Current progress in the adsorption, transport and biodegradation of antibiotics in soil

Effects of nitrogen-driven eutrophication on the horizontal transfer of extracellular antibiotic resistance genes in water-sediment environments

Excessive nitrogen and other nutrients can trigger the eutrophication of freshwater bodies. Antibiotic resistance genes (ARGs) are now recognized as environmental pollutants, with extracellular ARGs (eARGs) being the dominant form in sediments. However, research on the propagation characteristics of eARGs remains limited. This study investigated the transfer characteristics of kanamycin resistance (KR) genes in the pEASY-T1 plasmid to intracellular DNA (iDNA) and extracellular DNA (eDNA) in water and sediment microenvironments under increasing nitrogen concentrations, as well as the community structure of free-living (FL) and particle-attached (PA) bacteria. The results revealed KR genes relative abundance in free extracellular DNA (f-eDNA) and adsorbed extracellular DNA (a-eDNA) of the water initially decreased and then increased with rising nitrogen concentrations. Its abundance in iDNA of the sediments decreased significantly with increasing nitrogen content, with relative abundance ranging from 5.09 × 10-4 to 1.14 × 10-3 copies/16SrRNA. The transfer from eDNA to iDNA in the water showed a rising and then falling trend as nitrogen concentration rose. The transfer of iDNA from the water to iDNA in sediments exhibited the opposite pattern. Additionally, copper (Cu) and zinc (Zn) were identified as key factors influencing the abundance of KR genes in the water, but total phosphorus (TP) was the primary determinant of KR gene distribution in sediments according to random forest analysis. These findings reveal novel mechanisms of eARG propagation in eutrophic environments, providing a theoretical foundation for managing antibiotic resistance in aquatic ecosystems.

Vertical migration of antibiotics during rainfall throughout a year in long-term manure-fertilized soils differing in pH

The vertical migration behavior of antibiotics in long-term manure-fertilized soils during rainfall remains unclear. Here, we examined antibiotics in soil profiles (0-60 cm) and leachates following each rainfall event throughout a year for three soils (acidic, neutral, and calcareous) with a 13-year history of manure application. The total concentrations of all the antibiotics in the soil profile (11.04-190.32 μg/kg) and the yearly cumulative load of these antibiotics in the leachate (4070-6900 ng/m2) were significantly higher in the acidic and neutral soils than in the calcareous soil. Rainfall caused the migration of antibiotics (especially tetracyclines, quinolones, and sulfonamides) from soil to leachate, while the migration dynamics of some antibiotics differed among the three soil profiles. Random forest analysis revealed that precipitation, soil organic carbon content, pH, sand content, and the partition coefficient (Kow) of antibiotics were the key factors influencing the migration of antibiotics. Environmental risk assessment suggested that antibiotics in leachates pose low toxicity risks to aquatic organisms. Nevertheless, the vertical migration of some antibiotics (e.g., sulfachaloropyridazine and sufamerazine) was positively correlated with the dissemination of high-risk antibiotic resistance genes in leachates. This study advances our understanding of the precipitation-caused vertical migration of antibiotics in soil exposed to manure application, considering future increases in severe rainfall events.

Meta-analysis reveals the processes and conditions of using biochar to control antibiotic resistance genes in soil

Soil is a significant reservoir of antibiotic resistance genes (ARGs) and an important habitat for pathogens associated with many clinical infections and plant disease outbreaks. Although scientists have found that biochar can reduce ARGs in soil, the understanding of how biochar removes soil ARGs and the influencing factors remains limited. Here, a meta-analysis of 65 published studies was conducted to illuminate the mechanisms through which biochar remediates ARG-contaminated soils. In biochar-amended soil, the antibiotic content significantly decreased by 24.1 %, while the abundances of mobile genetic elements and ARG host bacteria declined by 23.5 % and 12.1 %, respectively. The reduced antibiotic content, suppressed mobile genetic elements, and altered bacterial community structure collectively led to a 41.8 % reduction in soil ARG abundance. In addition, wood-derived biochar pyrolyzed at 300-500 °C exhibited a substantial advantage in the remediation of ARGs. Furthermore, biochar application decreased the abundance of ARGs in alkaline and neutral soil more markedly than that in acidic soil. The results of this research confirmed the positive mitigating effect of biochar on ARGs in soil, providing valuable insights for the prevention and control of ARG pollution.

Remediation of sulfonamide antibiotic-containing wastewater by constructed wetlands: Importance and action mechanism of plants

Constructed wetlands (CWs) have been proved to be effective in treating sulfonamide antibiotics (SAs) wastewater. Nevertheless, as an essential element in CWs, the significance of plants, continues to be a topic of controversy. In this study, CWs with two different plant species were taken as the research object to investigate their treatment performance, in order to understand the impact of plants on the treatment of SAs wastewater in CWs and to discover the underlying action mechanisms. Experiment results showed that plants played an important role in the CWs, and significantly improved the efficiency of wastewater treatment, with average removal rates for conventional nutrients (COD, NH4+-N, NO3--N and TP) ranging from 73.69 % to 98.92 %, surpassing the non-plant control group (52.16 %-80.70 %). Similarly, for SAs, the removal efficiency in the plant-treated group was 74.15 %-83.67 %, higher than that in the non-plant control group (65.42 %-70.14 %). Although, as time passed, the efficacy of CWs had slightly decreased, but the rate of pollutant removal remained consistently over 60 %. Further analysis showed that plants promoted the removal of SAs through various mechanisms such as plant uptake, microbial degradation and substrate adsorption. Plants had the ability to absorb SAs from wastewater and eliminated them through metabolism or accumulation. Additionally, plants can improve soil enzyme activity to facilitate microbial degradation, indirectly promoting SAs removal. It's worth noting that most SAs can be degraded through plant metabolism after being absorbed by plants, while only a minority of SAs accumulated in plants in the form of parent compounds. Furthermore, the efficacy of CWs in treating wastewater differed between selected plant species. Specifically, Iris pseudacorus showed a higher purifing potential than Scirpus validus. These results revealed the effect of plants on the treatment of SAs wastewater in CWs, and provided a reference for the practical application of antibiotic wastewater removal by CWs.

The livestock and poultry farming impact on antibiotic pollution in China and the potential of nitrogen-doped biochar for remediation

As one of the largest global producers and consumers of antibiotics, China's annual antibiotic production reached 223,000 tons in 2022 and continues to rise. The extensive use of antibiotics has led to severe antibiotic residues and environmental pollution, with 52 % of antibiotic residues in the environment originating from the livestock and poultry farming industry. Biochar has been widely applied in the removal of antibiotics, including active biochar, modified biochar, and heteroatom-doped biochar. Among these, nitrogen-doped biochar shows promising application prospects in antibiotic removal due to its well-developed pore structure and excellent catalytic performance. Nitrogen-rich biomass can be directly pyrolyzed to produce self-doped biochar without external nitrogen sources, and selecting suitable raw materials is key to the widespread application of nitrogen-doped biochar in removing antibiotics from natural environments. This review examines the impact of livestock and poultry farming wastewater on antibiotic pollution in China, explores the current status of using different types of biochar for antibiotic removal, summarizes the nitrogen content in nitrogen-doped biochar and its application prospects in antibiotic pollution control, and provides references for the selection of raw materials in the preparation of self-doped nitrogen biochar. This study offers valuable insights for the application of nitrogen-doped biochar in antibiotic pollution removal in China.

The influence mechanism of environmental factors on DGT adsorbing sulfonamides and the migration between water and sediment

Obtaining the sulfonamides (SAs) concentrations in the water body and sediment bulk was a prerequisite to reveal their transport and partitioning behavior in sediment-water environments and accurately assess their ecological risk. In the present study, the influences of multifactor interactions on the performance of o-DGTs with XAD-18 binding gels were analyzed by central combination experiments and response surfaces analysis, in which the target compounds were 9 SAs. The results indicated that dissolved organic matter (DOM), pH, and suspended particulate matter (SS) had significant effects on the o-DGT sampling, whereas this o-DGT was independent of the ionic strength (IS). Concentning the composite influence of the four factors, the interaction between DOM and SS posed the most significant effect on all 9 SAs compounds. Subsequently, an o-DGT and DIFS model was applied to explore the SAs migration between the water-sediments interface. The difference between desorption rate (kb) and adsorption rates (kf) values suggested that the kinetics of SAs was dominated by adsorption. Moreover, the short-term sediment-water partitioning of SAs was clarified on the basis of distribution coefficient (Kdl) for the labile SAs, among which the sulfadiazine (SDZ) had the largest labile pool. The ability of sediments to release SAs to the liquid phase as a sink was determined by response time (Tc). Among the 9 SAs, the long-term release of soseulfamethoxypyridazine (SMP) from the solid phase of sediments would have a potential risk to the aquatic environment, to which more attention should be paid in the future.

