Long-term monitoring of sulfonamide leaching from manure amended soil into groundwater

A review on carbon-based biowaste and organic polymer materials for sustainable treatment of sulfonamides from pharmaceutical wastewater

Frequent detection of sulfonamides (SAs) pharmaceuticals in wastewater has necessitated the discovery of suitable technology for their sustainable remediation. Adsorption has been widely investigated due to its effectiveness, simplicity, and availability of various adsorbent materials from natural and artificial sources. This review highlighted the potentials of carbon-based adsorbents derived from agricultural wastes such as lignocellulose, biochar, activated carbon, carbon nanotubes graphene materials as well as organic polymers such as chitosan, molecularly imprinted polymers, metal, and covalent frameworks for SAs removal from wastewater. The promising features of these materials including higher porosity, rich carbon-content, robustness, good stability as well as ease of modification have been emphasized. Thus, the materials have demonstrated excellent performance towards the SAs removal, attributed to their porous nature that provided sufficient active sites for the adsorption of SAs molecules. The modification of physico-chemical features of the materials have been discussed as efficient means for enhancing their adsorption and reusable performance. The article also proposed various interactive mechanisms for the SAs adsorption. Lastly, the prospects and challenges have been highlighted to expand the knowledge gap on the application of the materials for the sustainable removal of the SAs.

Promoting the suitability of graphitic carbon nitride and metal oxide nanoparticles: A review of sulfonamides photocatalytic degradation

The widespread consumption of pharmaceutical drugs and their incomplete breakdown in organisms has led to their extensive presence in aquatic environments. The indiscriminate use of antibiotics, such as sulfonamides, has contributed to the development of drug-resistant bacteria and the persistent pollution of water bodies, posing a threat to human health and the safety of the environment. Thus, it is paramount to explore remediation technologies aimed at decomposing and complete elimination of the toxic contaminants from pharmaceutical wastewater. The review aims to explore the utilization of metal-oxide nanoparticles (MONPs) and graphitic carbon nitrides (g-C3N4) in photocatalytic degradation of sulfonamides from wastewater. Recent advances in oxidation techniques such as photocatalytic degradation are being exploited in the elimination of the sulfonamides from wastewater. MONP and g-C3N4 are commonly evolved nano substances with intrinsic properties. They possessed nano-scale structure, considerable porosity semi-conducting properties, responsible for decomposing wide range of water pollutants. They are widely applied for photocatalytic degradation of organic and inorganic substances which continue to evolve due to the low-cost, efficiency, less toxicity, and more environmentally friendliness of the materials. The review focuses on the current advances in the application of these materials, their efficiencies, degradation mechanisms, and recyclability in the context of sulfonamides photocatalytic degradation.

New insights into bioaugmented removal of sulfamethoxazole in sediment microcosms: degradation efficiency, ecological risk and microbial mechanisms

BACKGROUND

Bioaugmentation has the potential to enhance the ability of ecological technology to treat sulfonamide-containing wastewater, but the low viability of the exogenous degraders limits their practical application. Understanding the mechanism is important to enhance and optimize performance of the bioaugmentation, which requires a multifaceted analysis of the microbial communities. Here, DNA-stable isotope probing (DNA-SIP) and metagenomic analysis were conducted to decipher the bioaugmentation mechanisms in stabilization pond sediment microcosms inoculated with sulfamethoxazole (SMX)-degrading bacteria (Pseudomonas sp. M2 or Paenarthrobacter sp. R1).

RESULTS

The bioaugmentation with both strains M2 and R1, especially strain R1, significantly improved the biodegradation rate of SMX, and its biodegradation capacity was sustainable within a certain cycle (subjected to three repeated SMX additions). The removal strategy using exogenous degrading bacteria also significantly abated the accumulation and transmission risk of antibiotic resistance genes (ARGs). Strain M2 inoculation significantly lowered bacterial diversity and altered the sediment bacterial community, while strain R1 inoculation had a slight effect on the bacterial community and was closely associated with indigenous microorganisms. Paenarthrobacter was identified as the primary SMX-assimilating bacteria in both bioaugmentation systems based on DNA-SIP analysis. Combining genomic information with pure culture evidence, strain R1 enhanced SMX removal by directly participating in SMX degradation, while strain M2 did it by both participating in SMX degradation and stimulating SMX-degrading activity of indigenous microorganisms (Paenarthrobacter) in the community.

CONCLUSIONS

Our findings demonstrate that bioaugmentation using SMX-degrading bacteria was a feasible strategy for SMX clean-up in terms of the degradation efficiency of SMX, the risk of ARG transmission, as well as the impact on the bacterial community, and the advantage of bioaugmentation with Paenarthrobacter sp. R1 was also highlighted. Video Abstract.

Identification of sulfamethazine degraders in swine farm-impacted river and farmland: A comparative study of aerobic and anaerobic environments

Sulfonamides (SAs) are extensively used antibiotics in the prevention and treatment of animal diseases, leading to significant SAs pollution in surrounding environments. Microbial degradation has been proposed as a crucial mechanism for removing SAs, but the taxonomic identification of microbial functional guilds responsible for SAs degradation in nature remain largely unexplored. Here, we employed 13C-sulfamethazine (SMZ)-based DNA-stable isotope probing (SIP) and metagenomic sequencing to investigate SMZ degraders in three distinct swine farm wastewater-receiving environments within an agricultural ecosystem. These environments include the aerobic riparian wetland soil, agricultural soil, and anaerobic river sediment. SMZ mineralization activities exhibited significant variation, with the highest rate observed in aerobic riparian wetland soil. SMZ had a substantial impact on the microbial community compositions across all samples. DNA-SIP analysis demonstrated that Thiobacillus, Auicella, Sphingomonas, and Rhodobacter were dominant active SMZ degraders in the wetland soil, whereas Ellin6067, Ilumatobacter, Dongia, and Steroidobacter predominated in the agricultural soil. The genus MND1 and family Vicinamibacteraceae were identified as SMZ degrader in both soils. In contrast, anaerobic SMZ degradation in the river sediment was mainly performed by genera Microvirga, Flavobacterium, Dechlorobacter, Atopostipes, and families Nocardioidaceae, Micrococcaceae, Anaerolineaceae. Metagenomic analysis of 13C-DNA identified key SAs degradation genes (sadA and sadC), and various of dioxygenases, and aromatic hydrocarbon degradation-related functional genes, indicating their involvement in degradation of SMZ and its intermediate products. These findings highlight the variations of indigenous SAs oxidizers in complex natural habitats and emphasize the consideration of applying these naturally active degraders in future antibiotic bioremediation.

Acid-modified red mud biochar for the degradation of tetracycline: Synergistic effect of adsorption and nonradical activation

In this study, a novel acid-modified red mud biochar catalyst (MMBC) was synthesized by industrial waste red mud (RM) and peanut shell (PSL) to activate peroxodisulfate (PDS) for the degradation of TC. Meanwhile, MMBC exhibited remarkable adsorption capacity, reaching a 60% removal ratio of TC within 60 min (equilibrium adsorption capacity = 12 mg/g). After adding PDS, MMBC/PDS system achieved a 93.8% removal ratio of TC within 60 min. Quenching experiments and electron paramagnetic resonance (EPR) results showed that 1O2 played a dominant role in the degradation of TC and O2•- was the mainly precursor for the production of 1O2 in the MMBC/PDS system. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis showed that the surface Fe(II), -OH and -COOH provided the active sites for the activation of PDS by MMBC. In addition, acid modification optimised the surface structure of the catalyst and enhanced the conversion of Fe (mainly Fe(III) to Fe(II)), thereby improving the adsorption and catalytic efficiency of MMBC. This study confirmed that modified red mud biochar is an efficient composite with both adsorption and catalysis, providing new ideas for the practical treatment of antibiotic wastewater and the resource utilization of red mud.

