خيارات البحث
النتائج 2451 - 2460 من 3,208
Chronic exposures to low and high concentrations of ibuprofen elicit different gene response patterns in a euryhaline fish النص الكامل
2015
Jeffries, Ken M. | Brander, Susanne M. | Britton, Monica T. | Fangue, Nann A. | Connon, Richard E.
Ibuprofen is one of the most commonly detected pharmaceuticals in wastewater effluent; however, the effects of ibuprofen on aquatic organisms are poorly understood. This study presents the transcriptome-wide response of the inland silverside, Menidia beryllina, to chronic exposure to ibuprofen. At the lowest exposure concentration (0.0115 mg/L), we detected a downregulation of many genes involved in skeletal development, aerobic respiration, and immune function. At the highest exposure concentration (1.15 mg/L), we detected increased expression of regulatory genes in the arachidonic acid metabolism pathway and several immune genes involved in an inflammatory response. Additionally, there was differential expression of genes involved in oxidative stress responses and a downregulation of genes involved in osmoregulation. This study provides useful information for monitoring the effects of this common wastewater effluent contaminant in the environment and for the generation of biomarkers of exposure to ibuprofen that may be transferable to other fish species.
اظهر المزيد [+] اقل [-]Particulate matter concentration and chemical composition in the metro system of Rome, Italy النص الكامل
2015
Perrino, C. | Marcovecchio, F. | Tofful, L. | Canepari, S.
Air quality at the main station of the metro system of Rome (Termini hub) has been characterized by the point of view of particulate matter (PM) concentration and chemical composition. Indoor air in different environments (underground train platform and shopping center, metro carriages with and without air conditioning system) has been studied and compared with outdoor air at a nearby urban site. Air quality at the railway station, located outdoor at surface level, has been also considered for comparison. PM chemical characterization included ions, elemental carbon, organic carbon, macro-elements, and the bio-accessible and residual fractions of micro- and trace elements. Train platform and carriages without air conditioning resulted to be the most polluted environments, with indoor/outdoor ratio up to two orders of magnitude for many components. PM mass concentration was determined on filter membranes by the gravimetric procedure as well as from the optical particle counter (OPC) number concentration measurements. The OPC results, taken with the original calibration factor, were below 40 % of the value obtained by the gravimetric measurements. Only a chemical and morphological characterization of the collected dust could lead to a reconciliation of the results yielded by the two methods. Macro-components were used to estimate the strength of the main macro-sources. The most significant contribution is confirmed to derive from wheels, rails, and brakes abrasion; from soil re-suspension (over 50 % at the subway platform); and from organics (about 25 %). The increase in the concentration of elements was mostly due to the residual fraction, but also the bio-accessible fraction showed a remarkable enrichment, particularly in the case of Ba, Zn, Cd, and Ni.
اظهر المزيد [+] اقل [-]Adaptation of biomixtures for carbofuran degradation in on-farm biopurification systems in tropical regions النص الكامل
2015
Chin-Pampillo, Juan Salvador | Ruiz-Hidalgo, Karla | Masís-Mora, Mario | Carazo Rojas, Elizabeth | Rodríguez-Rodríguez, Carlos E.
A biomixture constitutes the active core of the on-farm biopurification systems, employed for the detoxification of pesticide-containing wastewaters. As biomixtures should be prepared considering the available local materials, the present work aimed to evaluate the performance of ten different biomixtures elaborated with by-products from local farming, in the degradation of the insecticide/nematicide carbofuran (CFN), in order to identify suitable autochthonous biomixtures to be used in the tropics. Five different lignocellulosic materials mixed with either compost or peat and soil were employed in the preparation of the biomixtures. The comprehensive evaluation of the biomixtures included removal of the parent compound, formation of transformation products, mineralization of radiolabeled CFN, and determination of the residual toxicity of the process. Detoxification capacity of the matrices was high, and compost-based biomixtures showed better performance than peat-based biomixtures. CFN removal over 98.5 % was achieved within 16 days (eight out of ten biomixtures), with half-lives below 5 days in most of the cases. 3-Hydroxycarbofuran and 3-ketocarbofuran were found as transformation products at very low concentrations suggesting their further degradation. Mineralization of CFN was also achieved after 64 days (2.9 to 15.1 %); several biomixtures presented higher mineralization than the soil itself. Acute toxicity determinations with Daphnia magna revealed a marked detoxification in the matrices at the end of the process; low residual toxicity was observed only in two of the peat-based biomixtures. Overall best efficiency was achieved with the biomixture composed of coconut fiber-compost-soil; however, results suggest that in the case of unavailability of coconut fiber, other biomixtures may be employed with similar performance.
اظهر المزيد [+] اقل [-]Recognizing the importance of exposure–dose–response dynamics for ecotoxicity assessment: nitrofurazone-induced antioxidase activity and mRNA expression in model protozoan Euplotes vannus النص الكامل
2015
Hong, Yazhen | Liu, Shuxing | Lin, Xiaofeng | Li, Jiqiu | Yi, Zhenzhen | Al-Rasheid, Khaled A. S.
