Ranking the risks of eighty pharmaceuticals in surface water of a megacity: A multilevel optimization strategy

Seawater Chlorella sp. biofilm for mariculture effluent polishing under environmental combined antibiotics exposure and ecological risk evaluation based on parent antibiotics and transformation products

Mariculture effluent polishing with microalgal biofilm could realize effective nutrients removal and resolve the microalgae-water separation issue via biofilm scraping or in-situ aquatic animal grazing. Ubiquitous existence of antibiotics in mariculture effluents may affect the remediation performances and arouse ecological risks. The influence of combined antibiotics exposure at environment-relevant concentrations towards attached microalgae suitable for mariculture effluent polishing is currently lack of research. Results from suspended cultures could offer limited guidance since biofilms are richer in extracellular polymeric substances that may protect the cells from antibiotics and alter their transformation pathways. This study, therefore, explored the effects of combined antibiotics exposure at environmental concentrations towards seawater Chlorella sp. biofilm in terms of microalgal growth characteristics, nutrients removal, anti-oxidative responses, and antibiotics removal and transformations. Sulfamethoxazole (SMX), tetracycline (TL), and clarithromycin (CLA) in single, binary, and triple combinations were investigated. SMX + TL displayed toxicity synergism while TL + CLA revealed toxicity antagonism. Phosphorus removal was comparable under all conditions, while nitrogen removal was significantly higher under SMX and TL + CLA exposure. Anti-oxidative responses suggested microalgal acclimation towards SMX, while toxicity antagonism between TL and CLA generated least cellular oxidative damage. Parent antibiotics removal was in the order of TL (74.5-85.2 %) > CLA (60.8-69.5 %) > SMX (13.5-44.1 %), with higher removal efficiencies observed under combined than single antibiotic exposure. Considering the impact of residual parent antibiotics, CLA involved cultures were identified of high ecological risks, while medium risks were indicated in other cultures. Transformation products (TPs) of SMX and CLA displayed negligible aquatic toxicity, the parent antibiotics themselves deserve advanced removal. Four out of eight TPs of TL could generate chronic toxicity, and the elimination of these TPs should be prioritized for TL involved cultures. This study expands the knowledge of combined antibiotics exposure upon microalgal biofilm based mariculture effluent polishing.

Anthropogenic activities drive the distribution and ecological risk of antibiotics in a highly urbanized river basin

Although antibiotics are widely detected in river water, their quantitative relationships with influencing factors in rivers remain largely unexplored. Here, 15 widely used antibiotics were comprehensively analyzed in the Dongjiang River of the Pearl River system. The total antibiotic concentration in river water ranged from 13.84 to 475.04 ng/L, with fluoroquinolones increasing from 11 % in the upstream to 38 % in the downstream. The total antibiotic concentration was high downstream and significantly correlated with the spatial distribution of population density, animal production, and land-use type. The total risk quotient of antibiotics for algae was higher than that for crustaceans and fish. Based on the optimized risk quotient method, amoxicillin, ofloxacin, and norfloxacin were identified as priority antibiotics. The key predictors of antibiotic levels were screened through Mantel test, correlation analysis, and multiple regression models. Water physicochemical parameters significantly impacted antibiotics and could be used as easy-to-measure surrogates associated with elevated antibiotics. Cropland negatively affected fluoroquinolones and sulfonamides, whereas urban land exerted positive impacts on fluoroquinolones, β-lactam, and sulfonamides. In the main stream, population, animal production, urbanization status, and economic development had key effects on the distribution of florfenicol, norfloxacin, ofloxacin, and sulfadiazine.

Global occurrence, distribution, and ecological risk assessment of psychopharmaceuticals and illicit drugs in surface water environment: A meta-analysis

Psychopharmaceuticals and illicit drugs (PIDs) in aquatic environments can negatively impact ecosystem and human health. However, data on the sources, distribution, drivers, and risks of PIDs in global surface waters are limited. We compiled a dataset of 331 records spanning 23 PIDs in surface waters and sediments across 100 countries by conducting a systematic review and meta-analysis of 108 studies published between 2005 and 2022. Most PIDs were sewage-derived, as wastewater treatment rarely achieved complete removal. The highest total PID levels were in Ethiopia, Australia, and Armenia, with many highly contaminated samples from low- and middle-income countries with minimal prior monitoring. Socioeconomic factors (population, GDP) and environmental variables (water stress) influenced the distribution of PIDs. 3,4-Methylenedioxy amphetamine hydrochloride (MDA), Δ9-tetrahydrocannabinol (THC), and 11- Δ9‑hydroxy-tetrahydrocannabinol (THCOH) posed the greatest ecological risks, especially in Oceania and North America. PIDs in surface waters present risks to aquatic organisms. Our findings elucidate the current status and future directions of PID research in surface waters and provide a scientific foundation for evaluating ecological risks and informing pollution control policies.

