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Resultados 4451-4460 de 4,937
Natural resources, globalization, and economic growth: evidence from Pakistan Texto completo
2019
Hassan, Syed Tauseef | Xia, Enjun | Huang, Jieping | Khan, Noor Hashim | Iqbal, Kashif
Globalization is increasingly a driving force behind vibrant economies around the world. This paper discusses the impact of globalization and natural resources on economic growth from 1970 to 2014 in Pakistan. Based on an auto-regressive distributive lag (ARDL) model, the paper infers that globalization promotes economic growth in Pakistan. Natural resources also contribute to economic growth, as the causality results suggest bi-directional causality between globalization and use of natural resources. Policy implications are that countries should emphasize security, increase exports, encourage technological strength, and increase its intellectual management capacity.
Mostrar más [+] Menos [-]Histopathological effects in gills and liver of Sparus aurata following acute and chronic exposures to erythromycin and oxytetracycline Texto completo
2019
Rodrigues, Sara | Antunes, Sara C. | Nunes, Bruno | Correia, Alberto Teodorico
Histopathological effects in gills and liver of Sparus aurata following acute and chronic exposures to erythromycin and oxytetracycline Texto completo
2019
Rodrigues, Sara | Antunes, Sara C. | Nunes, Bruno | Correia, Alberto Teodorico
Due to their worldwide use and environmental persistence, antibiotics are frequently detected in various aquatic compartments. Their toxic properties raise environmental concerns to non-target organisms. Histopathology data is frequently applied in ecotoxicology studies to assess the effects of different classes of environmental stressors in fish, including antibiotics. Tissue alterations in gills and liver of gilthead seabream (Sparus aurata) individuals acutely (96 h) and chronically (28 days) exposed to environmentally relevant concentrations of the antibiotics erythromycin (ERY: 0.0002–200 μg/L) and oxytetracycline (OTC: 0.0004–400 μg/L), including a control non-exposed group, were evaluated. Several disorders (circulatory, regressive, progressive, and inflammatory) were observed in both organs of all exposed animals. The hereby obtained data showed a higher and significant increase in gill histopathological index of organisms acutely exposed to ERY and of those chronically exposed to OTC. In terms of categorical lesions, only a significant increase of regressive and progressive alterations occurred in gills after chronic exposure to OTC. For the liver, a significant increase in pathological index was also detected, as well as regressive changes, after chronic exposure to OTC. Furthermore, the present study indicates that most of the changes observed in gills and liver were of mild to moderate severity, which might be adaptive or protective, non-specific, and mostly reversible. Despite being observed, irreversible lesions were not significant in any of the fish organs analyzed. Although there were histological changes, gill apparatus was considered still functionally normal, as well as liver tissue, not supporting the occurrence of severe toxicity. In general, the observed histological changes were not stressor-specific, and toxicological mechanistic explanations for the alterations observed in gills and liver are presented. The obtained data showed that histopathological biomarkers can be successfully applied in ecotoxicological studies, evidencing their relevance, responsivity, and complementarity to other biochemical biomarker-based approaches.
