Fate and Transport of Fourteen Pharmaceuticals and Personal Care Products in an Irrigated Soil Profile

Use of pharmaceuticals and personal care products (PPCPs) is on the rise and unfortunately, a large percentage passes through the human body. These compounds then find their way into the wastewater stream and into treatment facilities. Only a fraction of these compounds are removed from the stream prior to discharge. An environmentally acceptable alternative to discharging recycled water to rivers, lakes and other bodies of water is to use the water for irrigation of large areas of turfgrass. These PPCPs, of which some may have high mobilities in irrigated soil plant systems, may potentially impact groundwater resources. To determine the movement of 14 PPCPs under turfgrass irrigated conditions, a field based lysimeter study was conducted. The lysimeter study consisted of 24 lysimeters in which eight treatment combinations of soil type (loamy sand or sandy loam), leaching fraction (5 or 25%), and cropping systems (bare or turfgrass) were replicated in triplicate. Lysimeters were irrigated with tertiary treated reclaimed water. After 745 days of monitoring, nine of the 14 compounds were detected in drainage samples. Most of the detections occurred in sandy soils with high leaching fractions, averaging 74% for sulfamethoxazole, 72% for primidone and 40% for carbamazepine versus the lower leaching sandy loams, which had zero or very small detection rates. Factors influencing the movement of these compounds varied based on the compound and the imposed treatments. In the case of primidone, 94% of the variability in the mass discharge of primidone could be accounted for by taking into account the number of unsaturated pore volumes draining, the percent sand content and the redox potential at 105 cm. The highest mass flux, scaled on a hectare (ha) basis, was recorded for sulfamethoxazole (0.25 g ha-1yr-1). Soil sampling showed nine of the 14 pharmaceuticals in the soil profile. For example, Sulfamethoxazole had the highest average incoming concentration (1600 ng/l) but had only 150 ng/L in the upper most layer of soil with decreasing concentration with depth. Soil concentrations scaled to mass within the soil profile did not fully account for mass lost in the soil profile, with some compounds having greater than 90% unaccounted mass (Diclofenac, Dilantin, Meprobamate, Sulfamethoxazole, Trimethoprim). Based on our results, restricting the use of recycled water based solely on the presence of PPCP\u27s should only be a consideration at sites where soils are extremely sandy and irrigation regimes are not based on an evapotranspiration feedback approach