Ecological implications and drivers of emerging contaminants in Dongting Lake of Yangtze River Basin, China: A multi-substance risk analysis

Emerging contaminants (ECs) are increasingly recognized as a global threat to biodiversity and ecosystem health. However, the cumulative risks posed by ECs to aquatic organisms and ecosystems, as well as the influence of anthropogenic activities and natural factors on these risks, remain poorly understood. This study assessed the mixed risks of ECs in Dongting Lake, a Ramsar Convention-classified Typically Changing Wetland, to elucidate the major EC classes, key risk drivers, and magnitude of anthropogenic and natural impacts. Results revealed that ECs pose non-negligible acute (30% probability) and chronic (70% probability) mixed risks to aquatic organisms in the freshwater lake ecosystem, with imidacloprid identified as the primary pollutant stressor. Redundancy analysis (RDA) and structural equation modeling (SEM) indicated that cropland and precipitation were major drivers of EC contamination levels and ecological risk. Cropland was positively associated with EC concentrations, while precipitation exhibited a dilution effect. These findings provide critical insights into the ecological risk status and key risk drivers in a typical freshwater lake ecosystem, offering data-driven support for the control and management of ECs in China.

Freshwater water quality criteria for phthalate esters and recommendations for the revision of the water quality standards

With increasing urbanization and rapid industrialization, more and more environmental problems have arisen. Phthalates (PAEs) are the foremost and most widespread plasticizers and are readily emitted from these manufactured products into the environment. PAEs act as endocrine-disrupting chemicals (EDCs) and can have serious impacts on aquatic organisms as well as human health. In this study, the water quality criteria (WQC) of five PAEs (dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP)) for freshwater aquatic organisms were developed using a species sensitivity distribution (SSD) and a toxicity percentage ranking (TPR) approach. The results showed that long-term water quality criteria (LWQC) of PAEs using the SSD method could be 13.7, 11.1, 2.8, 7.8, and 0.53 μg/L, respectively. Criteria continuous concentrations (CCC) of PAEs were derived using the TPR method and determined to be 28.4, 13.1, 1.3, 2.5, and 1.6 μg/L, respectively. The five PAEs are commonly measured in China surface waters at concentrations between ng/L and μg/L. DBP, DEHP, and di-n-octyl phthalate (DnOP) were the most frequently detected PAEs, with occurrence rates ranging from 67% to 100%. The ecological risk assessment results of PAEs showed a decreasing order of risk at the national level, DEHP, DBP, DMP, DEP, DnOP. The results of this study will be of great benefit to China and other countries in revising water quality standards for the conservation of aquatic species.

Prediction of HC5s for phthalate esters by use of the QSAR-ICE model and ecological risk assessment in Chinese surface waters

Due to their endocrine-disrupting effects and the risks posed in surface waters, in particular by chronic low-dose exposure to aquatic organisms, phthalate esters (PAEs) have received significant attention. However, most assessments of risks posed by PAEs were performed at a selection level, and thus limited by empirical data on toxic effects and potencies. A quantitative structure activity relationship (QSAR) and interspecies correlation estimation (ICE) model was constructed to estimate hazardous concentrations (HCs) of selected PAEs to aquatic organisms, then they were used to conduct a multiple-level environmental risk assessment for PAEs in surface waters of China. Values of hazardous concentration for 5% of species (HC5s), based on acute lethality, estimated by use of the QSAR-ICE model were within 1.25-fold of HC5 values derived from empirical data on toxic potency, indicating that the QSAR-ICE model predicts the toxicity of these three PAEs with sufficient accuracy. The five selected PAEs may be commonly measured in China surface waters at concentrations between ng/L and μg/L. Risk quotients according to median concentrations of the five PAEs ranged from 3.24 for di(2-ethylhexhyl) phthalate (DEHP) to 4.10 × 10-3 for dimethyl phthalate (DMP). DEHP and dibutyl phthalate (DBP) had risks to the most vulnerable aquatic biota, with the frequency of exceedances of the predicted no-effect concentration (PNECs) of 75.5% and 38.0%, respectively. DEHP and DBP were identified as having "high" or "moderate" risks. Results of the joint probability curves (JPC) method indicated DEHP posed "intermediate" risk to freshwater species with a maximum risk product of 5.98%. The multiple level system introduced in this study can be used to prioritize chemicals and other new pollutant in the aquatic ecological.

