CSIRO Land and Water, Waite Campus, Adelaide, South Australia 5064, Australia; Environment Department, University of York, York YO10 5NG, UK.
CSIRO Land and Water, Waite Campus, Adelaide, South Australia 5064, Australia.
Sci Total Environ. 2018 Jul 1;628-629:18-25. doi: 10.1016/j.scitotenv.2018.01.337. Epub 2018 Feb 13.
Reuse of treated wastewater for irrigation of crops is growing in arid and semi-arid regions, whilst increasing amounts of biosolids are being applied to fields to improve agricultural outputs. Due to incomplete removal in the wastewater treatment processes, pharmaceuticals present in treated wastewater and biosolids can contaminate soil systems. Benzodiazepines are a widely used class of pharmaceuticals that are released following wastewater treatment. Benzodiazepines are represented by a class of compounds with a range of physicochemical properties and this study was therefore designed to evaluate the influence of soil properties on the sorption behaviour and subsequent uptake of seven benzodiazepines (chlordiazepoxide, clonazepam, diazepam, flurazepam, oxazepam, temazepam and triazolam) in two plant species. The sorption and desorption behaviour of benzodiazepines was strongly influenced by soil type and hydrophobicity of the chemical. The partitioning behaviour of these chemicals in soil was a key controller of the uptake and accumulation of benzodiazepines by radish (Raphanus sativus) and silverbeet (Beta vulgaris). Benzodiazepines such as oxazepam that were neutral, had low sorption coefficients (K) or had pH-adjusted log octanol-water partition coefficients (log D, pH6.3) values close to 2 had the greatest extent of uptake. Conversely, benzodiazepines such as flurazepam that had an ionised functional groups and greater K values had comparatively limited accumulation in the selected plant species. Results also revealed active in-plant metabolism of benzodiazepines, potentially analogous to the known metabolic transformation pathway of benzodiazepines in humans. Along with this observed biological transformation of benzodiazepines in exposed plants, previously work has established the widespread presence of the plant signalling molecule γ-amino butyric acid (GABA), which is specifically modulated by benzodiazepines in humans. This highlights the need for further assessment of the potential for biological activity of benzodiazepines following their plant uptake.
再生水用于灌溉农作物在干旱和半干旱地区越来越普遍，同时也有越来越多的生物固体被应用于农田以提高农业产量。由于废水处理过程不完全去除，处理废水中和生物固体中的药物可能会污染土壤系统。苯二氮䓬类药物是一种广泛使用的药物类别，它们在废水处理后被释放出来。苯二氮䓬类药物由一类具有多种物理化学性质的化合物组成，因此本研究旨在评估土壤性质对七种苯二氮䓬类药物（地西泮、氯氮䓬、安定、氟硝西泮、奥沙西泮、替马西泮和三唑仑）在两种植物物种中的吸附行为和随后吸收的影响。苯二氮䓬类药物的吸附和解吸行为受土壤类型和化学物质的疏水性强烈影响。这些化学物质在土壤中的分配行为是控制萝卜（Raphanus sativus）和甜菜（Beta vulgaris）吸收和积累苯二氮䓬类药物的关键因素。奥沙西泮等中性、吸附系数（K）低或 pH 调节的辛醇-水分配系数（log D，pH6.3）值接近 2 的苯二氮䓬类药物具有最大的吸收程度。相反，具有电离官能团和较大 K 值的氟硝西泮等苯二氮䓬类药物在所选植物物种中的积累相对有限。结果还表明，苯二氮䓬类药物在植物体内发生了活性代谢，可能类似于人类已知的苯二氮䓬类药物的代谢转化途径。除了在暴露植物中观察到的苯二氮䓬类药物的这种生物转化外，以前的工作还确立了植物信号分子γ-氨基丁酸（GABA）的广泛存在，GABA 在人类中被苯二氮䓬类药物特异性调节。这凸显了需要进一步评估苯二氮䓬类药物在被植物吸收后的生物活性潜力。
