Multimedia fate of sulfamethoxazole (SMX) in a water-scarce city by coupling fugacity model and HYDRUS-1D model

Comprehensive evaluation of antibiotic pollution in a typical tributary of the Yellow River, China: Source-specific partitioning and fate analysis

The partitioning and migrating of antibiotic residues pose a considerable pollution to the river environment. However, a source-specific approach for quantifying the fate of antibiotics is lacking. To further elucidate the migration behavior of antibiotics from different pollution sources in aquatic environments, we introduced a source-specific partition coefficient (S-Kp) based on Positive Matrix Factorization (PMF) model to improve the multimedia model. This study identified six sources of antibiotic pollution in the water and sediment of the Fenhe River. Farmland drainage contributed 2.6 times more antibiotics to sediment than to surface water, whereas livestock sources contributed 0.3 times less to sediment than to water. High S-Kp values were primarily obtained from livestock, aquaculture, and farmland drainage pollution sources, with an average S-Kp value exceeding 200 L/kg. Sulfaquinoxaline (SQX) in sulfonamides (SAs) from livestock sources exhibited the highest S-Kp value of 34,740.04 L/kg. The predicted environmental concentrations indicated that almost 99 % of the antibiotics from the six sources remained in the water phase, with the highest contribution (99.9 %) of azithromycin (AZM) from livestock, pharmaceutical wastewater, and domestic sewage. This study provides novel insights into the migration of antibiotics from source-specific partitions in multimedia environments of watersheds.

A distributed and process-based model coupling water-sediment-antibiotic interactions to simulate dynamic source-transport-fate of antibiotics at catchment scale

A lack of hydro-biogeochemical models for catchment-scale antibiotic dynamics limits our mechanistic understanding of the transport and fate of antibiotics. This study addresses this gap by developing a distributed and process-based model that focuses on the complex water-sediment-antibiotic interactions. We applied the model to a typical agricultural catchment and selected tetracyclines (TCs) as the target antibiotics. Parameter sensitivity analysis demonstrated that source distribution, groundwater discharge, and water-soil/sediment partitioning were crucial processes. The multi-site performance evaluation generally proved the model's validity, though some overestimation of riverine concentration dynamics was observed. The grid-based distribution of the annual source inputs of the summation of the four TCs (∑4TCs) highly varied in space (μ = 3494.92 mg·ha-1·yr-1, σ = 4761.20 mg·ha-1·yr-1). About 99 % of the source inputs were retained in soil, with mixing layer as the largest reservoir and degradation as the primary loss pathway. Daily terrestrial discharged loading of ∑4TCs peaked with rainfall events. Surface runoff contributed more than 50 % of the terrestrial load of ∑4TCs in summer, while groundwater discharge dominated in other seasons. These results imply that the catchment-scale TCs dynamics are transport-limited rather than source-limited. Our model offers new insights into the high-resolution sources-transport-fate of antibiotics, aiding in developing strategies to mitigate antibiotic contamination.

Fugacity-based multimedia transport modeling and risk assessment of PAHs in Urumqi

Currently, there is a lack of a comprehensive understanding of the behavior of polycyclic aromatic hydrocarbons (PAHs) in complex multimedia urban environmental systems. Taking Urumqi City as a case study, we developed an integrated multimedia urban environmental model to simulate the inter-media transport processes of PAHs across air, water, soil, sediment, vegetation, and impervious surfaces. The predictive results of this model were in good agreement with the actual monitoring data from 2021, confirming its accuracy. Notably, the simulated data for 2021 indicate that the total amount of PAHs in the soil reached 1.06 × 106 kg, accounting for 97.44% of the total PAHs in Urumqi City, highlighting soil as the primary sink for PAHs. Further analysis of transport fluxes revealed that atmospheric transfer pathways to soil and vegetation are the main mechanisms driving the distribution of PAHs in urban environments. Additionally, sensitivity analysis identified temperature, soil, and vegetation-related parameters as the primary factors influencing PAHs. Based on the simulated concentration, the risk assessment results showed that soil PAHs had a higher risk of carcinogenesis to human body. This study deepens our understanding of the behavior of PAHs in urban environments and provides insights into how human activities affect the fate and transformation of these contaminants in multimedia urban systems.

