Occurrence and risk assessment of tetracycline antibiotics in soil from organic vegetable farms in a subtropical city, south China

Ten-month comprehensive assessment of steroid hormones in the tributaries of Baiyun District, Guangzhou City, China: Spatiotemporal dynamics, source attribution, and environmental implications

The occurrence of steroid hormones in small river ecosystems raises environmental alarms due to their limited dilution capacity, heightened susceptibility to diverse pollution sources, and their substantial contribution to the contamination of larger river systems. Here, we investigated the occurrence of 40 steroid hormones over 10 months in 10 first-order tributaries (n = 250) of Guangzhou City, China. The observed concentrations of Σsteroid hormones ranged from 30.5 to 450 ng/L (mean: 55.6 ± 35.4 ng/L). No substantial variation in steroid hormone concentrations was observed between the flood and dry seasons, reflecting an intricate balance of dilution dynamics, agricultural runoff, and wastewater releases. Further correlation analysis underscored wastewater discharge as a consistent source of steroid hormone occurrence, with spikes coinciding with concurrent fertilizer application and rainfall intervals. Steroid hormone concentrations displayed significant spatial variations. Correlation analyses connected steroid hormone levels to nutrients in tributaries and agricultural ditch water and land usage, highlighting the joint effect of runoff and various wastewater types on steroid hormone distribution. Interestingly, steroid hormone levels displayed minimal variation along the tributaries, suggesting uniform and continuous pollution sources. Source attribution analysis revealed that 51.7 % of steroid hormones originated from untreated domestic wastewater, followed by treated wastewater, livestock wastewater, and runoff. Notably, 92.0 % of the sampling sites registered at least one steroid hormone level exceeding the risk quotient threshold of 1, indicating widespread ecological hazards. Our research emphasizes the persistent and stable nature of steroid hormone-related risks across seasons and along the tributaries, highlighting the imperative for vigilant monitoring. We further advocate for intensified surveillance efforts during pivotal periods (e.g., fertilization periods and low rainfall intervals), to better address these environmental challenges.

Tetracycline and fluoroquinolone antibiotics contamination in agricultural soils fertilized long-term with chicken litter: Trends and ravages

We investigated the potential accumulation of tetracyclines (TCs) such as chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DC), and fluoroquinolones (FQs) like enrofloxacin (ENR) and ciprofloxacin (CIP) in chicken litter and agricultural soils fertilized over short-term to long-term (<1-30 yrs) with chicken litter in a poultry hub for the first time from Tamil Nadu, India. CTC, OTC, DC, CIP, and ENR were detected in 46-92 % of the selected chicken litter samples, with mean levels ranging from 2.90 to 23.30 μg kg-1. Higher concentrations of TCs and FQs were observed in freshly collected chicken litter from poultry sheds than in those stockpiled in cultivated lands. CTC was the prevalent antibiotic in chicken litter. The overall occurrence, as well as the ecological risks of TCs and FQs, changed over a 30-yr period. The accumulation of veterinary antibiotics (VAs) (in μg kg-1) in short-term (>1 yr) to medium-term (1-3 yrs) chicken litter-fertilized soils reached a maximum of 11.60 for CTC, 6.50 for OTC, 0.80 for DC, 3.70 for CIP, and 3.60 for ENR, but decreased in long-term (10-30 yrs) fertilized soils. Ecological risk assessment revealed a Risk Quotient (RQ) of ≤0.10 for CTC, OTC, and DC in all soils, while an average risk (RQ >0.10-<1.0) was evident with CIP and ENR in short-term and medium-term fertilized soils. Antibiotic resistance genes (ARGs), including tetA, tetB, qnrA, qnrB and qnrS were detected in most of the chicken litter samples and litter-fertilized soils. Thus, it is critical to develop and adopt effective mitigation strategies before applying chicken litter in farmlands to decrease VAs and ARGs, reducing their associated risks to public health and ecosystems in India considering 'One Health' approach. Future investigations on the occurrence of other VAs and ARGs in soils fertilized with poultry litter at regional scale are required for effective risk mitigation of the widely used VAs.

Accumulation of microcystin toxin in irrigation water and alfalfa (Medicago sativa) forage plant, and assessing the potential risk to animal health

Microcystin (MC) toxin produced by cyanobacteria has become a significant concern for societies worldwide. The risk of MC in drinking water has been assessed to human health. Nonetheless, its risk to animal health has not been thoroughly evaluated. This study investigated MCs in irrigation water and alfalfa plant from nearby farmlands. Both irrigation water and alfalfa shoots contained greater MC concentrations (1.8-17.4 μg L-1 and 0.053-0.128 μg g-1) during summer than winter (2.4 μg L-1 and 0.017 μg g-1). These MC concentrations showed a correlation with the predominance of cyanobacteria in the sites, triggering the potential risk of these microorganisms in irrigation waters. Accordingly, there would be a high risk (risk quotient, RQ > 1) during summer and a moderate risk (0.1 Collapse

Key Words

• Animal feed
• Cyanotoxins
• Freshwaters
• Livestock
• cyanobacteria

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MESH Headings

• Microcystins/metabolism
• Microcystins/analysis
• Medicago sativa/metabolism
• Animals
• Agricultural Irrigation
• Risk Assessment
• Environmental Monitoring
• Seasons
• Cyanobacteria/metabolism
• Water Pollutants, Chemical/metabolism
• Water Pollutants, Chemical/analysis
• Cattle
• Sheep

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Grants Collapse

Affiliation(s)

Zakaria A Mohamed Department of Botany and Microbiology, Faculty of Science, Sohag University, Sohag, 82524, Egypt.
Yasser Mostafa King Khalid University, College of Science, Department of Biology, Abha, P.O. Box 9004, Saudi Arabia
Saad Alamri King Khalid University, College of Science, Department of Biology, Abha, P.O. Box 9004, Saudi Arabia
Mohamed Hashem Assiut University, Faculty of Science, Botany and Microbiology Department, Assiut 71516, Egypt

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The relationship between water quality and the microbial virulome and resistome in urban streams in Brazil

Urban streams that receive untreated domestic and hospital waste can transmit infectious diseases and spread drug residues, including antimicrobials, which can then increase the selection of antimicrobial-resistant bacteria. Here, water samples were collected from three different urban streams in the state of São Paulo, Brazil, to relate their range of Water Quality Indices (WQIs) to the diversity and composition of aquatic microbial taxa, virulence genes (virulome), and antimicrobial resistance determinants (resistome), all assessed using untargeted metagenome sequencing. There was a predominance of phyla Proteobacteria, Actinobacteria, and Bacteroidetes in all samples, and Pseudomonas was the most abundant detected genus. Virulence genes associated with motility, adherence, and secretion systems were highly abundant and mainly associated with Pseudomonas aeruginosa. Furthermore, some opportunistic pathogenic genera had negative correlations with WQI. Many clinically relevant antimicrobial resistance genes (ARGs) and efflux pump-encoding genes that confer resistance to critically important antimicrobials were detected. The highest relative abundances of ARGs were β-lactams and macrolide-lincosamide-streptogramin. No statistically supported relationship was detected between the abundance of virulome/resistome and collection type/WQI. On the other hand, total solids were a weak predictor of gene abundance patterns. These results provide insights into various microbial outcomes given urban stream quality and point to its ecological complexity. In addition, this study suggests potential consequences for human health as mediated by aquatic microbial communities responding to typical urban outputs.

