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Effects of cuticular wax content and specific leaf area on accumulation and partition of PAHs in different tissues of wheat leaf Texte intégral
2020
Wang, Jinfeng | Bao, Huanyu | Zhang, He | Li, Jiao | Hong, Huachang | Wu, Fuyong
An indoor simulation experiment was conducted to explore the effects of cuticular wax content and specific leaf area (SLA) on accumulation and distribution of PAHs in different tissues of wheat leaf. Three levels (0, 1.25, 6.0 mg L⁻¹) of mixed solution of five PAHs (Σ₅PAHs) including phenanthrene (PHE), anthracene (ANT), pyrene (PYR), benz[a]anthracene (BaA), and benzo[a]pyrene (BaP) were sprayed on leaves of seven varieties of winter wheat for every other day during 20 consecutive days. Shoot and root biomass of wheat under 6.0 mg L⁻¹ Σ₅PAHs exposure were 5.87 and 0.33 g, which were significantly (p < 0.05) lower than those (7.14 and 0.65 g) without spraying Σ₅PAHs solution, respectively. Elevated Σ₅PAHs concentration in spraying solution significantly (p < 0.0001) decreased cuticular wax content (59.1 and 65.1 vs. 67.8 mg g⁻¹) in leaves of wheat but exerted slight effects on SLA. Regardless of spraying Σ₅PAHs or not, SLA in leaves of Jiaomai (269–276 cm² g⁻¹) and Zhengmai (265–285 cm² g⁻¹) and cuticular wax content (104–118 mg g⁻¹) in leaves of Zhengmai were significantly higher than other varieties of wheat, respectively. Σ₅PAHs concentration in cuticular waxes ranged from 24,616 to 106,353 μg kg⁻¹, which was 2~3 orders and 1~2 orders of magnitude higher than that in mesophylls (46.0–535 μg kg⁻¹) and leaves (785–5366 μg kg⁻¹). There was a significant (r = 0.46, p < 0.05, n = 28) positive correlation between SLA and Σ₅PAHs concentration in wheat leaves when spraying 1.25 mg L⁻¹ of Σ₅PAHs. The present study indicated that cuticular wax content was significantly (p < 0.01) positive correlated with Σ₅PAHs concentration in the leaves and the translocation factor (TFw₋ₘ) of PHE, ANT, PYR, and Σ₅PAHs from cuticular wax to mesophyll. Based on principal component analysis (PCA), cuticular wax content was the main limiting factor for folia uptake of PAHs in winter wheat. The present study suggested that cuticular wax could play significant roles in foliar uptake of PAHs of wheat via affecting their accumulation in cuticular wax and translocation to mesophyll.
Afficher plus [+] Moins [-]Herbaceous dynamics and CO2 mitigation in an urban setup—a case study from Chhattisgarh, India Texte intégral
2020
K̲h̲ān, Nāhīd | Jhariya, Manoj Kumar | Yadav, Dhiraj Kumar | Banerjee, Arnab
Adjoining areas of urban environment has undergone rapid alteration in structure, composition and ecological changes, which makes them a dynamic entity. During the present investigation, herbaceous vegetation were studied in east, west, north and south directions of Ambikapur township at various seasons during March 2017 to April 2018. A total of 18 species representing 11 families were recorded at various directions of Ambikapur township in different seasons. Asteraceae was the predominant family in the study area. Highest species counts were recorded during summer season. Among the herbaceous vegetation, more than two-thirds of the herb species were exotic in nature, revealing the anthropogenic role towards loss of indigenous species. Highest species density was recorded in north direction (152,000 herb/ha during rainy, 104,000 herb/ha in winter and 184,000 herb/ha in summer) and lowest in south direction (90,000 herb/ha during rainy, 72,000 herb/ha in winter and 88,000 herb/ha in summer) in all seasons. Higher Shannon diversity (2.71 in rainy, 2.69 in winter and 3.07 in summer) and richness (0.67 in rainy, 0.52 in winter and 0.66 in summer after west direction) were recorded in the north direction. Total biomass, C storage and CO₂ mitigation were found to be highest towards north direction in all seasons. Argemone mexicana, Cassia tora, Ocimum tenuiflorum and Sida acuata are the most suitable species in terms of C storage, CO₂ mitigation under urban setup. Beside, some weed species also reflected significant potential. CO₂ mitigation by herb species can act as complimentary system towards climate cane adaptation beside other vegetal layers. Such studies are also very much effective towards development of greenery in an urban setup leading to climate mitigation process.
Afficher plus [+] Moins [-]Intensified simultaneous nitrification and denitrification performance in integrated packed bed bioreactors using PHBV with different dosing methods Texte intégral
2020
Yang, Zhongchen | Sun, Haimeng | Wu, Weizhong
To explore an effective approach of simultaneous nitrification and denitrification in wastewater with low C/N ratios, integrated packed bed bioreactors based on poly(3-hydroxybutyrate-hydroxyvalerate) (PHBV) with different dosing methods were designed. The removal efficiency of NH₄⁺-N in bioreactor with aeration was 88.62%, and higher NO₃⁻-N removal efficiency was observed in bioreactor filled with grainy PHBV (95.21%) than bioreactor filled with strip PHBV (93.34%). Microbial study indicated that microbes harboring amoA and nirS genes preferred to attach on the surface of ceramsite, and significant differences in microbial community compositions at phylum and genus levels were observed. To summarize, it is feasible to utilize grainy PHBV for simultaneous and efficient removal of NH₄⁺-N and NO₃⁻-N from wastewater with low C/N ratios.
