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Resultados 3011-3020 de 4,921
Contrastive removal of oxytetracycline and chlortetracycline from aqueous solution on Al-MOF/GO granules
2019
Yu, Lin-ling | Luo, Zi-fen | Zhang, Ying Ying | Wu, Shi-chuan | Yang, Cao | Cheng, Jian-hua
The presence of tetracycline antibiotics (TCS) in the water and wastewater has raised growing concern due to its potential environmental impacts; thus, their removal is of high importance. In this study, a novel aluminum-based MOF/graphite oxide (Al-MOF/GO) granule was prepared as an adsorbent for the removal of TCS including oxytetracycline (OTC) and chlortetracycline (CTC). The adsorbent was characterized via XRD, FTIR, BET, SEM, and XPS methods. The granules exhibited similar crystal structure and some new mesopores appearing compared to the parent Al-MOF/GO powder. In addition, the adsorption behavior of OTC and CTC on samples was explored as a function of initial concentration, contact time, pH, and ionic strength by means of batch experiments. The adsorption capacity reached to 224.60 and 240.13 mg·L⁻¹ for OTC and CTC, at C₀ = 60 mg·L⁻¹ as well as ambient temperature respectively. Moreover, the adsorption process of OTC and CTC on Al-MOF/GO samples can be better delineated by pseudo-second-order kinetics and Freundlich isotherm models. Besides, the adsorption mechanism over Al-MOF/GO granules was proposed, which could be ascribed to π-π interaction, cation-π bonding, and hydrogen bond. Finally, the great water stability, separation performance, and regeneration efficiency of these novel granules indicated their potential application in the OTC and CTC removals from aqueous solution.
Mostrar más [+] Menos [-]Removal of aqueous fluoroquinolones with multi-functional activated carbon (MFAC) derived from recycled long-root Eichhornia crassipes: batch and column studies
2019
Liu, Lili | Chen, Xin | Wang, Zhiping | Lin, Sen
Fluoroquinolones (FQs) occur broadly in natural media due to its extensive use, and it has systematic effects on our ecosystem and human immunity. In this study, long-root Eichhornia crassipes was reclaimed as a multi-functional activated carbon (MFAC) to remove fluoroquinolones (FQs) from contaminated water. To get insight into the adsorption mechanism, multiple measurements, including FTIR and XPS analyses, were employed to investigate the adsorption processes of ciprofloxacin and norfloxacin as well as the experiments of effect of exogenous factors on adsorption performances. The results confirmed that the adsorption of FQs by MFAC was mainly attributed to the electrostatic interaction, hydrogen bond interaction, and electronic-donor-acceptor (EDA) interaction. In addition, the kinetics and thermodynamics experiments demonstrated that the MFAC possessed great adsorption performance for FQs. According to the Langmuir model, the saturated adsorption capacities exceeded 145.0 mg/g and 135.1 mg/g for CIP and NOR at 303.15 K, respectively. The column experiments were conducted to explore the application performance of MFAC on the advanced treatment of synthetic water at different flow rates and bed depths. The adsorption capacity of CIP on MFAC was estimated by the Thomas models and the bed-depth service time (BDST) models, reaching 127.56 mg/g and 11,999.52 mg/L, respectively. These results also provide a valid approach for the resource recycling of the redundant long-root Eichhornia crassipes plants. Graphical abstract
Mostrar más [+] Menos [-]Tolerance of native and invasive bivalves under herbicide and metal contamination: an ex vivo approach
2019
El Haj, Yasmin | Bohn, Sofia | Souza, Marta Marques
The literature indicates that exotic species have a greater tolerance to environmental stressors compared with native species. In recent decades, the introduction of contaminants into the environment has increased as a result of industrialization. The objective of this study was to verify the resistance of bivalve mollusks from freshwater native (Anodontites trapesialis) and exotic (Limnoperna fortunei) species to chemical contamination using an ex vivo/in vitro approach. Gill and muscle tissues were exposed to two different types of environmental stressors, copper (metal), and Roundup Transorb® (herbicide). The tissues were submitted to a cytotoxicity test in which the lysosomal integrity was assessed, from the adaptation of a method to isolated cells, and multixenobiotic resistance (MXR) test which evaluated cellular defense. In the exotic species, only copper at 9000 μg/L and Roundup Transorb® at 5000 μg/L were cytotoxic. In the native species, copper cytotoxicity at 900 and 9000 μg/L and Roundup Transorb® at 50 and 5000 μg/L were observed. Results were the same in both tissues. The MXR, responsible for the extrusion of contaminants (cell defense), was inhibited in both species when exposed to the contaminants, this cell defense system seems to be more inhibited in the native species, when exposed to both pollutants, indicating greater sensitivity. Therefore, cytotoxicity may be related to the lack of capacity of cellular defense. In relation to lysosomal integrity, the native species was more sensitive to cytotoxic pollutants, where a greater number of experimental conditions of metals and herbicide showed cytotoxicity, as well as more experimental situations inhibited its ability to defend itself.