Influence of Manure as a Complex Mixture on Soil Sorption of Pharmaceuticals-Studies with Selected Chemical Components of Manure

Pharmaceutically active compounds (PhACs) enter soil with organic waste materials such as manure. Such complex substrates differently affect PhACs' soil sorption. For the first time, batch experiments were conducted using five selected chemicals as model constituents to elucidate the effects. Urea, phosphate (KH₂PO₄), acetic acid, phenol and nonadecanoic acid (C:19) altered the sorption strength and/or nonlinearity of sulfadiazine, caffeine, and atenolol in an arable Cambisol topsoil. The nonlinear Freundlich model best described sorption. Overall, the PhACs' Freundlich coefficients (sorption strength) increased in the sequence urea < phosphate < phenol < C:19 < acetic acid, while the Freundlich exponents largely decreased, indicating increasing sorption specificity. The effects on sulfadiazine and caffeine were rather similar, but in many cases different from atenolol. Phosphate mobilized sulfadiazine and caffeine and urea mobilized sulfadiazine, which was explained by sorption competition resulting from specific preference of similar sorption sites. Soil sorbed phenol strongly increased the sorption of all three PhACs; phenolic functional groups are preferred sorption sites of PhACs in soil. The large increase in sorption of all PhACs by acetic acid was attributed to a loosening of the soil organic matter and thus the creation of additional sorption sites. The effect of C:19 fatty acid, however, was inconsistent. These results help to better understand the sorption of PhACs in soil-manure mixtures.

Influence of manure application method on veterinary medicine losses to water

Veterinary medicines are routinely used within modern animal husbandry, which results in frequent detections within animal manures and slurries. The application of manures to land as a form of organic fertiliser presents a pathway by which these bioactive chemicals can enter the environment. However, to date, there is limited understanding regarding the influence of commonly used manure application methods on veterinary medicine fate in soil systems. To bridge this knowledge gap, a semi-field study was conducted to assess the influence of commonly used application methods such as, broadcast, chisel sweep, and incorporation on veterinary medicine losses to waters. A range of veterinary medicines were selected and applied as a mixture; these were enrofloxacin, florfenicol, lincomycin, meloxicam, oxytetracycline, sulfadiazine, trimethoprim and tylosin. All the assessed veterinary medicines were detected within surface runoff and leachates, and the concentrations generally decreased throughout the irrigation period. The surface runoff concentrations ranged from 0.49 to 183.47 μg/L and 2.26-236.83 μg/L for the bare soil and grass assessments respectively. The leachate concentrations ranged from 0.04 to 309.66 μg/L and 0.33-37.79 μg/L for the bare soil and grass assessments respectively. More advanced application methods (chisel sweep) were found to significantly reduce the mass loads of veterinary medicines transported to surface runoff and leachate by 13-56% and 49-88% over that of broadcast. Incorporating pig slurries reduced the losses further with surface runoff and leachate losses being 13-56% and 49-88% lower than broadcast. Our results show that manure application techniques have a significant effect on veterinary medicine fate in the environment and as such these effects should be considered in the decision-making processes for the management of manures as well as from a risk mitigation perspective for aquatic compartments.

Investigating the Effect of Bi2MoO6/g-C3N4 Ratio on Photocatalytic Degradation of Sulfadiazine under Visible Light

In this study, a series of Bi2MoO6/g-C3N4 composites were prepared through a wet-impregnation method, and their photocatalytic properties were investigated for the degradation of sulfadiazine (SDZ) under visible light irradiation. Physical and chemical characterizations were carried out using X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence spectroscopy (PL), UV-vis diffuse reflectance spectra (UV-vis), and electrochemical impedance spectra (EIS). Compared to pure g-C3N4, the introduction of Bi2MoO6 significantly enhanced the visible light responsive photocatalytic activity, with the 1:32 Bi2MoO6/g-C3N4 composite exhibiting the highest photodegradation efficiency towards SDZ under visible light irradiation with a photocatalytic efficiency of 93.88% after 120 min of visible light irradiation. The improved photocatalytic activity can be attributed to the formation of a heterojunction between Bi2MoO6 and g-C3N4, which promotes the transfer of photogenerated electron-hole pairs, thereby elevating its photocatalytic activity. The results suggest that Bi2MoO6/g-C3N4 composites have potential application for the degradation of sulfonamides in aquatic environments.

An analytical framework on the leaching potential of veterinary pharmaceuticals: A case study for the Netherlands

Veterinary pharmaceuticals (VPs) residues may end up on the soil via manure, and from there can be transported to groundwater due to leaching. In this study an analytical framework to estimate the leaching potential of VPs at the national scale is presented. This approach takes soil-applied VPs concentrations, soil-hydraulic and soil-chemical properties, groundwater levels, sorption and degradation of VPs into account. For six commonly soil-applied VPs in the Netherlands, we assess quantities leached to groundwater and their spatial distribution, as well as the relative importance of processes that drive leaching. Our results for VPs Oxytetracycline, Doxycycline, and Ivermectin indicate that maximum quantities that may leach to groundwater are very low, i.e. ≪1 μg/ha, hence spatial differences are not investigated. For VPs Sulfadiazine and Flubendazole we identify a few regions that are potentially prone to leaching, with leached quantities higher than 1 μg/ha. Leaching patterns of these two VPs are dominated by soil properties and groundwater levels rather than soil-applied quantities. For Dexamethasone, even though applied on the soil in much lower concentrations compared to other investigated VPs, spatially widespread leaching to groundwater is found, with leached quantities higher than 1 μg/ha. Due to the leaching affinity of Dexamethasone, variations in the soil-applied amounts have significant influence on the quantities leached to groundwater. Dexamethasone is highlighted as important for the future environmental risk assessment efforts. This study has shown that the leaching potential of VPs is not determined by one single parameter, but by a combination of parameters. This combination also depends on the compound investigated.

Stability of Important Veterinary Antibiotics Amoxicillin, Sulfadiazine, and Trimethoprim in Practice-Relevant Model Solutions

Due to the frequent use of veterinary drugs in animal husbandry, it is important to know their environmental behavior. In this context, little attention has been paid to the stability of the active ingredients in solutions prepared for administration. This is particularly problematic for antibiotics that trigger resistance when administered subtherapeutically. In order to investigate a possible influence of the preparation and storage of veterinary drugs on compound stability, three widely used antibiotics (amoxicillin, sulfadiazine, trimethoprim) were prepared in different model solutions. Depending on their individual stabilities, the incubation period lasted up to 70 days. Samples were analyzed at regular intervals by high-performance liquid chromatography-diode array detection and ultraviolet spectrophotometry. Following official recommendations, the investigations covered various parameters, e.g., pH, buffer substances, influence of light, and temperature. Sulfadiazine was incubated together with trimethoprim at concentrations of 120 mg L^-1 and 80 mg L^-1 for 70 days. Both compounds proved to be very stable under all experimental conditions and between 92 and 100% of the active ingredients remained. In 0.1% formic acid, a transformation product was found with less than 5% of the parent substance. In contrast, amoxicillin (500 mg L^-1) was instable in almost all solutions under investigation. Within 17 days, the concentration of AMO decreased to 72% in ultrapure water. With the exception of a physiological saline solution, the amount of amoxicillin dropped below 10% or even below the detection limit. Thus, a physiological saline solution is best suited for the storage of dissolved amoxicillin for later administration.

A critical review on retaining antibiotics in liquid digestate: Potential risk and removal technologies

Substantial levels of antibiotics remain in liquid digestate, posing a significant threat to human safety and the environment. A comprehensive assessment of residual antibiotics in liquid digestate and related removal technologies is required. To this end, this review first evaluates the potential risks of the residual antibiotics in liquid digestate by describing various anaerobic digestion processes and their half-lives in the environment. Next, emerging technologies for removing antibiotics in liquid digestate are summarized and discussed, including membrane separation, adsorption, and advanced oxidation processes. Finally, this study comprehensively and critically discusses these emerging technologies' prospects and challenges, including techno-economic feasibility and environmental impacts.

