Field study on loss of tetracycline antibiotics from manure-applied soil and their risk assessment in regional water environment of Guangzhou, China

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.

Polarity and fluorescent fractions of manure dissolved organic matter could affect differently the adsorption and desorption of antibiotics in soils

The impacts of manure dissolved organic matter (DOM) on the adsorption and desorption of veterinary antibiotics in soils have not been fully explored. In this study, the effects of pig manure (PM) DOM and its hydrophilic and hydrophobic fractions on antibiotic adsorption and subsequent desorption in three topsoils of bamboo stands under different fertilization conditions (control, with heavy manure application, and with heavy manure application suspended) were examined by batch experiments, with the aid of excitation-emission matrix fluorescence spectroscopy, Fourier transformed infrared spectroscopy, and X-ray photoelectron spectroscopy. The addition of 100 mg-C L-1 PM DOM was found to increase the adsorption (in terms of the Freundlich affinity coefficient (Kf)) of florfenicol by 71.27%-132.23% but decrease the adsorption of doxycycline, enrofloxacin, and sulfamethazine by 41.67%-94.78%, 98.09%-99.99%, and 22.93%-67.20%, respectively. These effects resulted mainly from the increases in solution pH by PM DOM addition and preferential adsorption of PM DOM's protein-like fraction to the soils. Effects of hydrophilic and hydrophobic fractions of PM DOM were antibiotic and soil specific, except the increases in adsorption Kf of florfenicol in all tested soils. Among the four antibiotics, sulfamethazine exhibited the lowest Kf values in the soils with PM DOM addition during both the adsorption and desorption processes, implying that sulfamethazine may be the most leachable antibiotic in the field. The results of this study indicate that it is essential to consider the varying effects of the aromaticity and hydrophobicity of manure DOM in assessing the leaching risk of veterinary antibiotics in manured soils.

Plot-scale observation on antibiotics migration in surface runoff and leachate from chicken-raising orchard of Entisol during rainstorms

Field investigation on manure-sourced veterinary antibiotics migrating via runoff processes under natural rainfalls is quite limited due to hydrological complexity. The impact of manure application on antibiotics migration in soil is also scarcely discussed at the plotscale. This study examined the dynamic changes of concentration and mass flux of eight antibiotics migrating from chicken-raising orchards during rainstorms. Results showed instantaneous presence of antibiotics in the flow samples collected upon generation of surface runoff and leachate. Their concentrations responded strongly towards the flow rate, with concentration peaks mostly overlapping with flow peaks. Chicken-raising treatment resulted in significantly higher runoff generation than orchard without chickens. The total mass flux of antibiotics reached up to 5.46 and 9.41 μg/(m2·h) for surface runoff and leachate respectively, with sulfonamides (SAs) showing the highest migration (0.02-4.52 μg/(m2·h)) and tetracyclines (TCs) and quinolones (QLs) the lowest (10-4-10-1 μg/(m2·h)). Leaching performed as an important pathway for contaminant migration in the studied soil, with mass fluxes 1.5-11 times higher than those of surface runoff, and manure-derived colloids accelerated antibiotics leaching. pH, colloid concentration and instantaneous rainfall intensity were the primary influencing factors, all displaying positive correlations with antibiotics migration (p < 0.05). This study implied that raising chickens in orchard poses a risk of antibiotic contamination to surrounding ecosystem. It also highlighted the importance of exploring soil hydrological process in assessing their migration, particularly the previously underestimated contribution of subsurface flow via leaching.

