Chlortetracycline Research Articles

Sequential removal of human antibiotics as a function of the dynamic of organic matter fractions and 3D fluorescence during sludge composting

This study investigated the fate of antibiotics during composting and its relationship with organic matter fractionation. Sludge was spiked with roxithromycin (ROX), chlortetracycline (CTC), oxytetracycline (OTC), and ciprofloxacin (CIP), at 3 different levels. Accelerated solvent extraction (ASE) and liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) were used for the extraction and the quantification of antibiotics. Sludge composting effectively removed parent compounds (p < 0.01) such as ROX, CTC, and OTC (52–87, 69–95 %, and 100 % respectively), while CIP persisted in the final compost (p > 0.05). The thermophilic stage was responsible for ROX removal, and the maturation stage was more implicated in removing CTC and OTC. Chemical accessibility and 3D fluorescence showed that high level of antibiotics affected the behavior of organic fractions. ROX removal was more associated with decreasing the most accessible fractions. The removals of CTC and OTC was more associated with the depletion of the complex organic matter. The observed results were confirmed by PCA and dendrograms analysis that confirmed the relationship between antibiotics removal and the evolution of organic pools. On the other hand, germination test indicated that cress and turnip were more sensitive to high antibiotic concentration. These results have been explored for the first time and they are recommended for controlling antibiotic removal based on organic matter fractionation.

The impact mechanism of chlortetracycline on different stages of anaerobic fermentation of organic wastes

Chlortetracycline (CTC) is widely used in animal husbandry, which is directly discharged into the environment through feces due to incomplete absorption by animals, resulting in the continuous accumulation of chlortetracycline in the soil and water environment. In order to explore the effect of CTC addition on the microbial population and richness during the three stages of the anaerobic fermentation (AF), firstly, the samples of control group (CK), hydrolysis + CTC (HC)，acidification + CTC (AC) and methanogenesis + CTC (MC) group were set, respectively. Then, the 100 mL of 4.0 g/L CTC solution was added into the AF reactor of the HC, AC and MC on the 8th, 16th and 24th day and sampled with high-throughput sequencing analysis of microbial flora. The results showed that no matter the CTC added in any fermentation stages, it would have impacts on the microbial activity, cumulative gas production, cellulose crystal structure and functional group absorption peak intensity during the AF. In particular, it had a significant inhibitory effect on the biological activities of the SBR1031, Hydrogenispora and Ruminiclostridium_1 in the acidification stage and the Anaerolinea in the methanogenesis stage, which showed that CTC mainly inhibited the growth and reproduction of microorganisms in the acidification stage to inhibit the subsequent advancement of the entire fermentation. Consequently, the CTC addition had a significant inhibitory effect on microorganisms in different stages, which illustrated the pretreatment of organic waste contained CTC was necessity before the AF treatment.

Effect of Acid–Base Modified Biochar on Chlortetracycline Adsorption by Purple Soil

We used three purple soil (Hechuan, Jialing, and Cangxi) samples from the Jialing River basin as the research objects and added different proportions of an acid–base modified Alternanthera philoxeroides biochar (Cm) to the purple soil to study the effect of Cm on the adsorption of chlortetracycline (CTC) in the purple soil. The results indicated the following: (1) At 30 °C and pH = 6, the soil adsorption capacity increased with an increasing initial concentration of CTC. The maximum adsorption amount of CTC for each tested sample was in the range of 2054.63–3631.21 mg/kg, and the adsorption capacity in different Cm amended soils was ranked in the order of 10% Cm &gt; 5% Cm &gt; 2% Cm &gt; CK. The adsorption capacity of CTC increased with an increase in the proportion of Cm. Furthermore, under the same addition ratio of Cm, Hechuan soil was found to have a better adsorption effect for CTC than Jialing and Cangxi soil. (2) The Langmuir model was the most suitable for fitting the adsorption behavior of CTC on different purple soils, and the fitting coefficients were all greater than 0.9, indicating that the adsorption of CTC on each soil sample occurred via monolayer adsorption. The thermodynamic experiment results showed that an increase in temperature was beneficial to the process of CTC adsorption, which was a spontaneous, endothermic, and entropy-adding process. (3) At pH = 6, the ionic strength ranged from 0.01 to 0.5 mol/L and the adsorption capacity of CTC of the soil samples decreased with an increase in ionic strength. In the range of pH 2–10, the adsorption capacity of CTC in all the soil samples decreased with an increase in pH. The inhibition capacity of CTC in the soil samples under acidic conditions was notably higher than that under alkaline conditions.