A perspective of spatial variability and ecological risks of antibiotics in the agricultural-pastoral ecotone soils in eastern Inner Mongolia

Antibiotics have garnered growing attention as pharmaceuticals ubiquitously present in human society. Within the soil environment, antibiotics exhibit a propensity for high environmental persistence, thereby posing a potential threat to the ecosystem. However, research on antibiotics in agricultural-pastoral ecotone soils is scarce. This study investigates the occurrence, distribution and risk of 11 common antibiotics in agricultural soils of the agro-pastoral transition zone in Horqin Left Middle Banner, eastern Inner Mongolia. The total concentration varies from not detectable to 609.62 μg/kg. Tetracyclines are the dominant antibiotic, with a higher detection frequency than Macrolides and Sulfonamides. The detection rates of the three types of antibiotics differ significantly. The study also finds that soil properties (organic matter content, pH, bulk density, clay, cation exchange capacity have no significant correlation with antibiotics in soil. Moreover, spatial regression analysis reveals that population density is the primary factor influencing the spatial distribution of antibiotics in soil. Ecological risk assessment shows that clarithromycin and erythromycin are the two most harmful factors in the ecological risk of agricultural soil.

Tetracyclines uptake from irrigation water by vegetables: Accumulation and antimicrobial resistance risks

Wastewater irrigation may introduce antibiotic residues in the soil-plant systems. This study aimed to investigate the uptake of tetracyclines by spinach and collard greens and assess associated ecological and human health risks. Synthetic wastewater spiked with 1 ppm and 10 ppm of oxytetracycline, doxycycline, and tetracycline was used to grow vegetables in a greenhouse pot experiment. The uptake and accumulation of the tetracyclines were low and residual concentrations in the soil were negligible. All the tetracyclines were detected at concentrations ranging from 1.68 to 51.41 μg/g (spinach) and 1.94-30.95 μg/g (collard greens). The accumulation rate was in a dose-response scenario with a bioconcentration factor of 6.34 mL/kg (spinach) and 2.64 mL/kg (collard greens). Oxytetracycline had the highest accumulation in leaves, followed by doxycycline and tetracycline, and the residual concentrations followed the same order. The highest residual concentration was in soils receiving 10 ppm oxytetracycline. Residual concentrations in the soil were lower than accumulated levels and exerted negligible ecological risks. Tetracyclines accumulation in spinach significantly differed between the vegetables demonstrating a subspecies difference in uptake and accumulation. Ecological risk quotient (RQ) and human health risk quotient (HQ) were below thresholds that would exert toxicity and resistance selection impacts. Although RQs and HQs are low (<0.1), this study shows that the vegetables accumulate tetracyclines from irrigation water, posing plausible human health risks to allergic individuals. Similarly, the ecological risks cannot be ignored because the synergistic and antagonistic effects of sublethal concentrations can perturb ecosystem processes.

Effects of microplastics and tetracycline on intestinal injury in mice

Microplastics (MPs) and tetracycline are both emerging environmental pollutants that threaten human health. The toxic impacts of their single and coexposure on the intestine and gut microbiota have not been well studied in mammals. Given the spatial functional characteristics of the intestine, it is important to know whether the toxicities of MPs and tetracycline in different intestinal segments are distinct. This study investigated the pathological and functional injuries of different intestinal segments and the microbial disorder upon exposure to polystyrene microplastics (PS-MPs) and/or tetracycline hydrochloride (TCH). Both PS-MPs and TCH altered the intestinal morphology and induced functional impairment. However, the PS-MPs primarily damaged the colon, while TCH mainly damaged the small intestine, especially the jejunum. Combined treatment evoked ameliorative adverse effects on the intestinal segments except for the ileum. Gut microbiota analysis revealed that PS-MPs and/or TCH decreased gut microbiota diversity, especially PS-MPs. In addition, PS-MPs and TCH affected the microflora metabolic processes, especially protein absorption and digestion. Gut microbiota dysbiosis could partly lead to the physical and functional damage induced by PS-MPs and TCH. These findings enhance our knowledge regarding the hazards of coexisting microplastics and antibiotics for mammalian intestinal health.

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

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

Urbanization-land-use interactions predict antibiotic contamination in soil across urban-rural gradients

Antibiotics ubiquitously occur in soils and pose a potential threat to ecosystem health. Concurrently, urbanization and land-use intensification have transformed soil ecosystems, but how they affect antibiotic contamination remain largely unknown. Therefore, we profiled a broad-scale pattern of antibiotics in soil from agricultural lands and green spaces across urbanization gradients, and explored the hypothetical models to verify the effects of urbanization and land-use intensity on antibiotic contamination. The results showed that antibiotic concentrations and seasonality were higher in agricultural soil than in green spaces, which respectively showed linear or hump-shaped declines along with the increasing distance to urban centers. However, the response of antibiotic pollution to land-use intensity depended strongly on the urbanization level. More importantly, interactions between urbanization and land-use explained, on average, 59.6 % of the variation in antibiotic concentrations in soil across urbanization gradients. The proposed interactions can predict the non-linear changes in soil vulnerability to antibiotic contamination. Our study revealed that the urbanization can modulate the effects of land-use intensity on antibiotic concentration and seasonality in the soil environment, and that there is high stress on peri-urban soil ecosystems due to ongoing land-use changes arising from rapid urbanization processes.

Poultry manure gleaned antibiotic residues in soil environment: A perspective of spatial variability and influencing factors

The antibiotics released by human and animals end up in the environmental sinks like soil and water to cause contamination and induce resistance in the microflora. The knowledge of fate and behavior of antibiotics in diverse geographical, climatological, and physicochemical is limited. Therefore, present study investigated the spatial distribution of antibiotics and their relationship with various factors and the source-sink relationship between soil and poultry manure. This was achieved by employing spatially constrained hierarchical clustering, global and local spatial autocorrelation, and spatial regression techniques. Most of the antibiotics co-occurred in both soil and poultry manure matrices, however antibiotic concentration in soil (1.20 μg kg^-1 < antibiotics ≤21.38 μg kg^-1) was lower than that in the poultry manure (7.05 μg kg^-1< antibiotics ≤60.2 μg kg^-1). Majority of the antibiotics showed spatial independence in both poultry manure and soil, except for sulfadiazine, sulfanilamide and sulfapyridine with Moran's I > - 0.111. Local indicator of spatial association indicated localized spatial clustering and outlier behavior of antibiotics. The underlying reasons for spatial heterogeneity of antibiotics resolved by spatial regression models indicated elevation, S%, C%, pH and mean annual temperature as the major factors. The influence of antibiotic concentration in poultry manure as a source was significant but marginal compared to the other predictors of spatial heterogeneity.

