BACKGROUND: Urban particulate matter (PM) can affect green plants either via deposition on the above-ground biomass, where the contaminants can penetrate the leaf surface, or indirectly via soil-root interaction. This experiment assessed the potential risk of PM-derived risk elements contained in vegetables. The bioavailable portions of arsenic (As), cadmium (Cd), iron (Fe), and zinc (Zn) in leafy vegetables amended by PM via soil and/or foliar application were investigated in a model pot experiment, in which lettuce and chard were cultivated. RESULTS: By using the physiologically based extraction test simulating in vitro human digestive processes in the stomach and small intestine, the bioavailable portions of toxic elements from PM-amended plant biomass were extracted. Extractable portions of elements by a simulated gastric solution from biomass decreased for lettuce in the order Zn > Cd > As > Fe; while for chard, the order was As > Zn > Cd > Fe. No significant effects of PM physical fractions or soil were observed. CONCLUSIONS: Although the bioavailable element portions in the PM samples were lower compared to plants, the bioavailable element contents in foliar PM-amended plant leaves exceeded the control and soil PM amendment levels, even after biomass washing.

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