Insights into the impact of manure on the environmental antibiotic residues and resistance pool

The intensive use of antibiotics in the veterinary sector, linked to the application of manure-derived amendments in agriculture, translates into increased environmental levels of chemical residues, AR bacteria (ARB) and antibiotic resistance genes (ARG). The aim of this review was to evaluate the current evidence regarding the impact of animal farming and manure application on the antibiotic resistance pool in the environment. Several studies reported correlations between the prevalence of clinically relevant ARB and the amount and classes of antibiotics used in animal farming (high resistance rates being reported for medically important antibiotics such as penicillins, tetracyclines, sulfonamides and fluoroquinolones). However, the results are difficult to compare, due to the diversity of the used antimicrobials quantification techniques and to the different amounts and types of antibiotics, exhibiting various degradation times, given in animal feed in different countries. The soils fertilized with manure-derived products harbor a higher and chronic abundance of ARB, multiple ARG and an enriched associated mobilome, which is also sometimes seen in the crops grown on the amended soils. Different manure processing techniques have various efficiencies in the removal of antibiotic residues, ARB and ARGs, but there is only a small amount of data from commercial farms. The efficiency of sludge anaerobic digestion appears to be dependent on the microbial communities composition, the ARB/ARG and operating temperature (mesophilic vs. thermophilic conditions). Composting seems to reduce or eliminate most of antibiotics residues, enteric bacteria, ARB and different representative ARG in manure more rapidly and effectively than lagoon storage. Our review highlights that despite the body of research accumulated in the last years, there are still important knowledge gaps regarding the contribution of manure to the AMR emergence, accumulation, spread and risk of human exposure in countries with high clinical resistance rates. Land microbiome before and after manure application, efficiency of different manure treatment techniques in decreasing the AMR levels in the natural environments and along the food chain must be investigated in depth, covering different geographical regions and countries and using harmonized methodologies. The support of stakeholders is required for the development of specific best practices for prudent – cautious use of antibiotics on farm animals. The use of human reserve antibiotics in veterinary medicine and of unprescribed animal antimicrobials should be stopped and the use of antibiotics on farms must be limited. This integrated approach is needed to determine the optimal conditions for the removal of antibiotic residues, ARB and ARG, to formulate specific recommendations for livestock manure treatment, storage and handling procedures and to translate them into practical on-farm management decisions, to ultimately prevent exposure of human population.

Thermal desorption behavior of fluoroquinolones in contaminated soil of livestock and poultry breeding

As a kind of typical veterinary drug, fluoroquinolone antibiotics (FQs) are widely used in the field of livestock and poultry breeding, but these FQs escape to surrounding soil through various pathways, polluting soil through long-term accumulation. Current study proposed a clean technology named thermal desorption to deal with FQs contaminated soils. It was observed that time, temperature and soil particle size were the critical factors in FQs thermal desorption. Results of the study showed that higher temperature was more effective in the removal of FQs, while removal of FQs attached with finer particles was more difficult compared to coarse particles. Fine soil particles (0.6-0.85 mm) were decontaminated up 99.4% when treated with 400 °C for 60min. Thermal desorption of FQs from contaminated soil was governed by first-order kinetics. Based on the detection of exhaust gas components, a possible thermal desorption mechanism was proposed. Study suggested that thermal desorption was a clean and effective remediation method to treat FQs-contaminated soils without generating any further waste.

Removal of Diverse and Abundant ARGs by MF-NF Process from Pig Manure and Digestate

Antimicrobial resistances are emerging as one main threat to worldwide human health and are expected to kill 10 million people by 2050. Intensive livestock husbandry, along with biogas digestate, are considered as one of the biggest ARG reservoirs. Despite major concerns, little information is available on the diversity and abundance of various ARGs in small to large scale pig farms and biogas digestate slurry in Germany, followed by their consequent removal using microfiltration (MF)-nanofiltration (NF) process. Here, we report the identification and quantification of 189 ARGs in raw manure and digestate samples, out of which 66 ARGs were shared among manures and 53 ARGs were shared among both manure and digestate samples. The highest reported total ARG copy numbers in a single manure sampling site was 1.15 × 10⁸ copies/100 µL. In addition, we found the absolute concentrations of 37 ARGs were above 10⁵ copies/100 μL. Filtration results showed that the highly concentrated ARGs (except aminoglycoside resistance ARGs) in feed presented high log retention value (LRV) from 3 to as high as 5 after the MF-NF process. Additionally, LRV below 2 was noticed where the initial absolute ARG concentrations were ≤10³ copies/100 μL. Therefore, ARG removal was found to be directly proportional to its initial concentration in the raw manure and in digestate samples. Consequently, some ARGs (tetH, strB) can still be found within the permeate of NF with up to 10⁴ copies/100 μL.

Fingerprinting pharmaceuticals of multiple sources at a provincial watershed scale

Pharmaceutical residues in the aquatic environment have increasingly attracted public concerns but their fingerprint of sources remain unclear at a watershed scale. This study systematically explored pharmaceutical residues in effluent of 8 different type of sources in a provincial watershed in China using a multi-category protocol of pharmaceutical quantification. Seventy-seven out of 94 target compounds from 6 categories were quantified in effluent, up to 71,318 ng L^-1 in total from urban hospital sources with 20 antibiotics and 32 others. The spectrum of the quantified compounds in effluent significantly differentiated the urban (hospitals, domestic sewages, and WWTPs), rural (health centers and domestic sewages), and agricultural production sources (poultry and swine breeding yards, aquaculture ponds, and paddy fields). Compounds of non-steroidal anti-inflammation drugs (NSAIDs), cardiovascular drugs (CVs), and central nervous drugs (CNs) could fingerprint the three groups of sources. However, the three categories contributed 7 out of 10 compounds with high risk (risk quotient >1.0) to the aquatic environment identified by the eco-environmental risk assessment. No high-risk compounds were identified in effluent of urban WWTPs. Findings of this study suggest source identification and compound spectrum fingerprinting are crucial for studies on pharmaceutical residues in the aquatic environment, especially the complexity of pharmaceutical residues in source effluents for exploring source-sink dynamics at a watershed scale.

Long-term sulfamethazine leaching simulation in two different soils using the MACRO model

Physically based models have been part of many risk assessment studies concerning pesticide or nutrient transport within (sub)catchments or at plot scale, but they are only poorly validated for simulating the transport of veterinary medicinal products. Veterinary medicinal products not only pose a risk to the quality of our waters but also tend to accumulate in soils, where they are associated with the appearance of resistant bacteria and long-term leaching. In this study, the physically based leaching model MACRO 5.2 was applied for simulating sulfamethazine (SMZ) transport over a period of more than 10 yr. The model was set up using reversible kinetic adsorption and equilibrium adsorption forming non-extractable residues. Two different calibration periods were used to estimate uncertainties in predicted SMZ leaching associated with calibration based on short-term data. Using the whole period for model calibration, SMZ leaching could be simulated adequately, but parameter ranges were wide due to correlation between the parameters. When using only the first period for calibration, the quality of the prediction strongly depended on the information content of the data set. The calculation of temporal sensitivity indices revealed that the effect of complex sorption parameters on the model output increased with time. Thus, parameters that appeared insensitive in a short-term calibration were required for reliable long-term simulations. In conclusion, a temporal sensitivity analysis beyond the calibration period might identify parameters that were not constrained enough by the calibration procedure. This could help to confirm leaching predictions even for periods without sampling data.

Mechanism for biodegradation of sulfamethazine by Bacillus cereus H38

Degradation of sulfonamides (SAs) by microorganisms has become a focus of current research. Sulfamethazine (SMZ) is a type of SA widely used in the livestock and poultry industry. However, understanding the intermediate products, degradation pathways and mechanism of SMZ biodegradation is limited at present. In this study, a SMZ degrading bacterium Bacillus cereus H38, which can use SMZ as its only carbon source, was isolated from farmland soil. The bacterium was gram-positive with rod-shaped cells. The effects of initial SMZ concentration, pH, temperature and amount of inoculation on the biodegradation of SMZ were investigated by a single factor experiment. The results showed that the maximum degradation rate of SMZ was achieved in the environmental conditions at an initial SMZ concentration of 5 mg/L, pH of 7.0, temperature of 25 °C and inoculation amount of 5%. Under these optimum degradation conditions, strain H38 can completely degrade SMZ within 3 days. The effects of intracellular enzymes, extracellular enzymes and periplasmic enzymes on the SMZ degradation process were compared. It was found that intracellular enzymes contributed the most to the biodegradation of SMZ, and the degradation rate approached 70%. Three possible intermediates were identified by LC-MS/MS, and two degradation pathways were proposed. Whole genome sequencing results showed that the genome size of strain H38 was 5,477,631 bp, including 5599 coding sequences (CDSs), and the GC content was 35.21%. In addition, functional annotation of CDSs was performed to analyze the metabolic pathways of nitrogen and sulfur in strain H38 combining genomics and bioinformatics. This study proposes new insights into the mechanism for biodegradation of SAs and will inform future research.