Migration and Accumulation Simulation Prediction of PPCPs in Urban Green Space Soil Irrigated with Recycled Water: A Review

The presence of pharmaceuticals and personal care products (PPCPs) in reclaimed water introduces an ongoing challenge as they infiltrate green space soils during irrigation, leading to a gradual buildup that poses considerable ecological risks. The simulation and forecasting of PPCPs accumulation in soil are pivotal for proactive ecological risk management. However, the majority of research efforts have predominantly concentrated on the vertical transport mechanisms of PPCPs in the soil, neglecting a holistic perspective that integrates both vertical and lateral transport phenomena, alongside accumulation dynamics. To address this gap, this study introduces a comprehensive conceptual model that encapsulates the dual processes of vertical and lateral transport, coupled with accumulation of PPCPs in the soil environment. Grounded in the distinctive properties of green space soils, we delve into the determinants governing the vertical and lateral migration of PPCPs. Furthermore, we consolidate existing simulation methodologies for contaminant transport, aiming to establish a comprehensive model that accurately predicts PPCPs accumulation in green space soils. This insight is critical for deducing the emission threshold of reclaimed water necessary for the protection of green space soils, informing the formulation of rational irrigation strategies, and anticipating future environmental risks. It provides a critical theoretical basis for more informed decision-making in the realm of urban water reuse and pollution control.

The introduction of influent sulfamethoxazole loads induces changes in the removal pathways of sulfamethoxazole in vertical flow constructed wetlands featuring hematite substrate

High frequent detection of sulfamethoxazole (SMX) in wastewater cannot be effectively removed by constructed wetlands (CWs) with a traditional river sand substrate. The role of emerging substrate of hematite in promoting SMX removal and the effect of influent SMX loads remain unclear. The removal efficiency of SMX in hematite CWs was significantly higher than that in river sand CWs by 12.7-13.8% by improving substrate adsorption capacity, plant uptake and microbial degradation. With increasing influent SMX load, the removal efficiency of SMX in hematite CWs slightly increased, and the removal pathways varied significantly. The contribution of plant uptake was relatively small (< 0.1%) under different influent SMX loads. Substrate adsorption (37.8%) primarily contributed to SMX removal in hematite CWs treated with low-influent SMX. Higher influent SMX loads decreased the contribution of substrate adsorption, and microbial degradation (67.0%) became the main removal pathway. Metagenomic analyses revealed that the rising influent load increased the abundance of SMX-degrading relative bacteria and the activity of key enzymes. Moreover, the abundance of high-risk ARGs and sulfonamide resistance genes in hematite CWs did not increase with the increasing influent load. This study elucidates the potential improvements in CWs with hematite introduction under different influent SMX loads.

Water, Water Everywhere, but Every Drop Unique: Challenges in the Science to Understand the Role of Contaminants of Emerging Concern in the Management of Drinking Water Supplies

The protection and management of water resources continues to be challenged by multiple and ongoing factors such as shifts in demographic, social, economic, and public health requirements. Physical limitations placed on access to potable supplies include natural and human-caused factors such as aquifer depletion, aging infrastructure, saltwater intrusion, floods, and drought. These factors, although varying in magnitude, spatial extent, and timing, can exacerbate the potential for contaminants of concern (CECs) to be present in sources of drinking water, infrastructure, premise plumbing and associated tap water. This monograph examines how current and emerging scientific efforts and technologies increase our understanding of the range of CECs and drinking water issues facing current and future populations. It is not intended to be read in one sitting, but is instead a starting point for scientists wanting to learn more about the issues surrounding CECs. This text discusses the topical evolution CECs over time (Section 1), improvements in measuring chemical and microbial CECs, through both analysis of concentration and toxicity (Section 2) and modeling CEC exposure and fate (Section 3), forms of treatment effective at removing chemical and microbial CECs (Section 4), and potential for human health impacts from exposure to CECs (Section 5). The paper concludes with how changes to water quantity, both scarcity and surpluses, could affect water quality (Section 6). Taken together, these sections document the past 25 years of CEC research and the regulatory response to these contaminants, the current work to identify and monitor CECs and mitigate exposure, and the challenges facing the future.