خيارات البحث
النتائج 3761 - 3770 من 5,153
Comparison of different advanced degradation processes for the removal of the pharmaceutical compounds diclofenac and carbamazepine from liquid solutions النص الكامل
2018
Capodaglio, Andrea G. | Bojanowska-Czajka, Anna | Trojanowicz, Marek
Carbamazepine and diclofenac are two examples of drugs with widespread geographical and environmental media proliferation that are poorly removed by traditional wastewater treatment processes. Advanced oxidation processes (AOPs) have been proposed as alternative methods to remove these compounds in solution. AOPs are based on a wide class of powerful technologies, including UV radiation, ozone, hydrogen peroxide, Fenton process, catalytic wet peroxide oxidation, heterogeneous photocatalysis, electrochemical oxidation and their combinations, sonolysis, and microwaves applicable to both water and wastewater. Moreover, processes rely on the production of oxidizing radicals (•OH and others) in a solution to decompose present pollutants. Water radiolysis-based processes, which are an alternative to the former, involve the use of concentrated energy (beams of accelerated electrons or γ-rays) to split water molecules, generating strong oxidants and reductants (radicals) at the same time. In this paper, the degradation of carbamazepine and diclofenac by means of all these processes is discussed and compared. Energy and byproduct generation issues are also addressed.
اظهر المزيد [+] اقل [-]A new approach to the renewable energy-growth nexus: evidence from the USA النص الكامل
2018
Gözgor, Giray
The climate change is one of the leading problems in the today’s world. The rise of the renewable energy meets the sustainable growth objectives since it can decelerate the climate change. For this purpose, this paper investigates the relationship between the renewable energy consumption and the economic growth in the United States (USA). Theoretically, the paper constructs the growth model that captures the effects of the economic complexity indicator as a measure of capabilities and productivity for exporting the “complex” (high value-added) products. Empirically, the paper uses the Autoregressive Distributed Lag (ARDL) estimations and observes that both the economic complexity and the renewable energy consumption lead to a higher rate of economic growth in the USA for the period from 1965 to 2016. The paper also discusses the potential policy implications of the results for achieving the sustainable growth objectives.
اظهر المزيد [+] اقل [-]Screening of seaweeds in the East China Sea as potential bio-monitors of heavy metals النص الكامل
2018
Pan, Yaoru | Wernberg, Thomas | de Bettignies, Thibaut | Holmer, Marianne | Li, Ke | Wu, Jiaping | Lin, Fang | Yu, Yan | Xu, Jiang | Zhou, Lisan | Huang, Zhixing | Xiao, Xi
Seaweeds are good bio-monitors of heavy metal pollution and have been included in European coastal monitoring programs. However, data for seaweed species in China are scarce or missing. In this study, we explored the potential of seaweeds as bio-monitor by screening the natural occurring seaweeds in the “Kingdom of seaweed and shellfish” at Dongtou Islands, the East China Sea. Totally, 12 seaweed species were collected from six sites, with richness following the sequence of Rhodophyta > Phaeophyta > Chlorophyta. The concentration of heavy metals (Cu, Cr, Ni, Zn, Pb, Cd, As) in the seaweeds was determined, and the bioaccumulation coefficient was calculated. A combination of four seaweeds, Pachydictyon coriaceum, Gelidium divaricatum, Sargassum thunbergii, and Pterocladiella capillacea, were proposed as bio-monitors due to their high bioaccumulation capabilities of specific heavy metals in the East China Sea and hence hinted the importance of using seaweed community for monitoring of pollution rather than single species. Our results provide first-hand data for the selection of bio-monitor species for heavy metals in the East China Sea and contribute to selection of cosmopolitan bio-monitor communities over geographical large area, which will benefit the establishment of monitoring programs for coastal heavy metal contamination.
اظهر المزيد [+] اقل [-]Phthalate esters and organochlorine pesticides in agricultural soils and vegetables from fast-growing regions: a case study from eastern China النص الكامل
2018
Sun, Jianteng | Pan, Lili | Tsang, DanielC.W. | Li, Zhiheng | Zhu, Lizhong | Li, Xiangdong
The present study investigated phthalate esters (PAEs) and organochlorine pesticides (OCPs) in agricultural soils and vegetables from eastern China. The concentrations of PAEs ranged from 109 to 5560 ng/g in soils and 60.1 to 2390 ng/g in cabbages, with average concentrations of 946 and 601 ng/g, respectively. The concentrations of OCPs ranged from <0.1 to 662 ng/g in soils and <0.1 to 42.8 ng/g in cabbages, with average concentrations of 134 and 11.6 ng/g, respectively. OCPs were mainly in the 0–30 cm surface soil layers, while PAEs could infiltrate in deep soil profiles to 70–80 cm layer. Potential source analysis traced the occurrence of OCPs to both historical application and current usage, whereas building materials and agricultural plastic film were possible input sources of PAEs in the ambient environment. OCPs showed no apparent effect on soil microbial communities, whereas significant negative relationship was observed between PAEs and fungi in soils (R = −0.54, p < 0.01). Human health risk assessment data revealed marginal noncarcinogenic risks and low carcinogenic risks in these soils. Notably, PAEs posed a comparable or higher risk level compared with that of OCPs. This study suggests the need for better regulation on pollution control and management of PAE-elevated sites to protect soil quality and food safety.
