Structural equation modeling of PAHs in surrounding environmental media and field yellow carrot in vegetable bases from Northern China: In comparison with field cabbage.

During a harvest period, a set of field samples, including ambient air (gaseous and particulate phases), dust fall, surface soil and peel-surrounding soil, and yellow carrot tissues (leaf, peel, and core), were collected in a vegetable bases near a large coking manufacturer in Shanxi Province, Northern China. Based on the determinations of the concentrations and compositions of 15 USEPA priority polycyclic aromatic hydrocarbons (PAHs), the statistical results determined by a factor analysis (FA), combined with the isomeric ratios of paired species and the local emission inventory, indicated that coal combustion and vehicular exhaust served as the main emission sources of PAHs in the local environment and in yellow carrot tissues and that the coking industry was a secondary source. In terms of the transport pathways of PAHs in the surrounding media and yellow carrot tissues, the simulation results of a structural equation model (SEM) showed that the PAHs in ambient air were closely associated with those in dust fall, and these in turn had a positive correlation with the PAHs in surface soil, due to air-soil exchange. Furthermore, the PAHs in yellow carrot leaf were mainly derived from those in dust fall via leaf surface absorption, while peel uptake played a dominant role in the accumulation of PAHs in the edible core of yellow carrot. This was different from the case of cabbage, which was characterized by the prevailing contribution from leaf surface absorption. The current study supplied additional evidence to explore the transport pathways of PAHs from environmental media to tissues of different vegetables (leafy vegetables and root vegetables). CAPSULE: A combination of structural equation modeling with factor analysis was employed to quantitatively identify the dominant transport pathways of PAHs among multiple surrounding media and the different tissues of yellow carrot.