Removal efficiency and mechanisms of formaldehyde by five species of plants in air-plant-water system

摘要

The foliar uptake and transport rates of formaldehyde as well as the abilities of leaf extracts to breakdown formaldehyde were investigated to discuss the formaldehyde removal efficiency and mechanism by five species of plants from air. Results showed that formaldehyde could be transported from air via leaves and roots to rhizosphere water. When exposed to 0.56 mg center dot m(-3) formaldehyde, the formaldehyde removal rate ranged from 18.64 to 38.47 mu g center dot h(-1)g(-1) FW (fresh weight). According to the mass balance in the air-plant-water system, the main mechanism of the formaldehyde loss was its breakdown in plant tissues caused by both enzymatic reaction and redox reaction. Higher oxidation potentials of the leaf-extracts of Wedelia chinensis and Desmodium motorium corresponded well to higher abilities to breakdown added formaldehyde than other plants. Based on the different abilities of fresh and boiled leaf-extracts to dissipate formaldehyde, the enzymatic reaction in Chenopodium album L. was the dominant mechanism while the redox reaction in Kochia scoparia (L.) Schrad. and Silene conoidea L. was the main formaldehyde breakdown mechanism when exposed to low-level formaldehyde in air. The redox mechanism suggested that the formaldehyde removal may be increased by an increasing level of reactive oxygen species (ROS) induced by the environmental stress.