Research status, key technologies and development trends of pharmaceutical waste salt treatment technology: A review

The expanding pharmaceutical industry generates a large amount of waste salt (WS) with a complex composition, which is difficult to treat and poses potential risks to the environment and human health. Removing toxic organic compounds has become a bottleneck issue that needs to be addressed. This article presents a comprehensive review of traditional and emerging treatment technologies based on the sources and characteristics of WS from the pharmaceutical industry. It also discusses the problems and challenges faced by typical WS treatment technologies and evaluates the application of innovative integrated processes. Building on this, a future outlook for pharmaceutical WS treatment technologies is outlined. This review aims to assist scientists in enhancing their understanding of different technologies used for treating WS, thereby accelerating the improvement of process parameters and technologies.

Underestimated Cumulative Intake Risk of Veterinary Antibiotics Across Multiple Matrices within a Coupled Breeding-Cropping Model

The coupled breeding-cropping model has been increasingly applied in organic agriculture due to its high resource efficiency; however, the environmental risks of veterinary antibiotics within the solid-liquid-biological system remain unclear. This study focused on a typical poultry-crop system and investigated the migration patterns of enrofloxacin (ENX), ciprofloxacin (CIP), oxytetracycline (OTC), doxycycline (DOX), and florfenicol (FF) in manure, drain, paddy soil, and agricultural products. A strong source-sink relationship was established, with paddy soil identified as the primary reservoir, retaining over 40.1% of the total emissions. The migration behavior of antibiotics in the soil-rice system was primarily influenced by their organic carbon-normalized distribution coefficients, ionization forms, and soil organic carbon contents. Importantly, the cumulative risk of the five antibiotics was 1.4-828 times higher, exceeding risk thresholds by 13.9-fold. These findings emphasize the underestimated cumulative risks of mixed antibiotic use in agroecosystems.

Antibiotic sorption onto MPs in terrestrial environment: a critical review of the transport, bioaccumulation, ecotoxicological effects and prospects

Microplastics (MPs) and antibiotics are prevalent contaminants in terrestrial environment. MPs possess the ability to absorb antibiotics, resulting in the formation of complex pollutants. While the accumulation and fate of MPs and antibiotics in marine ecosystems have been extensively studied, their combined pollution behavior in terrestrial environments remains relatively underexplored. This paper describes the sources, migration, and compound pollution of MPs and antibiotics in soil. It reviews the mechanisms of compound toxicity associated with antibiotics and MPs, combining different biological classifications. Moreover, we highlight the factors that influence the effects of MPs as vectors and the critical elements driving the spread of antibiotic resistance genes (ARGs). These information suggests the potential mitigation measures for MPs contamination from different perspectives to reduce the impact of ARGs-carrying MPs on human health, specifically through transmission via plants, microbes, or terrestrial vertebrates. Finally, we identify gaps in scientific knowledge regarding the interaction between MPs and antibiotics in soil environments, including the need for standardized research methods, multi-dimensional studies on complex ecological effects, and more comprehensive risk assessments of other pollutants on human health. In summary, this paper provides foundational information for assessing their combined toxicity, offers insights into the distribution of these emerging pollutants in soil, and contributes to a better understanding of the environmental impact of these contaminants.

Overall Evaluation of Antibiotics Occurrence from Large-Scale Livestock Farms in Sichuan Basin, China: Spatial Distribution, Source Apportionment, and Risk Assessment

The widespread application of antibiotics in intensive livestock production is increasingly contributing to antibiotic contamination, and their potential ecological risk to environmental media by resourceful utilization of livestock manure as fertilizers in China has been recognized. This study conducted a comprehensive investigation on 79 large-scale livestock farms and collected 86 livestock excrements and 20 soil and 20 surface water samples distributed in Sichuan Basin, where no similar studies were carried out before. In total, four tetracyclines (TCs), eight sulfonamides (SAs), and eight fluoroquinolones (QNs) were monitored by liquid chromatography-triple quadrupole mass spectrometry. The findings revealed that antibiotics occurrence varied remarkably in excrement (feces or manure) among different livestock farms and different livestock species, following the descending order as QNs > TCs > SAs of detection rates and as TCs > QNs > SAs of detected concentrations, respectively. By source apportionment, livestock manure was demonstrated as a possible source for TCs and QNs detected in soil, while the detection of antibiotics in surface water was probably related to other sources. The central, south, and southwest of Sichuan Basin displayed a higher contamination of antibiotics from livestock manure. The ecological risk of antibiotics was obtained from a medium to heavy level, particularly TCs from swine farms to green algae, water flea, and inflated duckweed in aquatic water and QNs from all livestock farms to sensitive organisms in soil. Overall, the prioritized resource utilization of livestock manure would probably increase the contamination level and ecological risk to environment; hence, rational and effective measurement was highly recommended for antibiotics prevention in some regions of Sichuan Basin.

Effectiveness of fullerene/magnesium oxide nanocomposite in removing ciprofloxacin and tetracycline from aqueous solutions

The excessive use of antibiotics, including ciprofloxacin (CIP) and tetracycline (TC), poses negative impacts on both human health and ecosystems. In this work, fullerene/magnesium oxide (F/MgO) nanocomposite was prepared and studied as adsorbent for CIP and TC removal. Adding metal oxide to F led to a change in its characteristics which was confirmed by XRD, FTIR, SEM, and TEM. A maximal removal for 50 mg L-1 CIP was 84.6% at 60 min, pH 7, and 0.2 g L-1 of adsorbent dose. 43.6% of 50 mg L-1 of TC adsorbed at 60 min, pH 5, and 1 g L-1 of adsorbent dose. Adsorption thermodynamics elucidated that the adsorption on F/MgO nanocomposite were spontaneous and exothermic, and non-spontaneous and endothermic for CIP and TC, respectively. Pseudo-second-order kinetic model fitted well the adsorption data of CIP and TC. Various coexisting ions had different impacts on the adsorption efficiency of CIP and TC. The competitive adsorption between CIP and TC on the surface of F/MgO nanocomposite was studied. The F/MgO nanocomposite was efficiently reused 5 cycles for CIP and TC removal and remained effective. This work explores a novel adsorbent for the elimination of CIP and TC from aqueous solutions.

Influence of goethite on the fate of antibiotic (tetracycline) in the aqueous environment: Effect of cationic and anionic surfactants

Over the last decades, the release and occurrence of organic pollutants in aquatic systems have become a major global concern due to their bioaccumulation, toxicity, and adverse effects on the ecosystem. Tetracycline (TC), a widely used antibiotic, is often found at high concentrations in the aqueous environment and tends to bind with the natural colloids. Post-COVID-19 pandemic, the release of surfactants in the environment has increased due to the excessive use of washing and cleaning products. This study systematically investigated the interaction of goethite with TC in the absence and presence of anionic (sodium dodecyl sulfate, SDS) and cationic (cetyltrimethylammonium bromide, CTAB) surfactants. The impact of various environmental parameters like pH, ionic strength, temperature, and organic matter was also studied. It was observed that SDS has drastically increased TC sorption onto goethite from 11 mg/g to 19 mg/g, while CTAB had the opposite effect. To delineate the goethite-TC interaction mechanisms, FTIR with two-dimensional correlation analysis (2D-COS) was performed. The pH of the solution was crucial in the presence of SDS, while ionic strength did not affect the interaction process. The sorption process was endothermic, as evidenced by the increase in sorption capacity with the rise in the temperature. The presence of organic matter hinders the sorption of TC onto goethite, which is also observed in river water where the organic content is very high. Overall, our study helps to predict the fate of organic pollutants like antibiotics in aqueous environments in the coexistence of surfactants and iron oxyhydroxides.

Sorption behavior of oxytetracycline on microplastics and the influence of environmental factors in groundwater: Experimental investigation and molecular dynamics simulation

Microplastics (MPs) and antibiotics can enter groundwater through the interaction of soil and surface water, and MPs as carriers of antibiotics can promote the migration of antibiotics and thus generate more serious ecological risks. Therefore, this paper used experimental and molecular dynamics (MD) simulation methods to investigate the sorption between four common types of MPs in groundwater, namely polyamide (PA), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene (PE), and oxytetracycline (OTC) with high detection rate in groundwater. Additionally, the impact of environmental factors on sorption was examined. The sorption kinetics of the four types of MPs followed the pseudo-second-order kinetics model, and the sorption isotherms of OTC on PA, PE, and PVC were highly linear, suggesting that the electrostatic interaction was the main sorption mechanism. Both experimental and simulation results indicated that PA had the highest affinity for OTC, due to the effect of the formation of hydrogen bonding between the amide groups of PA and OTC. The primary way pH affected sorption was by altering the form in which OTC exists. The effects of the representative substances of protein-like component (bovine serum albumin) and humus-like component (humic acid) in dissolved organic matter varied but were generally inhibitory. Ions could influence the sorption process by competitive sorption or forming complexes with the OTC.