The Source and Distribution of Tetracycline Antibiotics in China: A Review

In recent years, antibiotics have been listed as a new class of environmental pollutants. Tetracycline antibiotics (TCs) used in human medical treatment, animal husbandry and agricultural production are the most widely used antibiotics. Due to their wide range of activities and low cost, their annual consumption is increasing. TCs cannot be completely metabolized by humans and animals. They can be abused or overused, causing the continuous accumulation of TCs in the ecological environment and potential negative effects on non-target organisms. These TCs may spread into the food chain and pose a serious threat to human health and the ecology. Based on the Chinese environment, the residues of TCs in feces, sewage, sludge, soil and water were comprehensively summarized, as well as the potential transmission capacity of air. This paper collected the concentrations of TCs in different media in the Chinese environment, contributing to the collection of a TC pollutant database in China, and facilitating the monitoring and treatment of pollutants in the future.

Adaptation of Rhizosphere Microbial Communities to Continuous Exposure to Multiple Residual Antibiotics in Vegetable Farms

The constant application of manure-based fertilizers in vegetable farms leads to antibiotic residue accumulation in soils, which has become a major stressor affecting agroecosystem stability. The present study investigated the adaptation profiles of rhizosphere microbial communities in different vegetable farms to multiple residual antibiotics. Multiple antibiotics, including trimethoprim, sulfonamides, quinolones, tetracyclines, macrolides, lincomycins, and chloramphenicols, were detected in the vegetable farms; the dominant antibiotic (trimethoprim) had a maximum concentration of 36.7 ng/g. Quinolones and tetracyclines were the most prevalent antibiotics in the vegetable farms. The five most abundant phyla in soil samples were Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi and Firmicutes, while the five most abundant phyla in root samples were Proteobacteria, Actinobacteria, Bacteroidetes, Firmicutes and Myxococcota. Macrolides were significantly correlated with microbial community composition changes in soil samples, while sulfonamides were significantly correlated with microbial community composition changes in root samples. Soil properties (total carbon and nitrogen contents and pH) influenced the shifts in microbial communities in rhizosphere soils and roots. This study provides evidence that low residual antibiotic levels in vegetable farms can shift microbial community structures, potentially affecting agroecosystem stability. However, the degree to which the shift occurs could be regulated by environmental factors, such as soil nutrient conditions.

Source, occurrence and risks of twenty antibiotics in vegetables and soils from facility agriculture through fixed-point monitoring and numerical simulation

In this study, a universal method that combined fixed-point monitoring and numerical simulation was used to understand the source, fate and risks of antibiotics in environment. Results showed that the antibiotic concentration in vegetables, soil and manure from 53 fixed-point monitoring sampling sites were ND-18.47, ND-1438.50 and ND-24710.00 μg kg^-1, respectively. There were positive correlations between the antibiotic concentrations of vegetables and soil as well as between soil and manure. The average Amount_soil/manure values were 1.48-46.02, indicating that antibiotics built up pseudo persistent residues in soil due to repeated fertilization. The modified level-III fugacity model showed that tetracyclines and fluoroquinolones tend to remain in soil given their sorption and mobility, while sulfonamides were highly distributed in plants, especially in leaves. Norfloxacin, ofloxacin, sulfadiazine, sulfamethoxazole and sulfisoxazole were found to be risk factors in facility agriculture and should be continuously monitored during agricultural production. Most importantly, we used the inversion method to determine the recommended maximum residue limits of antibiotics in soil. This will not only allow for better control of the amount of the antibiotics in the environment, but also act as a potential method to assess the risks of pollutants without maximum residue limits in the environment.

Occurrence and removal of 25 antibiotics during sewage treatment processes and potential risk analysis

The occurrence and removal of 25 antibiotics, including ten quinolones (QNs), four macrolides (MLs), four tetracyclines (TCs) and seven sulfonamides (SNs), were analysed at two sewage treatment plants (STPs) with different treatment units in Guangxi Province, China. The results showed that 14 and 16 antibiotics were detected in the influent of the two STPs, with concentrations ranging from 13.7-4265.2 ng/L and 14.5-10761.7 ng/L, respectively. Among the antibiotics, TCs were the main type in the study area, accounting for more than 79% of the total concentration of all antibiotics. The antibiotic removal efficiencies of the different process units ranged from -56.73% to 100.0%. It was found that the SN removal efficiency of the multistage composite mobile bed membrane bioreactor (MBBR) process was better than that of the continuous-flow Intermission biological reactor (IBR) process, while the IBR process was better than the MBBR process in terms of removing TCs and MLs; however, there was no obvious difference in the QN removal efficiencies of these two processes. Redundancy analysis (RDA) showed a strong correlation between antibiotic concentration and chemical oxygen demand (COD). Risk assessments indicated that algae, followed by invertebrates and fish, were the most sensitive aquatic organisms to the detected antibiotics.

Photoelectrochemical aptasensor for sensitive detection of tetracycline in soil based on CdTe-BiOBr heterojunction: Improved photoactivity enabled by Z-scheme electron transfer pathway

Exploring effective methods for tetracycline (TC) detection in soil has great significance because of its emerging environmental problem and increasing threat to soil quality and general public health worldwide. In this work, a sensitive photoelectrochemical (PEC) aptasensor toward TC detection was designed and constructed based on an efficient photosensitive material of Z-scheme CdTe-BiOBr heterojunction. Due to the sensitization of CdTe quantum dots (QDs) on the BiOBr nanoflowers, the photocurrent intensity of the CdTe-BiOBr heterojunction was enhanced about 5.0-fold and 8.0-fold than that of pure BiOBr and CdTe under visible-light irradiation, which was attributed to the low electron-hole combination efficiency, high visible light utilization efficiency, and high carrier density of the heterojunction. On the merits of the excellent PEC activity of the CdTe-BiOBr and the specificity of the aptamer, the proposed PEC aptasensor has the advantages of satisfying linear range (from 10 to 1500 pM), low detection limit (9.25 pM), good selectivity, and reproducibility. In addition, acceptable accuracy was obtained for TC detection in real soil sample, giving acceptable accuracy in comparison with the referenced high-performance liquid chromatography-diode array detector method, revealing a promising avenue for accurate and ultrasensitive estimation of other kinds of contaminants in the broad field of analysis.