Mostrar más [+] Menos [-]A combined chemical and phytoremediation method for reclamation of acid mine drainage–impacted soils
2019
RoyChowdhury, Abhishek | Sarkar, Dibyendu | Datta, Rupali
Production of acid mine drainage (AMD) and acid sulfate soils is one of the most concerning environmental consequences associated with mining activities. Implementation of appropriate post-mining AMD management practices is very important to minimize environmental impacts such as high soil acidity, soil erosion, and metal leachability. The objective of this study was to develop a cost-effective and environment-friendly “green” technology for the treatment of AMD-impacted soils. This study utilized the metal-binding and acid-neutralizing capacity of an industrial by-product, namely drinking water treatment residuals (WTRs), and the extensive root system of a metal hyper-accumulating, fast-growing, non-invasive, high-biomass perennial grass, vetiver (Chrysopogon zizanioides L.) to prevent soil erosion. Aluminum (Al)-based and calcium (Ca)-based WTRs were used to treat AMD-impacted soil collected from the Tab-Simco coal mine in Carbondale, IL. Tab-Simco is an abandoned coal mine, with very acidic soil containing a number of metals and metalloids such as Fe, Ni, Zn, Pb, and As at high concentrations. A 4-month-long greenhouse column study was performed using 5% and 10% w/w WTR application rates. Vetiver grass was grown on the soil-WTR mixed media. Turbidity and total suspended solid (TSS) analysis of leachates showed that soil erosion decreased in the soil-WTR-vetiver treatments. Difference in pH of leachate samples collected from control (3.06) and treatment (6.71) columns at day 120 indicated acidity removal potential of this technology. A scaled-up simulated field study was performed using 5% WTR application rate and vetiver. Soil pH increased from 2.69 to 7.2, and soil erosion indicators such as turbidity (99%) and TSS (95%) in leachates were significantly reduced. Results from the study showed that this “green” reclamation technique has the potential to effectively treat AMD-impacted soils.
Mostrar más [+] Menos [-]Effects of cerium oxide nanoparticles on bacterial growth and behaviors: induction of biofilm formation and stress response
2019
Xu, Yi | Wang, Chao | Hou, Jun | Wang, Peifang | You, Guoxiang | Miao, Lingzhan
In this paper, the effects of cerium oxide nanoparticles (CeO₂ NPs) on the group bacterial behaviors were elaborated. After 36-h cultivation, the biofilm biomass was enhanced by the sub-lethal concentrations of 0.5 and 2 mg/L CeO₂ NP exposure. Meanwhile, the promoted production of total amino acids in microbes further resulted in the increased surface hydrophobicity and percentage aggregation. To resist the CeO₂ NPs stress, the biofilm exhibited a double-layer microstructure, with the protein (PRO) and living cells occupying the bottom, the polysaccharide (PS), and dead cells dominating the top. The bacterial diversity was highly suppressed and Citrobacter and Pseudomonas from the phylum of γ-Proteobacteria strongly dominated the biofilm, indicating the selective and enriched effects of CeO₂ NPs on resistant bacteria. The stimulated inherent resistance of biofilm was reflected by the reduced adenosine triphosphate (ATP) content after 4 h exposure. The increased levels of reactive oxygen species (ROS) in the treatments of 8 h CeO₂ NP exposure led to the upregulated quorum sensing signals of acylated homoserine lactone (AHL) and autoinducer 2 (AI-2), beneficial to mitigating the environmental disturbance of CeO₂ NPs. These results provide evidences for the accelerating effects of CeO₂ NPs on biofilm formation through oxidative stress, which expand the understanding of the ecological effects of CeO₂ NPs.