A contrasting alteration of sulfamethoxazole bioaccessibility in two different soils amended with polyethylene microplastic: In-situ measurement using diffusive gradients in thin films

Microplastics and veterinary antibiotics are both emerging environmental contaminants that could be co-occurrence in agricultural soils. However, it's still unclear how the microplastics affect the bioaccessibility of antibiotics in a real soil environment. An in-situ measurement using diffusive gradients in thin-films devices suitable for polar organic compounds (o-DGT) coupled with soil moisture sampling were used to reveal such effects. Sulfamethoxazole (SMX) that was selected as a representative antibiotic and polyethylene (PE) microplastic with an average diameter of 35 μm were amended to the paddy soil and saline soil for the study. The result indicated that SMX degradation in the paddy soil was higher than that in the saline soil, meanwhile, PE microplastic addition promoted SMX degradation in both soils. In the paddy soil, PE microplastic addition enhanced release of SMX from soil solid to soil solution but no effects on the bioaccessibile SMX. However, in the saline soil, the PE microplastic addition reduced both SMX in soil solution and bioaccessibile SMX significantly (p < 0.05). The potential resupply ability of the labile SMX from soil solid to soil solution which was expressed as R value enhanced significantly in saline soil, while such a change was negligible in the paddy soil. This implied that long-term release risk of SMX in the PE microplastic contaminated saline soil could not be neglected. Therefore, co-occurrence of PE microplastic and SMX in the soils might increase uptake of SMX by biotas and such effects depended on soil properties.

An integrated modelling approach to derive the grey water footprint of veterinary antibiotics

Water pollution by veterinary antibiotics (VAs) resulting from livestock production is associated with severe environmental and human health risks. While upward trends in global animal product consumption signal that these risks might exacerbate toward the future, VA related water pollution is currently insufficiently understood. To increase this understanding, the present research assesses processes influencing VA pollution from VA administration to their discharge into freshwater bodies, using an integrated modelling approach (IMA). For the VAs amoxicillin, doxycycline, oxytetracycline, sulfamethazine, and tetracycline we estimate loads administered to livestock, excretion, degradation during manure storage, fate in soil and transport to surface water. Fate and transport are modelled using the VA transport model (VANTOM), which is fed with estimates from the Pan-European Soil Erosion Risk Assessment (PESERA). The grey water footprint (GWF) is used to indicate the severity of water pollution in volumetric terms by combining VA loads and predicted no effect concentrations. We apply our approach to the German-Dutch Vecht river catchment, which is characterized by high livestock densities. Results show a VA mass load decrease larger than 99% for all substances under investigation, from their administration to surface water emission. Due to metabolization in the body, degradation during manure storage and degradation in soil, VA loads are reduced by 45%, 80% and 90% on average, respectively. While amoxicillin and sulfamethazine dissipate quickly after field application, significant fractions of doxycycline, oxytetracycline and tetracycline accumulate in the soil. The overall Vecht catchment's GWF is estimated at 250,000 m³ yr^-1, resulting from doxycycline (81% and 19% contribution from the German and Dutch catchment part respectively). Uncertainty ranges of several orders of magnitude, as well as several remaining limitations to the presented IMA, underscore the importance to further develop and refine the approach.

Interaction of pig manure-derived dissolved organic matter with soil affects sorption of sulfadiazine, caffeine and atenolol pharmaceuticals

Pharmaceutically active compounds (PhACs) released into the environment have an adverse impact on the soil and water ecosystem as well as human health. Sorption of PhACs by soils and its potential modification through introduced DOM in the applied animal manure or treated wastewater (TWW) determines the mobility and environmental relevance of PhACs. Sulfadiazine, caffeine and atenolol were selected as target PhACs to investigate their sorption behaviors by five selected arable soils in the absence and presence of pig manure DOM. Sulfadiazine was least sorbed, followed by caffeine and atenolol according to the Freundlich sorption isotherm fit (soil average K_f [μg^(1-n) mLⁿ g^-1] 4.07, 9.06, 18.92, respectively). The addition of manure DOM (31.34 mg C L^-1) decreased the sorption of sulfadiazine and especially of caffeine and atenolol (average K_f 3.04, 6.17, 5.79, respectively). Freundlich sorption isotherms of the PhACs became more nonlinear in the presence of manure DOM (Freundlich exponent n changed from 0.74-1.40 to 0.62-1.12), implying more heterogeneous sorption of PhACs in soil-DOM binary systems. Sorption competition of DOM molecules with sulfadiazine and caffeine mostly contributed to their decreased soil sorption when DOM was present. In contrast, the formation of DOM-atenolol associates in the solution phase caused the largely decreased soil sorption of atenolol in the presence of DOM. It is suggested that DOM concentration (e.g., ≥ 60 mg C L^-1) and its interaction with PhACs should be taken into consideration when assessing the environmental impact of land application of animal manure or irrigation with TWW.

Residue accumulation, distribution, and withdrawal period of sulfamethazine and N-acetylsulfamethazine in poultry waste from broilers

Sulfamethazine is one of the most frequently used sulfonamides in the poultry farming industry. However, the residue accumulation, distribution, and depletion of sulfamethazine (SMZ) and its metabolite, N4-acetylsulfamethazine (NAS), in poultry waste (manure and feathers) have yet to be evaluated. In our study, the residue levels of SMZ and NAS in manure and feathers are determined by liquid chromatography tandem mass spectrometry. Furthermore, the distribution, depletion, and withdrawal period of SMZ and NAS in manure and feathers are investigated under field conditions. Results show that high concentrations (0.7-43.3 mg/kg for SMZ, and 0.22-22.4 mg/kg for NAS) of SMZ and NAS residues remain in manure and feathers even when SMZ has been used. The withdrawal periods of SMZ and NAS in feathers are 97.0 d and 28.0 d, respectively. In manure, the withdrawal period is 18.2 d and 8.0 d, respectively. Poultry waste is a possible major reentry way of SMZ into the food chain and the environment.

A strategy to determine the fate of active chemical compounds in soil; applied to antimicrobially active substances

Data on the fate of chemical substances in the environment after e.g. manure application is mandatory input for risk assessment in perspective of a more circular biobased economy. Such fate studies include a persistence study to determine a half-life value and a mobility study. It is recognized that not only the native substance should be considered, but that also degradation products should be included that might exert a similar effect as the native substance. We report a tiered fate study strategy that starts with a persistence study. For non-persistent substances a study is performed to determine if degradation products have a similar effect as the native compound. If so, a procedure using high resolution mass spectrometry is suggested to identify the potentially active degradation products. Based on the outcomes, substances are divided into three categories: (I) persistent, (II) degradable to inactive products or (III) degradable to active products. Even though the priority is with category I and III, for all substances and possible degradation products a mobility study is proposed. The fate strategy is successfully applied to ten antimicrobially active substances originating from the tetracyclines, sulfonamides, diaminopyrimidines, fluoroquinolones, macrolides and lincosamides. The fluoroquinolones, tetracyclines and trimethoprim were relatively persistent. The sulfonamides, macrolides and lincomycin (the latter also depending on soil type) degraded relatively quickly. Tylosin A proved to degrade to antimicrobially active degradation products which were tentitatively identified as tylosin C, tylosin A acid, tylosin B acid and tylosin C acid.

Fragmentation of Polyfunctional Compounds Recorded Using Automated High-Throughput Desorption Electrospray Ionization

Using desorption electrospray ionization (DESI) as part of an automated high-throughput system, tandem mass spectra of the compounds in a pharmaceutical library were recorded in the positive mode under standardized conditions. Quality control filtering yielded an MS/MS library of 16 662 spectra. Fragmentation of subsets of the compounds in the library chosen to contain a single instance of a particular functional group (amide, piperazine, sulfonamide) was predicted by experts, and the results were compared with the experimental data. Expert performance was good to excellent for all the cases evaluated. Substituents on the functional groups were found to exert important secondary control over the fragmentation, with the main effect observed being product ion stabilization by aromatic substitution, which was consistent across the different groups evaluated. These substituent effects are generally explicable in terms of standard physical organic chemistry considerations of product ion stability as controlling fragmentation. A somewhat unexpected feature was the incidence of homolytic cleavages, driven by the stability of substituted amine radical cations. The findings of this study are intended to lay the groundwork for machine learning approaches to performing MS/MS spectrum → structure and structure → MS/MS spectrum operations on the same experimental data set. The effort involved and the success achieved in computer-aided interpretation, now underway, will be compared with the expert performance as described here.