Spatiotemporal distribution of ecological risk of antibiotics in seven major river basins of China: An optimized multilevel assessment approach

Antibiotics have been recognized as emerging pollutants due to their ecological and human health risks. This paper aims to enhance the ecological risk assessment (ERA) framework for antibiotics, to illustrate the distribution of these risks across different locations and seasons, and to identify the antibiotics that pose high ecological risk. This paper focuses on 52 antibiotics in seven major basins of China. Relying on the optimized approach of ERA and antibiotic monitoring data published from 2017 to 2021, the results of ERA are presented in multilevel. Across the study area, there are marked variations in the spatial distribution of antibiotics' ecological risks. The Huaihe River Basin, the Haihe River Basin, and the Liaohe River Basin are the top three in the ranking of present ecological risks. The research results also reveal significant differences in temporal variation, underscoring the need for increased attention during certain seasons. Ten antibiotics with high contribution rates to ecological risk are identified, which is an important reference to formulate an antibiotic control list. The multilevel results provided both risk values and their ubiquities across a broad study region, which is a powerful support for developing ecological risk management of antibiotics.

Insightful properties-performance study of Ti-Cu-O heterojunction sonochemically embedded in mesoporous silica matrix for efficient tetracycline adsorption and photodegradation: RSM and ANN-based modeling and optimization

This study aims to provide a comprehensive evaluation of the photocatalytic properties and performance of the Cu-Ti-O heterojunction sonochemically embedded in the mesoporous silica matrix. Various characterization analyses and adsorption/photodegradation experiments were performed to assess the potential of the sample for tetracycline (TC) removal. The characterization results indicated that sonication contributes to better dispersion of Ti-Cu-O species, resulting in more uniform particle sizes, stronger semiconductors-silica interaction, and less agglomeration. Furthermore, sonication significantly affected the optical nanocomposite features, leading to an improvement in charge carrier separation and a decrease in the band gap of Ti-Cu-Si (S) by approximately 2.6 eV. Based on the textural results, the ultrasound microjets increased the surface area and pore volume, which facilitate mass transfer and provide suitable adsorption sites for TC molecules. Accordingly, Cu-Ti-Si (S) demonstrated higher adsorption capacity (0.051 g TC/g adsorbent) and eliminated TC significantly faster (0.0054 L.mg-1.min-1) than a non-sonicated sample during 120 min of irradiation, resulting in 2.84 times improvement in the constant rate. In addition, experimental results were accurately modeled using a central composite design in combination with response surface methodology (RSM) and artificial neural networks (ANN) to predict and optimize TC photodegradation. Both RSM and ANN models revealed excellent predictability for TC degradation efficiency, with R2 = 99.47 and 99.71%, respectively. At optimal operational conditions (CTC = 20 ppm, photocatalyst dosage = 1.15 g.L-1, pH = 9, and irradiation time = 100 min), more than 95% and 87% of TC were degraded within the UV (375 W) and simulated solar light (400 W) irradiation periods, respectively. It was observed that the Cu-Ti-Si (S) nanocomposite maintained remarkable stability after four cycles with only a negligible 3% loss of activity, owing to the superior interaction between the bimetallic heterojunction and the silica matrix.

Ecological risk assessment of 50 emerging contaminants in surface water of the Greater Bay Area, China

Ecological risk assessment of emerging contaminants (ECs) is an international research hotspot and is also the focus of China's "14th Five-Year Plan". The Greater Bay Area (GBA) is one of the four major bay areas in the world and the most dynamic region in China. However, there are few studies on the risk assessment of ECs in the GBA, and there needs to be a systematic and comprehensive assessment of the ecological risk of ECs. We selectively collected environmental concentration and toxicity data reported in the literature before 2022 for 50 representative ECs. We use risk quotient (RQ), semi-probability, Margin of Safety (MOS), and joint Probability curve (JPC) methods for multiple-level risk assessment. The RQ results showed that there were primary ecological risks in 20 ECs. Nine ECs were screened by the semi-probability, MOS, and JPC methods. The total risk probability of nonylphenol (NP) to the GBA was 12.11 %, and the risk to the aquatic ecological environment was the highest, followed by α-endosulfan (α-END) and erythromycin (ERY). At the same time, a comprehensive assessment method was adopted to screen the list of medium and high-risk priority pollutants in the GBA. According to the comprehensive evaluation results, although the risk is low, perfluorooctanoic acid (PFOA) still deserves widespread attention. The results showed that NP, α-END, ERY, and PFOA may be the most concerned ECs in the GBA. This research fills the gap on the ECs ecological risk assessment of the GBA and can provide a theoretical reference for managers in the follow-up of ECs regulatory governance.