Distribution of antibiotic resistance genes in the environment

The prevalence of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the microbiome is a major public health concern globally. Many habitats in the environment are under threat due to excessive use of antibiotics and evolutionary changes occurring in the resistome. ARB and ARGs from farms, cities and hospitals, wastewater treatment plants (WWTPs) or as water runoffs, may accumulate in water, soil, and air. We present a global picture of the resistome by examining ARG-related papers retrieved from PubMed and published in the last 30 years (1990-2020). Natural Language Processing (NLP) was used to retrieve 496,640 papers, out of which 9374 passed the filtering test and were further analyzed to determine the distribution and diversity of ARG subtypes. The papers revealed seven major antibiotic families together with their respective ARG subtypes in different habitats on six continents. Asia, especially China, had the highest number of ARGs related papers compared to other countries/regions/continents. ARGs belonging to multidrug, glycopeptide, and β-lactam families were the most common in reports from hospitals and sulfonamide and tetracycline families were common in reports from farms, WWTPs, water and soil. We also highlight the 'omics' tools used in resistome research, describe some factors that shape the development of resistome, and suggest future work needed to better understand the resistome. The goal was to show the global nature of ARB and ARGs in order to encourage collaborate research efforts aimed at reducing the negative impacts of antibiotic resistance on the One Health concept.

[Simultaneous determination of 30 antibiotics in soil by ultra-high performance liquid chromatography-tandem mass spectrometry]

土壤基质复杂,土壤中残留的抗生素种类繁多,浓度多为痕量水平,高灵敏度的仪器方法、有效的净化和富集方法、多种类抗生素的同时检测是土壤中抗生素检测的重点和难点。该研究建立了固相萃取-超高效液相色谱-串联质谱法同时测定土壤中7类(磺胺类、氟喹诺酮类、四环素类、大环内酯类、β-内酰胺类、酰胺醇类和林可酰胺类)30种抗生素的方法。首先,通过参数优化确定最佳质谱条件,选择BEH-C18色谱柱,以0.1%(v/v)甲酸甲醇溶液-0.1%(v/v)甲酸水溶液为流动相,10%(v/v)甲醇水溶液为进样溶剂。然后,通过提取条件(萃取剂种类及体积)和固相萃取条件(上样液pH、淋洗液有机溶剂比例、洗脱液种类及体积)的优化,确定使用10 mL乙腈和Na₂EDTA-McIlvaine缓冲液的混合溶液(1:1, v/v)为萃取剂,萃取液pH调节至8.0后,采用HLB小柱进行固相萃取,并以10 mL超纯水淋洗净化,最后用10 mL甲醇-乙腈(1:1, v/v)洗脱目标分析物。在优化的分析条件下,该方法的定量限为0.043~4.04 μg/kg,目标化合物的标准曲线线性关系良好,相关系数在0.992~1.00的范围内,在20、100、200 μg/kg的添加浓度下,大多数目标化合物的加标回收率范围为44.8%~164%,相对标准偏差为0.700%~14.8%。将该方法用于6个实际土壤样品的分析,结果显示在30种抗生素中,17种抗生素有检出,其中12种抗生素的检出率为100%。环丙沙星和诺氟沙星是土壤样品中含量最高的两种抗生素,它们的含量范围分别是13.7~32.1和15.6~43.6 μg/kg。本研究建立的方法简单、快速、溶剂使用量少,能用于土壤样品中痕量水平的7类30种抗生素的同时测定。

Metabonomics reveals an alleviation of fitness cost in resistant E. coli competing against susceptible E. coli at sub-MIC doxycycline

High concentrations of antibiotics may induce bacterial resistance mutations and further lead to fitness costs by reducing growth of resistant bacteria. However, antibiotic concentrations faced by bacteria are usually low in common environments, which leads to questions about how resistant bacteria with fitness costs regulate metabolism to coexist or compete with susceptible bacteria during sublethal challenge. Our study revealed that a low proportion (< 15%) of resistant bacteria coexisted with susceptible bacteria due to the fitness cost without doxycycline. However, the cost for the resistant strain decreased at a doxycycline concentration of 1 mg/L and even disappeared when the doxycycline concentration was 2 mg/L. Metabonomics analysis revealed that bypass carbon metabolism and biosynthesis of secondary metabolites were the primary metabolic pathways enriching various upregulated metabolites in resistant bacteria without doxycycline. Moreover, the alleviation of fitness cost for resistant bacteria competed with susceptible bacteria at 1 mg/L doxycycline was correlated with the downregulation of the biomarkers pyruvate and pilocarpine. Our study offered new insight into the metabolic mechanisms by which the fitness cost of resistant mutants was reduced at doxycycline concentrations as low as 1 mg/L and identified various potential metabolites to limit the spread of antimicrobial resistance in the environment.

Tetracycline and Sulfonamide Antibiotics in Soils: Presence, Fate and Environmental Risks

Veterinary antibiotics are widely used worldwide to treat and prevent infectious diseases, as well as (in countries where allowed) to promote growth and improve feeding efficiency of food-producing animals in livestock activities. Among the different antibiotic classes, tetracyclines and sulfonamides are two of the most used for veterinary proposals. Due to the fact that these compounds are poorly absorbed in the gut of animals, a significant proportion (up to ~90%) of them are excreted unchanged, thus reaching the environment mainly through the application of manures and slurries as fertilizers in agricultural fields. Once in the soil, antibiotics are subjected to a series of physicochemical and biological processes, which depend both on the antibiotic nature and soil characteristics. Adsorption/desorption to soil particles and degradation are the main processes that will affect the persistence, bioavailability, and environmental fate of these pollutants, thus determining their potential impacts and risks on human and ecological health. Taking all this into account, a literature review was conducted in order to shed light on the current knowledge about the occurrence of tetracycline and sulfonamide antibiotics in manures/slurries and agricultural soils, as well as on their fate in the environment. For that, the adsorption/desorption and the degradation (both abiotic and biotic) processes of these pollutants in soils were deeply discussed. Finally, the potential risks of deleterious effects on human and ecological health associated with the presence of these antibiotic residues were assessed. This review contributes to a deeper understanding of the lifecycle of tetracycline and sulfonamide antibiotics in the environment, thus facilitating decision-making for the application of preventive and mitigation measures to reduce its negative impacts and risks to public health.

Recognition of typical antibiotic residues in environmental media related to groundwater in China (2009-2019)

The potential adverse environmental and health-related impacts of antibiotics are becoming more and more concerning. China is globally the largest antibiotic producer and consumer, possibly resulting in the ubiquity and high detection levels of antibiotics in environmental compartments. Clear status on the concentration levels and spatial distribution of antibiotic contamination in China's environment is necessary to gain insight into the establishment of legal and regulatory frameworks. This study collects information from over 170 papers reporting the occurrence and distribution of antibiotics in China's environment. A total of 110 antibiotics were detected, and 28 priority antibiotics were ubiquitous in China in almost all compartments of the environment, excluding the atmosphere. Seven dominant antibiotics in all environment compartments were identified by cluster analysis, including tetracycline, oxytetracycline, chlortetracycline, ofloxacin, enrofloxacin, norfloxacin, and ciprofloxacin. Meanwhile, sulfamethoxazole, sulfadiazine, and sulfamethazine were also frequently found in aqueous phases. Among the main basins where antibiotics were detected, the Haihe River Basin had higher median antibiotic concentrations in surface water compared to other basins, while the Huaihe River Basin had higher median concentrations in sediment. The median values of antibiotic concentrations in the sources were as follows: animal manure, 39 μg/kg (microgram per kilogram); WWTP (wastewater treatment plant) sludge, 39 μg/kg; animal wastewater, 156 ng/L (nanogram per liter); WWTP effluent: 15 ng/L. These concentrations are 1 - 2 orders of magnitude higher than that of the receptors (soil, 2.1 μg/kg; sediment, 4.7 μg/kg; surface water, 8.1 ng/L; groundwater, 2.9 ng/L), whether in solid or aqueous phases. Based on the number of detected antibiotics in various environmental compartments, animal farms and WWTPs are the main sources of antibiotics, and surface water and sediment are the main receptors of antibiotics. Hierarchical clustering identified the two main pathways of antibiotic transfer in various environmental compartments, which are from animal wastewater/WWTP effluent to surface water/sediment and from animal manure/WWTP sludge to soil/groundwater.