Mostrar más [+] Menos [-]Histopathological effects in gills and liver of Sparus aurata following acute and chronic exposures to erythromycin and oxytetracycline Texto completo
2019
Rodrigues, Sara | Antunes, Sara C. | Nunes, Bruno | Correia, Alberto Teodorico
Due to their worldwide use and environmental persistence, antibiotics are frequently detected in various aquatic compartments. Their toxic properties raise environmental concerns to non-target organisms. Histopathology data is frequently applied in ecotoxicology studies to assess the effects of different classes of environmental stressors in fish, including antibiotics. Tissue alterations in gills and liver of gilthead seabream (Sparus aurata) individuals acutely (96 h) and chronically (28 days) exposed to environmentally relevant concentrations of the antibiotics erythromycin (ERY: 0.0002-200 μg/L) and oxytetracycline (OTC: 0.0004-400 μg/L), including a control non-exposed group, were evaluated. Several disorders (circulatory, regressive, progressive, and inflammatory) were observed in both organs of all exposed animals. The hereby obtained data showed a higher and significant increase in gill histopathological index of organisms acutely exposed to ERY and of those chronically exposed to OTC. In terms of categorical lesions, only a significant increase of regressive and progressive alterations occurred in gills after chronic exposure to OTC. For the liver, a significant increase in pathological index was also detected, as well as regressive changes, after chronic exposure to OTC. Furthermore, the present study indicates that most of the changes observed in gills and liver were of mild to moderate severity, which might be adaptive or protective, non-specific, and mostly reversible. Despite being observed, irreversible lesions were not significant in any of the fish organs analyzed. Although there were histological changes, gill apparatus was considered still functionally normal, as well as liver tissue, not supporting the occurrence of severe toxicity. In general, the observed histological changes were not stressor-specific, and toxicological mechanistic explanations for the alterations observed in gills and liver are presented. The obtained data showed that histopathological biomarkers can be successfully applied in ecotoxicological studies, evidencing their relevance, responsivity, and complementarity to other biochemical biomarker-based approaches. | published
Mostrar más [+] Menos [-]Investigating the drinking and surface water quality and associated health risks in a semi-arid multi-industrial metropolis (Faisalabad), Pakistan Texto completo
2019
Mahfooz, Yusra | Yasar, Abdullah | Sohail, Muhammad Tayyab | Tabinda, Amtul Bari | Rasheed, Rizwan | Irshad, Samina | Yousaf, Balal
Urban areas under the influence of multi-industrial activities with arid and semi-arid environments witness the significant increase in environmental pollution especially in the water sector. The present study evaluated the water quality and associated health risk assessment through heavy metal pollution. Drinking (n = 48) and surface (n = 37) water samples were collected from semi-arid multi-industrial metropolis, Faisalabad, Pakistan. Physio-chemical and biological parameters and different metals (Al, As, Ba, Cd, Cr, Cu, Fe, Pb, Ni and Zn) were investigated using standard procedures and multivariate water quality assessments. Many physio-chemical and biological parameters and metals especially arsenic were exceeding the permissible limit of Punjab environmental quality standards and the World Health Organization. The results from water quality index showed that < 56% samples have poor, < 8% have very poor and < 6% have unsuitable water quality for drinking purposes. Water quality for the Gugera Branch Canal was found suitable with medium sodium (alkalinity) and salinity hazards, while it was found poor with magnesium absorption ratio. Hazard quotient (HQ) values for arsenic were found at the threshold level (HQ > 1) and carcinogenicity was found in case of arsenic and chromium (1 × 10⁻⁴) in adults and children. Semi-arid weather combined with different anthropogenic activities and unusual water features provoked metal contamination. Results of the present study can deliver basic information for effective management of water in the most populous and industrial areas.
Mostrar más [+] Menos [-]From environmental data acquisition to assessment of gardeners’ exposure: feedback in an urban context highly contaminated with metals Texto completo
2019
Pelfrêne, Aurélie | Sahmer, Karin | Waterlot, Christophe | Douay, Francis
Although growing vegetables in urban gardens has several benefits, some questions in relation with the safety of foods remain when the self-production is carried out on highly contaminated garden soils. To better assess the local population’s exposure to Cd and Pb induced by the past activities of a lead smelter, a participatory program was initiated in 115 private kitchen gardens located in northern France to assist gardeners in understanding their soil environment. The challenge included contributing to the database of urban garden soils with the collection of a large number of samples: 1525 crops grouped into 12 types (leaf, fruiting, root, stem and bulbous vegetables, tubers, cabbages, leguminous plants, celeriac, fresh herbs, fruits, and berries), 708 topsoils, and 52 samples of self-produced compost. The main results were as follows: (i) topsoils were strongly contaminated by Cd and Pb compared to regional reference values; (ii) great variability in physicochemical parameters and metal concentrations in topsoils; (iii) the highest concentrations of Cd and Pb for celeriac and fresh herbs and the lowest for fruits and fruiting vegetables; (iv) a high percentage of vegetables that did not comply with the European foodstuff legislation; and (v) most self-produced compost samples were strongly contaminated. This study aimed to raise awareness and generate functional recommendations to reduce human exposure and to provide useful data that could be considered in other environmental contexts.
