Effects of wind-wave disturbances on adsorption and desorption of tetracycline and sulfadimidine in water-sediment systems

Fine particulate matter as a key factor promoting the spread of antibiotics in river network

The extensive utilization of antibiotics has resulted in their frequent detection, contributing to an increased abundance of antibiotic resistance genes in rivers and posing a significant threat to environmental health. Particulate matter plays a crucial role as the primary carrier of various pollutants in river ecosystem. Its physicochemical properties and processes of sedimentation and re-suspension can influence the migration and transformation of antibiotics, yet the mechanisms of this impact remain unclear. In this study, we investigated the distribution characteristics at the micro-scale of particles in the upstream plain river network of the Taihu basin and the adsorption behaviors of antibiotics in particulate matter. The results revealed that particles were predominantly in the size range of 30 to 150 μm in the river network and highest total antibiotic concentrations in 0 to 10 μm particle size fractions. Adsorption experiments also confirmed that the smaller the suspended particle size, the stronger the adsorption capacity for antibiotics. Spatially, both the average particle size and total antibiotic concentrations were lower downstream than upstream. The distribution mechanism of antibiotic in river network sediments was significantly influenced by frequent resuspension and settling of fine particles with a stronger capacity to adsorb antibiotics under hydrodynamic conditions. This ultimately facilitated the release of antibiotics from sediment into the water, resulting in lower antibiotic concentrations in downstream sediments relative to upstream These findings suggest that fine particles serve as the primary carriers of antibiotics, and their sorting and transport processes can significantly influence the distribution of antibiotics in water-sediment systems. This study enhances our understanding of the migration mechanisms of antibiotics in river networks and will prove beneficial for the development of management strategies aimed at controlling antibiotic dissemination.

Migration and transformation behaviors of antibiotics in water-sediment system under simulated light and wind waves

Antibiotics can generally be detected in the water-sediment systems of lakes. However, research on the migration and transformation of antibiotics in water-sediment systems based on the influences of light and wind waves is minimal. To address this research gap, we investigated the specific impacts of light and wind waves on the migration and transformation of three antibiotics, norfloxacin (NOR), trimethoprim (TMP), and sulfamethoxazole (SMX), under simulated light and wind waves disturbance conditions in a water-sediment system from Taihu Lake, China. In the overlying water, NOR was removed the fastest, followed by TMP and SMX. Compared to the no wind waves groups, the disturbance of big wind waves reduced the proportion of antibiotics in the overlying water. The contributions of light and wind waves to TMP and SMX degradation were greater than those of microbial degradation. However, the non-biological and biological contributions of NOR to degradation were almost equal. Wind waves had a significant impact on the microbial community changes in the sediment, especially in Methylophylaceae. These results verified the influence of light and wind waves on the migration and transformation of antibiotics, and provide assistance for the risk of antibiotic occurrence in water and sediments.

The effects of wind-wave disturbances on sediment resuspension and phosphate release in Lake Chao

As a typical shallow lake with a wind-generated flow, the resuspension state of sediment and phosphorus release under wind field disturbance plays an important role in controlling lake eutrophication in Lake Chao. In this study, we proposed a combination of experimental analysis of dynamic disturbances, wind-wave disturbance shear stress calculation, and model simulation (experimental-calculative-modeling) to quantitatively investigate the effects of wind-wave disturbances on the resuspension state of Lake Chao bottom sediment and phosphorus release and distribution. The results showed that the release rate of phosphorus from the Lake Chao bottom sediment was affected by the wind field and bottom sediment content, which varied significantly spatially and showed some difference between different seasons. Under the condition of sufficient water body disturbance, the substrate in the Western Lake area of Lake Chao mainly adsorbed phosphate from the water body, while the substrate in the Central Lake area and the Eastern Lake area adsorbed phosphate along with the release. The magnitude of the phosphorus release rate due to sediment resuspension was mainly affected by wind speed, and the distribution of phosphorus content was influenced by the circulation generated by different dominant wind directions. The wind-wave disturbances have a significant effect on the spatial and temporal distribution of phosphorus in Lake Chao, and the proposed experimental-calculative-modeling ensemble can provide relevant technical support for the study of water pollution control strategies and comprehensive remediation and management of Lake Chao.

Adsorption of tetracycline from aqueous solution by ZIF-8: Isotherms, kinetics and thermodynamics

In this study, ZIF-8 nanoparticles were synthesized using a simple method at room temperature. The ZIF-8 nanoparticles were then characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET (Brunauer-Emmett-Teller) specific surface area, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and zeta potential. Subsequent batch adsorption experiments evaluated the adsorption performance of ZIF-8 on tetracycline, examining key pa-rameters like reaction time, pH, temperature, and adsorbent dosage. The results revealed a removal rate for TC of up to 90.59%. The adsorption data aligned with the Sips model, showcasing a maximum adsorption capacity of 359.61 mg/g at 303K. Further, the adsorption kinetics adhered to the pseudo-second-order kinetic model with an equilibrium adsorption capacity of 90 mg/g at 303K. The considerable specific surface area of ZIF-8, standing at 1674.169 m2/g, likely enhances the adsorption efficacy. Analysis using XRD and FTIR confirmed the adsorption of TC on the ma-terial's surface. Overall, the predominant driving forces behind the adsorption process were identified as electrostatic interactions and π-π stacking interactions.