Selenization governs the intrinsic activity of copper-cobalt complexes for enhanced non-radical Fenton-like oxidation toward organic contaminants

Non-radical oxidation pathways in the Fenton-like process have a superior catalytic activity for the selective degradation of organic contaminants under complicated water matrices. Whereas the synthesis of high-performance catalysts and research on reaction mechanisms are unsatisfactory. Herein, it was the first report on copper-cobalt selenide (CuCoSe) that was well-prepared to activate hydrogen peroxide (H2O2) for non-radical species generation. The optimized CuCoSe+H2O2 system achieved excellent removal of chlortetracycline (CTC) in 10 min at neutral pH along with pleasing reusability and stability. Moreover, it exhibited great anti-interference capacity to inorganic anions and natural organic matters even in actual applications. Multi-surveys verified that singlet oxygen (1O2) was the dominant active species in this reaction and electron transfer on the surface-bound of CuCoSe and H2O2 likewise played an important role in direct CTC oxidation. Where the synergetic metals of Cu and Co accounted for the active sites, and the introduced Se atoms accelerated the circulation efficiency of Co3+/Co2+, Cu2+/Cu+ and Cu2+/Co2+. Simultaneously, the produced Se/O vacancies further facilitated electron mediation to enhance non-radical behaviors. With the aid of intermediate identification and theoretical calculation, the degradation pathways of CTC were proposed. And the predicted ecotoxicity indicated a decrease in underlying environmental risk.

Enhanced chlortetracycline removal by iron oxide modified spent coffee grounds biochar and persulfate system

Chlortetracycline (CTC) is a tetracycline derivative antibiotic that has been widely used in the livestock industry for prophylactic and therapeutic purposes. Effective measures should be taken to decrease the environmental risks associated with CTC-rich waste. Biochar produced by biomass waste showed great potential for organic contaminants removal by adsorption and catalytic degradation. This study prepared iron oxide-modified coffee grounds biochar (CGF) at different temperatures for enhanced CTC removal by adsorption and degradation. The main mechanism for CTC removal was found to be electrostatic interaction. In addition, pore diffusion, hydrogen bonds, and π-π bonds also contributed to CTC adsorption. Maximum CTC adsorption capacity was 223.63 mg/g for CGF800 (CGF prepared at 800 °C pyrolysis). The free radical content of CGF600 (CFG prepared at 600 °C pyrolysis) was higher than CGF800, and there were no significant advantages in using biochar prepared at a higher temperature for persulfate activation. The ion mass-to-charge ratio (M/z) is used to describe the ratio of mass to charge of an ion or peak, which can infer compound structure. The structure of CTC degradation products was analyzed by UPLC-MS, and the M/z values were determined as 444, 273, and 154. Thus, pyrolysis of coffee grounds at higher temperatures increased CTC adsorption capacity, and CGF can indirectly assist in CTC degradation by persulfate activation.

Biodegradation of chlortetracycline by Bacillus cereus LZ01: Performance, degradative pathway and possible genes involved

Microbial degradation of chlortetracycline (CTC) is an effective bioremediation method. In the present study, an enrichment technique was used to isolate a Bacillus cereus LZ01 strain capable of effectively degrading CTC from cattle manure. Response surface methodology was used to identify optimized conditions under which strain LZ01 was able to achieve maximal CTC removal (83.58%): temperature of 35.77 °C, solution pH of 7.59, CTC concentration of 57.72 mg/L and microbial inoculum of 0.98%. The antibacterial effect of CTC degradation products on Escherichia coli was investigated by the disk diffusion test, revealing that the products by LZ01 degradation of CTC exhibited lower toxicity than parent compound. Shake flask batch experiments showed that the biodegradation of CTC was a synergistic effect of intracellular and extracellular enzymes, and intracellular enzyme had a better degradation effect on CTC (77.56%). Whole genome sequencing revealed that genes associated with ring-opening hydrolysis, demethylation, deamination and dehydrogenation in strain LZ01 may be involved in the biodegradation of CTC. Subsequent seven possible biodegradation products were identified by LC-MS analyses, and the biodegradation pathways were proposed. Overall, this study provides a theoretical foundation for the characterization and mechanism of CTC degradation in the environment by Bacillus cereus LZ01.