High-temperature and freeze-thaw aged biochar impacts on sulfonamide sorption and mobility in soil

Biomass-derived biochar is a carbon-rich product for soil amendment and sulfapyridine (SPY) is a typical sulfonamide of antibiotics in the soil. Amendment with biochar for soil could control SPY sorption or mobility. However, the pristine biochar inevitably goes through the long-term ageing in the environment and the information on such ageing impact on SPY sorption is not fully recognized. The simulated ageing process methods were employed for high-temperature and freeze-thraw climate to treat the biochar for two months in the present study. The batch adsorption of SPY and leaching column experiments were conducted for comparison of the fresh/aged biochar-soil system. The results showed that biochar addition could increase soil pH and saturated moisture, aged biochars own more O-containing functional groups and exhibit higher hydrophilicity and polarity. The sorption mechanism of unamended soil with SPY primarily resulted from the weak hydrophobic distribution. All fresh and aged biochar amended soil increased SPY sorption due to improvement of H-bonding interaction between SPY and biochar surface functional groups, indicating such initiative adsorption was stronger than passive partitioning. It is of importance for us to reconsider that aged biochar-amended soil, especially two-month high-temperature aged biochar-amended soil showed the highest adsorption performance and the lowest desorption capacity towards SPY. Both SPY leaching column experiments and the acid rain leaching tests suggested that the application of biochar in tropical or high-temperature climate regions for organics polluted soil remediation is favorable, but we should be aware of the uncertainty of soil amendment with biochar in cold regions.

Biotransformation mechanism of Vibrio diabolicus to sulfamethoxazole at transcriptional level

Sulfamethoxazole (SMX) has attracted much attention due to its high probability of detection in the environment. Marine bacteria Vibrio diabolicus strain L2-2 has been proven to be able to transform SMX. In this study, the potential resistance and biotransformation mechanism of strain L2-2 to SMX, and key genes responses to SMX at environmental concentrations were researched. KEGG pathways were enriched by down-regulated genes including degradation of L-Leucine, L-Isoleucine, and fatty acid metabolism. Resistance mechanism could be concluded as the enhancement of membrane transport, antioxidation, response regulator, repair proteins, and ribosome protection. Biotransformation genes might involve in arylamine N-acetyltransferases (nat), cytochrome c553 (cyc-553) and acyl-CoA synthetase (acs). At the environmental concentration of SMX (0.1-10 μg/L), nat was not be activated, which meant the acetylation of SMX might not occur in the environment; however, cyc-553 was up-regulated under SMX stress of 1 μg/L, which indicated the hydroxylation of SMX could occur in the environment. Besides, the membrane transport and antioxidation of strain L2-2 could be activated under SMX stress of 10 μg/L. The results provided a better understanding of resistance and biotransformation of bacteria to SMX and would support related researches about the impacts of environmental antibiotics.

Sulfadiazine, sulfamethazine and sulfachloropyridazine removal using three different porous materials: Pine bark, "oak ash" and mussel shell

This work focuses on studying the efficacy of three different by-products to adsorb three antibiotics (sulfadiazine, SDZ; sulfamethazine, SMT; sulfachloropyridazine, SCP). These antibiotics can be considered pollutants of the environment when they reach water, as well as in cases where they are spread on soils through irrigation or contained in sewage sludge or livestock manure. In this study, batch-type adsorption/desorption experiments were performed for each of the three sulfonamides, adding 7 different concentrations of the antibiotics, going from 1 to 50 μmol L^-1, and with contact time of 24 h. The results indicate that pine bark is the most efficient bioadsorbent among those studied, as it adsorbs up to 95% of the antibiotics added, while desorption is always less than 11%. However, for "oak ash" and mussel shell the adsorption is always lower than 45 and 15%, respectively, and desorption is high, reaching up to 49% from "oak ash" and up to 81% from mussel shell. Adsorption data showed good fitting to the Linear and Freundlich models, with R² values between 0.98 and 1.00 in both cases. K_d and K_F adsorption parameters showed similar values for the same sorbent materials but were much higher for pine bark than for the other two bioadsorbents. The Freundlich's n parameter showed values in the range 0.81-1.28. The highest K_F values (and therefore the highest adsorption capacities) were obtained for the antibiotic SCP in pine bark. Pine bark showed the highest capacity to adsorb each of the antibiotics, increasing as a function of the concentration added. When the concentration of sulfonamide added was 50 μM, the amounts adsorbed were 780 μmol kg^-1 for SDZ, 890 μmol kg^-1 for SMT, and 870 μmol kg^-1 for SCP. "Oak ash" and mussel shell have low adsorption capacity for all three sulfonamides, showing values always lower than 150 μmol kg^-1 (oak ash) and 20 μmol kg^-1 (mussel shell) when a concentration of 50 μmol L^-1 of antibiotic is added. The results of this study could aid to make an appropriate management of the by-products studied, in order to facilitate their valorization and recycling in the treatment of environmental compartments polluted with sulfonamide antibiotics.

Spatial distribution and temporal change of antibiotics in soils amended with manure using two field application methods

Compared to surface application, manure subsurface injection significantly reduces transport of manure-associated antibiotics via surface runoff. However, the environmental fate of antibiotics in manure injection slits is unknown. A field investigation was conducted to monitor distribution and dissipation of pirlimycin, tylosin, chlortetracycline, and sulfamerazine in soil following either surface application or subsurface injection of liquid dairy manure. A simulated rainfall was conducted on days 0, 3, and 7 after manure application. Soil samples were collected before, on the day of, and 5, 14, 60, and 180 days after the simulated rainfall. Around an hour after manure application, antibiotic concentrations in injection slits were 4-49 and 4-26 times higher than those outside the slits and in surface application plots, respectively. Antibiotics concentrated in the injection slits for an extended time with limited horizontal and vertical movement, exposing the microbial community inside the slits to an elevated level of antibiotics. Dissipation of antibiotics was the fastest during the first 14 d after manure application before slowing down. There were no significant differences in antibiotic dissipation patterns in soils amended with manure using two application methods. Although the half-lives ranged from 3-11 d for pirlimycin, 3-10 d for sulfamerazine, 5-12 d for tylosin, and 3-21 day for chlortetracycline; pirlimycin, sulfamerazine, and tylosin remained detectable in soil even 180 d after the single manure application, indicating that soils could be a long-term source for antibiotics to the surrounding environment. Overall, in addition to resulting in less surface runoff of antibiotics from the fields, manure subsurface injection can also retain antibiotics in the injection slits and limit their movement overtime. However, more studies are needed to better understand if elevated levels of antibiotics, nutrients, organic matter, and water would result in "hot zones" for antibiotic resistance development in the manure subsurface injected fields.

Study on the remediation of tetracycline antibiotics and roxarsone contaminated soil

Antibiotics are commonly used in livestock and poultry breeding along with organic arsenic. Through long-term accumulation, they can enter into the surrounding soil through various pathways and contaminate the soil. In this paper, tetracycline antibiotics (TCs) and roxarsone (ROX) contaminated soil were used as the representatives of the two kinds of veterinary drugs contaminated soil, respectively, to study the thermal desorption behavior and arsenic stabilization process. Different parameters like heating temperatures, heat duration, stabilizer type and dosage were optimized for effective removal of TCs and ROX. Furthermore, TCs and ROX removal path and ROX stabilization mechanism were explored. Results of the study showed that over 98% of tetracycline antibiotics and roxarsone were effectively removed at 300 °C for 60 min. The heat treatment process of TCs contaminated soil was controlled by the first-order kinetics. Based on the detection of degradation products and thermogravimetric analysis, the possible thermal degradation path of TCs and ROX was proposed. Addition of FeSO₄.7H₂O (10% by weight) as stabilizer during the heat treatment process yielded 96.7% stabilization rate. Through the analysis of arsenic fractions, valence and the characterization of soil samples collected after the heat treatment, mechanism of arsenic stabilization in ROX was explored. The results show that thermal treatment combined with chemical stabilization technology can not only degrade TCs and ROX efficiently and completely, but also convert organic arsenic into inorganic state, which is conducive to better stabilization, and finally achieve effective and safe remediation of this kind of contaminated soil.

Contamination, distribution, and risk assessment of antibiotics in the urban surface water of the Pearl River in Guangzhou, South China

To assess the impact of antibiotic pollution to the ecosystem in urban water, the occurrence, seasonal, and spatial distributions, potential sources, and ecological risks of 18 targeted antibiotics in urban river, Pearl River located in Guangzhou city, were investigated. Surface water samples were sampled from 24 sites in Guangzhou center of Pearl River during dry and wet seasons. The results indicated that the concentrations of antibiotic residues were at the nanogram per liter level, except sulfamethazine (SMD) (μg/L). Sulfonamides (SAs) were the dominant antibiotics, contributing 60.4-65.0% to the total antibiotics. The concentrations of SAs, fluoroquinolones (QUs), macrolides (MLs), tetracyclines (TCs), and lincosamides (LCs) were higher in dry season than those in wet season at most sampling sites, which possibly resulted from the dilution effect of heavy rainfall. The concentrations of the antibiotic residues in Guangzhou were comparable or higher than other urban rivers. The calculation on risk quotients indicated that erythromycin-H₂O (ETM-H₂O) and tetracycline (TC) were of high risks. The source identification by the Pearson correlation analysis and principal component analysis-multiple linear regression (PCA-MLR) method suggested that municipal wastewater treatment plants were primary sources of antibiotics. These results would provide important information for the environmental protect.

