Study into the effects of soil moisture depletion on crop uptake of pharmaceuticals and personal care products

As available freshwater resources continue to become compromised, the need to increase water efficiency is of upmost concern. A method being employed worldwide to meet this objective is the use of recycled wastewater (RW) for irrigation. However, there exists concern regarding its use for raw edible agricultural crops due to the prevalence of micro-contaminants, such as pharmaceuticals and personal care products (PPCPs) in the latter. PPCPs, many of which are endocrine disruptors, have been known to endure traditional wastewater treatment procedures and seem ubiquitous in RW, posing a potential health hazard to consumers of raw food crops irrigated with such; hence the need for their study within agricultural systems. We investigated the uptake of 3 PPCPs (atenolol, diclofenac and ofloxacin) at 3 different concentrations (0.5, 5 and 25ig/L) in relation to 3 varying volumetric soil moisture depletion levels of 14% (-4.26 kPa), 10% (-8.66 kPa), and 7% (-18.37 kPa) by various raw edible crop species. We also studied the effects of these PPCPs and applied soil moisture depletion treatments on crop yield by quantifying above and belowground plant biomass of selected crops. Experiments were conducted in a split-split block completely randomized design. PPCPs were extracted using a developed method of Accelerated Solvent Extraction (ASE) and Solid Phase Extraction (SPE), and analyzed via LC/MS. Results indicate that all treated crops are capable of PPCP uptake at ng g-1 concentrations independent of the tested soil moisture content levels and applied PPCP concentrations. Ofloxacin was the chemical with the highest uptake amounts followed by atenolol and then diclofenac. Although not statistically significant, higher concentrations of PPCPs were detected in plants maintained under higher soil moisture levels of 14% (-4.26 kPa). Plant biomass was not significantly affected by the presence of PPCPs, or by the applied soil moisture depletion treatments, therefore variations in plant biomass were completely attributed to crop species effects. Even though this study sheds light upon some of the aspects regarding RW and the presence of PPCPs within agricultural systems, there still exists extensive space for further research into this topic.