in chambers during 72 - 144 h were 1011.0 and 1421.9 μL‧L-1 for sterilized medium and sterilized medium with roots, respectively.
One, two, or three potted C. terminalis ‘Baby Doll’ had benzene removal rates of 17.0, 23.4, and 26.0 μg‧h-1, respectively when the plants were placed in chambers containing an initial 5 μL‧L-1 benzene. Benzene removal rate and CO2 concentration during dark period increased with increased number of potted plants in chambers.
|
|---|