Environmental contamination by veterinary medicinal products and their implications in the conservation of the endangered Pyrenean Capercaillie (Tetrao urogallus aquitanicus)

The endangered Pyrenean Capercaillie (Tetrao urogallus aquitanicus) inhabits perennial forests of the Pyrenees (Spain, France and Andorre). Feces of domestic animals (e.g., horses and cattle) are often found in this species' habitat as evidence of land use overlapping, especially during spring and summer. As a result, pharmaceutical residues found in feces of these domestic ungulates may be absorbed by plants and insects that are part of the diet of Pyrenean Capercaillies (e.g., blueberries [Vaccinium uliginosum, Vaccinium myrtillus], red wood ants [Formica rufa]). Based on the absence of data regarding the exposure of Pyrenean Capercaillie to residues of veterinary medicinal products (VMP), we selected 71 compounds as indicators of anthropogenically-related environmental contamination, analyzed in 90 samples collected in several subalpine forests, northwestern Spain. Residues of several VMP were detected in feces (capercaillie [ciprofloxacin, enrofloxacin, tetracycline and florfenicol], horse [ciprofloxacin, enrofloxacin, tetracycline and ivermectin], and cattle [ciprofloxacin and enrofloxacin]), and in entomofauna (ciprofloxacin and ivermectin). No VMP residues were detected in blueberry plants. Herein, we present novel data about the presence of VMP residues in the Pyrenean Capercaillie's environment, and identify potential VMP sources (i.e., livestock feces and entomofauna) and an exposure route (i.e., food chain) for Capercaillie chicks. Further studies are necessary to investigate the potential indirect or chronic effects of VMP residues in the species' breeding success and adult fitness, which must be taken into account by managers and policy makers to improve management and conservation actions.

Tetracycline antibiotics in agricultural soil: Dissipation kinetics, transformation pathways, and structure-related toxicity

Tetracyclines (TCs) are the most common antibiotics in agricultural soil, due to their widespread usage and strong persistence. Biotic and abiotic degradation of TCs may generate toxic transformation products (TPs), further threatening soil ecological safety. Despite the increasing attention on the environmental behavior of TCs, a systematic review on the dissipation of TCs, evolution of TPs, and structure-toxicity relationship of TCs in agricultural soil remains lacking. This review aimed to provide a comprehensive overview of the environmental fate of TCs in agricultural soil. We first introduced the development history and structural features of different generations of TCs. Then, we comparatively evaluated the dissipation kinetics, transportation pathways, and ecological impacts of three representative TCs, namely tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC), in agricultural soil. The results showed that the dissipation kinetics of TCs generally followed the first-order kinetic model, with the median dissipation half-lives ranging from 20.0 to 38.8 days. Among the three TCs, OTC displayed the lowest dissipation rates due to its structural stability. The typical degradation pathways of TCs in soil included epimerization/isomerization, demethylation, and dehydration. Isomerization and dehydration reactions may lead to the formation of more toxic TPs, while demethylation was accompanied by the alteration of the minimal pharmacophore of TCs thus potentially reducing the toxicity. Toxicological experiments are urgently needed in future to comprehensively evaluate the ecological risks of TCs in agricultural soil.

Occurrence, Source Apportionment, and Risk Assessment of Antibiotics in Mangrove Sediments from the Lianzhou Bay, China

In recent years, the widespread application of antibiotics has raised global concerns, posing a severe threat to ecological health. In this study, the occurrence, source, and ecological risks of 39 antibiotics belonging to 5 classes in mangrove sediments from Lianzhou Bay, China, were assessed. The total concentrations of the antibiotics (∑39 antibiotics) ranged from 65.45 to 202.24 ng/g dry weight (dw), with an average of 142.73 ± 36.76 ng/g dw. The concentrations of these five classes of antibiotics were as follows: Sulfonamides (SAs) > Tetracyclines (TCs) > Fluoroquinolones (QUs) > Penicillin (PCs) > Macrolides (MLs). The spatial distribution of antibiotics varied as high tidal zone > middle tidal zone > low tidal zone. The total organic carbon (TOC), pH, nitrate (NO3--N), and nitrite (NO2--N) of the sediment significantly influenced the distribution of antibiotics (p < 0.05). A source analysis identified untreated sewage from aquaculture as the primary source of antibiotics in the local mangrove. A risk assessment revealed that ciprofloxacin, norfloxacin, ofloxacin of QUs, and tetracycline of TCs exhibited medium risks to algae in certain sampling sites, while other antibiotics exhibited low or no risks to all organisms. Nevertheless, the total risk of all the detected antibiotics to algae was medium in 95% of the sites. The overall ecological risk level of antibiotics in the middle tidal zone was slightly lower than in the high tidal zone and the lowest in the low tidal zone. In summary, the experimental results provided insights into the fate and transport behaviors of antibiotics in mangrove sediments from Lianzhou Bay.

Exploring the sorption and degradation dynamics of validamycin-A in agricultural soils for environmental management

Validamycin A (VA) is one of the antibiotics that have been utilized in agriculture in Asia; nevertheless, there haven't been many investigations on what happens to VA in soil. The rate at which pesticides are adsorbed into the soil must be determined, since their usage in agriculture is growing. In order to accomplish this, the current study investigated the sorption and degradation of VA in ten distinct soil samples via batch equilibrium studies while maintaining strict laboratory controls. In thermodynamic analysis with a C-type curve, the negative values of Gibbs free energy (ΔG) are thoroughly evaluated using both linear and Freundlich models. These values vary from - 16.8 to - 22.2 kJ/mol. Impact of temperature (18, 23, and 30 °C) and pH (5, 7, and 9) on the degradation of this antibiotic in soil was also scrutinized. Our findings demonstrated that, as a result of enhanced microbial activity at higher temperatures, VA deteriorated more quickly at 23 °C and 30 °C than at 18 °C. In comparison to lower pH values, the VA removal efficiencies with sample-4 was significantly greater at pH 7.4 (92.9%) and pH 9 (97.4%). Moreover, first order reaction kinetics were followed in the degradation of VA. The results demonstrated that VA bound to the selected soils, resulting in medium to low persistence as demonstrated by degradation values. In summary, this study provides important information regarding the behavior and fate of VA in different types of soil, information that might be useful in developing workable management strategies and environmental risk assessments.

Assessment of Global Antibiotic Exposure Risk for Crops: Incorporating Soil Adsorption via Machine Learning

The overuse and misuse of antibiotics could significantly increase their accumulation in soils. Consequently, antibiotics possibly enter food chain through crop uptake, posing a threat to global food security. Assessing the exposure risks of antibiotics for crops is crucial for addressing this global issue. In this study, we assessed global antibiotic exposure risk for crops, incorporating a machine learning adsorption model based on 4893 data sets from nine antibiotics. The optimized machine learning adsorption model, using the eXtreme Gradient Boosting algorithm and the class-specific modeling strategy, demonstrated relatively good performance. Notably, we introduced unsaturated soil conditions and considered spatiotemporal variations in soil moisture and temperature for the first time in such a risk assessment. Global distributions of antibiotic exposure risk for crops were predicted for March, June, September, and December. The results indicate that soil moisture significantly influences the exposure risk assessment. Relatively high exposure risk for crops was observed during months with colder local temperatures: generally June for the Southern Hemisphere and December for the Northern Hemisphere. The resulting map highlights high-risk agricultural regions, including southern Canada, western Russia, and southern Australia.

Biogas slurry-derived dissolved organic matter inhibited oxytetracycline adsorption by tropical agricultural soils

The increasing presence of oxytetracycline (OTC) in agricultural soils has raised global environmental concerns. We investigated the environmental behavior and fate of OTC in two types of tropical agricultural soils, focusing on the impact of dissolved organic matter (DOM) from biogas slurry. Techniques such as three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM), Fourier Transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and Ultraviolet-visible spectrophotometer (UV-vis) were used to explore the adsorption mechanisms. Our findings revealed that biogas slurry-derived DOM decreased the OTC adsorption on soils and extended the time to reach adsorption equilibrium. Specifically, the equilibrium adsorption of OTC by the two soils decreased by 19.41 and 15.32 %, respectively. These adsorption processes were effectively modelled by Elovich, intraparticle diffusion, linear, and Freundlich thermodynamic models. Thermodynamic parameters suggested that OTC adsorption onto soils was spontaneous and endothermic, with competitive interactions between biogas slurry-derived DOM and OTC molecules intensifying at higher DOM concentrations. The adsorption mechanisms were governed by both physical and chemical processes. Furthermore, the presence of Ca2+ and Na+ ions significantly inhibited OTC adsorption. These insights advanced our understanding of the fate and risk of OTC in soil environments influenced by DOM, contributing to more informed agricultural and environmental management practices.