Tetracycline induces wsp operon expression to promote biofilm formation in Pseudomonas putida

The overuse and wanton discharge of antibiotics produces a threat to bacteria in the environment, which, in turn, stimulates the more rapid emergence of antibiotic-resistant bacteria. Pseudomonas putida actively forms biofilms to protect the population under tetracycline stress, but the molecular mechanism remains unclear. This study found that tetracycline at sub-minimal inhibitory concentrations increased cyclic diguanylate (c-di-GMP), a second messenger that positively regulates biofilm formation. Four c-di-GMP-metabolizing proteins were found to be involved in the tetracycline-mediated biofilm promotion, including DibA, WspR, PP_3242, and PP_3319. Among them, the diguanylate cyclase WspR displayed the most significant effect on c-di-GMP level and biofilm formation. WspR belongs to the wsp operon comprising seven genes (wspA-wspF and wspR). The wsp operon contained six promoters, including one major start promoter (PwspA) and five internal promoters (PwspB, PwspC, PwspD, PwspF, and PwspR), and tetracycline promoted the activity of PwspA. The stress-response sigma factor RpoS directly bound to PwspA and positively regulated its activity under tetracycline stress. Moreover, RpoS was required for tetracycline to induce PwspA activity and promote biofilm formation. Our results enrich the transcriptional regulation of the wsp operon and reveal the mechanism by which tetracycline promotes biofilm formation in P. putida.IMPORTANCEThe overuse and wanton discharge of antibiotics produces a threat to bacteria in the environment, which, in turn, stimulates the more rapid emergence of antibiotic-resistant bacteria. The Pseudomonas putida actively forms biofilm against antibiotic threats, but the mechanism remains unclear. Here, our results showed that tetracycline treatment at sub-minimal inhibitory concentrations could induce the expression of the Wsp system via the sigma factor RpoS in P. putida, resulting in elevated c-di-GMP levels, which leads to increased biofilm formation. The wsp operon contains one major promoter and five internal promoters, and RpoS directly binds to the major promoter to promote its activity.

Sorption of tetracycline antibiotics by microplastics, associated mechanisms, and risk assessments

In this study, we selected polyvinyl chloride (PVC), polyethylene (PE), and polystyrene (PS) as representative microplastics (MPs) to systematically investigate the sorption behavior of tetracycline (TC) antibiotics by MPs. Scanning electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, and adsorption experiments were applied to assess the sorption behavior of MPs. The results demonstrated that the sorption of TC by MPs was most favorable under neutral conditions, where a modest increase in the salt ion concentration enhanced the adsorption of TC by MPs. The saturation adsorption capacities for PVC, PE, and PS for TC were determined as 121.95 μg/g, 81.301 μg/g, and 178.57 μg/g, respectively. The strength of TC sorption by MPs followed the order of: PS > PVC > PE. Analysis of the sorption behavior of TC by MPs showed that the adsorption of TC by PE was weak and it readily desorbed, and thus their interaction will not lead to excessive compound pollution. By contrast, the adsorption of TC was high by PVC and PS, and they were not readily desorbed.

Combined pollution of tetracyclines and microplastics in the aquatic environment: Insights into the occurrence, interaction mechanisms and effects

Tetracyclines, a widely used class of antibiotics, and synthetic plastic products are both prevalent in the environment. When released into water bodies, these pollutants can pose significant risks due to their daily influx into aquatic ecosystems. Microplastics can adsorb tetracyclines, acting as a transport vector that enhances their impact on aquatic species. Understanding the co-exposure effects of microplastics and tetracyclines is crucial. This review comprehensively examines the occurrence and distribution of microplastics and tetracyclines across various environmental contexts. The interactions between these two contaminants are primarily driven by electrostatic interactions, hydrophobic effects, hydrogen bonding, π-π interactions, and others. Factors such as the presence of heavy metals, ions, and dissolved organic matter can influence the adsorption and desorption of tetracyclines onto microplastics. The stability of microplastic-tetracycline complexes is highly dependent on pH conditions. The combined pollution tetracyclines and microplastics leads to negative impacts on marine species. Future research should focus on understanding the adsorption behavior of tetracyclines on microplastics and developing effective treatment techniques for these contaminants in aquatic environments.