Sample Preparation to Determine Pharmaceutical and Personal Care Products in an All-Water Matrix: Solid Phase Extraction

Pharmaceuticals and personal care products (PPCPs) are abundantly used by people, and some of them are excreted unaltered or as metabolites through urine, with the sewage being the most important source to their release to the environment. These compounds are in almost all types of water (wastewater, surface water, groundwater, etc.) at concentrations ranging from ng/L to µg/L. The isolation and concentration of the PPCPs from water achieves the appropriate sensitivity. This step is mostly based on solid-phase extraction (SPE) but also includes other approaches (dispersive liquid-liquid microextraction (DLLME), buckypaper, SPE using multicartridges, etc.). In this review article, we aim to discuss the procedures employed to extract PPCPs from any type of water sample prior to their determination via an instrumental analytical technique. Furthermore, we put forward not only the merits of the different methods available but also a number of inconsistencies, divergences, weaknesses and disadvantages of the procedures found in literature, as well as the systems proposed to overcome them and to improve the methodology. Environmental applications of the developed techniques are also discussed. The pressing need for new analytical innovations, emerging trends and future prospects was also considered.

Adsorption-desorption of doxycycline in agricultural soils: Batch and stirred-flow-chamber experiments

With the aim of obtaining information about the environmental fate and dynamics of the antibiotic doxycycline (DC) when it reaches soil, adsorption and desorption processes were studied for this compound in 20 agricultural soils, by means of batch-type and stirred-flow-chamber experiments. The results indicate that the studied soils adsorbed high amounts of DC, with adsorption percentages >91% in all cases. In addition, adsorption results were satisfactorily modeled, with good fittings to the Langmuir and Freundlich equations, with the values for Langmuir's maximum adsorption capacity (q_max) varying between 14,692 and 26,141 μmol kg^-1 (average 17,816), and between 1,906 and 13,120 Lⁿ μmol^1-n kg^-1 (average 6,969) for the Freundlich affinity coefficient, which are very high. The soil variables most related to the adsorption of the antibiotic were linked to organic matter (specifically, soil organic carbon-SOC- and soil nitrogen -N- contents), and to the clay fraction, as well as to cation exchange capacity, being the soils with a greater content in these variables those that presented a greater adsorption. FTIR results shown that DC adsorption mechanisms were based on interactions such as hydrogen bonds and π-π interactions between the antibiotic and soils. Desorption was very low, reaching values between 1 and 2% in batch experiments, and between 5 and 15% in stirred flow chamber experiments, which indicates a strong hysteresis affecting adsorption and desorption processes. This fact can be considered positively, as these soils could retain DC very strongly, thus reducing risks to human and ecological health.

Simultaneous analysis of multiclass antibiotic residues in complex environmental matrices by liquid chromatography with tandem quadrupole mass spectrometry

A simultaneous extraction and cleanup method was optimized and validated for the determination of 40 antibiotics from cephalosporin, fluoroquinolone, lincosamide, macrolide, nitroimidazole, quinolone, sulfonamide and tetracycline groups in sediments by liquid chromatography with tandem quadrupole mass spectrometry (LC-MS/MS). The method involved hydration of freeze-dried sediment sample (2.0 g) with 2.5 ml of 0.1 M Na-EDTA McIlvaine buffer and extraction with 5 ml of MeOH and MeCN (1:3 v/v) followed by dispersive solid phase extraction by using 100 mg mix of C18 and PSA (1:2 w/w) and 50 mg MgSO₄ prior to LC-MS/MS analysis. The method was validated for 10, 20, 50 and 100 µg/kg spiking levels by using blank sediment sample obtained from a drinking water reservoir according to the guidelines of European Commission Decision (2002) 2002/657/EC. The method produced clean extracts with generally low matrix effect during LC-MS/MS analysis. The mean recoveries ranged between 24-162%, 48-151%, 51-159%, and 50-149% for 10, 20, 50 and 100 µg/kg spiking levels, respectively, with acceptable precision. The analytical method was sensitive enough to achieve 0.01-34.3 µg/kg and 0.03-115 µg/kg limits of detection and quantitation, respectively. The scope of the method was demonstrated by analyzing complex solid environmental matrices (chicken manure, swine manure, poultry feed and soil) spiked at 10, 20, 50 and 100 µg/kg levels. The method was also applied for the antibiotic analysis in samples with incurred residues. Different matrices in the order of the magnitude as sediments < poultry feed < swine manure < soil < chicken manure were detected with the residues of fluoroquinolone, macrolide, sulfonamide and tetracycline antibiotics.

The response of soil nematode Caenorhabditis elegans on the sewage sludge-derived micropollutants

Sewage sludge application to soil is of great interest, due to required organic matter and the wide spectra of nutrients it provides. However, the presence of unpredictable content of emerging contaminants may turn this valuable raw material into a hazardous substance. In this study, three selected sewage sludges derived micropollutants from different origins; that is, one each under persistent organic pollutants (POPs), pharmaceuticals and personal care products (PPCPs) were considered. The effect of each micropollutant on the feeding activity of free-living soil nematode Caenorhabditis elegans was analysed. The analysis was performed in model soil solution using a larval feeding inhibition assay. The results showed no significant effects from selected POP-2,2',4,4',5-pentabromodiphenyl either and pharmaceutical-chlortetracycline on the feeding activity of tested nematodes. On the contrary, feeding activity was inhibited by PPCP-galaxolide (HHCB) with an effective concentration of 12.2 ± 2.2 mg.l-1. The calculated risk quotient for galaxolide (RQ = 0.14) demonstrated a medium ecological risk to the nematodes. Based on our findings, concentrations of micropollutants in sewage sludge treated soil pose negligible risk to feeding activity of soil nematode. However, the potential impact of musk compounds on free-living soil biota requires detailed evaluation in further research.