Afficher plus [+] Moins [-]The removal of lead, copper, zinc and cadmium from aqueous solution by biochar and amended biochars Texte intégral
2020
Cairns, Stuart | Robertson, Iain | Sigmund, Gabriel | Street-Perrott, Alayne
The exponential growth in the use of motor vehicles is a key contributor to freshwater degradation. Current remediation techniques require prohibitively expensive contaminant treatment and extraction. Biochar represents an inexpensive option to ameliorate contaminants from motorway runoff. Biochar from Norway spruce (Picea abies (L.) Karst.) was produced under fast pyrolysis-gasification (450–500 °C for 90 s) and amended with wood ash and basaltic rock dust to evaluate sorption of Pb, Cu, Zn and Cd. The column study, designed to mimic field conditions, confirmed that unamended biochar can bind contaminants for short periods, but that the addition of amendments, particularly wood ash, significantly improves contaminant removal. Wood ash-amended biochar removed 98–100% of all contaminants during the study, driven by pH (r = 0.73–0.74; p < 0.01 dependent on metal species) and phosphorus levels causing precipitation (r = 0.47–0.59; p < 0.01, dependent on metal species). The contaminants’ progression through the biochar subsections in the column indicated that increasing the thickness of the biochar layer increased contaminant residence time and removal.
Afficher plus [+] Moins [-]Degradation of ciprofloxacin using a low-grade titanium ore, persulfate, and artificial sunlight Texte intégral
2020
Macías-Vargas, José-Alberto | Zanella, Rodolfo | Ramírez-Zamora, Rosa-María
In this study, the magnetic fraction (MF) of a low-grade titanium ore (TO) was successfully used as an alternative Fe²⁺ source in five reuse cycles, in combination with persulfate (PS) and simulated sunlight (SSL) for the degradation of ciprofloxacin (CIP). The best response of the CIP initial concentration, irradiation time, and doses of MF and PS to degrade completely this pollutant were determined based on an experimental design. However, the individual application of MF, PS, or SSL fails to achieve this goal at the optimal experimental condition. Furthermore, the MF-PS-SSL system showed a higher production of sulfate radicals and a concentration of dissolved Fe²⁺ ions compared with data obtained for the MF-PS system. The best performance attained by the former system is due to the synergy produced between the photo-generated electrons, and the reaction of PS with the Fe²⁺ ions leached gradually from the MF, which increased sulfate radical production. After five reuse cycles of the MF, the oxidation system showed a CIP degradation of 100% in 100 min, no residual content of PS, a CIP mineralization of 6%, a marginal increase in the biodegradability (BOD₅/COD ratio), a MF loss of 7.5%, and a twofold increase in toxicity; however, this parameter was lower than the effective concentration at 50% inhibition (EC₅₀). The substitution of MF with an iron salt decreased the degradation efficiency of the antibiotic by 14%, probably owing to the immediate excess of Fe²⁺ in the solution, which can be oxidized to Fe³⁺ ions, and as a consequence of this, the production rate of the sulfate radical was also reduced.
Afficher plus [+] Moins [-]Does carbon dioxide, methane, nitrous oxide, and GHG emissions influence the agriculture? Evidence from China Texte intégral
2020
Rehman, Abdul | Ma, Hengyun | Irfan, Muhammad | Ahmad, Munir
Carbon dioxide emission and greenhouse gas emissions are considered core issue in the world that influence agricultural production and also cause climate change. The present study seeks to investigate the linkage of methane emissions, nitrous oxide emissions, carbon dioxide emission, and greenhouse gas emissions with agricultural gross domestic product in China. The long-term association was checked by using an autoregressive distributed lag (ARDL) bounds testing approach, fully modified least squares method, and canonical cointegrating regression analysis. The results from long-run analysis exposed that carbon dioxide emission and greenhouse gas emissions have positive coefficients that demonstrate the long-run linkage with the agricultural gross domestic product having p values of 0.5709 and 0.3751, respectively. Similarly, results also revealed that agricultural methane emissions and agricultural nitrous oxide emissions have a negative association with the agricultural gross domestic product having p values of 0.1737 and 0.0559. China is a huge emitter of CO₂ emission and greenhouse gas emissions. Possible conservative policies are required to form the Chinese government to tackle this challenge to decrease CO₂ emission in order to increase agricultural production.