A luminescent Eu3+-functionalized MOF for sensitive and rapid detection of tetracycline antibiotics in swine wastewater and pig kidney

Tetracyclines (TCs), a type of antibiotics, are widely used in human therapy and animal husbandry. Public concerns about tetracyclines residues have been raised due to their negative impact on the environment and food, causing bacterias drug resistance and human health concerns. In this work, a luminescent europium MOF (EuUCBA) is constructed via post-synthetic attachment of Eu3+ into a UiO-66 type MOF. The luminescent of EuUCBA exhibits high stability in aqueous media in the pH range of 4–11. Among 36 common veterinary drugs, the synthesized probe is highly selective and sensitive to six tetracyclines with low detection limits of 0.118 μM, 0.228 μM, 0.102 μM, 0.138 μM, 0.206 μM, and 0.078 μM for oxytetracycline (OTC), chlortetracycline (CTC), methylenetetracycline (MTC), minocycline (MOC), tetracycline (TC), and doxycycline (DOXY), respectively. Furthermore, the probe shows good anti-interference ability and fast response. Finally, EuUCBA was successfully to detect DOXY in swine wastewater and pig kidney with good recoveries. This work provides an excellent fluorescent sensor for highly selective and rapid detection of TCs residues in wastewater and complex biological samples.

Enhanced visible-light photocatalytic performance of ZIF-8-derived ZnO/TiO2 nano-burst-tube by solvothermal system adjustment

A novel strategy for the preparation of heterojunction derivants by regulating the loading of precursors was proposed and applied for the first time to effectively remove dyes and antibiotics. Zeolite imidazole framework-8 (ZIF-8)-derived ZnO/TiO2 nano-burst-tube (NBT) was prepared by calcination of ZIF-8 as precursor grown in a solvothermal system adjusted by NH4OH or NaOH, TiO2 NBT as solvothermal substrate. Through a reasonable selection of solvothermal system, ZIF-8-derived ZnO/TiO2 NBT not only provides enhanced specific surface area (1012.3 m2/g), but also enhances the visible light response and charge separation of TiO2 NBT, whose instantaneous photocurrent density is up to 53 mA cm−2, which is three times that of TiO2 NBT. Under visible light irradiation, ZnO/TiO2 NBT achieved rapid degradation of Rhodamine B(RhB), tetracycline hydrochloride (TCH) and chlortetracycline hydrochloride (CTC) with complete removal within 20 min, outperforming ZnO, ZIF-8, TiO2 NBT and ZIF-8/TiO2 NBT, with excellent cyclic photocatalytic performance. The results show that the degradation pathways of RhB, TCH and CTC are different. The work provides a promising strategy for multifunctional derivative photocatalytic materials preparation.

Adsorption of chlortetracycline in aquaculture wastewater by lanthanum modified multi-walled carbon nanotubes

The lanthanum modified multi-walled carbon nanotubes (La-CNTs) prepared by an impregnation method were investigated for the adsorption of chlortetracycline (CTC) in aquaculture wastewater. The adsorbents were characterized by SEM, EDS, XRD and BET. The effects of some factors including La-containing impregnant concentration, adsorbent dosage, CTC adsorbate concentration, adsorption time, pH of the adsorbate solution and additional ions on the CTC adsorption by La-CNTs were investigated in detail, and the optimal adsorption conditions were determined. The adsorption kinetics obeyed the quasi-second-order kinetic model. The adsorption isotherms obeyed the Langmuir model and the fitted maximum capacity of La-CNTs for CTC adsorption was 55.3 mg/g.