The equivocality of dose–response relationships has, in practice, hampered the application of biomarkers as a means to evaluate environmental risk, yet this important issue has not yet been fully recognized or explored. This paper evaluates the potential of antioxidant enzymes in the ciliated protozoan Euplotes vannus for use as biomarkers. Dose–response dynamics, together with both the enzyme activity and the gene expression of the antioxidant enzymes, superoxide dismutase, and glutathione peroxidase, were investigated when E. vannus were exposed to graded doses of nitrofurazone for several discrete durations. Mathematical models were explored to characterize the dose–response profiles and, specifically, to identify any equivocality in terms of endpoint. Significant differences were found in both enzyme activity and messenger RNA (mRNA) expression in the E. vannus treated with nitrofurazone, and the interactions between exposure dosage and duration were significant. Correlations between enzyme activity, mRNA expression, and nitrofurazone dose varied with exposure duration. Particularly, the dose–responses showed different dynamics depending on either endpoint or exposure duration. Our findings suggest that both the enzyme activity and the gene expression of the tested antioxidant enzymes can be used as biomarkers for ecotoxicological assessment on the premise of ascertaining appropriate dosage scope, exposure duration, endpoint, etc., which can be achieved by using dose–response dynamics.
اظهر المزيد [+] اقل [-]An inexact mixed risk-aversion two-stage stochastic programming model for water resources management under uncertainty النص الكامل
2015
Li, W. | Wang, B. | Xie, Y. L. | Huang, G. H. | Liu, L.
Uncertainties exist in the water resources system, while traditional two-stage stochastic programming is risk-neutral and compares the random variables (e.g., total benefit) to identify the best decisions. To deal with the risk issues, a risk-aversion inexact two-stage stochastic programming model is developed for water resources management under uncertainty. The model was a hybrid methodology of interval-parameter programming, conditional value-at-risk measure, and a general two-stage stochastic programming framework. The method extends on the traditional two-stage stochastic programming method by enabling uncertainties presented as probability density functions and discrete intervals to be effectively incorporated within the optimization framework. It could not only provide information on the benefits of the allocation plan to the decision makers but also measure the extreme expected loss on the second-stage penalty cost. The developed model was applied to a hypothetical case of water resources management. Results showed that that could help managers generate feasible and balanced risk-aversion allocation plans, and analyze the trade-offs between system stability and economy.
اظهر المزيد [+] اقل [-]Assessment of life cycle environmental benefits of an industrial symbiosis cluster in China النص الكامل
2015
Yu, Fei | Han, Feng | Cui, Zhaojie
Reusing industrial waste may have impressive potential environmental benefits, especially in terms of the total life cycle, and life cycle assessment (LCA) has been proved to be an effective method to evaluate industrial symbiosis (IS). Circular economy and IS have been developed for decades and have been successful in China. However, very few studies about the environmental benefit assessment of IS applied by LCA in China have been conducted. In the current article, LCA was used to evaluate the environmental benefits and costs of IS, compared with a no-IS scenario for four environmental impact categories. The results showed that four environmental benefits were avoided by the 11 symbiosis performances, namely, 41.6 thousand TJ of primary energy, 4.47 million t CO₂e of greenhouse gasses, 19.7 thousand t SO₂e of acidification, and 81.1 t PO₄³⁺e of eutrophication. Among these IS performances, the comprehensive utilization of red mud produced the most visible benefit. The results also present that energy conservation was the distinctive feature of IS in China.
اظهر المزيد [+] اقل [-]Nonylphenol biodegradation, functional gene abundance and bacterial community in bioaugmented sediment: effect of external carbon source النص الكامل
2015
Wang, Zhao | Dai, James Y. | Zhao, Qun | Li, Ningning | Zhou, Qiheng | Xie, Shuguang
Nonylphenol (NP) biodegradation in river sediment using Stenotrophomonas strain Y1 and Sphingobium strain Y2 were proved to be an effective strategy to remediate NP pollution in our earlier study. The purpose of this study is to investigate the influence of glucose addition on their ability to degrade NP in both liquid cultures and sediment microcosms. The shift in bacterial community structure and relative abundance of NP degraders in sediment microcosms were characterized using terminal restriction fragment length polymorphism analysis. The proportion of NP-degrading alkB and sMO genes was assessed using quantitative polymerase chain reaction (PCR) assay. The growth of Stenotrophomonas strain Y1 and its NP biodegradation efficiency were inhibited by glucose supplementation, while the relative abundance of alkB gene increased. However, NP degradation, as well as the growth of added degraders and proportion of sMO gene, was enhanced in the glucose-amended sediment microcosms inoculated with Sphingobium strain Y2. Moreover, external glucose addition altered bacterial community structures in bioaugmented sediment microcosms, depending on the level of glucose dosage.
اظهر المزيد [+] اقل [-]Fate of parasites and pathogenic bacteria in an anaerobic hybrid reactor followed by downflow hanging sponge system treating domestic wastewater النص الكامل
2015
Tawfik, A. | El-Zamel, T. | Herrawy, A. | El-Taweel, G.