Emerging organic compounds in European groundwater

In Europe, emerging organic compounds (EOCs) in groundwater is a growing research area. Prioritisation for monitoring EOCs in Europe was formalised in 2019 through the development of the first voluntary groundwater watch list (GWWL). Despite this, groundwater occurrence data in the peer reviewed literature for Europe has not been reviewed to date. Questions surrounding the effect, toxicity, movement in the subsurface and unsaturated zone make the process of regulating EOC use difficult. The aim in Europe is to develop a unified strategy for the classification, and prioritisation of EOCs to be monitored in groundwater. This paper compiles evidence from the recent published studies from across Europe, since 2012, when the last major literature global review of EOCs in groundwater took place. A total of 39 studies were identified for review based on specific selection criteria (geography, publication date, sample size>10, inclusion of EOCs data). Data on specific compounds, and associated meta-data, are compiled and reviewed. The two most frequently detected EOCs, carbamazepine and caffeine, occurred in groundwater at concentrations of up to 2.3 and 14.8 μg/L, respectively. The most frequently reported category of compounds were 'Pharmaceuticals'; a highly studied group with 135 compounds identified within 31 of the 39 studies. In Europe, the majority of reviewed studies (23) were at a regional scale, looking specifically at EOCs in a specific city or aquifer. The use of analytical methods is not uniform across Europe, and this inevitably influences the current assessment of EOCs in groundwater. A correlation between the number of compounds analysed for, and the number detected in groundwater highlights the need for further studies, especially larger-scale studies throughout Europe. For the development of EU and national regulation, further work is required to understand the occurrence and impacts of EOCs in groundwater throughout Europe and elsewhere.

Assessment of water-quality parameters of groundwater contaminated by fly ash leachate near Koradi Thermal Power Plant, Nagpur

Thermal power generating industries affect the surrounding environment in various ways. Fly ash escapes along with flue gases and can be found in undesirable quantities in soil and water sources in the region. The water quality of an area must be evaluated regularly to ensure the quality of potable water. The present study evaluates the pre-monsoon and post-monsoon concentrations of several important physico-chemical parameters and heavy-metal contents of groundwater samples collected from sites near the Koradi Thermal Power Plant, a major source of power generation in the Nagpur Region. The maximum amount of total dissolved solids observed during the two seasons studied were 1571 mg/l and 1591 mg/l which is within the desirable limit implying that fly ash contamination did not affect this water quality parameter. The total hardness of samples from GW-3, GW-5 and GW-9 were 844 mg/l, 775 mg/l and 675 mg/l during pre-monsoon season, while GW-3 and GW-5 along with GW-4 continued to show high levels of total hardness at 1015 mg/l, 741 mg/l and 650 mg/l, respectively. These values are higher than the permissible limit due to the high levels of ions of bicarbonate, calcium, sodium and sulphate derived from fly ash leachate. Statistical analysis showed that sulphides, total hardness, electrical conductivity and total dissolved solids were the significant water quality parameters of the region. The evaluation of the parameters found that the three water sources (GW-3, GW-5 and GW-9) out of 10 are the most affected groundwater sources of fly ash pollution.

Long-term monitoring of sulfonamides and tetracyclines in manure amended soils and leachate samples - A follow-up study

Antibiotics can be detected in manure and digestate samples worldwide. As manure is a frequently used fertilizer, antibiotics are found in soil and leachate samples. Only little is known about the long-term fate of antibiotics in the soil environment. One shortcut is the lack of appropriate monitoring studies. Here we present the results of an unequalled soil monitoring study over 18 years from an agricultural field site in Lower Saxony (Germany). Sulfonamides and tetracycline are mainly fixed in the upper soil layer. Contents showed a sharp decrease below sampling depth of 30 cm (plough depth). Sulfaguanidine and sulfamethazine (SMZ) were detected down to 90 cm. Water samples taken below the field site revealed the transfer of sulfonamides into leachate. High variances were observed between sampling points emphasizing the need for sampling strategies for environmental studies. In addition, field lysimeters with defined input of sulfonamides enabled a long-term monitoring and mass balance of antibiotic transfer into leachate over 10 years. SMZ showed the highest mobility with concentrations up to 65 ng L-1. Less than 0.5% of the applied SMZ was transferred into the leachate. Data of lysimeter and field water samples support the theory of a steady state process with a continuous input of sulfonamides such as SMZ into leachate. Soils contaminated with antibiotics can be a long-term source for the input of antibiotic active compounds into deeper soil layers and groundwater.

Multimedia mass balance approach to characterizing the transport potential of antibiotics in soil-plant systems following manure application

Antibiotics are ubiquitous in agro-ecosystems worldwide, which can pose remarkable risks to ecological security and human health. However, comprehensive evaluation on the multimedia fate and transport potential of antibiotics in soil-plant systems is still lacking. A mass balance approach was performed to gain insights into the transport and fate of antibiotics in soil-plant systems following manure application. Our results showed that more than 99 % of antibiotics were released from applied manure fertilizer into the soil-plant system. Antibiotic concentrations in soil and plant compartments increased over 120 days. Most of the antibiotics persisted in soil (about 65 %), while less than 0.1 % accumulated in the plants. Rainfall-induced runoff, subsurface interflow and soil water infiltration were alternative transport pathways for antibiotics in soil-plant systems although their contributions were limited. Dissipation was the main removal pathway for antibiotics accounting for about 33 % of total input mass. Tetracyclines had higher mass proportion in soil following by quinolones, whereas most of sulfonamides and macrolides were dissipated. Mass balance approach based on tracking environmental fates of antibiotics can facilitate the understandings in the source comparisons and mitigation strategies, and therefore provide insights to inform modeling and limiting the transport of manure-borne antibiotics to neighboring environmental compartments.

Effects of pine bark amendment on the transport of sulfonamide antibiotics in soils

In the present work, laboratory column experiments were carried out to study the effect of pine bark amendment (at doses of 0, 12, 48 and 96 Mg ha^-1) on the transport of three sulfonamide antibiotics (sulfadiazine -SDZ-, sulfamethazine -SMT-, and sulfachloropyridazine -SCP-) through two crop soils. All three sulfonamides showed high mobility in the unamend soils, with absence of retention in most cases. However, some differences were detected regarding the degree of interactions between sulfonamides and soils, being higher for soil 1, which was attributed to its higher organic carbon content. For both soils, interactions with the antibiotics studied followed the sequence SDZ < SMT < SCP, indicating an increase as a function of the hydrophobicity of sulfonamides. Pine bark amendment significantly increased the retention of the three sulfonamides in both soils. Specifically, in the case of soil 1, the incorporation of the highest dose of pine bark (96 Mg ha^-1) caused that retention increased from 0% to 70.3% for SDZ, from 2.7% to 71.3% for SMT, and from 0% to 85.4% for SCP. This effect of pine bark is mainly attributed to its high organic carbon content (48.6%), including substances with potential to interact and retain antibiotics, as well as to its acidic pH (4.5). Therefore, pine bark amendment would be an effective alternative to reduce the transport of sulfonamides in soils and, thus, decrease risks of passing to other environmental compartments, as well as harmful effects on the environment and public health.

Spatial and temporal variations of antibiotics in a tidal river

Estuary is an important route for the transport of terrestrial contaminants to the ocean. Its unique hydrodynamic properties may influence the fate and distribution of pollutants. Previous studies have shown that severe pollution because of antibiotics has occurred in many inland surface waterbodies; however, the behavior of antibiotic residuals remains poorly understood in estuarine environments. In this study, the occurrence and spatiotemporal distribution of seven selected antibiotics (i.e., sulfamethazine, sulfamethoxazole, trimethoprim, ofloxacin, ciprofloxacin, erythromycin, and roxithromycin) in a tidal river were investigated through one continuous and four synoptic sampling events. Results show that the concentrations of most antibiotics are in the nanogram per liter level, except for trimethoprim with the highest concentration up to 12,440 ng L^-1 during the wet season. Except for sulfamethazine, the other six antibiotics showed high concentrations (i.e., > 100 ng L^-1) in at least one sampling campaign. Different temporal distribution patterns of these antibiotics indicated that they were mainly controlled by source loading, flow condition, and discharge amounts. Spatial distribution indicated that the main pollution source of trimethoprim was located in lower reaches, while the other six antibiotics mainly came from the upstream sources. Based on the theoretical dilution line, erythromycin and roxithromycin degraded in the tidal river, whereas the other five types of antibiotics showed a conservative behavior. Tide has important effects on the spatial distribution of antibiotics, especially those with a wide concentration range, in estuarine environments. Furthermore, risk assessment based on the calculated risk quotients showed that five types of antibiotics pose high risks to aquatic organisms. These observations provided new insight into the distribution and transport of common antibiotics in estuarine environments.