Afficher plus [+] Moins [-]Development of electrospun lignin nanofibers for the adsorption of pharmaceutical contaminants in wastewater Texte intégral
2020
Camiré, Alexandre | Espinasse, Julie | Chabot, Bruno | Lajeunesse, André
Emerging contaminants present a challenge for water preservation, threatening humans’ health and all ecosystems. They consist of a variety of molecules ranging from pharmaceutical and personal care products to pesticides and endocrine disruptors detectable in wastewater, sewage effluent, surface water, drinking water, and ground waters at trace level concentrations (e.g., ng/L, μg/L). Conventional wastewater treatment plants (WWTPs) possess low efficiency to remove them. Therefore, new technologies capable of removing such residues are needed. Lignin recognized as a renewable and abundant biopolymer is transformed through electrospinning into an anionic nanofibrous nonwoven adsorbent to extract those contaminants and dispose them safely. Electrospinning allows the manufacture of fibers at the micro- or nanoscale under the influence of an electric current. In this study, nanofibers of alkali lignin and a co-polymer, poly(vinyl alcohol), were developed and tested on the adsorption of a pharmaceutical contaminant (fluoxetine) in an aqueous solution. Results showed that the lignin nanofibers, of 156 nm in diameter, adsorbed 70% of fluoxetine in solution which corresponds to 32 ppm of contaminants removed in water.
Afficher plus [+] Moins [-]Enhanced catalytic activity of MIL-101(Fe) with coordinatively unsaturated sites for activating persulfate to degrade organic pollutants Texte intégral
2020
Guo, Huaisu | Su, Shengnan | Liu, Yang | Ren, Xiaohua | Guo, Weilin
In this work, four novel defective MIL-101(Fe) catalysts with coordinatively unsaturated sites were successfully prepared via a facile synthesis strategy by employing benzoic acid, acetic acid, oxalic acid, or citric acid as a modulator. The modified catalysts were demonstrated the existence of defects in the parent framework by a series of characterizations. As compared to the initial MIL-101(Fe), the electronic structure of defective MIL-101(Fe) catalyst was effectively adjusted; meanwhile, the coordinatively unsaturated Fe sites were efficiently generated and the pore sizes were enlarged. Besides, the defective MIL-101(Fe) catalysts exhibited excellent catalytic performance for rhodamine B degradation by persulfate activation. To be specific, the degradation rates of rhodamine B increased from 58.70 to 94.05%, 86.11%, 78.70%, and 82.62%, respectively. The defective MIL-101(Fe) with coordinatively unsaturated sites showed good reusability and stability, and the probable catalytic mechanism was also investigated.
Afficher plus [+] Moins [-]Evaluating trends in the performance of Chilean water companies: impact of quality of service and environmental variables Texte intégral
2020
Molinos-Senante, María | Maziotis, Alexandros | Sala Garrido, Ramón
In monopoly services that provide drinking water, it is of paramount importance to evaluate the total factor productivity (TFP) change of water companies. Most of the previous studies have computed the Malmquist productivity index (MPI) by applying non-parametric methods. By contrast, following a pioneering approach, in this study, we estimated the MPI using a parametric method that allows us to decompose TFP change into a larger number of drivers, including exogenous and quality of service variables. An empirical application for the Chilean water industry over 2007–2015 was conducted. We found that productivity change estimates were variable across years, differentiating a first period (2007/11) in which productivity declined and a second period (2011/15) in which TFP notably improved. In both periods, scale efficiency change and input mixed effect were the main drivers of productivity change, illustrating the importance of operation scale in water companies’ performance. The decomposition of the TFP change in a large number of drivers is essential to propose incentives and measures to promote productivity across time.
Afficher plus [+] Moins [-]Health benefits on cardiocerebrovascular disease of reducing exposure to ambient fine particulate matter in Tianjin, China Texte intégral
2020
Zhang, Jingwei | Feng, Lihong | Hou, Changchun | Gu, Qing
With the development of the industrialization level in China, high concentrations of fine particulate matter (≤ 2.5 μg/m³ in aerodynamic diameter (PM₂.₅)) could have a great impact on the health of the population. Our study is to quantify the health benefits on cardiocerebrovascular disease of reducing exposure to PM₂.₅ in Tianjin, China. We obtained the data on cardiovascular disease (CVD), ischemic heart disease (IHD), and cerebrovascular disease (CD) mortalities to quantify the association between CVD, CD, and IHD mortalities and PM₂.₅ and calculate health and economic benefits when the annual average concentration of PM₂.₅ was reduced to National Ambient Air Quality Standard (NAAQS) and World Health Organization (WHO) guidelines by using our concentration response (C-R) functions. There were 435.22 (95% CI 253.86 to 616.57) all-cause, 130.22 (95% CI 66.34 to194.09) IHD, and 204.07 (95% CI 111.66 to 296.47) CD deaths attributed to PM₂.₅ and the economic benefits obtained by preventing all-cause, IHD, and CD mortalities were equivalent to be 2.79%, 0.83%, and 1.31% of Baodi’s GDP in Tianjin in 2017, respectively. PM₂.₅ concentration was positive with all-cause, IHD, and CD mortalities in rural, suburban, and urban area of Tianjin, China. Meanwhile, the number of avoidable deaths and economic cost of reducing PM₂.₅ concentrations to NAAQS and WHO guidelines was highest in the rural area.
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