Refine search
Results 1-10 of 65
Enhanced adsorption of oxytetracycline to weathered microplastic polystyrene: Kinetics, isotherms and influencing factors
2018
Zhang, Haibo | Wang, Jiaqing | Zhou, Bianying | Zhou, Yang | Dai, Zhenfei | Zhou, Qian | Chriestie, Peter | Luo, Yongming
Microplastic polystyrene foam has been found widely in the environment and is readily transported by wind or water. Beached and virgin foams of size 0.45–1 mm were prepared as sorbents to study oxytetracycline sorption. Enhanced adsorption were found in the beached foams compared to the virgin foams, corresponding to the higher specific surface area, micropore area and the degree of oxidation of the former. The Freundlich Kf value was 894 ± 84 ((mg kg⁻¹) (mg L⁻¹)¹/ⁿ) for oxytetracycline adsorption on the beached foams, approximately twice as high as on the virgin foams. Effects of solution pH on adsorption to the beached foams were more pronounced to the virgin foams. Maximum adsorption occurred at pH 5 at which electrostatic repulsion between the microplastic surface and the oxytetracycline zwitterion was minimal, indicating that electrostatic interaction may have regulated adsorption. Moreover, H-bonding and multivalent cationic bridging mechanisms may also have affected the adsorption of oxytetracycline to the beached foams as reflected by the ionic effects. Adsorption was promoted more in the presence of humic acid than of fulvic acid, perhaps owing to π-π conjugation between the humic acid and the microplastic surface which led to enhanced electrostatic attraction for oxytetracycline. This study suggests that weathered polystyrene foams may act as carriers of antibiotics in the environment and their potential risks to ecosystem and human health merit further investigation.
Show more [+] Less [-]Spatial and temporal distribution of antibiotic resistomes in a peri-urban area is associated significantly with anthropogenic activities
2018
Xiang, Qian | Chen, Qing-Lin | Zhu, Dong | An, Xin-Li | Yang, Xiao-Ru | Su, Jian-Qiang | Qiao, Min | Zhu, Yong-Guan
With the rapid development of urbanization and industrialization, the peri-urban areas are often the sites for waste dumps, which may exacerbate the occurrence and spread of antibiotic resistance from waste to soil bacteria. However, the profiles of antibiotic resistomes and the associated factors influencing their dissemination in peri-urban areas have not been fully explored. Here, we characterized the antibiotic resistance genes (ARGs) in peri-urban arable and pristine soils in four seasons at the watershed scale, by using high-throughput qPCR. ARGs in peri-urban soils were diverse and abundant, with a total of 222 genes were detected in the peri-urban soil samples. The arable soil harbored more diverse ARGs compared to the pristine soils, and nearly all the ARGs detected in the pristine soils were also detected in the farmlands. A random forest prediction showed that the overall patterns of ARGs clustered closely with the landuse type. Mantel test and partial redundancy analysis indicated that bacterial community variation is a major contributor to antibiotic resistome alteration. Significant positive correlation was found between the abundance of ARGs and mobile genetic elements (MGEs), suggesting potential mobility of ARGs in peri-urban areas. Our results extend knowledge of the resistomes compositions in peri-urban areas, and suggest that anthropogenic activities driving its spatial and temporal distribution.
Show more [+] Less [-]Occurrence and ecological risk assessment of organic micropollutants in the lower reaches of the Yangtze River, China: A case study of water diversion
2018
Yan, Zhenhua | Yang, Haohan | Dong, Huike | Ma, Binni | Sun, Hongwei | Pan, Ting | Jiang, Runren | Zhou, Ranran | Shen, Jie | Liu, Jianchao | Lü, Guanghua
Water diversion has been increasingly applied to improve water quality in many water bodies. However, little is known regarding pollution by organic micropollutants (OMPs) in water diversion projects, especially at the supplier, and this pollution may threaten the quality of transferred water. In the present study, a total of 110 OMPs belonging to seven classes were investigated in water and sediment collected from a supplier of the Yangtze River within four water diversion projects. A total of 69 and 58 target OMPs were detected in water and sediment, respectively, at total concentrations reaching 1041.78 ng/L and 5942.24 ng/g dry weight (dw). Polycyclic aromatic hydrocarbons (PAHs) and pharmaceuticals were the predominant pollutants identified. When preliminarily compared with the pollution in the receiving water, the Yangtze River generally exhibited mild OMPs pollution and good water quality parameters, implying a clean water source in the water diversion project. However, in Zongyang and Fenghuangjing, PAHs pollution was more abundant than that in the corresponding receiving water in Chaohu Lake. Ammonia nitrogen pollution in the Wangyu River was comparable to that in Taihu Lake. These findings imply that water diversion may threaten receiving waters in some cases. In addition, the risks of all detected pollutants in both water and sediment were assessed. PAHs in water, especially phenanthrene and high-molecular-weight PAHs, posed high risks to invertebrates, followed by the risks to fish and algae. Pharmaceuticals, such as antibiotics and antidepressants, may also pose risks to algae and fish at a number of locations. To the best of our knowledge, this report is the first to describe OMPs pollution in water diversion projects, and the results provide a new perspective regarding the security of water diversion projects.