Mostrar más [+] Menos [-]Stability and uptake of methylphenidate and ritalinic acid in nine-spine stickleback (Pungitius pungitius) and water louse (Asellus aquaticus)
2019
McCallum, Erin S. | Lindberg, Richard H. | Andersson, Patrik L. | Brodin, Tomas
The presence of human pharmaceuticals in the environment has garnered significant research attention because these compounds may exert therapeutic effects on exposed wildlife. Yet, for many compounds, there is still little research documenting their stability in the water column and uptake in organism tissues. Here, we measured the uptake and stability of methylphenidate (Ritalin®, a frequently prescribed central nervous system stimulant) and its primary metabolite, ritalinic acid, in (1) water only or (2) with nine-spine stickleback and water louse. Methylphenidate degraded to ritalinic acid in both studies faster at a higher temperature (20 °C versus 10 °C), with concentrations of ritalinic acid surpassing methylphenidate after 48–100 h, depending on temperature. The concentration of methylphenidate in stickleback was highest at the first sampling point (60 min), while the concentration in water louse tissues reached comparatively higher levels and peaked after ~ 6 days. Neither stickleback nor water louse took up ritalinic acid in tissues despite being present in the water column. Our findings provide valuable data for use in future risk assessment of methylphenidate and will aid in the design of studies aimed at measuring any ecotoxicological effects on, for example, the behaviour or physiology of aquatic organisms.
Mostrar más [+] Menos [-]A comprehensive evaluation of the association between ambient air pollution and adverse health outcomes of major organ systems: a systematic review with a worldwide approach
2019
Bazyar, Jafar | Pourvakhshoori, Negar | Khankeh, Hamidreza | Farrokhi, Mehrdad | Delshad, Vahid | Rajabi, Elham
Ambient air pollution is nowadays one of the most crucial contributors to deteriorating health status worldwide. The components of air pollution include PM₂.₅ and PM₁₀, NO₂, SO₂, CO, O₃, and organic compounds. They are attributed to several health outcomes, for instance, cardiovascular diseases (CVD), respiratory diseases, birth outcomes, neurologic diseases, and psychiatric diseases. The objective of this study is to evaluate the association between different ambient air pollutants and the above-mentioned health outcomes. In this systematic review, a total of 76 articles was ultimately selected from 2653 articles, through multiple screening steps by the aid of a set of exclusion criteria as non-English articles, indoor air pollution assessment, work-related, occupational and home-attributed pollution, animal studies, tobacco smoking effects, letters to editors, commentaries, animal experiments, reviews, case reports and case series, out of 19,862 published articles through a systematic search in PubMed, Web of Science, and Scopus. Then, the associations between air pollution and different health outcomes were measured as relative risks and odds ratios. The association between air pollutants, PM₂.₅ and PM₁₀, NO₂, SO₂, CO, O₃, and VOC with major organ systems health was investigated through the gathered studies. Relative risks and/or odds ratios attributed to each air pollutant/outcome were ultimately reported. In this study, a thorough and comprehensive discussion of all aspects of the contribution of ambient air pollutants in health outcomes was proposed. To our knowledge up to now, there is no such comprehensive outlook on this issue. Growing concerns in concert with air pollution-induced health risks impose a great danger on the life of billions of people worldwide. Should we propose ideas and schemes to reduce ambient air pollutant, there will be dramatic reductions in the prevalence and occurrence of health-threatening conditions.
