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Resultados 2641-2650 de 5,151
Regulation of the ascorbate-glutathione cycle in leaves of poplar exposed to combined stresses (ozone and/or drought). Texto completo
2018
Dusart, Nicolas | Vaultier, Marie-Noëlle | Collignon, Christelle | Gérard, Joëlle | Le Thiec, D | Jolivet, Yves
Changes in multiple facets of macroinvertebrate alpha diversity are linked to afforestation in a subtropical riverine natural reserve Texto completo
2018
Wang, Jun | Jiang, Xiaoming | Li, Zhengfei | Meng, Xingliang | Heino, Jani | Xie, Zhicai | Wang, Xiaoming | Yu, Jiang
Land use change is one of the major factors impacting freshwater biodiversity. Afforestation could convert new lands from agriculture or urban land uses to reduce erosion and lead to landscape alterations and biodiversity changes. Here, we examined the changes in the three facets of macroinvertebrate alpha diversity (i.e., taxonomic, functional, and phylogenetic diversity) and further explored possible mechanisms driving their variations before (2007) and after (2016) afforestation along the undammed Chishui River, the core of the National Nature Reserve of Rare and Endemic Fishes in the Upper Yangtze River. We found that taxonomic diversity measures (e.g., species richness, Shannon-Wiener index and Simpson index) increased but all measures of functional diversity (e.g., FRic, FEve, FDiv, and RaoQ) and phylogenetic diversity (e.g., indices of taxonomic distinctness) exhibited stability after the afforestation practice. We also found that only significant taxonomic diversity variation was detected and it showed a relationship to alterations of land use rather than local environmental condition changes across the 10-year afforestation practice. Moreover, hydrology and nutrients levels showed changes after afforestation, but these changes had no effect on the biodiversity changes based on multiple linear regression models. In each survey, the three facets of alpha diversity were significantly explained by natural physical factors and showed inconsistent responses to these underlying environmental variables. In addition, the biodiversity-environment relationships remained stable before and after afforestation, indicating that the inherent mechanisms that drive macroinvertebrate community variation have not changed. Our findings highlight that different alpha diversity measures of lotic macroinvertebrates provide different information about biodiversity and respond differently to various environmental variables. Thus, it is necessary to integrate them into one framework when applying routine monitoring, assessment, and conservation procedures based on lotic macroinvertebrates.
Mostrar más [+] Menos [-]Recycling of wastes from fish beneficiation by composting: chemical characteristics of the compost and efficiency of their humic acids in stimulating the growth of lettuce Texto completo
2018
Busato, Jader Galba | de Carvalho, Caroline Moreira | Zandonadi, Daniel Basilio | Sodré, Fernando Fabriz | Mol, Alan Ribeiro | Oliveira, Aline Lima de | Navarro, Rodrigo Diana
Waste from the beneficiation of fish was composted with crushed grass aiming to characterize their chemical composition and investigate the possibility of the use of the final compost as source of humic acids (HA) able to stimulate the growth of lettuce. Compost presented pH value, C/N ratio, and electrical conductivity that allow its use as an organic fertilizer. The element content was present in the following order of abundance in the compost: P > Ca > N > Mg > K > Fe > Zn > Mn > Mo > Cu, and the humus composition was similar to that observed in others kind of organic residues composted. The high content of oxygen pointed out a high level of oxidation of HA, in line with the predominance of phenolic acidity in the functional groups. The ¹³C-NMR spectra showed marked resonances due to the presence of lipids and other materials resistant to degradation as methoxy substituent and N-alkyl groups. A concentration of 20 mg L⁻¹ HA increased significantly both dry and wet root matter in lettuce but the CO₂ assimilation, stomatal conductance, and number of lateral roots of the plants were not affected. However, increases of 64% in the water-use efficiency was observed due to the HA addition, probably related to the root morphology alteration which resulted in 1.6-fold increase of lateral root average length and due to the higher H⁺ extrusion activity. Reuse of residues from the fish beneficiation activity by composting may represent a safe tool to increase the value of recycled organic residues and generate HA with potential use as plant growth stimulants.
Mostrar más [+] Menos [-]Techno-economic and environmental assessment of biogas production from banana peel (Musa paradisiaca) in a biorefinery concept Texto completo
2018
Martínez-Ruano, Jimmy Anderson | Caballero-Galván, Ashley Sthefanía | Restrepo-Serna, Daissy Lorena | Cardona, Carlos Ariel
Two scenarios for the biogas production using Banana Peel as raw material were evaluated. The first scenario involves the stand-alone production of biogas and the second scenario includes the biogas production together with other products under biorefinery concept. In both scenarios, the influence of the production scale on the process economy was assessed and feasibility limits were defined. For this purpose, the mass and energy balances were established using the software Aspen Plus along with kinetic models reported in the literature. The economic and environmental analysis of the process was performed considering Colombian economic conditions. As a result, it was found that different process scales showed great potential for biogas production. Thus, plants with greater capacity have a greater economic benefit than those with lower capacity. However, this benefit leads to high-energy consumption and greater environmental impact.
