Controlled Exposure Chamber Study of Uptake and Clearance of Airborne Polycyclic Aromatic Hydrocarbons by Wheat Grain

详细信息    查看全文

• 作者：Reiko Kobayashi ; Thomas M. Cahill ; Robert A. Okamoto ; Randy L. Maddalena ; Norman Y. Kado
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：November 15, 2007
• 年：2007
• 卷：41
• 期：22
• 页码：7934 - 7940
• 全文大小：197K
• 年卷期：v.41,no.22(November 15, 2007)
• ISSN：1520-5851

文摘

Polycyclic aromatic hydrocarbons (PAHs) can partitionfrom the atmosphere into agricultural crops, contributingto exposure through the dietary pathway. In this study,controlled environmental chamber experiments wereconducted to investigate the transfer of PAHs from airinto wheat grain, which is a major food staple. A seriesof PAHs ranging in size from naphthalene to pyrene weremaintained at elevated gas-phase concentrations in thechamber housing mature and dry wheat grain both on theplant and with the husk removed. The PAHs did notachieve equilibrium between the air and grain over the6.5 month monitoring period used in this study. Therefore,PAH uptake under field conditions is expected to bekinetically limited. A clearance study conducted for thegrain showed the half-life of clearance was approximately20 days for all compounds studied. The results suggestthat atmospheric contaminants that partition into grain mayremain in the grain long enough to contribute to dietaryexposure for humans. Mass transfer across the air/graininterface appeared to be limited by grain-side resistance.The grain may act as a multicompartment system withrapid exchange at the surface followed by slower transferinto the grain. A grain/air concentration relationship wasderived for the uptake time that is relevant to field conditions.