Dynamic distribution and accumulation of PAHs in winter wheat during whole plant growth: Field investigation.

A field investigation was conducted to study the dynamic distribution and accumulation of polycyclic aromatic hydrocarbons (PAHs) in winter wheat in the surrounds of a coal-fired power plant. During March to June 2019, various tissues of winter wheat and the corresponding rhizosphere soil were collected for determination of PAHs. A clear spatial downward trend was found in concentration of ΣPAHs in rhizosphere soil and wheat grain (194-237 μg kg DM) with the increasing distance from the coal-fired power plant. Moreover, ΣPAHs concentration in rhizosphere soil (1081 μg kg DM), root (464 μg kg DM) and stem (365 μg kg DM) of winter wheat at regreening stage and leaf (323 μg kg DM) at anthesis stage were significantly (p < 0.001) higher than that (895, 432, 287 and 265 μg kg DM) at maturity stage, respectively. From regreening to maturity stage, root concentration factors (RCF) of 3- and 4-ring PAHs exhibited an increasing trend but the 5-ring PAHs showed an apparently downward trend. However, stem concentration factors (SCF) of 3- and 4-ring PAHs showed a decrease trend while the 5- and 6-ring showed first down and then stable trend. There were positive linear relationship between logKow and logSCF at anthesis (r = 0.681, p < 0.05) and maturity stage (r = 0.751, p < 0.05). Based on linear regression analysis, PAHs in grain mainly came from the transfer of vegetative tissues, and the contribution of PAHs from stem and leaf to grain was higher than that from root. In addition, the present study also found that the physicochemical properties of PAHs play a crucial role in transfer of PAHs from root to vegetative tissues and then to grain. The present research provided more comprehensive information on the fate of PAHs in winter wheat and the safety of the agricultural products.