Mostrar más [+] Menos [-]Study on the removal of hormones from domestic wastewaters with lab-scale constructed wetlands with different substrates and flow directions Texto completo
2018
Herrera-Melián, José Alberto | Guedes-Alonso, Rayco | Borreguero-Fabelo, Alejandro | Santana-Rodríguez, José Juan | Sosa-Ferrera, Zoraida
Eight wastewater samples from a university campus were analysed between May and July of 2014 to determine the concentration of 14 natural and synthetic steroid hormones. An on-line solid-phase extraction combined with ultra-high performance liquid chromatography coupled with mass spectrometry (on-line SPE-UHPLC-MS/MS) was used as extraction, pre-concentration and detection method. In the samples studied, three oestrogens (17β-estradiol, estrone and estriol), two androgens (boldenone and testosterone), three progestogens (norgestrel, progesterone and norethisterone) and one glucocorticoid (prednisone) were detected. The removal of hormones was studied in primary and secondary constructed wetland mesocosms. The porous media of the primary constructed wetlands were palm tree mulch. These reactors were used to study the effect of water flow, i.e. horizontal (HF1) vs vertical (VF1). The latter was more efficient in the removal of 17β-estradiol (HF1: 30%, VF1: 50%), estrone (HF1: 63%, VF1: 85%), estriol (100% both), testosterone (HF1: 45%, VF1: 73%), boldenone (HF1:-77%, VF1: 100%) and progesterone (HF1: 84%, VF1: 99%). The effluent of HF1 was used as influent of three secondary constructed wetland mesocosms: two double-stage vertical flow constructed wetlands, one with gravel (VF2gravel) and one with palm mulch (VF2mulch), and a mineral-based, horizontal flow constructed wetland (HFmineral). VF2mulch was the most efficient of the secondary reactors, since it achieved the complete removal of the hormones studied with the exception of 17ß-estradiol. The significantly better removal of BOD and ammonia attained by VF2mulch suggests that the better aeration of mulch favoured the more efficient removal of hormones.
Mostrar más [+] Menos [-]A theoretical method for the high-sensitivity fluorescence detection of PAEs through double-substitution modification Texto completo
2018
Qiu, Youli | Li, Yu
A highly sensitive method for the detection of phthalate acid ester (PAE) derivatives by fluorescence spectroscopy based on a double-substitution modification is reported. The fluorescence intensities of 18 PAE derivatives and the template PAEs after docking with the protein bovine serum albumin (BSA) are compared; the fluorescence intensities of the PAE derivatives increase significantly (28.20 to 110.00 times) with high sensitivities, but the functionalities (stability and insulation) are not affected. The persistence, mobility, and toxicity of the PAE derivatives are reduced by varying degrees, and their amounts of bioaccumulation are not significantly changed, indicating that the derivatives are more environmentally friendly. Within the wavelength range 240–420 nm in the fluorescence spectrum, there is no interference between the PAE derivatives and polycyclic aromatic hydrocarbons (PAHs), and the derivatives can be detected with good precision. Based on the analysis of fluorescence characteristics using a 2D quantitative structure-activity relationship (QSAR) model, the occupied orbital energies and Mulliken charge numbers are the main factors that influence the spectral characteristics of the PAE derivatives.
Mostrar más [+] Menos [-]Favorable compatibility of nitenpyram with the aphid predator, Coccinella septempunctata L. (Coleoptera: Coccinellidae) Texto completo
2018
Jiang, Jiangong | Ma, Dicheng | Zhang, Zhengqun | Yu, Caihong | Liu, Feng | Mu, Wei
The increasing demand for lessening the chemical input in agricultural ecosystems requires an efficient combination of pesticides and biological controls. Thus, fully understanding the compatibility of pesticides and beneficial arthropod predators is helpful and essential. In this study, we evaluated the influence of nitenpyram on both larvae and adults of Coccinella septempunctata using exposure doses of 10, 25, 50, 100, and 150% of the maximum recommended field rate (MRFR) (3, 7.5, 15, 30, and 45 g a.i. ha⁻¹, respectively) and a blank control based on a preliminary acute 72-h toxicity experiment. In the long-term test, the LR₅₀ (application rate causing the mortality of 50% of the individuals) of nitenpyram for C. septempunctata decreased from 73.43 to 63.0 g a.i. ha⁻¹, while the HQ (hazard quotient) values remained below the threshold value of 2. Nitenpyram did not significantly influence the survival rate, fecundity, pupation, or adult emergence at 150% of the label rate (lowest LR₅₀ = 63.0 g a.i. ha⁻¹), and its demonstrated NOER (No Observed Effect application Rates) values are all above 45 g a.i. ha⁻¹. Likewise, the total developmental time and egg hatchability were not significantly affected at 100% of the label rate (NOER = 30 g a.i. ha⁻¹). The assessment of the total effect (E) suggested that nitenpyram could be classified as harmless to C. septempunctata below/at a dose of 30 g a.i. ha⁻¹. The lowest LR₅₀ and NOER values were both above the maximum recommended field application rate for nitenpyram (30 g a.i. ha⁻¹) for controlling aphids in China. All results indicated that the on-label use of nitenpyram is compatible with the natural enemy C. septempunctata in agricultural ecosystems.