Facile and green synthesis of carbon nanopinnacles for the removal of chlortetracycline: Performance, mechanism and biotoxicity

In an attempt to convert environmental pollutants into wealth, a new-type carbon nanopinnacles (CNPs) has been first designed and synthesized by high-temperature carbonization of chemical pollutant RB19 for the efficient removal of chlortetracycline via a non-radical pathway. • Chemical pollutant Reactive Blue 19 was first transformed into carbon nanopinnacles. • Carbon nanopinnacle was found to be an efficient metal-free catalyst for CTC removal via a non-radical pathway. • The surface-confined electron transfer between CTC and PMS is the major contribution for CTC degradation. • Zebrafish toxicology assays verifed that the biotoxicity of degradation products was dramatically reduced. In an attempt to convert environmental pollutants into wealth, herein, we have first designed and synthesized a new-type carbon nanopinnacles (CNPs) from Reactive Blue 19 (RB19), as a common dye pollutant, for chlortetracycline removal via a non-radical pathway. The kinetic model, quenching experiments and mechanism studies have verified that singlet oxygen ( 1 O 2 ) is selectively generated from CNPs/PMS system without any radicals (e. g. SO 4 − , HO and O 2 − ), but it is only contributed to 18.0 % of total chlortetracycline (CTC) degradation. The major contribution (82.20%) for CTC degradation probably is attributed to the surface-confined electron transfer between CTC and PMS. In addition, the full-scale zebrafish toxicology assays have indicated that antibiotic chlortetracycline exerted significantly toxic effects on zebrafish, while the biotoxicity of the chlortetracycline degradation products has been dramatically reduced. This work provides an interesting dual-decontamination strategy: First, chemical pollutant RB19 is entirely transformed into carbon nanopinnacles, Second, this carbon nanopinnacles has been successfully used as an efficient metal-free catalyst for CTC removal.

Rapid Degradation of Chlortetracycline Using Hydrodynamic Cavitation with Hydrogen Peroxide.

Chlortetracycline (CTC), which has been frequently detected in surface water, is generated primarily by the discharge of high-concentration CTC wastewater from pharmaceutical and livestock plants. The development of effective CTC degradation technology is critical. In this study, the extent of CTC degradation at 80 mg/L was investigated by combining hydrodynamic cavitation (HC) and hydrogen peroxide (H2O2). The results indicate degradation ratios of 88.7% and 93.8% at 5 and 30 min, respectively. Furthermore, the possible mechanisms of CTC degradation were determined via HPLC-MS. The CTC degradation pathways include ring openings, C–N bond cleavage, demethylation, dehydroxylation, and desaturation in the sole system of HC, and a series of additional reactions, such as glycine conjugation and the cleavage of C–C double bonds, occurs in the binary system of HC + H2O2. Nevertheless, the treated water poses ecological risks and cannot be directly discharged into the environment. Therefore, HC + H2O2 treatment may be a rapid and effective primary method for the degradation of high-concentration CTC in pharmaceutical factories.

Heterostructure coal-bearing strata kaolinite/MnFe2O4 composite for activation of peroxydisulfate to efficiently degrade chlortetracycline hydrochloride

The excessive discharge of the antibiotic chlortetracycline hydrochloride (CTC·HCl) directly threatens human life and health. Different from previous studies on MnFe2O4 (MFO) combined with bulk BT or disc-shaped DE in the treatment of antibiotic wastewater, in this study, layered coal-bearing strata kaolinite (CK) was used as a carrier to prepare MnFe2O4/coal-bearing strata kaolinite (MFO/CK) catalyst, and used to evaluate the effect of activated peroxodisulfate (PDS) in the removal of CTC·HCl in wastewater under visible light. Compared with MFO and CK, the specific surface area of MnFe2O4/coal-bearing strata kaolinite-40% (MFO/CK-40%) was significantly increased, the reactive sites increased, and the PDS activation and CTC·HCl degradation were better. After 60 min of reaction under visible light, the removal rate of CTC·HCl can reach 85.1%. In addition, the influence of various factors on the degradation of CTC·HCl was investigated. It is concluded that the most effective removal of CTC·HCl occurs when there is an additional 25 mg of MFO/CK-40%, the concentration of CTC·HCl is 50 mg/L, pH= 4, and PDS is 1.5 mL. Then, through electron spin resonance and radical trapping experiments, it was determined that h+ and ·O2− were the main active species for removing CTC·HCl. The mechanism of CTC·HCl degradation by the MFO/CK-40%/PDS/Vis system was discussed. Finally, the stability and reusability of the MFO/CK-40% composite material were tested. After 3 cycles of experiments, the removal rate of CTC·HCl is still more than 70%, indicating that the MFO/CK-40% composite material has good stability and catalytic activity. Therefore, the MFO/CK catalyst can be used as a new and efficient PDS activator, which is widely used in the photocatalytic degradation of organic matter in wastewater. Data AvailabilityNot applicable.