Bioelectrochemical remediation of soil antibiotic and antibiotic resistance gene pollution: Key factors and solution strategies

In recent years, owing to the overuse and improper handling of antibiotics, soil antibiotic pollution has become increasingly serious and an environmental issue of global concern. It affects the quality and ecological balance of the soil and allows the spread of antibiotic resistance genes (ARGs), which threatens the health of all people. As a promising soil remediation technology, bioelectrochemical systems (BES) are superior to traditional technologies because of their simple operation, self-sustaining operation, easy control characteristics, and use of the metabolic processes of microorganisms and electrochemical redox reactions. Moreover, they effectively remediate antibiotic contaminants in soil. This review explores the application of BES remediation mechanisms in the treatment of antibiotic contamination in soil in detail. The advantages of BES restoration are highlighted, including the effective removal of antibiotics from the soil and the prevention of the spread of ARGs. Additionally, the critical roles played by microbial communities in the remediation process and the primary parameters influencing the remediation effect of BES were clarified. This study explores several strategies to improve the BES repair efficiency, such as adjusting the reactor structure, improving the electrode materials, applying additives, and using coupling systems. Finally, this review discusses the current limitations and future development prospects, and how to improve its performance and promote its practical applications. In summary, this study aimed to provide a reference for better strategies for BES to effectively remediate soil antibiotic contamination.

Effect of ph on migration patterns and degradation pathways of sulfamethazine in soil systems

Sulfonamide antibiotics (SAs) are widely used antimicrobial agents in livestock and aquaculture, and most of them entering the animal's body will be released into the environment as prodrugs or metabolites, which ultimately affect human health through the food chain. Both acid deposition and salinization of soil may have an impact on the migration and degradation of antibiotics. Sulfamethazine (SM2), a frequently detected compound in agricultural soils, has a migration and transformation process in the environment that is closely dependent on environmental pH. Nevertheless, scarcely any studies have been conducted on the effect of soil pH changes on the environmental behavior of sulfamethazine. We analyzed the migration and degradation mechanisms of SM2 using simulation experiments and ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) techniques. The results showed that acidic conditions limited the vertical migration of sulfadimidine, and SM2 underwent different reaction processes under different pH conditions, including S-C bond breaking, S-N bond hydrolysis, demethylation, six-membered heterocyclic addition, methyl hydroxylation and ring opening. The study of the migration pattern and degradation mechanism of SM2 under different pH conditions can provide a solid theoretical basis for assessing the pollution risk of sulfamethazine degradation products under acid rain and saline conditions, and provide a guideline for remediation of antibiotic contamination, so as to better prevent, control and protect groundwater resources.

Biotransformation characteristics of tetracycline by strain Serratia marcescens MSM2304 and its mechanism evaluation based on products analysis and genomics

Microbial biotransformation is a recommended and reliable method in face of formidable tetracycline (TC) with broad-spectrum antibacterial activity. Herein, comprehensive characteristics of a newfound strain and its molecular mechanism in process of TC bioremediation were involved in this study. Specifically, Serratia marcescens MSM2304 isolated from pig manure sludge grew well in presence of TC and achieved optimal removal efficiency of 61% under conditions of initial TC concentration of 10 mg/L, pH of 7.0, cell inoculation amount of 5%, and tryptone of 10 g/L as additional carbon. The pathways of biotransformation include EPS biosorption, cell surface biosorption and biodegradation, which enzymatic processes of biodegradation were occurred through TC adsorbed by biofilms was firstly broken down by extracellular enzymes and part of TC migrated towards biofilm interior and degraded by intracellular enzymes. Wherein extracellular polysaccharides in extracellular polymeric substances (EPS) from biofilm of strain MSM2304 mainly performed extracellular adsorption, and changes in position and intensity of CO, =CH and C-O-C/C-O of EPS possible further implied TC adsorption by it. Biodegradation accounting for 79.07% played a key role in TC biotransformation and could be fitted well by first-order model that manifesting rapid and thorough removal. Potential biodegradation pathway including demethylation, dihydroxylation, oxygenation, and ring opening possibly involved in TC disposal process of MSM2304, TC-degrading metabolites exhibited lower toxicity to indicator bacteria relative to parent TC. Whole genome sequencing as underlying molecular evidence revealed that TC resistance genes, dehydrogenases-encoding genes, monooxygenase-encoding genes, and methyltransferase-encoding genes of strain MSM2304 were positively related to TC biodegradation. Collectively, these results favored a theoretical evaluation for Serratia marcescens MSM2304 as a promising TC-control agent in environmental bioremediation processes.

Insights into the pH-dependent interactions of sulfadiazine antibiotic with soil particle models

Sulfonamide antibiotics (SAs) are widely used as a broad-spectrum antibiotic, leading to global concerns due to their potential soil accumulation and subsequent effects on ecosystems. SAs often exhibit remarkable environmental persistence, necessitating further investigation to uncover the ultimate destiny of these molecules. In this work, molecular dynamics simulations combined with complementary quantum chemistry calculations were employed to investigate the influence of pH on the behavior of sulfadiazine (SDZ, a typical SAs) in soil particle models (silica, one of the main components of soil). Meanwhile, the quantification of SDZ molecules aggregation potential onto silica was further extended. SDZ molecules tend to form a monolayer on the soil surface under acidic conditions while forming aggregated adsorption on the surface under neutral conditions. Due to the hydrophilicity of the silica, multiple hydration layers would form on its surface, hindering the further adsorption of SDZ molecules on its surface. The calculated soil-water partition coefficient (Psoil/water) of SDZ+ and SDZ were 9.01 and 7.02, respectively. The adsorption evaluation and mechanisms are useful in controlling the migration and transformation of SAs in the soil environment. These findings provide valuable insights into the interactions between SDZ and soil components, shedding light on its fate and transport in the environment.

Prediction of antibiotic sorption in soil with machine learning and analysis of global antibiotic resistance risk

Although the sorption of antibiotics in soil has been extensively studied, their spatial distribution patterns and sorption mechanisms still need to be clarified, which hinders the assessment of antibiotic resistance risk. In this study, machine learning was employed to develop the models for predicting the soil sorption behavior of three classes of antibiotics (sulfonamides, tetracyclines, and fluoroquinolones) in 255 soils with 2203 data points. The optimal independent models obtained an accurate predictive performance with R2 of 0.942 to 0.977 and RMSE of 0.051 to 0.210 on test sets compared to combined models. Besides, a global map of the antibiotic sorption capacity of soil predicted with the optimal models revealed that the sorption potential of fluoroquinolones was the highest, followed by tetracyclines and sulfonamides. Additionally, 14.3% of regions had higher antibiotic sorption potential, mainly in East and South Asia, Central Siberia, Western Europe, South America, and Central North America. Moreover, a risk index calculated with the antibiotic sorption capacity of soil and population density indicated that about 3.6% of soils worldwide have a high risk of resistance, especially in South and East Asia with high population densities. This work has significant implications for assessing the antibiotic contamination potential and resistance risk.

Urban agglomerations as an environmental dimension of antibiotics transmission through the "One Health" lens

The spatiotemporal distributions of antibiotics in different media have been widely reported; however, their occurrence in the environmental dimension of the Chinese urban agglomerations has received less attention, especially in bioaccumulation and health risks of antibiotics through the "One Health" lens. The review presents the current knowledge on the environmental occurrence, bioaccumulation, as well as health exposure risks in urban agglomerations through the "One Health" lens, and identifies current information gaps. The reviewed studies suggested antibiotic concentrations in water and soil were more sensitive to social indicators of urban agglomerations than those in sediment. The ecological risk and resistance risk of antibiotics in water were much higher than those of sediments, and the high-risk phenomenon occurred at a higher frequency in urban agglomerations. Erythromycin-H2O (ETM-H2O), amoxicillin (AMOX) and norfloxacin (NFC) were priority-controlled antibiotics in urban waters. Tetracyclines (TCs) posed medium to high risks to soil organisms in the soil of urban agglomerations. Health risk evaluation based on dietary intake showed that children had the highest dietary intake of antibiotics in urban agglomerations. The health risk of antibiotics was higher in children than in other age groups. Our results also demonstrated that dietary structure might impact health risks associated with target antibiotics in urban agglomerations to some extent.