Biodegradation, photolysis, and sorption of antibiotics in aquatic environments: A scoping review

The presence of antibiotics in surface waters is a potential driver of antibiotic resistance and thus of concern to human and environmental health. Key factors driving the potential impact of antibiotics are their persistence and transport in rivers and lakes. The goal of this study was to describe the peer-reviewed published literature on the photolysis (direct and indirect), sorption, and biodegradation of a selected group of antibiotic compounds following a scoping review methodology. Primary research from 2000 to 2021 was surveyed to compile information on these processes for 25 antibiotics from 6 classes. After compilation and assessment of the available parameters, the results indicate that information is present to predict the rates of direct photolysis and reaction with hydroxyl radical (an indirect photolysis process) for most of the selected antibiotics. There is insufficient or inconsistent information for including other indirect photolysis processes, biodegradation, or removal via sorption to settling particles for most of the targeted antibiotic compounds. Future research should focus on collecting fundamental parameters such as quantum yields, second-order rate constants, normalized biodegradation rates, and organic carbon or surface area normalized sorption coefficients rather than pseudo-first order rate constants or sorption equilibrium constants that apply only to specific conditions/sites.

Determination of the pharmaceuticals-nano/microplastics in aquatic systems by analytical and instrumental methods

Pharmaceutical residues and nanoplastic and microplastic particles as emerging pollutants in the aquatic environment are a subject of increasing concern in terms of the effect on water sources and marine organisms. There is lack of information about pharmaceutical-nanoplastic and pharmaceutical-microplastic mixtures. The present study aimed to investigate the fate and effect of pharmaceutical residues and nanoplastic and microplastic particles, the results of combinations of pharmaceutical residues with nanoplastic and microplastic particles, and toxic effects of pharmaceutical residues and nanoplastic and microplastic particles. Moreover, the objective was also to introduce analytical methods for pharmaceuticals, along with instrumental techniques for nanoplastic and microplastic particles in aquatic environments and organisms. PhAC alone can affect marine environments and aquatic organisms. When pharmaceutical residues combine with nanoplastic and microplastic particles, the rate of toxicity increases, and the result of this phenomenon constitutes this kind of pollutant in wastewater. Hence, the rate of mortality in organisms enhances. This study aimed to investigate the effect of pharmaceuticals residues and nanoplastic and microplastic particles, and a mixture of pharmaceutical residues and nanoplastic and microplastic particles in aquatic biota. Another object was survey methods for recognizing pharmaceutical residues and nanoplastic and microplastic particles. The findings show that pharmaceutical residues in organisms caused cell structure damage, inflammatory response, and nerve cell apoptosis. This study aimed to investigate the effect of microplastic particles in the human food chain and their impact on human health. Moreover, this review aims to present an innovative methodology based on comprehensive analytical techniques used to determine and identify pharmaceuticals adsorbed on nano- and microplastics in aquatic ecosystems. Finally, this review addresses the knowledge gaps and provides insights into future research strategies to better understand their interactions.

Effects of suspended particulate matter from natural lakes in conjunction with coagulation to tetracycline removal from water

Coagulation is a common method used to remove suspended particulate matter (SPM) from the water supply. SPM has preferable adsorption ability for antibiotics in water; therefore, SPM adsorption and coagulation may be a possible way to remove tetracycline (TC) from water. This study carried out coagulation experiments combining SPM collected from a natural lake at a location with three common coagulants-polyaluminum sulfate, polyaluminum chloride, and polyferric sulfate-under different pH values, exploring the adsorption of TC by SPM, coagulation of SPM with TC, and the primary influencing factors of this process. The maximum removal rate of TC can reach 97.87% with an SPM concentration of 1000 mg/L. Multi-factor analysis of variance showed the importance of various TC removal factors, which were ranked as follows: SPM concentration ≫ initial TC concentration > type of coagulant > pH values. The higher the SPM concentration, the better the TC removal (p < 0.001). Fourier infrared spectroscopy results demonstrated the strong adsorption effect of SPM on TC after being combined with a coagulant, and scanning electron microscopy also indicated that SPM becomes effective nuclei in the coagulation process, which is a possible reason for better TC removal. However, the effluent turbidities under 1000 mg/L SPM concentrations were high without coagulant aid. With the addition of coagulant aid anion polyacrylamide, the TC removal remained unchanged, effluent turbidity significantly reduced, and the TC desorption became low. These results indicate that applying SPM from natural lakes in the coagulation process could potentially remove TC in water.

Tetracycline-induced effects on the nitrogen transformations in sediments: Roles of adsorption behavior and bacterial activity

Nitrification and denitrification are the most important nitrogen transformation processes in the environment. Recently, due to widespread use, antibiotics have been reported to lead to environmental risks. Tetracycline (TC) is one of the most extensively used antibiotics in many areas. However, its reported effects on nitrogen transformations were conflicting in previous studies. In this study, the effects of TC on nitrogen transformations in sediment were investigated by analyzing TC transport and bacterial activity. It was found that the adsorption of TC onto the sediment was favorable and spontaneous, with adsorption capacity 54.3 mg/kg. The adsorption kinetics of TC onto the sediment and the isotherm fitted the Elvoich and Freundlich models, respectively, indicating that the adsorption was a chemisorption process, including electrostatic interactions and chemical bonding between TC and the sediment. TC showed no effect on nitrification in the sediment, but significantly inhibited the reduction of nitrate and nitrite during denitrification, consistent with observations made for the model denitrifier Paracoccus denitrificans under TC stress. Mechanistic study indicated that TC at 130 μg/g-cell inhibited 50.7% of P. denitrificans growth and 61.6% of cell viability. Meanwhile, the catalytic activities of the key denitrifying enzymes, nitrate reductase (NAR) and nitrite reductase (NIR), decreased to 29.1% and 68.0% of the control levels when the TC concentration was 130 μg/g-cell, suggesting that NAR was more sensitive to the TC than NIR, which contributed to a delay in nitrite accumulation.