Show more [+] Less [-]Responses of the nitrogen-fixing aquatic fern Azolla to water contaminated with ciprofloxacin: Impacts on biofertilization
2018
Gomes, Marcelo Pedrosa | de Brito, Júlio César Moreira | Carvalho Carneiro, Marília Mércia Lima | Ribeiro da Cunha, Mariem Rodrigues | Garcia, Queila Souza | Figueredo, Cleber Cunha
We investigated the ability of the aquatic fern Azolla to take up ciprofloxacin (Cipro), as well as the effects of that antibiotic on the N-fixing process in plants grown in medium deprived (-N) or provided (+N) with nitrogen (N). Azolla was seen to accumulate Cipro at concentrations greater than 160 μg g⁻¹ dry weight when cultivated in 3.05 mg Cipro l⁻¹, indicating it as a candidate for Cipro recovery from water. Although Cipro was not seen to interfere with the heterocyst/vegetative cell ratios, the antibiotic promoted changes with carbon and nitrogen metabolism in plants. Decreased photosynthesis and nitrogenase activity, and altered plant's amino acid profile, with decreases in cell N concentrations, were observed. The removal of N from the growth medium accentuated the deleterious effects of Cipro, resulting in lower photosynthesis, N-fixation, and assimilation rates, and increased hydrogen peroxide accumulation. Our results shown that Cipro may constrain the use of Azolla as a biofertilizer species due to its interference with nitrogen fixation processes.
Show more [+] Less [-]Monitoring the occurrence of pharmaceuticals in soils irrigated with reclaimed wastewater
2018
Biel-Maeso, Miriam | Corada-Fernández, Carmen | Lara-Martín, Pablo A.
The use of reclaimed wastewater for irrigation is foreseen as a possible strategy to mitigate the pressure on water resources in dry regions. However, there is the risk of potential accumulation of contaminants of emerging concern (CECs) in the edaphic environment, their percolation and consequently contamination of aquifers. In the present study, we measured the levels of a wide range of commonly used pharmaceutically active compounds (PhACs) in sewage from a local wastewater treatment plant (WWTP) and in soils irrigated with treated wastewater. Analysis of target compounds showed total concentrations between 73 and 372 μg L⁻¹ in WWTP influents, and from 3 to 41 μg L⁻¹ in effluents. The total concentrations of PhACs detected in surface soil samples were in the range of 2 and 15 ng g⁻¹, with predominance of analgesics and anti-inflammatories (maximum concentration = 10.05 ng g⁻¹), followed by antibiotics and psychiatric drugs (maximum concentration = 5.45 ng g⁻¹ and 3.78 ng g⁻¹, respectively). Both effluent samples and irrigated soils shared similar compositional patterns, with compounds such as hydrochlorothiazide and diclofenac being predominant. Additionally, PhACs were also detected in soil samples at a depth of 150 cm, indicating that these chemical undergo leaching associated with heavy-rain episodes. Their occurrence in soils was affected by temperature too, as maximum concentrations were measured in colder months (up to 14 ng g⁻¹), indicating higher persistence at lower temperatures. Finally, the ecotoxicological risk of PhACs in soil was evaluated by calculating their risk quotients (RQs). The risk was very low as RQ values ranged between <0.01 and 0.07. However, this initial assessment could be improved by future works on toxicity using specific terrestrial organisms.