Spatiotemporal variations and priority ranking of emerging contaminants in nanwan reservoir: A case study from the agricultural region in huaihe river basin in China

The presence of emerging contaminants (ECs) in drinking water sources is an increasing concern, yet limited data exists on their occurrence and risk in the upper Huaihe River Basin, an important agricultural region in Central China. This study investigated 70 ECs, including pesticide and antibiotics in surface water from drinking water source areas in Nanwan Reservoir along the upper reaches of the Huaihe River Basin to prioritize the ECs based on ecological risk and health risk assessment. A total of 66 ECs were detected in the surface water at least once at the selected 38 sampling sites, with concentrations ranging from 0.04 to 2508 ng/L. Ecological risk assessment using the risk quotient (RQ) method revealed high risks (RQ > 1) from 7 ECs in the dry season and 15 ECs in the wet season, with triazine pesticides as the main contributors. Non-carcinogenic risks were below negligible levels, but carcinogenic risks from neonicotinoid and carbamate pesticides and macrolide antibiotics were concerning for teenagers. Ciprofloxacin exhibited a high level of resistance risk during the wet season. A multi-indicator prioritization approach integrating occurrence, risk, and chemical property data ranked 6 pesticides and 3 antibiotics as priority pollutants. The results highlight EC contamination of drinking water sources in this agriculturally-intensive region and the need for targeted monitoring and management to protect water quality.

Integrated assessment of the spatial distribution, sources, degradation, and human risk of tetracyclines in honey in China

Tetracyclines are widely used in Chinese apiculture. However, limited information is available on the presence of tetracycline residues in honey and the sources, degradation patterns, and associated health risks of these compounds. In this study, the presence of tetracyclines in honey samples across China was investigated over a four-year period. Additionally, the risks of dietary intake, as well as the sources and degradation patterns of tetracyclines in honey, were assessed. The three-dimensional spatial distributions (floral region, geographical region and entomological origin) of tetracyclines contamination varied significantly. Tetracycline residues in honey posed a moderate risk to children aged 3-10 years in Northwest China. Source analysis indicated that colony migration serves as the primary source of tetracyclines in honey. Based on the degradation patterns of tetracyclines in honey within colonies and during storage, oxytetracycline is more readily degraded than other tetracyclines. The main degradation products of tetracyclines are epimers and dehydration products, and the effects of these products on human health and the environment should be further evaluated in future studies. This comprehensive investigation provides valuable insights into the safe use and regulation of tetracyclines in Chinese apiculture.

Biochar reduces antibiotic transport by altering soil hydrology and enhancing antibiotic sorption

The performance of biochar (BC) in reducing the transport of antibiotics under field conditions has not been sufficiently explored. In repacked sloping boxes of a calcareous soil, the effects of different BC treatments on the discharge of three relatively weakly sorbing antibiotics (sulfadiazine, sulfamethazine, and florfenicol) via runoff and drainage were monitored for three natural rain events. Surface application of 1 % BC (1 %BC-SA) led to the most effective reduction in runoff discharge of the two sulfonamide antibiotics, which can be partly ascribed to the enhanced water infiltration. The construction of 5 % BC amended permeable reactive wall (5 %BC-PRW) at the lower end of soil box was more effective than the 1 %BC-SA treatment in reducing the leaching of the most weakly sorbing antibiotic (florfenicol), which can be mainly ascribed to the much higher plant available and drainable water contents in the 5 %BC-PRW soil than in the unamended soil. The results of this study highlight the importance of BC's ability to regulate flow pattern by modifying soil hydraulic properties, which can make a significant contribution to the achieved reduction in the transport of antibiotics offsite or to groundwater.

Oxytetracycline Increases the Residual Risk of Imidacloprid in Radish (Raphanus sativus) and Disturbs the Plant-Rhizosphere Microbiome Holobiont Homeostasis

Antibiotics can be accidentally introduced into farmland by wastewater irrigation, and the environmental effects are still unclear. In this study, the effects of oxytetracycline on the residue of imidacloprid in soil and radishes were investigated. Besides, the rhizosphere microbiome and radish metabolome were analyzed. It showed that the persistence of imidacloprid in soil was unchanged, but the content of olefin-imidacloprid was increased by oxytetracycline. The residue of imidacloprid in radishes was increased by nearly 1.5 times, and the hazard index of imidacloprid was significantly raised by 1.5-4 times. Oxytetracycline remodeled the rhizosphere microbiome, including Actinobe, Elusimic, and Firmicutes, and influenced the metabolome of radishes. Especially, some amino acid metabolic pathways in radish were downregulated, which might be involved in imidacloprid degradation. It can be assumed that oxytetracycline increased the imidacloprid residue in radish through disturbing the plant-rhizosphere microbiome holobiont and, thus, increased the pesticide dietary risk.