Treatment of domestic wastewater in a pilot-scale upflow anaerobic hybrid (AH) reactor (0.9 m³) in combination with downflow hanging sponge (DHS) system (1.3 m³) was investigated. The combined system was operated at a hydraulic retention time (HRT) of 6.0 h for AH and 3.2 h for DHS system. The total process achieved a substantial reduction of CODₜₒₜₐₗ resulting in an average effluent concentration of only 39 ± 12 mg/l. Moreover, 90 ± 7 % of ammonia was eliminated in the DHS system. Nitrate and nitrite data revealed that 49 ± 3.2 % of the ammonia removal occurred through nitrification process. The removal efficiency of total coliform (TC), fecal coliform (FC), and fecal streptococci (FS) was relatively low in the AH reactor. The major portion of TC, FC, and FS was removed in the DHS system resulting to an average count of 1.7 × 10⁵ ± 1.1 × 10²/100 ml for TC, 7.1 × 10⁴ ± 1.2 × 10²/100 ml for FC, and 7.5 × 10⁴ ± 1.3 × 10²/100 ml for FS in the final effluent. Likely, the combined system was very efficient for the removal of protozoological species such as sarcodins (Entamoeba cysts), flagellates (Giardia cysts), and ciliates (Balantidium cysts). This was not the case for coccidia (Cryptosporidium oocysts), where 36.4 and 27.3 % were detected in the effluent of AH and DHS system, respectively. Only 10 % of intestinal nematode and cestode ova were recorded in the effluent of AH reactor and were completely removed in the DHS system.
اظهر المزيد [+] اقل [-]PAHs in leachates from thermal power plant wastes and ash-based construction materials النص الكامل
2015
Irha, Natalya | Reinik, Janek | Jefimova, Jekaterina | Koroljova, Arina | Raado, Lembi-Merike | Hain, Tiina | Uibu, Mai | Kuusik, Rein
The focus of the current study is to characterise the leaching behaviour of polycyclic aromatic hydrocarbons (PAHs) from oil shale ashes (OSAs) of pulverised firing (PF) and circulating fluidised-bed (CFB) boilers from Estonian Thermal Power Plant (Estonia) as well as from mortars and concrete based on OSAs. The target substances were 16 PAHs from the EPA priority pollutant list. OSA samples and OSA-based mortars were tested for leaching, according to European standard EN 12457-2 (2002). European standard CEN/TC 15862(2012) for monolithic matter was used for OSA-based concrete. Water extracts were analysed by GC–MS for the concentration of PAHs. Naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene were detected. Still, the release of PAHs was below the threshold limit value for inert waste. The amount of the finest fraction (particle size <0.045 mm), the content of the Al–Si glass phase and the surface characteristics were the main factors, which could affect the accessibility of PAHs for leaching. The mobility of PAHs from OSA of CFB and PF boilers was 20.2 and 9.9 %, respectively. Hardening of OSA-based materials did not lead to the immobilisation of soluble PAHs. Release of PAHs from the monolith samples did not exceed 0.5 μg/m². In terms of leaching of PAHs, OSA is safe to be used for construction purposes.
اظهر المزيد [+] اقل [-]Dissipation kinetics and degradation mechanism of amicarbazone in soil revealed by a reliable LC-MS/MS method النص الكامل
2015
Dong, Maofeng | Han, Wei | Ediage, Emmanuel Njumbe | Fan, Liangxiu | Tang, Hongxia | Wang, Weimin | Han, Lijun | Zhao, Zhihui | Song, Weiguo | Han, Zheng
A sensitive and reliable analytical method was developed for simultaneous determination of amicarbazone (AMZ) and its two major metabolites including desamino amicarbazone (DA) and isopropyl-2-hydroxy-DA-amicarbazone (Ipr-2-OH-DA-AMZ) in soil for the first time. Targeted analytes were extracted and purified using a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure, and then analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with a total run time of 9 min. The established approach was extensively validated by determining the linearity (R ² ≥ 0.99), recovery (84–96), sensitivity (limits of quantification at 5–10 μg kg⁻¹), and precision (RSDs ≤12 %). Based on the methodological advances, the subsequent dissipation kinetics and degradation mechanism of amicarbazone in soil were thoroughly investigated in an illumination incubator. As revealed, AMZ was easily degraded with the half-lives of 13.9–19.7 days in soil. Field trial results of AMZ (40 g a.i. ha⁻¹) in Shanghai showed that the residues of AMZ and its metabolite Ipr-2-OH-DA-AMZ decreased from 0.505 mg kg⁻¹ (day 50) to 0.038 mg kg⁻¹ (day 365) and from 0.099 mg kg⁻¹ (day 50) to 0.028 mg kg⁻¹ (day 365), respectively, while the content of DA increased from 0.097 mg kg⁻¹ (day 50) to 0.245 mg kg⁻¹ (day 365). This study provided valuable data to understand the toxicity of AMZ and substantially promote its safe application to protect environment and human health.
اظهر المزيد [+] اقل [-]