Show more [+] Less [-]Urinary level of triclosan in a population of Chinese pregnant women and its association with birth outcomes
2018
Huo, Wenqian | Xia, Wei | Wu, Chuansha | Zhu, Yingshuang | Zhang, Bin | Wan, Yanjian | Zhou, Aifen | Qian, Zhenming | Chen, Zhong | Jiang, Yangqian | Liu, Hongxiu | Hu, Jie | Xu, Bing | Xu, Shunqing | Li, Yuanyuan
Triclosan (TCS) is a suspected endocrine disrupting chemical which is widely used in consumer products as an antibacterial agent. But findings in human studies focusing on the fetal developmental effects of prenatal TCS exposure were rare and inconsistent. This study aimed to determine maternal urinary TCS and investigate its association with birth outcomes. Pregnant women (n = 1006) were randomly selected from the prospective Healthy Baby Cohort (HBC) enrolled in 2014. TCS levels were determined in maternal urine samples collected at delivery and recorded birth outcomes were obtained from the medical records. Multiple linear regressions were applied to evaluate associations of maternal urinary TCS levels with birth outcomes including birth weight, birth length, and gestational age. Logistic regressions were used to evaluate associations with preterm birth, late term birth, and low birth weight. The geometric mean concentrations for TCS and specific gravity (SG) adjusted TCS in maternal urines were 0.73, 0.78 ng/mL, respectively. In the crude model, one ln-unit increase of urinary SG-adjusted TCS concentration was associated with a 0.30-day [95% confidence interval (CI): 0.00, 0.60] increase in gestational age; however, the associations were not statistically significant after adjustment for covariates. No significant associations of SG-adjusted TCS concentrations with birth weight and birth length were observed. Maternal SG-adjusted TCS concentrations were not related to preterm birth, late term birth, and low birth weight (all p > 0.10). Our findings reported a relatively low level of TCS among Chinese pregnant women. With such exposure level, we did not find strong evidence for associations between maternal TCS exposure and birth outcomes. Longitudinal studies concerning about different potential effects of TCS on perinatal health are necessary.
Show more [+] Less [-]DNA methylation and gene expression alterations in zebrafish early-life stages exposed to the antibacterial agent triclosan
2018
There is increasing evidence that toxicant exposure can alter DNA methylation profile, one of the main epigenetic mechanisms, particularly during embryogenesis when DNA methylation patterns are being established. In order to investigate the effects of the antibacterial agent Triclosan on DNA methylation and its correlation with gene expression, zebrafish embryos were exposed during 7 days post-fertilization (starting at maximum 8-cells stage) to 50 and 100 μg/l, two conditions for which increased sensitivity and acclimation have been respectively reported. Although global DNA methylation was not significantly affected, a total of 171 differentially methylated fragments were identified by Reduced Representation Bisulfite Sequencing. The majority of these fragments were found between the two exposed groups, reflecting dose-dependant specific responses. Gene ontology analysis revealed that pathways involved in TGF-β signaling were enriched in larvae exposed to 50 μg/l, while de novo pyrimidine biosynthesis functions were overrepresented in fish exposed to 100 μg/l. In addition, gene expression analysis revealed a positive correlation between mRNA levels and DNA methylation patterns in introns, together with significant alterations of the transcription of genes involved in nervous system development, transcriptional factors and histone methyltransferases. Overall this work provides evidence that Triclosan alters DNA methylation in zebrafish exposed during embryogenesis as well as related genes expression and proposes concentration specific modes of action. Further studies will investigate the possible long-term consequences of these alterations, i.e. latent defects associated with developmental exposure and transgenerational effects, and the possible implications in terms of fitness and adaptation to environmental pollutants.
Show more [+] Less [-]Sewer sediment-bound antibiotics as a potential environmental risk: Adsorption and desorption affinity of 14 antibiotics and one metabolite
2018
Kaeseberg, Thomas | Zhang, Jin | Schubert, Sara | Oertel, Reinhard | Siedel, Heiner | Krebs, Peter
In this study, 14 antibiotics and one metabolite were determined in sewages and size-dependent sewer sediments at three sampling sites in the city of Dresden, Germany. Adsorption and desorption experiments were conducted with fractionated sediments. All antibiotics and the metabolite investigated were determined in the sewages; 9 of 14 antibiotics and the metabolite were adsorbed to sewer sediments. The adsorbed antibiotic loads in ng of antibiotic per g of sediment correlated with antibiotic concentrations in ng of antibiotic per litre of sewage. The size fractions <63 μm, 63–100 μm and 100–200 μm had significantly higher loads of adsorbed antibiotics than bigger size fractions. In general, the adsorbed load decreased with an increasing size fraction, but size fractions >200 μm had similar levels of adsorbed antibiotic loads. An antibiotic-specific adsorption coefficient, normalized to organic content, was calculated: four antibiotics exceeded 10.0 L g⁻¹, three antibiotics fell below 1.0 L g⁻¹ and all residual antibiotics and the metabolite were in the range of 1.0–10.0 L g⁻¹. The adsorbed antibiotic load and the organic matter increased with time, generally. The mineral composition had a minor effect on the adsorption coefficients. Desorption dynamics of five antibiotics and the metabolite were quantified. Regardless of the size fraction, the predominant part of the equilibrium antibiotic concentration was desorbed after 10 min. The calculated desorption distribution coefficient indicated adsorption as irreversible at the pH investigated (7.5 ± 0.5).