Mostrar más [+] Menos [-]Nuclear contamination sources in surface air of Finnish Lapland in 1965–2011 studied by means of 137Cs, 90Sr, and total beta activity
2019
Salminen-Paatero, Susanna | Thölix, Laura | Kivi, Rigel | Paatero, Jussi
Radionuclides ¹³⁷Cs and ⁹⁰Sr and total beta activity were determined from air filters collected in Rovaniemi (Finnish Lapland) in 1965–2011. Nuclear contamination sources present in the air filter samples as well as temporal changes in radionuclide concentrations were examined. Ozone observations and meteorological modeling were used in combination with radionuclide analyses to study the reasons behind the observed seasonal concentration variation. In general, the magnitude and variation in activity concentrations of ¹³⁷Cs and ⁹⁰Sr and total beta activity in the surface air of Rovaniemi in 1965–2011 corresponded well with values from other countries. However, the obtained results prove in practice that hardly any refractory or intermediate radionuclides from the destroyed Chernobyl reactor fuel were introduced to Finnish Lapland. The main source of ¹³⁷Cs and ⁹⁰Sr and total beta activity in the surface air of Rovaniemi in 1965–2011 has been intense atmospheric nuclear weapon testing in 1950s–1960s and later tests performed in 1965–1980, as well as leakages from underground nuclear tests in Semipalatinsk, 1966, and Novaya Zemlya, 1987. For ¹³⁷Cs and total beta activity, the influence of Chernobyl and Fukushima accidents was detected.
Mostrar más [+] Menos [-]Adsorption studies of 17β-estradiol from aqueous solution using a novel stabilized Fe–Mn binary oxide nanocomposite
2019
Dai, Ming-yang | Liu, Yun-guo | Zeng, Guang-ming | Liu, Shao-bo | Ning, Qi-meng
The removal of 17β-estradiol (E2) from contaminated water on nanoscale Fe–Mn binary oxide-loaded multiwalled carbon nanotubes (MWCNTs/FMBO) was evaluated in this work. The characterizations of the mesoporous adsorbent were analyzed by using SEM, TEM, VSM, XRD, XPS, and FTIR measurements. The effects of experimental conditions in E2 removal, including stabilizer additional level, adsorption time, initial E2 concentration, solution pH, reaction temperature, and foreign ions, were examined. The maximum monolayer adsorption capacity (qₘ) of MWCNTs/FMBO for E2 in the experiment was 47.25 mg/g as verified by the Langmuir sorption isotherm study. The adsorption process was pH-sensitive with an optimum pH of 7.0. On the kinetics study, the adsorption data could be satisfactorily fitted by the pseudo-second-order kinetics. Thermodynamic parameters indicated that the adsorption process was spontaneous and exothermal. In addition, the foreign ions did not show any noticeable inhibition for E2 removal from the water solution except for PO₄³⁻ that was adversely affected for E2 uptake than other anions in a certain concentration. The adsorption capacities of the mesoporous adsorbent remained at 86.16% even after five adsorption–desorption cycles without significant loss of capacity, which demonstrated the stability and reusability for further removal of E2. Moreover, both hydrogen bond and π–π interaction might be the dominating adsorption mechanisms for E2 adsorption onto MWCNTs/FMBO.
Mostrar más [+] Menos [-]Co-exposure to environmental endocrine disruptors in the US population
2019
Chen, Lin | Luo, Kai | Etzel, Ruth | Zhang, Xiaoyu | Tian, Ying | Zhang, Jun
Exposure to environmental endocrine disruptors (EEDs) has been linked to adverse health outcomes. The vast majority of studies examined one class of EEDs at a time but humans often are exposed to multiple EEDs at the same time. It is, therefore, important to know the co-exposure status of multiple EEDs in an individual, to preclude and control for potential confounding effects posed by co-exposed EEDs. This study examined the concentrations of seven classes of EEDs in the US population utilizing the data from the National Health and Nutrition Examination Survey (NHANES), 2009–2014 survey cycles. We applied linear correlation and cluster analysis to characterize the correlation profile and cluster patterns of these EEDs. We found that EEDs with a similar structure are often highly correlated. Among between-class correlations, mercury and perfluoroalkyl substances (PFAS) and cadmium and polycyclic aromatic hydrocarbons (PAHs) were two significantly correlated EEDs. In epidemiologic studies, measurement and control for co-exposure to pollutants, especially those with similar biological effects, are critical when attempting to make causal inferences. Appropriate statistical methods to handle within- and between-class correlations are needed.
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