Fate and uptake of pharmaceuticals in soil-plant systems

Abstract

Pharmaceuticals have been detected in the soil environment where there is the potential for uptake into crops. This study explored the fate and uptake of pharmaceuticals (carbamazepine, diclofenac, fluoxetine, propranolol, sulfamethazine) and a personal care product (triclosan) in soil-plant systems using radish (Raphanus sativus) and ryegrass (Lolium perenne). Five of the six chemicals were detected in plant tissue. Carbamazepine was taken up to the greatest extent in both the radish (52 μg/g) and ryegrass (33 μg/g), whereas sulfamethazine uptake was below the limit of quantitation (LOQ) (<0.01 μg/g). In the soil, concentrations of diclofenac and sulfamethazine dropped below the LOQ after 7 days. However, all pharmaceuticals were still detectable in the pore water at the end of the experiment. The results demonstrate the ability of plant species to accumulate pharmaceuticals from soils with uptake apparently specific to both plant species and chemical. Results can be partly explained by the hydrophobicity and extent of ionization of each chemical in the soil.

Figure 1

Uptake of carbamazepine, diclofenac, fluoxetine, propranolol, and triclosan into ryegrass, radish leaf, and radish bulb after plants were grown from seed in pharmaceutically spiked soil for 40 days. Average concentrations (dry weight) provided with error bars representing the standard error. Sulfamethazine uptake was below LOQ.

Figure 2

Average measured soil (closed) and pore water (open) concentrations during fate study (40 days) for test pharmaceuticals: carbamazepine (A), diclofenac (B), fluoxetine (C), propranolol (D), sulfamethazine (E), and triclosan (F). Best model fit provided by dashed line for soil and a solid line for pore water where necessary and error bars represent standard error of mean.