Show more [+] Less [-]Systematic characterization and proposed pathway of tetracycline degradation in solid waste treatment by Hermetia illucens with intestinal microbiota
2018
Cai, Minmin | Ma, Shiteng | Hu, Ruiqi | Tomberlin, Jeffery K. | Yu, Chan | Huang, Yongping | Zhan, Shuai | Li, Wu | Zheng, Longyu | Yu, Ziniu | Zhang, Jibin
Antibiotics can effectively protect livestock from pathogen infection, but residual antibiotics in manure bring risks to ecosystems and public health. Here, we demonstrated that black soldier fly larvae (BSFL) could provide an environmentally friendly manure treatment based on their ability to effectively and rapidly degrade tetracycline (TC). Investigation of the biological mechanisms and degradation pathways of TC by BSFL indicated that nearly 97% of TC was degraded within 12 days in a non-sterile BSFL treatment system, which is up to 1.6-fold faster than that achieved by normal composting. Our results showed that rapid TC-degradation was largely carried out by the intestinal microbiota of the larvae, which doubled the TC-degradation rates compared to those achieved in sterile BSFL systems. This conclusion was further supported by highly-efficient TC-biodegradation both in vivo and in vitro by four larval intestinal isolates. Moreover, detailed microbiome analysis indicated that intestinal bacterial and fungal communities were modified along with significantly increased tet gene copy number in the gut, providing the means to tolerate and degrade TC. Through analysis of TC degradation in vitro, four possible biodegradation products, two hydrolysis products and three conceivable inactivation products were identified, which suggested TC degradation reactions including hydrolysis, oxygenation, deamination, demethylation, ring-cleavage, modification, etc. In conclusion, our studies suggested an estimation of the fate of TC antibiotics in manure treatment by BSFL colonized by gut microbes. These results may provide a strategy for accelerating the degradation of antibiotics by adjusting the intestinal microbiota of BSFL.
Show more [+] Less [-]Effects of long-term pig manure application on antibiotics, abundance of antibiotic resistance genes (ARGs), anammox and denitrification rates in paddy soils
2018
Rahman, M Mizanur | Shan, Jun | Yang, Pinpin | Shang, Xiaoxia | Xia, Yongqiu | Yan, Xiaoyuan
Previous studies of long-term manure applications in paddy soil mostly focused on the effects on denitrification, occurrence of antibiotics and antibiotic resistance genes (ARGs) without considering the effects on anaerobic ammonium oxidation (anammox). Here, we investigated the potential rates of anammox and denitrification, occurrence of antibiotics and AGRs in response to three fertilization regimes (C, no fertilizer; N, mineral fertilizer; and NM, N plus pig manure) in six long-term paddy experiment sites across China. The potential rates of anammox (0.11–3.64 nmol N g−1 h−1) and denitrification (1.5–29.05 nmol N g−1 h−1) were correlated with the abundance of anammox genes (hzsB) and denitrification functional genes (narG, nirK, nirS and nosZ), respectively. The anammox and denitrification rates were affected by soil organic carbon (SOC) and significantly (p < 0.05) increased in NM treatments relative to those in N treatments. Although pig manure application increased antibiotic concentrations and abundance of ARGs compared with N treatments, the increased antibiotics did not directly affect the anammox and denitrification rates. Our results suggested that long-term pig manure application significantly increased antibiotic concentrations, abundance of ARGs, and rates of anammox and denitrification, and that the effects of pig manure-derived antibiotics on anammox and denitrification were marginal. This is the first report that investigates the effects of long-term pig manure application on anammox in paddy soils. More attention should be paid to the potential ecological risk of increased ARGs caused by pig manure application in paddy soils.
Show more [+] Less [-]