Multimedia and Full-Life-Cycle\nMonitoring Discloses\nthe Dynamic Accumulation Rules of PFAS and Underestimated Foliar Uptake\nin Wheat near a Fluorochemical Industrial Park

The escalating concern of perfluoroalkyl and polyfluoroalkyl\nsubstances\n(PFAS), particularly at contaminated sites, has prompted extensive\ninvestigations. In this study, samples of multimedia including air,\nrhizosphere soil, and tissues of wheat at various growing stages were\ncollected near a mega fluorochemical industrial park in China. Perfluorooctanoic\nacid (PFOA) was predominant in both air and soil with a strong correlation,\nhighlighting air deposition as an important source in the terrestrial\nsystem. PFAS concentrations in wheat decreased in the stem and ear\nbut increased in the leaves as wheat matured. Specifically, perfluorobutanoic\nacid (PFBA) dominated in the aboveground tissues in the full-life-cycle,\nexcept that PFOA surpassed and became predominant in leaves during\nthe filling and maturing stages, hinting at an airborne source. For\nall PFAS, both bioaccumulation factors and translocation factors (TFs)\nwere inversely correlated with the carbon chain length during the\nfull-life-cycle. The obtained TF values were considerably higher than\nthose obtained from ambient sites reported previously, further suggesting\nan unneglectable foliar uptake from air, which was estimated to be\n25% for PFOA. Moreover, spray irrigation remarkably enhanced the absorption\nof PFAS in wheat via foliar uptake relative to flood irrigation. The\nestimated daily intake of PFBA via wheat consumption and air inhalation\nwas 0.50 μg/kg/day for local residents, at least one magnitude\nhigher than the corresponding threshold, suggesting an alarmingly\nhigh exposure risk.