Nutrient condition modulates the antibiotic tolerance of Pseudomonas aeruginosa

The variation in nutrient content across diverse environments has a significant impact on the survival and metabolism of microorganisms. In this study, we examined the influence of nutrients on the antibiotic tolerance of the PAO1 strain of Pseudomonas aeruginosa. Our findings indicate that under nutrient-rich conditions, this strain exhibited relatively high tolerance to ceftazidime, chloramphenicol, and tetracycline, but not aminoglycosides and fluoroquinolones. Transcriptome analysis revealed that genes associated with antibiotic tolerance were expressed more efficiently in nutrient-rich media, including ribosomal protein genes and multidrug efflux pump genes, which conferred higher tetracycline tolerance to the strain. Furthermore, the genes responsible for translation, biosynthesis, and oxidative phosphorylation were suppressed when nutrients were limited, resulting in decreased metabolic activity and lower sensitivity to ciprofloxacin. Artificial interference with ATP synthesis utilizing arsenate confirmed that the curtailment of energy provision bolstered the observed tolerance to ciprofloxacin. In general, our results indicate that this strain of P. aeruginosa tends to activate its intrinsic resistance mechanisms in nutrient-rich environments, thereby enhancing resistance to certain antibiotics. Conversely, in nutrient-limited environments, the strain is more likely to enter a dormant state, which enables it to tolerate antibiotics to which it would otherwise be sensitive. These findings further suggest that antibiotics released in environments with varying eutrophication levels may have divergent effects on the development of bacterial antibiotic resistance.

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.

3D variable Co species carbon foam enhanced reactive oxygen species generation and ensured long-term stability for water purification

Cobalt (Co) and oxides are the most common catalysts for activating peroxymonosulfate (PMS). However, practical applications of Co-based PMS-advanced oxidation processes are difficult to realize the degradation of the targeted pollutants due to poor yield of reactive oxygen species (ROS) and inaccessible active sites. Here, we designed 3D oxygen vacancy-rich (V_o-rich) variable Co species@carbon foam (Co_xO_y@CF) via coupling solvent-free and pyrolysis strategies for degrading tetracycline by PMS activation. The kinetic rate of optimized (Co@CoO) Co_xO_y@CF-1.0 (1.0 presented the molar ratio of Co²⁺ and 2-methylimidazole) enhanced by an order of magnitude compared to that of ZIFs derivatives (ZIFs-500) (0.073 vs 0.155 min^-1) due to the special structure. The flow-through unit maintained over 90% removal within 12 h, which was far better than that of ZIFs-500/PMS system. We used electrochemical analysis, quenching experiment, in-situ FTIR and Raman spectra to further investigate the possible mechanism of the 3D Co_xO_y@CF-1.0/PMS system. 3D Co_xO_y@CF-1.0 stimulated the production of the metastable catalyst-PMS* complex obtained O₂^- as intermediates accompanied by the redox cycling of Co²⁺/Co³⁺, which created the dominant ROS (more ¹O₂) in the presence of V_o, which was completely different for ZIFs-500/PMS with coordinated and dominant radical and non-radical pathways. This study could large-scale generate variable cobalt-based catalysts for enhanced ROS generation, leading the new insight for boosting practical applications.