High ecological and human health risks from microcystins in vegetable fields in southern China

Frequent cyanobacterial blooms in the eutrophic waters produce a variety of toxins such as the monocyclic heptapeptide microcystins, greatly harming aquatic ecosystems and human health. However, little information of microcystins in agricultural fields is known. This field study of three common microcystin variants (MC-LR, MC-RR, and MC-YR) in vegetables (n = 161), soils (n = 161) and irrigation water samples (n = 23) collected from southern China regions affected by cyanobacteria blooms, shows their prevalence with total concentrations up to 514 μg/L water, 187 μg/kg soil (dry weight) and 382 μg/kg vegetable (fresh weight). MC-RR was the primary variant in all types of samples, accounting for 51.3-100% of total microcystin concentrations. Significant concentration-dependent correlations (p < 0.05) demonstrated that microcystin-contained irrigation waters were the major source of microcystin accumulation in both vegetables and soils. Meanwhile, intracellular-microcystins in irrigation water was found to play an important role in microcystins bioaccumulation in vegetables for the first time. Most vegetable samples (≥60%), particularly celery posed moderate or high human health risk via diet based on toxicity equivalents of the microcystins and reference dose for MC-LR (0.04 μg/kg/d), showing high food safety hidden dangers. Soil microcystins, especially MC-RR in 46.4-88.3% of soils could pose high ecological risks. This study highlights the potential high ecological and human health risks of microcystins in the real soil-vegetable systems of areas affected by cyanobacteria blooms, implying the profound significance and urgent need of investigation on microcystins in terrestrial ecosystems.

The accumulation and distribution of five antibiotics from soil in 12 cultivars of pak choi

There is a lack of understanding about the potential accumulation of antibiotics in plants exposed to low-dose contaminated soil. 12 Brassica rapa subsp. chinensis cultivars were used to investigate the different accumulation capacities of sulfamethoxypyridazine, tetracycline, ofloxacin, norfloxacin and difloxacin from the soil. The results showed a significant variation (p < 0.05) among the 12 cultivars in the accumulation of antibiotics. Cultivars Y1 and Y2 had the highest accumulation capacity with average concentrations of 3.26 and 3.00 μg kg^-1, respectively, while cultivars Y4 and Y9 had the lowest accumulation capacity with average concentrations of 0.83 and 0.89 μg kg^-1. The average antibiotic concentration in all edible part samples (2.74 μg kg^-1) of the treatment group was about 3.0-fold of that of the control group (0.93 μg kg^-1). The average bioconcentration factors of sulfamethoxypyridazine, tetracycline, ofloxacin, norfloxacin and difloxacin were 0.051, 0.031, 0.017, 0.036 and 0.034, respectively, indicating a higher uptake of sulfamethoxypyridazine compared to ofloxacin. And the mobility of antibiotics in soil is a main factor affecting the bioavailability for plants. The average concentration of antibiotics in edible parts of cultivar Y12 on the 25th and 45th day were 1.52 and 1.73 μg kg^-1 and that of the roots were 3.73 and 6.61 μg kg^-1, respectively. The concentrations of tetracycline and difloxacin in the edible parts and roots significantly increased with growing time, while the concentration of sulfamethoxypyridazine and ofloxacin changed little throughout the growing period. The potential risks of antibiotics in vegetables on human health cannot be ignored. Overall, attention should be paid to the translocation of antibiotics from soil to plants.

Occurrence and distribution of antibiotics and antibiotic resistant genes in water and sediments of urban rivers with black-odor water in Guangzhou, South China

Urban rivers in some countries have been heavily polluted and the water became black and odor. Nevertheless, only few studies reported the occurrence of antibiotics and their corresponding antibiotic resistant genes (ARGs) in urban rivers with black-odor water with and without remediation. In this study, nine antibiotics (belonging to sulfonamides, tetracyclines, quinolones, and macrolides) and their corresponding ARGs in water and sediments of six urban rivers in Guangzhou, South China were analyzed to investigate their spatial distribution and the influence of water remediation. The concentrations of individual antibiotics varied from ND (not detectable) to 2702 ng/L and ND to 449 μg/kg in surface water and sediments, respectively. Norfloxacin displayed the highest average concentrations, followed by ciprofloxacin. The relative abundance of quinolone-resistance gene qnrA (~10³ ARGs/16S rRNA) was the highest, followed by tetracyclines-resistance genes tetC (~10^-2 ARGs/16S rRNA). The antibiotics and ARGs in sediments from various rivers exhibited distinct spatial distribution with large variation from upstream to downstream. Generally, levels of antibiotics and tetracyclines-resistance genes (tetA, tetC and tetM) in urban rivers with black-odor water (affected by industrial and domestic sewage) were higher than those in remediated urban rivers. Significant positive correlations were observed only between the relative abundances of tetA (or tetC) with the concentrations of some antibiotics (e.g., ciprofloxacin and norfloxacin). TetA was also significantly positively correlated with the concentrations of Ni, Cr, and As in sediments. This study found that urban rivers remediated with dredging might lower antibiotic levels in sediment, but high relative abundance of certain ARGs (e.g., tetB, qnrA) may still exist.

Occurrence and distribution of antibiotics and resistance genes in greenhouse and open-field agricultural soils in China

This study conducted a national scale survey to assess the levels and distributions of 13 commonly used antibiotics and nine antibiotic resistance genes (ARGs) in the greenhouse and open-field agricultural soils in China. The concentrations of antibiotics in the greenhouse and open-field soils were 428 ng/g (n = 51) and 193 ng/g (n = 51), respectively. The abundances of ARGs ranged from 1.15 × 10^-7 to 9.78 × 10^-2 copies/16S rRNA copies and from <LOD to 4.92 × 10^-2 copies/16S rRNA copies in the greenhouse and open-field soils, respectively. The levels of antibiotics in the greenhouse were significantly higher than those in the open-field soils (p < 0.05). The concentrations of antibiotics in eastern and northern China were higher than those in the other regions of China. The abundances of ARGs were relatively higher in Guangdong, Shandong, Beijing, and Liaoning provinces. The sulII, tetA, tetG, tetO, and tetX in the greenhouse soils and sulII, tetG, and tetX in the open-field soils were significantly correlated with the levels of total antibiotics. The intI1 played a key role in the transfer of three classes of ARGs, especially in the greenhouse soils. These may indicate that the ARGs in the greenhouse could be easily affected by antibiotics and intI1 genes compared with those in the open-field soils. This study provides useful information to evaluate pollution of ARGs and contamination management in greenhouse agriculture in China.

Occurrence of seventeen veterinary antibiotics and resistant bacterias in manure-fertilized vegetable farm soil in four provinces of China

This study focused on the occurrence of seventeen veterinary antibiotics and six resistant bacterias in soils from the vegetable farms fertilized with animal manure in China. Seventeen veterinary antibiotics, including sulfonamides, quinolones, tetracyclines, macrolides and amphenicols, were detected by high performance liquid chromatography/tandem mass spectrometer in all the 53 soil samples collected in four provinces during August 2016. The concentrations of target antibiotics in the soil samples ranged from not detectable to 415.00 μg/kg dry weight with the mean residual levels of the five classes followed order: tetracyclines (82.75 μg/kg) > quinolones (12.78 μg/kg) > macrolides (12.24 μg/kg) > sulfonamides (2.61 μg/kg) > amphenicols (0.06 μg/kg). Moreover, the highest antibiotic levels were found mainly in soil from organic vegetable farms. Risk assessment by using the methods of risk quotient, suggested that oxytetracycline, chlortetracycline, enrofloxacin and ciprofloxacin could pose severe ecological risk in sampled soils. Resistant strains were isolated in 30 samples, with Escherichia coli and Klebsiella pneumonia found the dominant bacterial hosts with resistance genes. Antibiotic resistance genes, including tetA, tetB, qnrS, oqxA, sul1, sul2, ermA and floR, were detected in the strains resistant to: tetracyclines, quinolones, sulfonamides, macrolides and amphenicols resistance, respectively. Overall, there was a correlation between the results of antibiotic risk assessment with the detection of resistance genes from isolated strains in the soils.