Mostrar más [+] Menos [-]Adsorption characteristics of Cu(II) and Zn(II) by nano-alumina material synthesized by the sol-gel method in batch mode Texto completo
2019
This study mainly focuses on the preparation, characterization, and sorption performance for Cu(II) and Zn(II) by using nano-alumina material (NA) synthesized through the sol-gel method. The SEM, EDS, FT-IR, and XRD analysis methods were implemented to identify the micromorphology and crystal structure of the synthesized NA absorbent and its structure after the adsorbing procedure. The effect of effective variables including various absorbent dose, contact time, initial ion concentration, and temperature on the removal of Cu(II) and Zn(II) from aqueous solution by using NA was investigated through a single factor experiment. Kinetic studies indicated that adsorption of copper and zinc ions by NA was chemical adsorption. The adsorption isotherm data were fitted by Langmuir (R²: 0.919, 0.914), Freundlich (R²: 0.983, 0.993), and Temkin (R²: 0.876, 0.863) isotherms, indicating that copper and zinc ions were easily adsorbed by NA with maximum adsorption capacities of 87.7 and 77.5 mg/g for Cu²⁺ and Zn²⁺, respectively. Thermodynamic parameters indicated that the adsorption of Cu²⁺ was spontaneous(G<0) and the adsorption of Zn²⁺ might not be spontaneous (G > 0) by NA. Graphical abstract ᅟ
Mostrar más [+] Menos [-]Spatial distribution of heavy metal concentrations in peri-urban soils in eastern China Texto completo
2019
Complex land use patterns and intense human activities significantly affect the spatial distribution of heavy metals in soils. This is especially true in peri-urban areas. The land use in peri-urban areas is complex and the risk of heavy metal pollution is relatively high. Identifying the correlations between land use patterns and spatial distribution of heavy metals in peri-urban soils is important for enhancing soil security and sustaining soil ecosystem services in areas undergoing rapid urbanisation. In this study, soil samples were collected from 82 experimental sites in a typical peri-urban watershed in eastern China. Copper (Cu), zinc (Zn), cadmium (Cd), nickel (Ni), arsenic (As), chromium (Cr), lead (Pb) and mercury (Hg) concentrations at different soil depths were analysed. Results showed that heavy metal concentrations in peri-urban soils were significantly affected by land use type and varied with soil depth. Farmland had the highest heavy metal concentrations, whereas forestland had the lowest concentrations; the concentrations in soils decreased with increasing soil depth. Spatial analysis of heavy metals in soils showed that their concentrations rapidly increased with the increasing percentage of town areas in buffer zones. This indicated that land use structure influenced the heavy metal concentrations in peri-urban soils and the influences were correlated to the locations of towns and villages. Correlation analysis showed that Cu, Zn, Cd, Pb and Hg concentrations in soils were significantly affected by altitude, distance from roads, distance from towns and villages and soil clay content. Interestingly, historic land use was also found to affect heavy metal concentrations in forestland. These results can provide scientific guidance for designing effective soil management practices for peri-urban areas.
Mostrar más [+] Menos [-]Nitrate removal performance and diversity of active denitrifying bacteria in denitrification reactors using poly(L-lactic acid) with enhanced chemical hydrolyzability Texto completo
2019
Yamada, Takeshi | Tsuji, Hideto | Daimon, Hiroyuki
Poly(L-lactic acid) (PLLA) can be used as an external electron donor in denitrification reactors to treat drinking water, aquaculture water, and industrial wastewater with an imbalanced carbon/nitrogen ratio. However, for PLLA to function in these applications, its chemical hydrolyzability requires improvement. Although the adjustment of the crystallinity (Xc) is effective in improving the hydrolyzability of PLLA, the condition for the Xc of PLLA, in which a sufficient amount of lactic acid is released for denitrification, must be clarified. Therefore, this study investigated the effective Xc range and optimal PLLA content as an electron donor for continuous nitrate removal in denitrification reactors. This study also explored the abundance, succession, and diversity of active denitrifying bacteria in denitrification reactors. The nitrate removal activity of activated sludge using the highly crystalline PLLA (Xc = 39.4%) was 1.8 mg NO₃⁻ -N g MLSS⁻¹ h⁻¹, which is 2.4 times higher than that using the nearly amorphous PLLA (Xc = 0.9%). During the 57 days of operation, the denitrification reactor with 3% (w/v) highly crystalline PLLA continued to completely remove nitrate, with a maximum nitrate removal activity of 22.8 mg NO₃⁻ -N g MLSS⁻¹ h⁻¹. The 16S rRNA amplicon sequencing and clone library analyses are using transcripts of two nitrite reductase genes, encoding cytochrome cd₁ nitrite reductase, and copper-containing nitrite reductase revealed that bacteria belonging to the families Comamonadaceae, Rhodocyclaceae, and Alcaligenaceae were active denitrifying bacteria in the denitrification reactor using PLLA.