Antibiotic Chlortetracycline Causes Transgenerational Immunosuppression via NF-κB.

The extensive and increasing global use of antibiotics results in the ubiquitous presence of antibiotics in the environment, which has made them “pseudo persistent organic contaminants.” Despite numerous studies showing wide adverse effects of antibiotics on organisms, the chronic environmental risk of their exposure is unknown, and the molecular and cellular mechanisms of antibiotic toxicity remain unclear. Here, we systematically quantified transgenerational immune disturbances after chronic parental exposure to environmental levels of a common antibiotic, chlortetracycline (CTC), using zebrafish as a model. CTC strongly reduced the antibacterial activities of fish offspring by transgenerational immunosuppression. Both innate and adaptive immunities of the offspring were suppressed, showing significant perturbation of macrophages and neutrophils, expression of immune-related genes, and other immune functions. Moreover, these CTC-induced immune effects were either prevented or alleviated by the supplementation with PDTC, an antagonist of nuclear factor-κB (NF-κB), uncovering a seminal role of NF-κB in CTC immunotoxicity. Our results provide the evidence in fish that CTC at environmentally relevant concentrations can be transmitted over multiple generations and weaken the immune defense of offspring, raising concerns on the population hazards and ecological risk of antibiotics in the natural environment.

Transformation of houttuynia cordata into a surface-loaded cobalt/biocarbon activated peroxymonosulfate for degradation of chlortetracycline

Peroxymonosulfate (PMS) has attracted great interest over the past few years owing to its great capacity and versatility for the breakdown of developing antibiotic contaminants. It is under intensive investigation for its potential for alternative advanced oxidation processes (AOPs) in wastewater treatment. In this study, we used activated cobalt-doped carbon as a new and excellent metal catalyst to activate PMS. The synthesis of novel Co3O4@C-900 hybrids with numerous active interfaces and superior surface electron transfer was achieved. Co3O4@C-900 and carbon matrix mixed evenly to create a stable catalytic structure. The Co3O4@C-900 structure equipped them with enhanced catalytic efficacy, thus decreasing environmental harm during actual Chlortetracycline (CTC) degradation. The CTC removal rate reached 100% within 10 min, exhibiting outstanding stability and high efficiency of Co3O4@C-900 hybrids. Additionally, we elucidated the PMS activation mechanism by Co3O4@C-900 via electron paramagnetic resonance (EPR) spectroscopy, radical quenching studies, and characterization analyses. Free radical quenching experiments and EPR spectroscopy revealed that the degradation of CTC by the Co3O4@C-900 PMS system was a concomitant process of free-radical and non-radical reactions. The free-radical reactions were based on the activation of PMS by Co3O4@C-900 to generate O2-, SO4- and OH, whereas the non-radical reactions were based on the activation of PMS by C to generate the active species 1O2. Therefore, this study presents Co3O4@C-900 as a promising candidate for PMS activation and also demonstrates a novel mechanism of CTC degradation.

Research Note: Effects of Bacillus coagulans X26 on the production performance, intestinal structure, short-chain fatty acids and flora composition of laying hens during the peak laying period

This study investigated the effects of Bacillus coagulans X26 on the production performance, egg quality, intestinal structure, intestinal short-chain fatty acids, and microbial diversity of laying hens during the peak laying period and explored the possibility of using B. coagulans X26 as an alternative to antibiotics. The results showed that adding 1.0 × 106 CFU/g B. coagulans X26 to the basal diet had the best effect: the average laying rate increased by 4.20% (P < 0.05), the survival rate increased by 7.15% (P < 0.05), the feed intake decreased by 3.06% (P < 0.05), the ratio of feed to egg decreased by 7.42% (P < 0.05), the rate of soft-broken eggshell decreased by 73.04% (P < 0.05), the average egg weight increased by 2.94% (P < 0.05), and the content of egg white protein increased by 5.77% (P < 0.05). The production performance and egg quality of laying hens reached the same level as that of hens fed a diet supplemented with chlortetracycline hydrochloride in this study, and there were significant advantages in the average laying rate and feed-egg ratio (P < 0.05). Both chlortetracycline hydrochloride and B. coagulans X26 altered the flora composition and the SCFA content of the intestinal contents; however, B. coagulans X26 also significantly increased the villus height of the ileum and the ratio of villus height to crypt depth (P < 0.05).

