| Popis: |
Impact of wild-land fires to the ecosystem is highly complex. Damages to the ecosystem can be attributed not only to the direct impact of fire and release of toxic post-combustion gasses but also to the spraying of fire-fighting chemicals. Fire-fighting foam (FFF) agents are frequently applied for controls in wild-land fires including forest fire. However, effects of FFFs on the composition of the post-combustion gasses and the phytotoxicity of smoke derived from burning woods have not been determined to date. In the present study, with Fourier transform infrared spectroscopy (FT-IR), we have analyzed the chemical composition of the gasses derived from wood slices exposed to two distinct manners of combustion, namely, smoldering (gradual combustion without flame) and rapid burning (combustion with flame). Tested samples include slices of Japanese cedar, Japanese cypress, and Western hemlock. The amount of hydrocarbons, detected in the post-combustion gas such as methane, ethane, ethylene, propane, hexane, formaldehyde, acrolein and phenol, were higher in the gasses from smoldered samples. The major hydrocarbon found in the post-combustion gases processed in the presence of pilot flame was methane. Other hydrocarbons were hardly detectable. Addition of FFFs, namely, a soap-based FFF (designated as MK-08) and a detergent co cocktail-based FFF (Phos-chek) onto wooden slices resulted in slight increase in other hydrocarbons in the gasses derived from flame-driven combustion of wood slices. Interestingly, addition of Phos-chek drastically elevated the phytotoxicity of post-combustion gas derived from Western hemlock slices heated in the presence of pilot flame when assessed using the suspension cultured tobacco cells. In contrast, the soap-based FFF tested here did not alter the phytotoxicity of the post-combustion gasses, suggesting that soap-based FFF might minimize the impact of the fire-fighting activity to the living plants consisting the ecosystem in the forests and wild-land. |
