Evaluation of a plant uptake model for BTEX by three plant species under accidental release scenarios

摘要

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are widely used in the chemical industry, and they are often episodically released by chemical accidents or spills. When an accidental release occur, plants may uptake released chemicals via various routes. We evaluated a plant uptake model to predict time-course changes of the internal concentration of BTEX in plant leaf from air under accidental release scenarios. Three plant species, i.e., rice (Oryza sativa), Areca palm (Dypsis lutescens) and Hoya (Hoya carnosa), were chosen as model species to cover plants both in outdoor and indoor. The accidental release scenario assumes a large amount of gaseous BTEX release in 10 min. Partition coefficients for BTEX between test plant leaves and water (KPW) were measured in batch tests and subsequent plant-air partition coefficients (KPA) were obtained by multiplying KPW with the Henry's law constant. The performance of the uptake model was evaluated using small chamber tests. Gaseous concentration of BTEX agreed very well with predicted values under the accidental release scenarios. It was found that the overall uptake is dominated by the mass transfer resistance in plant leaf. The logarithm of mass transfer coefficient was proportional to log KPA for a given plant species. However, differences in mass transfer coefficients among plant species suggest that parameters describing plant physiology should be included to enhance the predictability of the generic uptake model.