Development of organic-diffusive gradients in thin films technique for measuring freely dissolved concentrations of tetracyclines using a commercial SPE packing

The freely dissolved concentrations (FDCs) of pollutants are related to their bioavailability in the environment, and the diffusive gradients in thin films technique (DGT) can obtain the FDC of an analyte. Aiming for the detection of the FDCs of tetracyclines (TCs), we used a polyacrylamide hydrogel comprising acrylamide and acrylaide agarose cross-linker as diffusive and binding gels, and a commercial solid-phase extraction (SPE) packing, namely polymer sorbent (PLS), as an adsorption material in the binding gel for the preparation of the organic-diffusive gradients in thin films (o-DGT) devices. The results showed that the diffusion coefficients of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) in the diffusive gels were 1.08 × 10−6, 1.08 × 10−6 and 1.03 × 10−6 cm2/ s at 25 °C, respectively. The binding gel showed excellent performance with adsorption capacities of 534.88–569.42 µg/disc for TC, 527.18–565.98 µg/disc for OTC and 1320.12–1320.86 µg/disc for CTC, respectively. The uptake efficiencies were 94.21–111.12, 71.25–88.44 and 76.10–86.62% for TC, OTC and CTC, respectively, with the TCs concentration of 0.05–10 mg/L. The adsorption kinetics of TCs could be described with a pseudo-second-order model (POSM, R2 >0.97). According to the result of adsorption kinetics, the adsorption rate of TCs in the binding gel was not as fast as that of heavy metals, suggesting that the TCs concentrations at the boundary of binding gels in the o-DGT devices could not decrease to zero. After correction of the boundary concentration, the FDCs accounted for 30.30–56.90, 48.10–64.68 and 16.55–50.16% for TC, OTC and CTC, respectively, while their concentrations ranged from 0.2 to 10.0 mg/L. Our results suggested that SPE packing might be an ideal adsorption material for o-DGT binding gels, and that adsorption kinetics should be corrected when calculating the FDCs of organic pollutants.

Deciphering antibiotic resistance genes and microbial community of anammox consortia under sulfadiazine and chlortetracycline stress

The responses of anammox consortia to typical antibiotics sulfadiazine (SDZ) and chlortetracycline (CTC) were evaluated on the aspects of general performance, microbial activity, diversity and abundance of antibiotic resistance genes (ARGs), and microbial host of ARGs in anammox system. Results showed the anammox consortia had a stable performance and great resistance to 10 mg/L of SDZ, while 1 mg/L of CTC induced an unrecoverable inhibitory influence on nitrogen removal performance and anammox activity without any special treatment. The absolute abundances of anammox functional genes (nirS, hzsA and hdh) were stimulated by the acclimation to SDZ stress, however, they were much lower than the initial levels under CTC stress. In anammox consortia, ARGs comprised 18 types (94 subtypes) derived from over 20 genera. Strikingly, the anammox bacteria (AnAOB) “Ca. Brocadia” occupied 46.81% of the SDZ resistance genes (sul1 and sul2) and 38.63% of CTC resistance genes (tetX, tetG and rpsJ), and thus were identified as the dominant antibiotic resistance bacteria (ARB). Therefore, harboring the corresponding ARGs by AnAOB could be the primary protective mechanism to interpret the resistance of anammox consortia to antibiotics stress. Meanwhile, co-occurring of ARGs in anammox consortia suggested the synergistic cooperation of different ARGs could be an essential strategy to alleviate the SDZ and CTC stress. The present study proposed a new interpretation of possible mechanism that cause antibiotic resistance of anammox consortia.