Urbanization and land use regulate soil vulnerability to antibiotic contamination in urban green spaces

The presence of antibiotics in environment is an emerging concern because of their ubiquitous occurrence, adverse eco-toxicological effects, and promotion of widespread antibiotic resistance. Urban soil, which plays a noticeable role in human health, may be a reservoir of antibiotics because of intensive human disturbance. However, little is understood about the vulnerability of soil to antibiotic contamination in urban areas and the spatial-temporal characteristics of anthropogenic and environmental pressures. In this study, we developed a framework for the dynamic assessment of soil vulnerability to antibiotic contamination in urban green spaces, combining antibiotic release, exposure, and consequence layers. According to the results, soil vulnerability risks shown obvious spatial-temporal variation in urban areas. Areas at a high risk of antibiotic contamination were usually found in urban centers with high population densities and in seasons with low temperature and vegetation coverage. Quinolones (e.g., ofloxacin and norfloxacin) were priority antibiotics that posed the highest vulnerability risks, followed by tetracyclines. We also confirmed the effectiveness of the vulnerability assessment by correlating soil vulnerability indexes and antibiotic residues in urban soils. Furthermore, urbanization- and land use-related parameters were shown to be critical in regulating soil vulnerability to antibiotic contamination based on sensitivity analysis. These findings have important implications for the prediction and mitigation of urban soil contamination with antibiotics and strategies to improve human health.

Potential mechanism of biochar enhanced degradation of oxytetracycline by Pseudomonas aeruginosa OTC-T

Extensive use of oxytetracycline (OTC) and the generation of its corresponding resistance genes have resulted in serious environmental problems. Physical-biological combined remediation is an attractive method for OTC degradation because of its high remediation efficiency, stability, and environmental friendliness. In this study, an effective OTC-degrading strain identified as Pseudomonas aeruginosa OTC-T, was isolated from chicken manure. In the degradation experiment, the degradation rates of OTC in the degradation systems with and without the biochar addition were 92.71-100 % and 69.11-99.59 %, respectively. Biochar improved the tolerance of the strain to extreme environments, and the OTC degradation rate increased by 20.25 %, 18.61 %, and 13.13 % under extreme pH, temperature, and substrate concentration conditions, respectively. Additionally, the degradation kinetics showed that biochar increased the reaction rate constant in the degradation system and shortened the degradation period. In the biological toxicity assessment, biochar increased the proportion of live cells by 17.63 % and decreased the proportion of apoptotic cells by 58.87 %. Metabolomics revealed that biochar had a significant effect on the metabolism of the strains and promoted cell growth and reproduction, effectively reducing oxidative stress induced by OTC. This study elucidates how biochar affects OTC biodegradation and provides insights into the future application of biochar-assisted microbial technology in environmental remediation.

Antibiotics soil-solution chemistry: A review of environmental behavior and uptake and transformation by plants

The increased use of antibiotics by humans for various purposes has left the environment polluted. Antibiotic pollution remediation is challenging because antibiotics exist in trace amounts and only highly sensitive detection techniques could be used to quantify them. Nevertheless, their trace quantity is not a hindrance to their transfer along the food chain, causing sensitization and the development of antibiotic resistance. Despite an increase in the literature on antibiotic pollution and the development and transfer of antibiotic-resistant genes (ARGs), little attention has been given to the behavior of antibiotics at the soil-solution interface and how this affects antibiotic adsorption-desorption interactions and subsequent uptake and transformation by plants. Thus, this review critically examines the interactions and possible degradation mechanisms of antibiotics in soil and the link between antibiotic soil-solution chemistry and uptake by plants. Also, different factors influencing antibiotic mobility in soil and the transfer of ARGs from one organism to another were considered. The mechanistic and critical analyses revealed that: (a) the charge characteristics of antibiotics at the soil-root interface determine whether they are adsorbed to soil or taken up by plants; (b) antibiotics that avoid soil colloids and reach soil pore water can be absorbed by plant roots, but their translocation to the stem and leaves depends on the ionic state of the molecule; (c) few studies have explored how plants adapt to antibiotic pollution and the transformation of antibiotics in plants; and (d) the persistence of antibiotics in cropland soils can be influenced by the content of soil organic matter, coexisting ions, and fertilization practices. Future research should focus on the soil/solution-antibiotic-plant interactions to reveal detailed mechanisms of antibiotic transformation by plants and whether plant-transformed antibiotics could be of environmental risk.

Applications of waste polyethylene terephthalate (PET) based nanostructured materials: A review

While polyethylene terephthalate (PET) has enjoyed widespread use, a large volume of plastic waste has also been produced as a result, which is detrimental to the environment. Traditional treatment of plastic waste, such as landfilling and incinerating waste, causes environmental pollution and poses risks to public health. Recycling PET waste into useful chemicals or upcycling the waste into high value-added materials can be remedies. This review first provides a brief introduction of the synthesis, structure, properties, and applications of virgin PET. Then the conversion process of waste PET into high value-added materials for different applications are introduced. The conversion mechanisms (including degradation, recycling and upcycling) are detailed. The advanced applications of these upgraded materials in energy storage devices (supercapacitors, lithium-ion batteries, and microbial fuel cells), and for water treatment (to remove dyes, heavy metals, and antibiotics), environmental remediation (for air filtration, CO2 adsorption, and oil removal) and catalysis (to produce H2, photoreduce CO2, and remove toxic chemicals) are discussed at length. In general, this review details the exploration of advanced technologies for the transformation of waste PET into nanostructured materials for various applications, and provides insights into the role of high value-added waste products in sustainability and economic development.

Prediction of the mobility and persistence of eight antibiotics based on soil characteristics

Antibiotics are widely used in intensive animal husbandry in the Netherlands and are subsequently emitted to soil via manure. To predict degradation and mobility in soil, generic sorption models have been derived. However, most of the coefficients used in generic models are based on a limited range of soils and have not been validated for agricultural soils in the Netherlands. To improve model predictions and assess to what extent differences among soils affect sorption and degradation, an experimental study has been performed. Using a recently developed experimental approach, both the degradation (DT50) and mobility (Kd) of eight selected commonly used antibiotics were determined in 29 typical Dutch agricultural soils. Median DT50 values range from 5.3 days for Sulfadiazine to 120 days for Trimethoprim but are affected by soil type. The ratio of the lowest and highest DT50 for a given antibiotic among soils can be as large as 151, for Tylosin. Measured values of the logKd also range from 0.19 for Sulfadiazine to more than 2 for Doxycycline, Flumequine, Trimethoprim, Tylosin and Enrofloxacine. The impact of soil on Kd is large, especially for more mobile antibiotics such as Sulfadoxine and Sulfadiazine. Both the range in DT50 and Kd can be predicted reasonably well using a Freundlich type regression model that accounts for the variation in soil type and sampling depth. Organic matter, iron oxides, pH and clay content appear to be the main constituents and explain between 29 % (Trimethoprim) and 77 % of the variation in DT50 and between 64 % (Lincomycin) and 87 % (Sulfadoxine and Sulfadiazine) of the variation of Kd. The effect of depth on DT50 and Kd is however limited. The information thus obtained in combination with local data on soil type can be used to more accurately predict the potential risk of relevant antibiotics in soil and transport to ground- and nearby surface waters.

Adsorption of antibiotics onto low-grade charcoal in the presence of organic matter: Batch and column tests

Antibiotics contaminate diverse ecosystems and threaten human health. In ecosystems including water, sediment, and soil, the amount of antibiotics present is tiny compared to the amount of natural organic matter. However, most studies have ignored the co-presence of natural organic matter in the adsorption of target antibiotics. In this study, we quantitatively evaluated the effect of co-presenting natural organic matter on the adsorption of sulfamethazine (SMZ) through batch and column experiments using low-grade charcoal, an industrial by-product. SMZ was used as a model antibiotic compound and humic acid (HA) was used to represent natural organic matter. The co-presence of 2000 mg/L HA (400 times the concentration of SMZ) lowered the adsorption rate of SMZ from 0.023 g/mg·min to 0.007 g/mg·min, and the maximum adsorption capacity from 39.8 mg/g to 15.6 mg/g. HA blocked the charcoal's pores and covered its surface adsorption sites, which dramatically lowered its capacity to adsorb SMZ. Similar results were obtained in the flow-through column experiments, where the co-presence of natural organic matter shortened the lifetime of the charcoal. As a result, the co-presence of a relatively high concentration of natural organic matter can inhibit the adsorption of SMZ and likely other antibiotic compounds, and thus the presence of natural organic matter should be accounted for in the design of adsorption processes to treat antibiotics in water.