اظهر المزيد [+] اقل [-]Effects of bacterial-feeding nematodes and organic matter on microbial activity and oil degradation in contaminated soil النص الكامل
2018
Zhou, Jihai | Huang, Rongxia | Cheng, Shuanghuai | Tang, Jiajie | Fan, Houbao
Increasing rates of oil exploitation and utilization are associated with increasing rates of oil pollution in soil. Nematodes are abundant in soils with or without oil contamination, among which bacterial-feeding nematodes are the dominant group. However, their function in oil-contaminated soil is unclear. This study explores the effects of bacterial-feeding nematode and organic matter addition on microbial activity and oil degradation in contaminated soil. Experiments were conducted using six treatments of oil-contaminated soil: sterilized (Control), nematode-free (OC), nematode addition (OCN), nematode + wheat straw addition (OCNW), nematode + rapeseed cake addition (OCNR), and nematode + biochar addition (OCNB). At the end of a 168-day incubation experiment, the oil concentration of OCN soil was 26.77% lower than that of OC soil, and those of OCNW, OCNR, and OCNB were 12.83%, 27.81%, and 4.77% lower, respectively, than that of OCN soil. Over the experiment, soil microbial biomass carbon, fluorescein diacetate hydrolysis activity, and dehydrogenase activity increased by 4.35–382.30%, 1.75–302.22%, and − 2.73–224.55%, respectively, in oil-contaminated soils, with or without nematode and organic matter addition. These results suggest that the addition of organic matter and bacterial-feeding nematodes to oil-contaminated soil can promote the growth and activity of microorganisms that break down oil.
اظهر المزيد [+] اقل [-]The N-shaped environmental Kuznets curve: an empirical evaluation using a panel quantile regression approach النص الكامل
2018
Allard, Alexandra | Takman, Johanna | Uddin, GaziSalah | Ahmed, Ali
We evaluate the N-shaped environmental Kuznets curve (EKC) using panel quantile regression analysis. We investigate the relationship between CO₂ emissions and GDP per capita for 74 countries over the period of 1994–2012. We include additional explanatory variables, such as renewable energy consumption, technological development, trade, and institutional quality. We find evidence for the N-shaped EKC in all income groups, except for the upper-middle-income countries. Heterogeneous characteristics are, however, observed over the N-shaped EKC. Finally, we find a negative relationship between renewable energy consumption and CO₂ emissions, which highlights the importance of promoting greener energy in order to combat global warming.
اظهر المزيد [+] اقل [-]Temporal dynamics of gut microbiota in triclocarban-exposed weaned rats النص الكامل
2018
Kennedy, Rebekah C. | Fling, Russell R. | Robeson, Michael S. | Saxton, Arnold M. | Schneider, Liesel G. | Darcy, John L. | Bemis, David A. | Zhao, Ling | Chen, Jiangang
Widely used as an antimicrobial in antibacterial bar soaps, triclocarban (3,4,4′-trichlorocarbanilide; TCC) is effective against Gram-positive bacteria but shows little efficacy against Gram-negative strains, potentially altering the composition of indigenous microflora within and on the human body. To date, the consequence of continuous or previous nonprescription antimicrobial exposure from compounds in personal care products on commensal microflora is still elusive. Previous research has shown that TCC exposure during gestation and lactation induced dysbiosis of gut microbial communities among exposed dams and neonates. However, the impact of antimicrobial exposure specifically after discontinuation of the use of TCC on the gut microbiota has not been investigated. In this study, weaned Sprague Dawley rats (postnatal day, PND 22) were provided ad lib access to TCC-supplemented diet (0.2% w/w or 0.5% w/w) for 4 weeks (phase I) followed by a 4-week washout period (phase II) to determine gut microflora changes both during continuous exposure to TCC and to determine the potential rebound following TCC withdrawal. Fecal samples were collected at baseline (PND 22) prior to TCC exposure and throughout phase I and phase II. The V4 region of 16S rDNA was sequenced from extracted total fecal DNA with the MiSeq platform. Exposure to both 0.2% w/w and 0.5% w/w TCC was sufficient to alter diversity of microbiota during phase I of treatment. This effect was further prolonged into phase II, even when TCC exposure was discontinued. Collectively, these data highlight the impact of both continuous and prior TCC exposure on gut microbial ecology and shed light onto the potential long-term health risk of daily nonprescription antimicrobial personal care product use.