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

Tetracycline antibiotics (TCs) introduced into agricultural fields via manure application tend to accumulate in soils and further reach water environments via surface runoff and leachate, posing potential risks to regional water environment. This study investigated the loss of tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) in surface runoff and leachate samples collected from a vegetable farmland with manure application in Guangzhou, South China. A risk assessment method was constructed for evaluating the ecological and health risks of manure-associated antibiotics released from soil into water environment. The results showed that the concentrations of three TCs in surface runoff, 30-cm leachate, and 60-cm leachate after the first rainfall event were 2.79–35.97, 1.71–18.44, and 0.4–2.66 μg/L, respectively, which all decreased with sampling depth and the time after rainfall events. Up to 0.13% of TCs were transported into the surface water through surface runoff, while less than 0.01% of TCs were transported into the groundwater through leachate at 60 cm. OTC had a higher total mass percentage (0.13%) into surface water via runoff than CTC (0.11%) and TC (0.07%) likely due to its smallest Kd value and largest input mass. Based on loss percentages, their predicted environmental concentrations (PEC) ranged from 4.87 (TC) to 16.91 (OTC) ng/L in regional surface water and 1.42 (TC) to 5.20 (CTC) ng/L in regional groundwater. The risk assessment based on PEC results suggested non-negligible health risk (HQ > 1.0 × 10−6) and low ecological risk (RQ < 0.1) in both regional surface water and groundwater, drawing concerns on the potential hazards of TCs released from manure-amended soil into water environments.

In-situ covalent bonding of carbon dots on two-dimensional tungsten disulfide interfaces for effective monitoring and remediation of chlortetracycline residue

• 2D WS 2 /CDs multifunctional nanomaterial was prepared by in-situ covalent bonding. • 2D WS 2 /CDs nanocomposite could be simultaneous detection and degradation of CTC. • The possible mechanisms for the detection and degradation of CTC were investigated. • This work is expected to provide a new idea for design of multifunctional platform. In view of the increasing threat of chlortetracycline (CTC) in water to human health and the ecological environment, how to detect and remove CTC in wastewater simply and effectively remains an important and challenging task. Herein, a multifunctional platform for the simultaneous detection and degradation of CTC is developed by in-situ synthesis of carbon dots (CDs) in the two-dimensional (2D) WS 2 interface by covalent bonding. The as-prepared 2D WS 2 /CDs nanocomposites can not only be used as an intelligent fluorescence probe for CTC detection with good sensitivity (LOD = 7.5 nM) and selectivity but also has good photodegradation ability for CTC (degradation efficiency attained 85.58%). Moreover, the possible mechanisms for the detection and photodegradation of CTC by 2D WS 2 /CDs were also investigated by theoretical calculations, time-resolved fluorescence decay curves, and electron spin resonance (ESR) analyses. The exceptional photoelectric properties of 2D WS 2 /CDs are ascribed to the CDs bound onto the 2D WS 2 interface by covalent bonding forming heterojunctions, which effectively promote strong interfacial interactions between CDs and 2D WS 2 , thereby providing more effective charge transfer and enhancing the detection efficiency and photocatalytic activity. In addition, the possible degradation pathway for CTC was speculated via identification of intermediates and frontier electron density calculation. Overall, this study not only proves that the 2D WS 2 /CDs nanocomposites have great potential for the simultaneous detection and degradation of CTC in aquatic environments but also provides a novel idea for the efficient and stable design of multifunctional nanomaterials for environmental pollution monitoring and purification, which is of great significance to both practical applications and basic research.

Effects of chlortetracycline on growth performance and intestinal functions in weaned piglets.

Weaning stress can cause serious damage to piglet's health. Chlortetracycline (CTC) is widely used to ameliorate weaning stress and prevent infectious diseases in weaned piglets. However, antibiotics as growth promoters have to be limited because of increased antimicrobial resistance. In this study, we evaluated the effects of CTC on growth performance and intestinal functions in order to provide evidence for seeking antibiotic substitutes in weaned piglets. A total of 20 weaned piglets were fed a basal diet or a diet supplemented with 75mg/kg CTC. CTC decreased the crypt depth and increased the ratio of villus height to crypt depth, whilst failing to affect growth performance and serum biochemical parameters and cytokines. 16S rRNA sequencing suggested that CTC supplementation had no effect on the diversity and composition of colonic microbiota. We speculated that gut microbiota is no longer sensitive to a low concentration of CTC due to the long-term use and low bioavailability of CTC in weaned piglets.