Mostrar más [+] Menos [-]Impact of calcium peroxide dosage on the control of nutrients release from sediment in the anoxic landscape water Texto completo
2019
Wang, Yi | Wang, Wen-Huai | Lu, Xin-Xin | Feng, Lin-Lin | Xue, Fu-Rong | Sun, Lu-Qin
The anoxic and reductive aquatic environment is formed easily in summer due to the global warming, which may accelerate endogenous release. In this experiment, four different dosages of calcium peroxide (CaO₂) were adopted to study the control effects of nutrients release from the sediments in the simulated landscape waters. The results demonstrated that CaO₂ addition could effectively improve the physicochemical properties and microbial composition in sediments, and an obvious improvement was achieved with a larger dosage. It was observed that the surface sediments of experiment groups were oxidized to form a capping barrier between the sediment and overlying water, which might cut off the pollutant diffusion in sediment. Meanwhile, CaO₂ could decrease the nutrients concentration in water obviously, and the reduced effect was positively correlated with the CaO₂ dosage. Compared with the nutrients release fluxes in CK (105.89 mg-TN m⁻² day⁻¹, 106.48 mg-NH₄⁺-N m⁻² day⁻¹, 4.14 mg-TP m⁻² day⁻¹, and 4.30 mg-SRP m⁻² day⁻¹), the CaO₂ dosages of 0.12 and 0.18 kg m⁻² could entirely inhibit the nutrients release from sediment, and partially reduce the original pollutants in the overlying water. However, 0.18 kg m⁻² CaO₂ would cause a higher increase of pH value and NO₂⁻-N concentration, and bring potential risk to the aquatic ecosystem. Therefore, 0.12 kg-CaO₂ m⁻²-sediment was selected as the optimal dosage by considering the control effect, economic cost, and potential risk comprehensively. In general, this study provided a quantitative usage method of CaO₂, which is convenient and effective to prevent or control the nutrients release from sediment caused by anoxic and reductive condition in summer.
Mostrar más [+] Menos [-]Does “replacing business tax with value-added tax” promote the energy efficiency of the logistics industry in China? Texto completo
2019
Liu, Zuankuo | Jiang, Yufan | Bolayog, Dennis
This paper investigates the relationship between “replacing business tax with value-added tax” (RBTVT) and the total factor energy efficiency (TFEE) of the logistics industry using regression discontinuity (RD) method, and the research shows that the TFEE of the logistics industry in China has presented a benign growth trend. RBTVT has significantly promoted the development of TFEE in the logistics industry, and its influence has mainly stemmed from the improvement of green technology progress. Moreover, the promotion mechanism of policy in the eastern region reacts more sharp than that in the central and western regions does. So this paper claims that the government should built a tax incentive mechanism of green production and energy conservation. It is necessary to use RBTVT to promote the high-quality development of the logistics industry and create an environment which coexist low-carbon environmental protection and economic benefits.
Mostrar más [+] Menos [-]Oxidation stability of yeast biodiesel using Rancimat analysis: validation using infrared spectroscopy and gas chromatography–mass spectrometry Texto completo
2019
Biodiesel and single cell oils obtained from oleaginous yeasts grown in industrial waste are attractive alternatives to the conventional fuels. However, there are only few articles dealing with the stability of the microbial biofuels. Hence, this study aimed at characterizing the storage time of biodiesels using Rancimat methods. The microbial oil and the biodiesel obtained from microbial oil have been characterized with storage stability due to various oxidizing and thermal damage. Here, the microbial fuels were subject to Rancimat analysis and found to have high thermal-oxidative stability of 18 and 8.78 h for biodiesel and oil, respectively. The storage stability resulting from storage conditions was extrapolated for biodiesel and oil and has been found to be 1.62 and 0.54 years, respectively. The infrared spectroscopic analysis reveals the degree of oxidation found after the induction time was reached and shows the characteristic peaks for degradation products. Gas chromatography revealed the compounds that were responsible for the stability as well as the amount of degradation products left.
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