اظهر المزيد [+] اقل [-]Impact of dynamical and microphysical schemes on black carbon prediction in a regional climate model over India النص الكامل
2018
Srivastava, Rohit | Bran, Sherin Hassan
Aerosol concentrations and their properties strongly depend on dynamics of atmosphere. Effects of physical and dynamical parameterizations on meteorology and black carbon (BC) mass in Weather Research and Forecasting model coupled with Chemistry (WRF-CHEM) are investigated over India. Simulations are performed in ten experiments considering two boundary layer, three cumulus parameterization, and five microphysics schemes during winter and monsoon of 2008. Morrison double-moment physical parameterization, Yonsei University boundary layer parameterization with Kain-Fritsch and Grell-Freitas cumulus parameterization schemes are found suitable to simulate meteorology and BC mass over India. BC mass is found to be underestimated in almost all experiments during winter; while, BC mass is overestimated in monsoon over Ahmedabad, Delhi, and Kanpur, which suggests inefficient wet scavenging of BC in monsoon, while lower emission rate may cause differences in winter. The results will be useful in understanding parameterizations and their impact on aerosols.
اظهر المزيد [+] اقل [-]Estimating tomato tolerance to heavy metal toxicity: cadmium as study case النص الكامل
2018
Piotto, Fernando Angelo | Carvalho, Marcia Eugenia Amaral | Souza, Lucas Anjos | Rabêlo, Flávio Henrique Silva | Franco, Mônica Regina | Batagin-Piotto, Katherine Derlene | Azevedo, Ricardo Antunes
This work aimed to develop a reliable and fast approach to estimate the plant tolerance degree to heavy metal (HM) phytotoxicity. Two independent experiments were carried out using tomato accessions, with contrasting morphological features, that were grown in a hydroponic solution containing different CdCl₂ concentrations for 7 days. Plant dry weight and chlorophyll content (SPAD units) were evaluated, and tolerance degree to Cd toxicity was estimated according to the tolerance index (TI), which is a new mathematical formula based on plant biomass proposed in this study. Although with different magnitudes, tomato exhibited reductions in their dry weight concurrently with the increasing CdCl₂ concentration. By contrast, chlorophyll content presented no standard response, decreasing and even increasing according to CdCl₂ concentrations, indicating that only under certain conditions (particularly, at CdCl₂ 50 μM), this parameter can be used to estimate plant tolerance to Cd toxicity. TI was efficiently able to segregate tomato cultivars with similar performance (based on the total dry weight of plants), and such segregation was optimized when the hydroponic solution contained from 25 to 50 μM CdCl₂. Within this range, data pointed at 35 μM CdCl₂ as the best concentration to be employed in studies related to the tomato tolerance/sensitivity to Cd toxicity. In conclusion, TI proved to be a reliable estimator of tolerance degree to Cd exposure in genetically distinct tomato accessions. Moreover, TI can be used for this same purpose in plants under other HM-induced stresses.
اظهر المزيد [+] اقل [-]Use of nicotinamide decorated polymeric cryogels as heavy metal sweeper النص الكامل
2018
Bilgin, Elif | Erol, Kadir | Köse, Kazım | Köse, Dursun A.
Cryogels are synthetic polymers used in adsorption experiments in recent years. Because of their macropores, they provide an excellent advantage as an adsorbent in continuous and batch adsorption processes. In this study, nicotinamide (NAA) decorated poly(2-hydroxyethyl methacrylate-glycidyl methacrylate), poly(HEMA-GMA), cryogels were synthesized. Heavy metal adsorption was carried out in wastewater obtained from six different sources in Çorum, Turkey. This study has a novelty regarding the application, i.e., it is the first time to use a polymeric adsorbent for the removal of 15 different heavy metal at the same time without any competition (despite the fact that there is a competition between the metals, the only thing is the removal regarding the purpose the study) as a heavy metal sweeper. Inductively coupled plasma-mass spectrometer (ICP-MS) was used for the determination of the initial amount of heavy metal in the wastewater samples. Adsorption studies were performed using poly(HEMA-GMA) and NAA-decorated poly(HEMA-GMA) cryogel to see the effect of NAA decoration. Higher adsorption capacity was achieved using NAA decorated poly(HEMA-GMA) cryogel. The total heavy metal amount adsorbed from six different sources was about 686 and 387 mg for poly(HEMA-GMA)-NAA and poly(HEMA-GMA) cryogels, respectively. The highest heavy metal adsorption value was obtained in the wastewater from source 2, and Zn (II) was the heavy metal adsorbed most for both cryogel. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal, surface area, elemental, and computerized microtomography (μCT) analyses were used for the characterization of cryogels.
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