From pollution to prediction: Modelling contamination scenarios and their impact on the retention of pharmaceuticals dynamics in a Black Soil

Treated wastewater and sewage sludge contain frequently persistent organic micropollutants (OMPs) that tend to accumulate during wastewater treatment. Long-term impacts of these pollutants on human health, plant productivity and ecosystem functioning are of concern, as they can accumulate and alter the soil-water-plant continuum. The introduction of OMPs during the early vegetation period alters the soil-colloid system's physicochemical properties, reshaping the availability and nature of adsorption sites. The joint mechanism of action (combined accumulation and interaction) of OMPs influence subsequent interactions between the soil and newly introduced contaminants, requiring later OMPs to establish different intermolecular reactions with the soil's organic and mineral phases. As a result, the soil's retention capacity and sorption dynamics evolve throughout the vegetation period, driven by the cumulative effects of prior contamination. Consequently, PhACs exhibits different transport, accumulation and bioaccumulation behaviour during the vegetation period, which is shaped by the changing contaminated and uncontaminated soil environment.

In this study, we investigated how contamination introduced at the start of a simulated vegetation period influences the retention capacity of Phaeozem and its effects on the sorption activity of pharmaceuticals (PhACs). Specifically, we investigated the impacts of ciprofloxacin (CPX), difenoconazole (DFZ), and PhACs such as (carbamazepine (CBZ), 17α-ethynylestradiol (EE2), diclofenac sodium (DFC), trans-10,11-dihydro-10,11-dihydroxycarbamazepine (TCBZ), estrone (E1), estriol (E3), 17β-estradiol (17β-E2), 17α-estradiol (17α-E2), 5-hydroxydiclofenac (5-HODFC)) separately, as well as their combined effects, under different contamination scenarios. Fixed-bed experiments simulated vegetation period scenarios to evaluate changes in retention capacity, while chemometric modelling was used to analyse adsorption-desorption interactions. Our research additionally, tracked changes in soil organic matter (SOM) dynamics and enzymatic activities (phosphatases and dehydrogenases) indicative of microbial community functions throughout the vegetation period. According to the statistical modelling, OMPs significantly alter the quantity of SOM in the rhizosphere under different contamination scenarios, as well as its quality, including the ratio of aliphatic, aromatic, and phenolic lignin compounds. These changes represent a significant transformation in the adsorbent, reshaping the initial competitive groups of adsorbates (PhACs). Throughout the simulated vegetation period, shifts in the dominant physicochemical properties of the adsorbates drive dynamic changes in the sorption behaviour and bioavailability of PhACs. This research highlights the complex and scenario-dependent interactions between soil composition and contaminants, offering insights for predicting the environmental impacts of pharmaceutical pollution in agricultural systems.

This research was supported by OTKA K142865, NKFIH 2020–1.1.2-PIACI-KFI-2021-00309; 2021–1.2.4-TÉT-2021-00029, HUSK_2302_1.2_070 INTERREG and DKOP-23 _03.