A multi-year, collaborative research project was conducted to investigate the fate and transport of pharmaceuticals and personal care product chemicals (PPCPs) in turfgrass/soil systems irrigated with recycled water. The project involved laboratory adsorption and degradation experiments, controlled lysimeter experiments, field-scale controlled plot monitoring of drainage concentrations, and mass flux below fairways on four different golf courses. Fourteen different compounds were monitored in the irrigation and drainage waters in these studies.
The laboratory experiments indicated only a few PPCPs were susceptible to biodegradation under aerobic conditions, while the other target compounds were relatively persistent, with half-lives longer than 100 days (d). The low sorption and long persistence of some PPCPs suggest potentially high mobility in sandy soils. However, the absence of plants in the laboratory degradation experiments and the use of extremely sandy soils may have contributed to the observed persistence, indicating a need for evaluation of the attenuation of PPCPs under more representative simulated or field conditions.
The lysimeter experiment revealed breakthrough of nine of 14 compounds in the drainage water, after migrating through 120 cm soil profiles. The experiment lasted 745 days, and varied by leaching fractions (0.05 vs. 0.25), soil type (loamy sand vs. sandy loam), and treatment of the soil surface (turfgrass vs. bare soils). Only primidone, sulfamethoxazole, and carbamazepine concentration patterns correlated with the number of unsaturated pore volumes displaced from the soil profile. In the case of primidone, 94% of the variation in mass flux could be described by soil conditions (e.g., number of unsaturated pore volumes drained, the percent sand in the soil, and the average redox potential at the 105 cm depth).
The controlled plot experiment showed that after irrigation with recycled water for six months on mature turfgrass plots, only a few PPCPs were detected in the drainage water collected at the 90-cm depth. Primidone, trimethoprim, and carbamazepine were the only compounds appearing in the drainage water. Despite the heavy irrigation rates (100% and 130% of reference evapotranpiration or ETo), most PPCPs were completely removed by the turfgrass/soil system. After correcting for leaching fractions, the removal was greater than 75% even for the few compounds that were detected in the drainage water. Therefore, the plot experiment validated the lysimeters experiment and clearly demonstrated that turfgrass has an outstanding capacity to attenuate PPCPs introduced via irrigation with recycled water.
In the golf course experiments, sulfamethoxazole, meprobamate, and carbamazepine were the most commonly found PPCPs in drainage water; however, when concentrations of samples taken from the drain gauges were normalized to the hectare scale, the researchers found that fluxes for all compounds were less than 0.100 grams/hectare, and the majority of all fluxes were recorded during the second year of the field monitoring.
In summary, the results support the use of recycled water for irrigation purposes, as long as sound, science-based irrigation management practices (e.g., cycle and soak irrigation) are implemented. The use of recycled water allows communities to extend their water resources while minimizing the discharge of such waters into aquatic systems.
This title belongs to WERF Research Report Series.
ISBN: 9781780403977 (Print)
ISBN: 9781780400235 (eBook)
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