Distribution of Anticancer Drugs in River Waters and Sediments of the Yodo River Basin, Japan

This article reviews the pollution status of anticancer drugs present in the Yodo River basin located in the Kansai district of Japan, covering both the soluble and insoluble (adsorbed on the river sediments and suspended solids) levels. Procedures ranging from sampling in the field and instrumental analytical methods to the data processing for mass balance estimation of the target basin are also described. All anticancer drugs concerned with this article were detected in sewage and river waters, where the presence of bicalutamide (BLT) was identified at considerably high concentrations (maximum 254 ng/L in the main stream, 151 ng/L in tributaries, and 1032 ng/L in sewage treatment plant (STP) effluents). In addition, sorption distribution coefficient (logKd) values showed a tendency to become higher in the silty sediments at Suita Bridge than in the sandy sediments at Hirakata Bridge; these trends were supported by the results of the laboratory-scale sorption experiment. STPs were concluded to be the main sources of the anticancer drug load in the river, and a mass flux evaluation revealed that the effect of attenuation in the river environment was small. The effectiveness of ozonation in the sewage treatment process for removal of these anticancer drugs was further confirmed. The present article should be of value for facilitating the environmental risk assessment of a wide range of drugs in a broader geographical area.

Presence of Antibiotics in Shallow Groundwater in the Northern and Southwestern Regions of China

Antibiotics are widely used, and there is a serious concern about its adverse impacts on the environment and human health. To our knowledge, prior to this work, there was no evidence of the potential presence of antibiotics in groundwater in China, despite populous speculations. This study reported the detection of 35 target antibiotics of 6 groups (chloramphenicois, lincosamides, marcrolides, quinolones, sulfonamides, and tetracyclines), in shallow groundwater samples collected in northern and southwestern China. Thirty-four of thirty-five target antibiotics were detected in the groundwater samples; 73 of 74 monitoring wells contained at least one antibiotic; and at least two antibiotics were detected in 72 of the 74 wells. Ofloxacin (1199.7 ng/L), lincomycin (860.7 ng/L), and norfloxacin (441.9 ng/L) as well as antibiotics with the highest detection frequency such as sulfapyridine (70%), norfloxacin (69%), and lincomycin (64%) were detected at elevated concentrations. The highest detection frequency and concentration of lincosamides were observed in those groundwater samples, but no clear distribution patterns were observed for the six antibiotic groups. Moreover, shallow groundwater in southwestern China seemed to contain most antibiotics, likely due to the high antibiotics discharge and frequent exchange of groundwater with surface matrices. The findings from this work suggest that groundwater in China has been widely contaminated by antibiotics, and presumably other pharmaceutical compounds that have not been investigated to date.

A new approach for the extraction of tetracyclines from soil matrices: application of the microwave-extraction technique

The widespread use of tetracyclines (TCs) in animal husbandry is associated with their constant penetration into the environment and the threat they might pose to living organisms. While the literature data on the analysis of these substances in such matrices as food, tissues, or wastewater are quite extensive, there are still only a few methods presented for the determination of these compounds in soil samples. Moreover, among the literature methods for the extraction of TCs from soil samples, microwave-assisted solvent extraction (MAE) was used only once and in combination with liquid chromatography with spectrophotometric detection (LC-UV). However, according to the EU Commission Decision 2002/657/EC, the use of LC-UV for the determination of compounds, including pharmaceuticals, in environmental samples is not sufficient. Therefore, the development and application of a sensitive and selective method using the MAE-SPE-LC-MS/MS(MRM) technique for the isolation and identification of a mixture of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) in soils is presented in our study. The credibility of this method has been confirmed with good parameters of validation. The optimal extraction conditions of three TCs using MAE techniques were to conduct double extraction for 10 min each, at 60 °C, using a mixture of ACN:McIlvaine buffer:0.1 M EDTA (2:1:1, v/v/v) and an additional cleaning of the extracts by SPE. The effectiveness of the extraction of these compounds was assessed based on two different ways (absolute recovery from 46 to 65.1% and relative recovery from 101.1 to 109.5%). Finally, the validated MAE-SPE-LC-MS/MS(MRM) method was used for the analysis of six samples from agricultural areas of northern Poland. OTC and TC, at concentrations of 11.7 and 14.5 μg kg^-1 were determined in two different samples. An assessment of risk quotients was also performed. The presented method was proven to be a useful tool in the analysis of residues of selected TCs in the soil ecosystem. Obtained data on the presence of these drugs in Polish soils is the first report for this country.

Insights into doxycycline adsorption onto graphene nanosheet: a combined quantum mechanics, thermodynamics, and kinetic study

Recently, pharmaceutically active compounds including antibiotics have been detected in drinking water at very low levels, mostly nanogram/liter concentrations, proposing that these materials were unaffected by water treatment processes. Adsorption processes were suggested to play a significant role in the removal of antibiotics. In this study, the adsorption behavior of doxycycline (DC) in aqueous solution was evaluated. The four factors influencing the adsorption of DC onto graphene nanosheet (GNS) were studied. The results showed that initial pH ∼ 6 to 7 and contact time ∼ 200 min are optimum. The monolayer adsorption capacity was reduced with the increasing temperature from 25 to 45 °C. Nonlinear regressions were carried out to define the best fit model for every system. Among various models, the Hill isotherm model represented the equilibrium adsorption data of antibiotics while the kinetic data were well fitted by the Elovich kinetic model. The maximum adsorption capacity (q _max) was 110 mg.g^-1, obtained from the Hill equation. Semiempirical molecular orbital theory was used to investigate the molecular interaction of the adsorption system. The experiments and semiempirical computation have systematically demonstrated that DC could be adsorbed onto GNS by π- π and electrostatic interactions. It was shown that there is a good compromise with the experimental results. Graphical abstract Insights into doxycycline adsorption onto graphene nanosheet: quantum mechanics, thermodynamics, and kinetic study.