The grey water footprint of human and veterinary pharmaceuticals

Water pollution by pharmaceuticals is widespread, causing both environmental and human health risks. We assess pharmaceutical water pollution from human and veterinary pharmaceuticals at three geographical levels: global, national (considering Germany and the Netherlands) and catchment level (with a case study for the Vecht catchment shared by Germany and the Netherlands). The grey water footprint (GWF), a measure of water pollution in volumetric terms, is estimated from pharmaceutical loads entering the aquatic environment, considering different pollutant sources and pathways. We study different substances depending on data availability, which varies across geographical levels. Results show a global per capita GWF of 1900 m³ yr^-1 resulting from human consumption of ciprofloxacin. The largest GWFs in both Germany and the Netherlands were found for ethinylestradiol for human and amoxicillin for veterinary use. The estimated per capita GWF from human use of ethinylestradiol is 2300 m³ yr^-1 for Germany and 11,300 m³ yr^-1 for the Netherlands. The per capita GWFs of German and Dutch consumers of animal products are 12,900 and 10,600 m³ yr^-1, respectively. For the Vecht catchment, we estimate the water pollution level per sub-catchment by comparing the GWF to available runoff, which enables us to identify geographic hotspots. In the basin as a whole, GWFs from human and veterinary pharmaceuticals both exceed available runoff. At all levels, pharmaceutical water pollution substantially adds to earlier water footprint studies that excluded this type of pollution, which demonstrates the importance to include pharmaceutics in water footprint studies.

Environmentally Benign Nanoantibiotics with a Built-in Deactivation Switch Responsive to Natural Habitats

The massive use of antibiotics in healthcare and agriculture has led to their artificial accumulation in natural habitats, which risks the structure and function of the microbial communities in ecosystems, threatens food and water security, and accelerates the development of resistome. Ideally, antibiotics should remain fully active in clinical services while becoming deactivated rapidly once released into the environment, but none of the current antibiotics meet this criterion. Here, we show a nanoantibiotic design that epitomizes the concept of carrying a built-in "OFF" switch responsive to natural stimuli. The environmentally benign nanoantibiotics consist of cellulose backbones covalently grafted with hydrophilic polymer brushes that by themselves are antimicrobially inactive. In their nanostructured forms in services, these cellulose-based polymer molecular brushes are potent killers for both Gram-positive and Gram-negative bacteria, including clinical multidrug-resistant strains; after services and being discharged into the environment, they are shredded into antimicrobially inactive pieces by cellulases that do not exist in the human body but are abundant in natural habitats. This study illuminates a new concept of mitigating the environmental footprints of antibiotics with rationally designed nanoantibiotics that can be dismantled and disabled by bioorthogonal chemistry occurring exclusively in natural habitats.

Investigating the biodegradation of sulfadiazine in soil using Enterobacter cloacae T2 immobilized on bagasse

The application of the antibiotic sulfadiazine (SD) in veterinary medicine has created serious environmental issues due to its high mobility and non-degradability. A novel immobilized cell system has been developed and showed significant SD biodegradation potential in soil.

Multiresidue Determination of 27 Sulfonamides in Poultry Feathers and Its Application to a Sulfamethazine Pharmacokinetics Study on Laying Hen Feathers and Sulfonamide Residue Monitoring on Poultry Feathers

A method for the simultaneous determination of 27 sulfonamides in poultry feathers using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established in this study. The samples were extracted using 0.1 mol/L HCl solutions in a 60 °C water bath for 2 h, purified using hydrophilic-lipophilic balance solid-phase extraction, nitrogen-dried, and then reconstituted for UPLC-MS/MS analysis, which was performed with a CSH-C18 column. Linearity, limit of detection, limit of quantification, recovery, and precision were calculated in accordance with Commission Decision 2002/657/EC. For linearity, all standard curves showed a standard coefficient greater than 0.99, and the recoveries and coefficient of variation were 89-115% and <20%, respectively. The limit of detection and limit of quantification were 0.2-5 and 0.5-20 ng/g, respectively. The method was successfully applied to sulfamethazine (SMZ) residue accumulation monitoring in laying hen feathers and sulfonamide residue monitoring on poultry feathers. SMZ residue accumulation in the laying hen feathers was studied after administration with 100 mg/kg of SMZ for 21 consecutive days. SMZ residues were still detected in feathers 14 days after drug administration and persisted for up to 85 days. Results from 42 poultry feather samples showed that the feather is a suitable medium to monitor the illegal use of sulfonamides in poultry production.

Genomic characterization, kinetics, and pathways of sulfamethazine biodegradation by Paenarthrobacter sp. A01

Biodegradation is an important route for the removal of sulfamethazine (SMZ), one of the most commonly used sulfonamide antibiotics, in the environment. However, little information is known about the kinetics, products, and pathways of SMZ biodegradation owing to the complexity of its enzyme-based biotransformation processes. In this study, the SMZ-degrading strain A01 belonging to the genus Paenarthrobacter was isolated from SMZ-enriched activated sludge reactors. The bacterial cells were rod-shaped with transient branches 2.50-4.00 μm in length with most forming in a V-shaped arrangement. The genome size of Paenarthrobacter sp. A01 had a total length of 4,885,005 bp with a GC content of 63.5%, and it contained 104 contigs and 55 RNAs. The effects of pH, temperature, initial substrate concentration and additional carbon source on the biodegradation of SMZ were investigated. The results indicated that pH 6.0-7.8, 25 °C and the addition of 0.2 g/L sodium acetate favored the biodegradation, whereas a high concentration of SMZ, 500 mg/L, had an inhibitory effect. The biodegradation kinetics with SMZ as the sole carbon source or 0.2 g/L sodium acetate as the co-substrate fit the modified Gompertz model well with a correlation coefficient (R²) of 0.99. Three biodegradation pathways were proposed involving nine biodegradation products, among which C₆H₉N₃O₂S and C₁₂H₁₂N₂ were two novel biodegradation products that have not been reported previously. Approximately 90.7% of SMZ was transformed to 2-amino-4, 6-dimethylpyrimidine. Furthermore, sad genes responsible for catabolizing sulfonamides were characterized in A01 with high similarities of 96.0%-100.0%. This study will fill the knowledge gap in the biodegradation of this ubiquitous micropollutant in the aquatic environment.

Microbial diversity and antibiotic resistome in swine farm environments

Swine feedlots are recognized as a reservoir of antibiotic resistance genes (ARGs). However, the microbiome and antibiotic resistome in swine wastewater and its impact on receiving environments remain to be further explored by culture independent metagenomics. We investigated the microbial diversity of swine wastewater and the receiving environments in three swine farms by 16S rRNA gene sequencing. Metagenomic sequencing was utilized to further study the antibiotic resistome in the different depths of soils in vegetable fields, which had been fertilized with swine wastewater for at least 24 years. The 16S rRNA gene sequencing showed that the microbiome of the well water, fishpond, vegetables and the field soils was affected by the respective swine farms. Significant positive correlations were found between 20 ARGs and 41 genus of bacteria across all environmental samples. The metagenomic sequencing showed that a total of 79 types of ARGs were found in soil cores (at depth of 0-20 cm, 20-40 cm and 40-70 cm) and the irrigation water (swine wastewater). Antibiotics were detected in vertical soil profiles and wastewater. Compared with the vegetable fields without animal manure application, the soils irrigated with swine wastewater harbored higher diversity of ARGs and contained higher concentrations of antibiotics. Co-occurrence of integron-related scaffolds was found in different depths of soil cores and the swine wastewater. The results suggest that environmental microbiome was changed under the impact of swine farms, and long-term manure/wastewater application have resulted in the accumulation of ARGs in deeper soils Prudent use of antibiotics and reasonable management of animal wastes in livestock feedlots should therefore be considered to reduce the dissemination of antibiotic resistance to the environment.

