Sorption and plant uptake of pharmaceuticals from an artificially contaminated soil amended with biochars

Abstract

Plant uptake of active pharmaceutical ingredients (APIs) is increasingly leading to concerns about their potential exposure to humans and wildlife via dietary intake. Due to the extraordinary ability of biochars to bind organic compounds, plant uptake experiments were conducted to assess the effect of soil-amendment of three different biochars on the uptake of APIs from spiked soil. Pot experiments were undertaken to assess the extent of sorption and corresponding bioaccessibility of two APIs (carbamazepine - CBZ and propranolol -PRL) to ryegrass (Lolium perenne) grown in an API-spiked loamy sand, with and without biochar amendment (5 t/ha equivalent). The soil was amended with three different biochars produced from eucalyptus wood and wheat residues. Both APIs were taken up by ryegrass, with CBZ preferentially accumulated (14.3 mg/kg CBZ, 3.8 mg/kg PRL in unamended soil) due to its comparatively high concentration in porewater. Soil amendment with biochars increased partitioning of the two APIs by up to three- fold, with corresponding decreases in porewater (34–72 % of unamended soil) and plant tissue (17–64 %) concentrations. Biochars were effective in reducing the uptake of APIs into plant tissues from a contaminated soil and may be effective in the management of API residues in contaminated soils.