Cu2+ coordination-induced in situ photo-to-heat on catalytic sites to hydrolyze β-lactam antibiotics pollutants in waters

For degradation of β-lactam antibiotics pollution in waters, the strained β-lactam ring is the most toxic and resistant moiety to biodegrade and redox-chemically treat among their functional groups. Hydrolytically opening β-lactam ring with Lewis acid catalysts has long been recognized as a shortcut, but at room temperature, such hydrolysis is too slow to be deployed. Here, we found when Cu2+ was immobilized on imine-linked COF (covalent organic framework) (Cu2+/Py-Bpy-COF, Cu2+ load is 1.43 wt%), as-prepared composite can utilize the light irradiation (wavelength range simulated sunlight) to in situ heat anchored Cu2+ Lewis acid sites through an excellent photothermal conversion to open the β-lactam ring followed by a desired full-decarboxylation of hydrolysates. Under 1 W/cm2 simulated sunlight, Cu2+/Py-Bpy-COF powders placed in a microfiltration membrane rapidly cause a temperature rising even to ~211.7 °C in 1 min. It can effectively hydrolyze common β-lactam antibiotics in waters and even antibiotics concentration is as high as 1 mM and it takes less than 10 min. Such photo-heating hydrolysis rate is ~24 times as high as under dark and ~2 times as high as Cu2+ homogenous catalysis. Our strategy significantly decreases the interference from generally coexisting common organics in waters and potential toxicity concerns of residual carboxyl groups in hydrolysates and opens up an accessible way for the settlement of β-lactam antibiotics pollutants by the only energy source available, the sunlight.

Chemistry of soil-type dependent soil matrices and its influence on behaviors of pharmaceutical compounds (PCs) in soils

Behaviors of pharmaceutical compounds (PCs) in soil are usually determined by experimental extrapolation of results from separate constitutes to the soil, or from a special soil to other regional soil conditions. However, such extrapolation is problematic due to variations in soil clay mineral and organic matter (OM) compositions with soil types, which dominate the interaction mechanisms of PCs in soil. It is essential to review current literature to enhance our understanding of the soil-type dependent surface chemistry of soil matrices and the environmental behavior of PCs in different soil types. Major types of soils occur globally in parallel to the latitudinal or altitudinal zonation due to regional climate conditions with distinct clay mineral and OM compositions. The soil-type dependent surface chemistry results in variations in retention, distribution, transport, and transformation PCs in soil. The mixture of PCs of different classes usually exhibited enhanced sorption due to the cooperative multilayer sorption on soil constituents, and that of the same class often caused differential adsorption capacity compared to the sorption from single compound due to competitive sorption. PCs preferentially adsorb to a soil component, or to a special soil type, and exhibit notably soil-type dependent sorption affinity, mobility, and dissipation. The soil-dependent surface chemistry of soil is critical to predict the persistence and bioavailability of PCs in soil. In the future, more detailed studies of influence of individual soil factor on the behaviors of PCs and especially the practical field site investigation are required to better understand the sorption, transport, transformation, and ecotoxicology of PCs in typical soil types.

Insight into typical photo-assisted AOPs for the degradation of antibiotic micropollutants: Mechanisms and research gaps

Due to the incomplete elimination by traditional wastewater treatment, antibiotics are becoming emerging contaminants, which are proved to be ubiquitous and promote bacterial resistance in the aquatic systems. Antibiotic pollution has raised particular concerns, calling for improved methods to clean wastewater and water. Photo-assisted advanced oxidation processes (AOPs) have attracted increasing attention because of the fast reaction rate, high oxidation capacity and low selectivity to remove antibiotics from wastewater. On the basis of latest literature, we found some new breakthroughs in the degradation mechanisms of antibiotic micropollutants with respect to the AOPs. Therefore, this paper summarizes and highlights the degradation kinetics, pathways and mechanisms of antibiotics degraded by the photo-assisted AOPs, including the UV/O3 process, photo-Fenton technology, and photocatalysis. In the processes, functional groups are attacked by hydroxyl radicals, and major structures are destroyed subsequently, which depends on the classes of antibiotics. Meanwhile, their basic principles, current applications and influencing factors are briefly discussed. The main challenges, prospects, and recommendations for the improvement of photo-assisted AOPs are proposed to better remove antibiotics from wastewater.

Transport of bisphenol A, bisphenol S, and three bisphenol F isomers in saturated soils

With the limitation of the use of bisphenol A (BPA), the production of its substitutes, bisphenol S (BPS), and bisphenol F (4,4'-BPF) is increasing. Understanding the fate and transport of BPA and its substitutes in porous media can help reduce their risk of contaminating soil and groundwater systems. In this study, column and batch adsorption experiments were performed with 14C-labeled bisphenol analogs and combined with mathematical models to investigate the interaction of BPA, BPS, 4,4'-BPF, 2,2'-BPF, and 2,4'-BPF with four standard soils with different soil organic matter (SOM) contents. The results show that the transport capacity of BPS and 4,4'-BPF in the saturated soils is significantly stronger than that of BPA. Meanwhile, the mobility of the three isomers of bisphenol F exhibits variability in saturated soils with high SOM content. The two-site nonequilibrium sorption model was applied to simulate and interpret column experimental data, and model simulations described the interactions between the bisphenol analogs and soil very well. The fitting results underscore SOM's role in providing dynamic adsorption sites for bisphenol analogs. Hydrophobicity primarily accounts for the disparity in adsorption affinity between BPA, BPS, 4,4'-BPF, and soil, whereas hydrogen bonding forces may predominantly influence the differential adsorption affinity between 4,4'-BPF and its isomers and soil. The results of this study indicate that BPS and three isomers of BPF, as alternatives to BPA, have higher mobility in saturated soils and may pose a substantial risk to groundwater quality. This study enhances our understanding of bisphenol analogs' behavior in natural soils, facilitating an assessment of their environmental implications, particularly regarding groundwater contamination.

Diversity of antibiotic resistance genes in soils with four different fertilization treatments

Although the enrichment of resistance genes in soil has been explored in recent years, there are still some key questions to be addressed regarding the variation of ARG composition in soil with different fertilization treatments, such as the core ARGs in soil after different fertilization treatments, the correlation between ARGs and bacterial taxa, etc. For soils after different fertilization treatments, the distribution and combination of ARG in three typical fertilization methods (organic fertilizer alone, chemical fertilizer alone, and conventional fertilizer) and non-fertilized soils were investigated in this study using high-throughput fluorescence quantitative PCR (HT-qPCR) technique. The application of organic fertilizers significantly increased the abundance and quantity of ARGs and their subtypes in the soil compared to the non-fertilized soil, where sul1 was the ARGs specific to organic fertilizers alone and in higher abundance. The conventional fertilizer application also showed significant enrichment of ARGs, which indicated that manure addition often had a more decisive effect on ARGs in soil than chemical fertilizers, and three bacteria, Pseudonocardia, Irregularibacter, and Castllaniella, were the key bacteria affecting ARG changes in soil after fertilization. In addition, nutrient factors and heavy metals also affect the distribution of ARGs in soil and are positively correlated. This paper reveals the possible reasons for the increase in the number of total soil ARGs and their relative abundance under different fertilization treatments, which has positive implications for controlling the transmission of ARGs through the soil-human pathway.

Adsorption of oxytetracycline on subalpine meadow soil from Zoige Plateau, China: Effects of the coexisting Cu2

Subalpine meadow soil with high moisture and humus content is a unique soil type in the Zoige Plateau. Oxytetracycline and copper are common soil contaminants which interact to form compound pollution. Oxytetracycline's adsorption on natural subalpine meadow soil and its components (humin and the soil without iron and manganese oxides) was studied in the laboratory with and without the presence of Cu2+. The effects of temperature, pH and Cu2+ concentration were documented in batch experiments, allowing deduction of the main sorption mechanisms. The adsorption process had two phases: one rapid, taking place in the first 6 h, and another slower, reaching equilibrium at around 36 h. The adsorption kinetics were pseudo-second-order, and the adsorption isotherm conformed to the Langmuir model at 25 °C. Higher concentrations oxytetracycline increased the adsorption, but higher temperature did not. The presence of Cu2+ had no effect on the equilibrium time, but the amount and rate adsorbed were much greater with Cu2+ concentration increased (except for the soil without iron and manganese oxides). The amounts adsorbed with/without Cu2+ were in the order the humin from subalpine meadow soil (7621 and 7186 μg/g) > the subalpine meadow soil (7298 and 6925 μg/g) > the soil without iron and manganese oxides (7092 and 6862 μg/g), but the difference among those adsorbents was slight. It indicates that humin is a particularly important adsorbent in the subalpine meadow soil. The amount of oxytetracycline adsorbed was greatest at pH 5-9. In addition, Surface complexation through metal bridging was the most important sorption mechanism. Cu2+ and oxytetracycline formed positively-charged complex that was adsorbed and then formed a ternary complex "adsorbent-Cu(II)-oxytetracycline", in which Cu2+ acted as a bridge. These findings provide a good scientific basis for soil remediation, and for assessing environmental health risks.

