Contaminants of emerging concern (CECs) in Zea mays: Uptake, translocation and distribution tissue patterns over the time and its relation with physicochemical properties and plant transpiration rate

Abstract

Passive uptake of contaminants of emerging concern (CECs) and its relationship with physicochemical properties, such as lipophilicity (LogKow), ionization behavior (pKa), distribution coefficient (LogDow) and transpiration rate are scarcely studied. In the current study, hydroponically grown corn (Zea mays) was exposed to carbamazepine (CBZ), fluoxetine (FLX), gemfibrozil (GBZ), triclosan (TRI) and atrazine (ATZ)) at environmentally relevant concentrations (20 μg/L each one). Plant tissue concentrations of CECs were determined several times over 21 days. Eighteen plants were used, nine exposed to the CECs and nine untreated. Whole plants were harvested at 7, 14 and 21 days and separated into roots, stem, leaf and male bud flower (only at 21 days). Hydroponic solution was maintained at pH 5.5 throughout the study. CECs concentrations in the exposure solution and tissues were determined by LC-MS/MS. ATZ metabolites desisopropylatrazine (DIA) and desethylatrazine (DEA) were determined by LC-DAD. In shoot tissues, CBZ, FLX and ATZ were detected, while TRI and GBZ were detected only in roots. Root concentrations were related with LogKow (R2ROOT = 0.415). Leaf and stem concentrations of CBZ, FLX and ATZ were linked with LogKow and strongly linked with pKa. Transpiration was related with CBZ and ATZ in shoot, but not related with FLX shoot levels. Neutral compounds such as CBZ (pKa = 13.94; 100% neutral) and ATZ (pKa = 1.6; 85% neutral) were taken up passively with transpiration. Root accumulation was related with CECs lipophilicity, while translocation and bioaccumulation in shoot were not only related with lipophilicity, but also with CECs ionization behavior and transpiration.