Antibiotics in the agricultural soils from the Yangtze River Delta, China

This study focused on the occurrence and spatial distribution of 13 common antibiotics in the agricultural soils of the Yangtze River Delta (YRD), China. Antibiotics were detected in all the 241 soil samples (i.e., 100% detection rate) with the total concentrations ranging from 4.55 to 2,010 ng/g dry weight. The concentrations of three antibiotic classes decreased in the order: quinolones (mean 48.8 ng/g) > tetracyclines (mean 34.9 ng/g) > sulfonamides (mean 2.35 ng/g). Ciprofloxacin was the prevalent compound with a mean concentration of 27.7 ng/g, followed by oxytetracycline (mean of 18.9 ng/g). A distinct spatial distribution was observed, where high concentrations of antibiotics were detected in the sites adjacent to the livestock and poultry farms. The potential sources of antibiotics in the agricultural soils were the application of manure and wastewater irrigation in this region. Risk assessment for single antibiotic compound indicated that tetracyclines and quinolones could pose a potential risk, in which doxycycline and ciprofloxacin had the most severe ecological effect in the agricultural soils. Antibiotic resistance genes (ARGs), such as tetA, sulI, and qnrS, were detected in 15 analyzed soil samples, and sulI showed significant correlations with quinolones, tetracyclines, copper, and zinc. Further studies on the distribution of other ARGs in agricultural soil at a region-scale are needed for the risk management of extensively used antibiotics and major ARGs.

Environmental and human health challenges of industrial livestock and poultry farming in China and their mitigation

Driven by the growing demand for food products of animal origin, industrial livestock and poultry production has become increasingly popular and is on the track of becoming an important source of environmental pollution in China. Although concentrated animal feeding operations (CAFOs) have higher production efficiency and profitability with less resource consumption compared to the traditional family-based and "free range" farming, they bring significant environmental pollution concerns and pose public health risks. Gaseous pollutants and bioaerosols are emitted directly from CAFOs, which have health implications on animal producers and neighboring communities. A range of pollutants are excreted with the animal waste, including nutrients, pathogens, natural and synthetic hormones, veterinary antimicrobials, and heavy metals, which can enter local farmland soils, surface water, and groundwater, during the storage and disposal of animal waste, and pose direct and indirect human health risks. The extensive use of antimicrobials in CAFOs also contributes to the global public health concern of antimicrobial resistance (AMR). Efforts on treating the large volumes of manure generated in CAFOs should be enhanced (e.g., by biogas digesters and integrated farm systems) to minimize their impacts on the environment and human health. Furthermore, the use of veterinary drugs and feed additives in industrial livestock and poultry farming should be controlled, which will not only make the animal food products much safer to the consumers, but also render the manure more benign for treatment and disposal on farmlands. While improving the sustainability of animal farming, China also needs to promote healthy food consumption, which not only improves public health from avoiding high-meat diets, but also slows down the expansion of industrial animal farming, and thus reduces the associated environmental and public health risks.

Distribution of six anticancer drugs and a variety of other pharmaceuticals, and their sorption onto sediments, in an urban Japanese river

The distributions of 31 pharmaceuticals grouped into nine therapeutic classes, including six anticancer drugs, were investigated in the waters and sediments of an urban river in Japan. The coefficients of sorption (logK _d) to the river sediments were also determined from the results of a field survey and laboratory-scale experiment. Three anticancer drugs-bicalutamide, doxifluridine, and tamoxifen-were detected in the river sediments at maximum concentrations of 391, 392, and 250 ng/kg, respectively. In addition, the transformation products of psychotropic carbamazepine (2-hydroxy carbamazepine, acridine, and acridone) were detected in the range of 108 ng/kg (2-hydroxy carbamazepine) to 2365 ng/kg (acridine), and the phytoestrogen glycitein was detected in the range of N.D. to 821 ng/kg. The logK _d values of the targeted pharmaceuticals in river sediments in the field survey ranged from 0.5 (theophylline) to 3.3 (azithromycin). These results were in accord with those of the laboratory-scale sorption experiment. To the best of our knowledge, this is the first report of the detection of the anticancer drugs bicalutamide and tamoxifen, the transformation products of carbamazepine (2-hydroxy carbamazepine, acridine, and acridone), and the phytoestrogen genistein in river sediments.

Occurrence, distribution, and risk assessment of antibiotics in the Songhua River in China

The occurrence, distribution, and risk assessment of antibiotics in freshwater systems are receiving global attention, because of their impact on the environment and human health. However, few studies have focused on this topic in Northeast China and its Songhua River, the third-largest river in China. This study investigated the occurrence and distribution of 12 antibiotics, including three cephalosporins (cefazolin, cefmetazole, cefotaxime), three macrolides (azithromycin, clarithromycin, roxithromycin), three fluoroquinolones (ofloxacin, norfloxacin, flumequine), and three sulfonamides (sulfadiazine, sulfapyridine, sulfamethoxazole) in the mainstream and tributaries of the Songhua River. A total of 152 surface water samples were collected in January, May, July, and October 2016. These samples were analyzed using solid-phase extraction (SPE) and ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The results indicated the wide use of all 12 antibiotics in the mainstream of the Songhua River. Sulfamethoxazole and cefazolin were the dominant antibiotics, with maximum concentrations of 73.1 and 65.4 ng L^-1, respectively. Other antibiotics were present at mean concentrations below 15 ng L^-1, except cefmetazole, present at a mean concentration of 35.6 ng L^-1. The spatial distribution of antibiotics showed that unbalanced regional development may lead to the distribution pattern of the antibiotics in the tributaries and the mainstream. Thus study also assessed the seasonal variation of antibiotics in urban surface water; cephalosporin, sulfonamide, fluoroquinolone, and macrolide concentrations were significantly higher during the icebound season than during non-icebound season. This may be due to the low temperature and water flow of the river in winter. Risk assessment showed that azithromycin, clarithromycin, roxithromycin, flumequine, and sulfamethoxazole posed a low or median risk to the aquatic organisms in the mainstream. The potential risks created by antibiotics to the aquatic environment should not be neglected in the Songhua River. The potential risks created by antibiotics to the aquatic environment should not be neglected in the Songhua River.

Efficient phytoremediation of organic contaminants in soils using plant-endophyte partnerships

Soil pollution with organic contaminants is one of the most intractable environmental problems today, posing serious threats to humans and the environment. Innovative strategies for remediating organic-contaminated soils are critically needed. Phytoremediation, based on the synergistic actions of plants and their associated microorganisms, has been recognized as a powerful in situ approach to soil remediation. Suitable combinations of plants and their associated endophytes can improve plant growth and enhance the biodegradation of organic contaminants in the rhizosphere and/or endosphere, dramatically expediting the removal of organic pollutants from soils. However, for phytoremediation to become a more widely accepted and predictable alternative, a thorough understanding of plant-endophyte interactions is needed. Many studies have recently been conducted on the mechanisms of endophyte-assisted phytoremediation of organic contaminants in soils. In this review, we highlight the superiority of organic pollutant-degrading endophytes for practical applications in phytoremediation, summarize alternative strategies for improving phytoremediation, discuss the fundamental mechanisms of endophyte-assisted phytoremediation, and present updated information regarding the advances, challenges, and new directions in the field of endophyte-assisted phytoremediation technology.