Abiotic transformation products of tetracycline and chlortetracycline in salt solutions and manure

Tetracyclines belong to the group of the most applied antibiotics in veterinary medicine worldwide. Due to their incomplete absorption and/or metabolism in the animal gut, tetracyclines are frequently detected in manure samples. Within the matrix, an elimination of these compounds has been reported in several studies. However, only little information about potential transformation products of tetracyclines in manure and the environment is available. Therefore, the fate of tetracycline (TC) and chlortetracycline (CTC) was investigated in aqueous solutions and manure. Abiotic incubation of TC in phosphate buffer led to a remarkable red-brown coloring of the solution. Subsequent compound isolation and structure elucidation by MS/MS and NMR techniques revealed the formation of seco-cycline A, a compound formerly described as a fungal biotransformation product of TC. For CTC, two comparable products were identified which were derived from its isomeric form isoCTC. All transformation products showed no antimicrobial activity for concentrations up to 500 mg L^-1. When TC and CTC were incubated in cow manure for 7 d, the above mentioned three transformation products were also formed in this complex matrix (up to 5.1 mg kg^-1). Manure, soil and leachate samples from Lower Saxony revealed the presence of seco-cycline A in manure and soil, but not in water. To obtain a better insight in the fate of tetracyclines in environmental matrices, future analytical and ecotoxicological studies dealing with this subject should include the analysis especially of seco-cycline A.

A new extraction procedure to abate the burden of non-extractable antibiotic residues in manure

Through agricultural soil fertilization using organic manure, antibiotic residues can accumulate in the environment. In order to assess the risks of environmental pollution by veterinary drugs, monitoring of manure for antibiotic residues is necessary. As manure is a complex matrix, extraction of antibiotics proved to be challenging. In this study, 24 extraction solvents were assessed for the extraction of residues from manure representing ten antibiotics from the antibiotic classes tetracyclines, quinolones, macrolides, lincosamides and sulfonamides. Especially for the tetracyclines and quinolones the extraction solvent selection is critical, due to high fractions of non-extractable residues especially when using aqueous solvents (62-77% and 90-95% respectively when using milli-Q water). In contrast, sulfonamides can effectively be extracted with aqueous solvents. Overall, 0.125% trifluoroacetic acid in acetonitrile in combination with McIlvain-EDTA buffer proved to be the most effective extraction solvent. A longitudinal study pointed out that most antibiotics bind to solid manure particles instantaneously after addition. Trimethoprim is an exception, but because by using the optimal extraction solvent, the optimum fraction of bound residues is desorbed, this does not hamper quantitative analysis when using spiked manure quality control samples. Based on these new insights, the current in-house multi-residue LC-MS/MS method for manure analysis, containing 48 antibiotics, was revised, additionally validated and applied to 34 incurred manure samples.

Metabolism of Sulfamethoxazole by the Model Plant Arabidopsis thaliana

Phytometabolism of antibiotics is a potentially significant route of human exposure to trace concentrations of antibiotics, prompting concerns about antibiotic resistance. The present study evaluated the metabolism of sulfamethoxazole (SMX), a commonly used sulfonamide antibiotic, by Arabidopsis thaliana. SMX was intensively metabolized by A. thaliana, with only 1.1% of SMX in plant tissues present as the parent compound after 10 days of exposure. Untargeted screening of extractable metabolites revealed that N-glycosylation was the main transformation pathway of SMX in A. thaliana plants, with N⁴-glycosyl-SMX accounting for more than 80% of the extractable metabolites. Additionally, N⁴-glycosyl-glycoside SMX accounted for up to 4.4% of the extractable metabolites, indicating glycosylation of N⁴-glycosyl-SMX. The majority of minor extractable SMX metabolites were also conjugates of the parent compound, such as pterin-SMX and methyl salicylate-SMX conjugates. In ¹⁴C-SMX trials, ¹⁴C-radioactivity was detected in both extractable and bound residues in plant tissues. Extractable residues, which included ¹⁴C-SMX and its soluble metabolites, accounted for 35.8-43.6% of the uptaken ¹⁴C-radioactivity, while bound residues were 56.4-64.2%. Approximately 27.0% of the initially applied ¹⁴C-radioactivity remained in the culture media at the conclusion of the experiments, composed of both ¹⁴C-SMX and its metabolites, likely due to plant excretion.

Occurrence and distribution of pharmaceutical and personal care products, artificial sweeteners, and pesticides in groundwater from an agricultural area in Korea

This study investigated the occurrence and distribution of 33 pharmaceutical and personal care products (PPCPs), five artificial sweeteners (ASs), and six pesticides in groundwater in rural agricultural and rural non-agricultural area in South Korea. A total of 31 target compounds (15 antibiotics, four anthelmintics, seven other PPCPs, four ASs, and one pesticide) were detected in agricultural groundwater at concentrations from not detected (ND) to 49.3 ng/L for PPCPs, ND to 1340 ng/L for ASs, and ND to 116 ng/L for pesticides. Four target compounds (two PPCPs and two ASs) were detected in rural non-agricultural groundwater in the range of 0.085-5.74 ng/L for PPCPs and 5.64-1330 ng/L for ASs. Among the target compounds, ASs, especially acesulfame (detection frequency 69% in rural agricultural areas and 100% in the rural non-agricultural area) were predominantly detected in both agricultural (mean: 32.9 ng/L) and non-agricultural (mean: 536 ng/L) groundwater, but different occurrence patterns were observed according to the sources of contamination. Known markers of sewage leakage were detected in both agricultural and non-agricultural groundwater samples (e.g., acesulfame (69% and 100%), caffeine (88% and 100%), and crotamiton (62% and 100%)), while compounds related to agricultural activities were only observed in agricultural groundwater (e.g., sulfathiazole (38%), sulfamethoxazole (31%), oxfendazole (69%), and carbofuran (42%)).

Short-term geochemical investigation and assessment of dissolved elements from simulated ash reclaimed soil into groundwater

A soil column migration trough was used to study the leaching behavior and geochemical partitioning of fifteen elements Al, As, Cr, Cu, Fe, Mg, Sn, Sb, Zn, V, Co, Mn, Pb, Ni and Cd in simulated ash reclaimed soil. According to the results of cluster analysis for the sampling stations, there were three clusters: Cluster 1 of 7 wells with relative good groundwater quality originated from the background control area, Cluster 2 of 9 wells with worst groundwater quality in the downstream parts of the simulated ash reclaimed soil, and Cluster 3 of 2 wells with representative of samples influenced by the combined effect of injection of leaching solution and the main current. Statistical analysis identified five factor types that accounted for 83.055% of the total variance, which declined in the order: ash-soil rate > leaching intensity > water depths > flow velocity > leaching time. As, Sb, Cd, Pb and Ni were the dominant contaminants. The water around ash reclaimed soil was unsuitable for drinking. As, Mn, Cd, Sb, Co and V were the largest contributors to health risks. Soils reclaimed with fly ash can consequently be a long-time source for the transfer of toxic elements into groundwater.

Bioaccumulation of antibiotics in crops under long-term manure application: Occurrence, biomass response and human exposure

Long-term manure application gives rise to the uptake of antibiotics by plants and antibiotics subsequent entry into the food chain, representing an important alternative pathway for human exposure to antibiotics. The antibiotics can cause negative effects on crop growth and productivity. The bioaccumulation and translocation of 14 target antibiotics in peanuts (Arachis hypogaea L.) and their effects on peanut relative biomass in fields with long-term (≥15 years) manure application were studied. The results showed that all the target antibiotics were found in manures and rhizosphere soils, and most of them were found in all peanut tissues (roots, shells, kernels, stem, and leaves). The antibiotic concentrations in peanut tissues were varied with the characteristics of antibiotics in soils. Tetracyclines were the dominating antibiotic compounds in all peanut tissues, accounting for 61%-80% of total antibiotics due to their relatively high concentration in rhizosphere soil. Most tetracyclines and quinolones preferentially accumulated in the roots and translocated to other peanut tissues than sulfonamides and macrolides. Furthermore, the influence of antibiotics in soil and crops on relative biomass of crop tissues varied with tissues and antibiotic types. Antibiotics significantly inhibited the tissue relative biomass in most cases, although stimulation of some antibiotics to crop biomass was also observed. We found that 18.3% of the variance of the peanut relative biomass was explained by antibiotics in soils and tissues. The estimated threshold of daily intake values suggests that the consumption of peanut kernels grown in field conditions with long-term manure application presents a moderate risk to human health.