Energy transfer mediated rapid and visual discrimination of tetracyclines and quercetin in food by using N, Cu Co-doped carbon dots

The appearance of multi-drug resistant Escherichia coli makes the combination of tetracyclines (TCs) and quercetin (QCT) more common to fight stubborn bacterial infections so that the effective detections of TCs and QCT are essential and necessary. Here, a novel fluorescence probe for differentiating TCs and QCT is developed based on the nitrogen and copper co-doped carbon dots (N, Cu-CDs). The N, Cu-CDs are prepared from ethylene diamine tetraacetic acid (EDTA) and anhydrous copper chloride as precursors through hydrothermal process and exhibit bright blue fluorescence with excellent optical stability. With the presence of four tetracyclines (DOX, TC, CTC and OTC), the fluorescence intensity of N, Cu-CDs is quenched directly due to the internal filtration effect (IFE), and the detection limit obtained through single-signal fluorescence sensing is as low as 23.8 nM for DOX, 37.2 nM for TC, 43.8 nM for OTC and 28.8 nM for CTC. More remarkably, three dimensional ratiometric fluorescence probe for detecting QCT is proposed based on the appearance of another emission at (410 nm, 490 nm) due to electron transform (ET) process. This new method shows a good linear relationship in the range of 10-100 μM with a low detection limit of 59.3 nM. Furthermore, a dual-channel fluorescence sensing platform based on microfluidics paper-based analytical devices (μPADs) is developed for simultaneously visual discrimination of TCs (DOX is chosen as the typical detecting model for TCs) and QCT. This investigation provides a new way for the development of CDs as multifunction fluorescence probes.

Temporal trends in risk of bisphenol A, benzophenone-3 and triclosan exposure among U.S. children and adolescents aged 6-19 years: Findings from the National Health and Nutrition Examination Survey 2005-2016

BACKGROUND

Phenolic compounds with potential adverse health effects are gradually being replaced. Little is known about the potential health risks of BPA, BP3, and TCS exposure in children and adolescents aged 6-19 years in the United States.

OBJECTIVES

To determine trends and rates of change in hazard indices (HI) for three phenolics in U.S. children and adolescents for BPA, BP3, TCS, and to assess changes in gender, race/ethnicity, age, and potential health risks.

METHODS

Metabolic biomonitoring data from field-collected urine samples from the National Health and Nutrition Examination Survey (NHANES) were utilized. Daily intake of three phenols (bisphenol A, benzophenone-3, and triclosan) between 2005 and 2016 in children and adolescents were obtained. Cumulative risk indicators, including hazard quotient (HQ), hazard index (HI), and maximum cumulative ratio (MCR), were used for the health risk assessment of the three phenols.

RESULTS

During this period, the change in LSGM HI was -2.9% per cycle [95% Cl: (-3.7%, -2.2%)], and the percentage of participants with HI > 0.1 decreased from 15.6% to 10.5%. Children (6-11 years) had higher mean HI values than adolescents (12-19 years), while female had higher LSGM HI values than male. MCR values were generally low and negatively correlated with HI. However, the average value of MCR increased from 1.722 to 2.107 during this period.

CONCLUSION

Exposure to phenolics among U.S. children and adolescents has changed in recent decades. However, gaps in data limit the interpretation of trends but legislative activity and advocacy campaigns by nongovernmental organizations may play a role in changing trends. Moreover, there are growing concerns about the potential health risks associated with exposure to multiple phenols in children and adolescents.

Influence of pyrolysis atmosphere and temperature co-regulation on the sorption of tetracycline onto biochar: structure-performance relationship variation

Presently, as the prevalent pyrolysis atmospheres, N₂ is widely used, while air-limitation and CO₂ are rarely considered, to produce biochar to adsorb tetracycline. This study thus used N₂, CO₂, and air-limitation to produce various biochars at 300 ∼ 750 °C, and explored their structure-performance relationship for tetracycline sorption. The maximum sorption capacities of biochars produced in CO₂ and air-limitation were 55.36 mg/g and 71.11 mg/g (at 750 °C), respectively, being 2.34 and 3.01 times that of biochars produced in N₂ (23.60 mg/g at 750 °C). Interestingly, except for high pore volume and specific surface area supported pore filling and sites providing effect, ash (containing metal cations, P-O, and S=O) induced complexing effect was the primary mechanism for tetracycline sorption, rather than hydrophobic effect, π-π interaction, and hydrogen bond caused by C composition. This study provides important information about adjusting the pyrolysis atmosphere to improve the sorption performance of biochar toward tetracycline.