Change of tetracycline speciation and its impacts on tetracycline removal efficiency in vermicomposting with epigeic and endogeic earthworms

Tetracycline pollution is common in Chinese arable soils, and vermicomposting is an effective approach to accelerate tetracycline bioremediation. However, current studies mainly focus on the impacts of soil physicochemical properties, microbial degraders and responsive degradation/resistance genes on tetracycline degradation efficiencies, and limited information is known about tetracycline speciation in vermicomposting. This study explored the roles of epigeic E. fetida and endogeic A. robustus in altering tetracycline speciation and accelerating tetracycline degradation in a laterite soil. Both earthworms significantly affected tetracycline profiles in soils by decreasing exchangeable and bound tetracycline but increasing water soluble tetracycline, thereby facilitating tetracycline degradation efficiencies. Although earthworms increased soil cation exchange capacity and enhanced tetracycline adsorption on soil particles, the significantly elevated soil pH and dissolved organic carbon benefited faster tetracycline degradation, attributing to the consumption of soil organic matter and humus by earthworms. Different from endogeic A. robustus which promoted both abiotic and biotic degradation of tetracycline, epigeic E. foetida preferently accelerated abiotic tetracyline degradation. Our findings described the change of tetracycline speciation during vermicompsiting process, unraveled the mechanisms of different earthworm types in tetracycline speciation and metabolisms, and offered clues for effective vermiremediation application at tetracycline contaminated sites.

The fate of sulfonamides in microenvironments of rape and hot pepper rhizosphere soil system

Sulfonamides (SAs) in agricultural soils can be degraded in rhizosphere, but can also be taken up by vegetables, which thereby poses human health and ecological risks. A glasshouse experiment was conducted using multi-interlayer rhizoboxes to investigate the fate of three SAs in rape and hot pepper rhizosphere soil systems to examine the relationship between the accumulation and their physicochemical processes. SAs mainly entered pepper shoots in which the accumulation ranged from 0.40 to 30.64 mg kg-1, while SAs were found at high levels in rape roots ranged from 3.01 to 16.62 mg kg-1. The BCFpepper shoot exhibited a strong positive linear relationship with log Dow, while such relationship was not observed between other bioconcentration factors (BCFs) and log Dow. Other than lipophilicity, the dissociation of SAs may also influence the uptake and translocation process. Larger TF and positive correlation with log Dow indicate preferential translocation of pepper SAs. There was a significant (p < 0.05) dissipation gradient of SAs observed away from the vegetable roots. In addition, pepper could uptake more SAs under solo exposure, while rape accumulated more SAs under combined exposure. When SAs applied in mixture, competition between SAs might occur to influence the translocation and dissipation patterns of SAs.

A comprehensive and global evaluation of residual antibiotics in agricultural soils: Accumulation, potential ecological risks, and attenuation strategies

The occurrence of antibiotics in agricultural soils has raised concerns due to their potential risks to ecosystems and human health. However, a comprehensive understanding of antibiotic accumulation, distribution, and potential risks to terrestrial ecosystems on a global scale is still limited. Therefore, in this study, we evaluated the accumulation of antibiotics and their potential risks to soil microorganisms and plants, and highlighted the driving factors of antibiotic accumulation in agricultural soils based on 134 peer-reviewed studies (between 2000 and 2022). The results indicated that 56 types of antibiotics were detected at least once in agricultural soils with concentrations ranging from undetectable to over 7000 µg/kg. Doxycycline, tylosin, sulfamethoxazole, and enrofloxacin, belonging to the tetracyclines, macrolides, sulfonamides, and fluoroquinolones, respectively, were the most accumulated antibiotics in agricultural soil. The accumulation of TCs, SAs, and FQs was found to pose greater risks to soil microorganisms (average at 29.3%, 15.4%, and 21.8%) and plants (42.4%, 26.0%, and 38.7%) than other antibiotics. East China was identified as a hot spot for antibiotic contamination due to high levels of antibiotic concentration and ecological risk to soil microorganisms and plants. Antibiotic accumulation was found to be higher in vegetable fields (245.5 µg/kg) and orchards (212.4 µg/kg) compared to croplands (137.2 µg/kg). Furthermore, direct land application of manure resulted in a greater accumulation of TCs, SAs, and FQs accumulation in soils than compost fertilization. The level of antibiotics decreased with increasing soil pH and organic matter content, attributed to decreasing adsorption and enhancing degradation of antibiotics. In conclusion, this study highlights the need for further research on the impacts of antibiotics on soil ecological function in agricultural fields and their interaction mechanisms. Additionally, a whole-chain approach, consisting of antibiotic consumption reduction, manure management strategies, and remediation technology for soil contaminated with antibiotics, is needed to eliminate the potential environmental risks of antibiotics for sustainable and green agriculture.

Adsorption of fluoroquinolone antibiotics onto ferrihydrite under different anionic surfactants and solution pH

To date, little information is available regarding the impacts of the widespread anionic surfactants on the adsorption behaviors of antibiotics onto typical iron oxides. Herein, we have investigated the effects of two typical surfactants (sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS)) on the adsorption of two widely used antibiotics (i.e., levofloxacin (LEV) and ciprofloxacin (CIP)) onto ferrihydrite. Results of kinetic experiments showed that the adsorption of antibiotics was well fitted by the pseudo-second-order kinetic models, indicating that the adsorption process might be controlled by chemisorption. The affinity of ferrihydrite toward CIP was greater than that toward LEV, which was ascribed to the higher hydrophobicity of CIP than LEV. Both surfactants enhanced antibiotic adsorption owing to SDS or SDBS molecules as bridge agents between ferrihydrite particles and antibiotics. Interestingly, the extent of the enhanced effects of surfactants on antibiotic adsorption declined as the background solution pH increased from 5.0 to 9.0, which was mainly due to the weaker hydrophobic interactions between antibiotics and the adsorbed surfactants on the iron oxide surfaces as well as the greater electrostatic repulsion between the anionic species of antibiotics and the negatively charged ferrihydrite particles at higher pH. Together, these findings emphasize the importance of widespread surfactants for illustrating the interactions between fluoroquinolone antibiotics and iron oxide minerals in the natural environment.

Insights into the driving factors of vertical distribution of antibiotic resistance genes in long-term fertilized soils

The prevalence of antibiotic resistance genes (ARGs) in soils has aroused wide attention. However, the influence of long-term fertilization on the distribution of ARGs in different soil layers and its dominant drivers remain largely unknown. In this study, a total of 203 ARGs were analyzed in greenhouse vegetable soils (0-100 cm from a 13-year field experiment applied with different fertilizers (control, chemical fertilizer, organic manure, and mixed fertilizer). Compared with unfertilized and chemically fertilized soils, manure application significantly increased the abundance and alpha diversity of soil ARGs, where the assembly of ARG communities was strongly driven by stochastic processes. The distribution of ARGs was significantly driven by manure application within 60 cm, while it was insignificantly changed in soil below 60 cm under different fertilization regimes. The inter-correlations of ARGs with mobile genetic elements (MGEs) and microbiota were strengthened in manured soil, indicating manure application posed a higher risk for ARGs diffusion in subsurface soil. Bacteria abundance and MGEs directly influenced ARG abundance and composition, whereas soil depth and manure application indirectly influenced ARG abundance and composition by affecting antibiotics. These results strengthen our understanding of the long-term anthropogenic influence on the vertical distribution of soil ARGs and highlight the ecological risk of ARGs in subsurface soil induced by long-term manure application.

Competitive adsorption and desorption of three antibiotics in distinct soil aggregate size fractions

Multiple antibiotics that are used in veterinary medicine coexist in soils, but their interaction and the effects on adsorption and desorption in soils have not been extensively studied. In this study, using batch experiments, we evaluated the adsorption and desorption of sulfadiazine (SDZ), tetracycline (TC), and norfloxacin (NFX) using four different soil aggregate size fractions and discovered that: (1) TC had the highest adsorption (76-98 %) and the lowest desorption in each tested system, whereas SDZ showed opposite adsorption and desorption ability, (2) the highest adsorption and the lowest desorption of all three tested antibiotics were observed with soil macroaggregates (250-2000 µm) in all the cases; in contrast, opposite adsorption and desorption ability were observed for soil clay (<53 µm), and (3) adsorption of each antibiotic was in the following order: single system (71-89 %) > binary system (56-84 %) > ternary system (50-78 %); however, desorption were in the reverse order. The Freundlich equation fitting and Brunauer-Emmett-Teller (BET) analysis further demonstrated that the adsorption competition between the tested antibiotics depended mainly on the specific surface area of each soil aggregate size fractions and its chemical properties. In conclusion, soil macroaggregates play a key role in the retention of antibiotics in soils, and the coexistence of multiple antibiotics greatly increases leaching risk.

