Distribution Characteristics and Ecological Risk Assessment of Pharmaceutical and Personal Care Products (PPCPs) in Different Water Sources, Soil Profiles and Rice Crops Under Rural Domestic Reclaimed Water Irrigations

Pharmaceutical and personal care products (PPCPs) have the characteristics of environmental persistence, bioaccumulation, and high toxicity, and their environmental behavior has attracted the attention in the process of sewage resource utilization in recent years. In this study, four kinds of irrigation water sources (the primary treated water of rural domestic sewage (RDS) R1, the secondary treated water of RDS R2, the ecological pond purified water R3 and river water (CK) and three kinds of water level regulations (low-, medium- and high-water level regulation of W1, W2, and W3) were set to study the migration law of 22 kinds of PPCPs in rural domestic reclaimed water (RDRW), paddy soil and rice plants. Five rice plant and soil samples were, respectively, taken from each treatment using the five-point sampling method in this study. The samples were pretreated using the solid-phase extraction (SPE) method. After pretreatment, PPCPs were quantitatively analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The objective of the research was to explore the distribution patterns in soil-crop system, further evaluating the ecological risks of PPCPs in soil and rice plants under the regulation of RDRW irrigation. The results showed that 21 kinds of PPCPs were detected in RDRW and CK, among which the concentration of ofloxacin (OFL) was the highest. Fifteen kinds of PPCPs were detected in paddy soil and rice grain, among which atenolol (ATE) content was relatively higher. Compared with CK, the total content of PPCPs in the soil surface layer (0–20 cm) was the highest under RDRW irrigation. The impacts of different water level regulations on the PPCPs content between soil profile and rice grain were not significant. In addition, the reduction rate of 15 PPCPs in soil under RDRW irrigation was greater than 85%, and the bio-concentration factor (BCF) of PPCPs in rice grain was less than 0.1. The ecological risk assessment showed that ibuprofen (IBU) was a high-risk substance pollutant, triclocarban (TRIC) was a medium-risk pollutant, ofloxacin (OFL) was a low-risk pollutant, while the other PPCPs were all risk-free pollutants under RDRW irrigation. Therefore, R3 water sources can be selected for direct agricultural irrigation, while direct irrigation of R1 and R2 water sources should be avoided.