Tween 80 assisted washing ciprofloxacin-contaminated soil, and recycled it using active chlorines

Active chlorines (ACs) can selectively oxidize contaminants with benzene rings to recycle surfactants, which greatly facilitates the resource cycle. This paper firstly utilized Tween 80 to assist in ex-situ washing the ciprofloxacin (CI) contaminated soil, including the solubilization experiment, shake washing and soil column washing, all of which showed that 2 g/L of Tween 80 (TW 80) was the most effective in removing CI. Then electrochemically treated the collected soil washing effluent (SWE) at 10 V with an electrolyte of 20 mM NaCl + 10 mM Na₂SO₄; Pre-experiments screened the range of electrode spacing, pH and temperature, based on which an orthogonal design Table L₉ (3⁴) was designed. Visual analysis and ANOVA were performed on the ciprofloxacin removal efficiency and Tween 80 retention efficiency during the orthogonal experiments in 9 groups, and the results showed that CI was usually degraded within 30 min, and 50% of TW 80 was still present at the end of the experiment, and there was no significant effect of all three factors. LC-MS demonstrated that CI was mainly degraded synergistically by ·OH and ACs, and ·OH effectively reduced the biotoxicity of the SWE, so the mixed electrolyte may be more suitable for the electrochemical recycling system of ACs. This paper conducted the washing remediation study of CI-contaminated soil for the first time, and applied the theory of selective oxidation by ACs on benzene ring to treat the SWE, which provides a new treatment idea for antibiotic-contaminated soil.

Distribution and risk assessment of antibiotics under water level fluctuation in the riparian zone of the Hanjiang River

The riparian zone (RZ) is an important region connecting surface water and groundwater, and it has widely been acknowledged for its pollutant buffering capacity. However, the decontaminating effect of RZ on trace organic compounds such as antibiotics has received little attention. This study explored the distribution of 21 antibiotics and 4 sulfonamide metabolites in river water and groundwater in the lower reaches of the Hanjiang River. The diffusion and exchange of contaminants between the river and riverbanks under the influence of water conservancy projects (Xinglong Dam and the Yangtze-Hanjiang Water Diversion Project) were investigated. Macrolide antibiotics were prevalent in river water (62.5-100%) and groundwater samples (42.9-80.4%). Ofloxacin and chlortetracycline were detected with the highest concentrations in river water (12.2 ng L^-1) and groundwater (9.3 ng L^-1) respectively. Higher levels of antibiotics were observed in spring and winter than in other seasons. The river-groundwater interaction has a certain interception effect on antibiotics, especially near riverbanks. Redox sensitive element Fe²⁺ showed significantly positive correlations with some tetracycline and macrolide antibiotics (p < 0.05), and thus the migration mechanism between Fe²⁺ and antibiotics under the condition of redox change should be investigated further. Environmental risks posed by antibiotics were assessed for algae, daphnids, and fish in surface water and groundwater. Only clarithromycin and chlortetracycline presented a medium risk to algae (0.1 < RQ < 1), and the rest presented low risk (RQ < 0.1). Nevertheless, the risk range may be further extended by interactions between groundwater and surface water. Accurate understanding of antibiotic transport in RZ is critical for developing management strategies aimed at reducing the pollution load on the watershed.

Synergistic effect between Ce-doped SnO2 and bio-carbon for electrocatalytic degradation of tetracycline: Experiment, CFD, and DFT

Carbon-based sandwich-like electrocatalyst with a hierarchical structure, carbon sheet (CS)-loaded Ce-doped SnO₂ nanoparticles, were successfully prepared using a simple method, which presented a high-efficiency electrocatalytic performance for tetracycline decomposition. Among them, Sn_0.75Ce_0.25O_y/CS exhibits superior catalytic activity, such as more than 95% of tetracycline was removed (120 min), and over 90% of total organic carbon was mineralized (480 min). It is found from morphology observation and computational fluid dynamics simulation that the layered structure is conducive to improving the mass transfer efficiency. Through X-Ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectrum, and density functional theory calculation analyze that the structural defect in Sn_0.75Ce_0.25O_y caused by Ce doping is considered to play the key role. Moreover, electrochemical measurements and degradation experiments further prove that the outstanding catalytic performance is attributable to the initiated synergistic effect established between CS and Sn_0.75Ce_0.25O_y. These results explain the effectiveness of Sn_0.75Ce_0.25O_y/CS for the remediation of tetracycline-contaminated water and mitigating the potential risks and imply that the Sn_0.75Ce_0.25O_y/CS composite has a deeply practical value in tetracycline wastewater degradation and a promise for further application.

Effect of photocatalysis on the physicochemical properties of liquid digestate

Antibiotic residues pose a risk to the agricultural application of liquid digestate. In our previous study, photocatalysis was employed to degrade the antibiotics in liquid digestate and observed that the removal efficiency of TC, OTC, and CTC was up to 94.99%, 88.92%, and 95.52%, respectively, at the optimal experimental level, demonstrating the feasibility of this technology. In this study, the liquid digestate after photocatalysis was analyzed to evaluate the effect of photocatalysis on the nutrients, phytotoxicity, and bacterial community of liquid digestate. The results showed that photocatalysis had little effect on the major nutrients TN, TP, and TK in liquid digestate. However, photocatalysis could cause an increase in tryptophan substances as well as soluble microbial by-products and a decrease in humic acid substances in the liquid digestate. The toxicity of liquid digestate after photocatalysis exhibited an increasing trend followed by a decreasing trend, and the liquid digestate after photocatalysis for 2 h had a promoting effect on seed germination and root growth. The richness, diversity, and evenness of bacterial communities in liquid digestate were decreased as a result of photocatalysis. The dominant species in the liquid digestate was dramatically changed by photocatalysis, and the antibiotic concentration also had a major effect on the dominant species in the liquid digestate after photocatalysis. After photocatalysis for 2 h, the dominant species in the liquid digestate changed from Firmicutes to Proteobacteria.

Assessing the bioavailability of antibiotics in soil with the diffusive gradients in thin films (DGT)

The diffusive gradients in thin films (DGT) technique is an excellent method for investigating the dynamic processes of antibiotics in soils. However, whether it is applicable in antibiotic bioavailability assessment is yet to be disclosed. This study employed DGT to determine the antibiotic bioavailability in soil, and compared the results with plant uptake, soil solutions, and solvent extraction methods. DGT exhibited predictive capability for plant taking in antibiotics proved by the significant linear relationship between the DGT based concentration (C_DGT) and antibiotic concentration in roots and shoots. Although the performance of soil solution was acceptable based on linear relationship analysis, its stability was weaker than DGT. The results based on plant uptake and DGT indicated the bioavailable antibiotic contents in different soils were inconsistent because of the distinct mobility and resupply of sulphonamides and trimethoprim in different soils, as represented by K_d and R_ds, which were affected by soil properties. Plant species played an important role in antibiotic uptake and translocation. Antibiotic uptake by plants depends on antibiotic, plant and soil. These results confirmed the capability of DGT in determining antibiotic bioavailability for the first time. This work provided a simple and powerful tool for environmental risk evaluation of antibiotics in soils.

A comprehensive review on quinolone contamination in environments: current research progress

Quinolone (QN) antibiotics are a kind of broad-spectrum antibiotics commonly used in the treatment of human and animal diseases. They have the characteristics of strong antibacterial activity, stable metabolism, low production cost, and no cross-resistance with other antibacterial drugs. They are widely used in the world. QN antibiotics cannot be completely digested and absorbed in organisms and are often excreted in urine and feces in the form of original drugs or metabolites, which are widely occurring in surface water, groundwater, aquaculture wastewater, sewage treatment plants, sediments, and soil environment, thus causing environmental pollution. In this paper, the pollution status, biological toxicity, and removal methods of QN antibiotics at home and abroad were reviewed. Literature data showed that QNs and its metabolites had serious ecotoxicity. Meanwhile, the spread of drug resistance induced by continuous emission of QNs should not be ignored. In addition, adsorption, chemical oxidation, photocatalysis, and microbial removal of QNs are often affected by a variety of experimental conditions, and the removal is not complete, so it is necessary to combine a variety of processes to efficiently remove QNs in the future.