Mostrar más [+] Menos [-]Heavy metal enrichment in roadside soils in the eastern Tibetan Plateau Texto completo
2018
Guan, Zhen-Huan | Li, Xiaogang | Wang, Lin
The effects of human activities on heavy metal pollution in soil have been less investigated on the Tibetan Plateau. The present study was designed to assess the effects of highway traffic on Cu, Zn, Pb, and Cd enrichments in the 0–60-cm soil profile in the eastern Tibetan Plateau. Soils were sampled at four transects (with an altitude range of 2643–2911 m) across the G212 highway and five transects (3163–3563 m) across the G213 highway. Background concentrations of Cu, Zn, Pb, and Cd to the 60-cm soil depth (measured at each transect 400 m away from highways) varied greatly among transects and between highways. However, this spatial variation in the heavy metal concentrations was not related to the altitude of the investigated areas. On each the left and right sides of G212 or G213, Cu, Zn, and Pb concentrations to the 60-cm depth, at 5, 10, 20, and 50 m away from the highway, were all generally greater than the respective metal background concentrations. Cd concentrations to the 20 cm on G212 or 60-cm soil depth on G213 increased prominently within a distance of 20 m away from the highways, compared to background values in different depths. From the curb to 400 m away from highways, concentrations of Cu, Zn, Pb, and Cd were generally higher in the upper than in the lower soil layers. This may suggest that other factors such as atmospheric deposition were also contributable to the accumulation of heavy metals in soil. The contamination factor (C f) calculation showed that roadside soils to the 60-cm depth, within a distance of 50 m from the curbs of both G212 and G213, were moderately (1 ≤ C f < 3) contaminated with Cu, Zn, and Pb. The contamination from Cd mainly occurred (1 ≤ C f < 8) in the top 20 cm soil with a closer distance from the highways. Our results indicated that traffic effects in enriching heavy metals reached 60-cm depth in roadside soils on the eastern Tibetan Plateau. For assessment of heavy metal pollutions in soil in mountainous areas, it is necessary to in situ identify the background values.
Mostrar más [+] Menos [-]The crop-residue of fiber hemp cv. Futura 75: from a waste product to a source of botanical insecticides Texto completo
2018
In the attempt to exploit the potential of the monoecious fiber hemp cv. Futura 75 in new fields besides textile, cosmetics and food industry, its crop-residue given by leaves and inflorescences was subjected to hydrodistillation to obtain the essential oils. These are niche products representing an ideal candidate for the development of natural insecticides for the control and management of mosquito vectors, houseflies and moth pests. After GC-MS analysis highlighting a safe and legal chemical profile (THC in the range 0.004–0.012% dw), the leaf and inflorescence essential oils were investigated for the insecticidal potential against three insect targets: the larvae of Culex quinquefasciatus and Spodoptera littoralis and the adults of Musca domestica. The essential oil from inflorescences, showing (E)-caryophyllene (21.4%), myrcene (11.3%), cannabidiol (CBD, 11.1%), α-pinene (7.8%), terpinolene (7.6%), and α-humulene (7.1%) as the main components, was more effective than leaf oil against these insects, with LD₅₀ values of 65.8 μg/larva on S. littoralis, 122.1 μg/adult on M. domestica, and LC₅₀ of 124.5 μl/l on C. quinquefasciatus larvae. The hemp essential oil moderately inhibited the acetylcholinesterase (AChE), which is a target enzyme in pesticide science. Overall, these results shed light on the future application of fiber hemp crop-residue for the development of effective, eco-friendly and sustainable insecticides.
Mostrar más [+] Menos [-]Regenerable, innovative porous silicon-based polymer-derived ceramics for removal of methylene blue and rhodamine B from textile and environmental waters Texto completo
2018
The presence of residual color in treated textile wastewater above the regulation limits is still a critical issue in many textile districts. Innovative, polymer-derived ceramics of the Si–C–O system were here synthesized in order to obtain porous nanocomposite materials where a free carbon phase is dispersed into a silicon carbide/silicon oxycarbide network. The sorbents were comprehensively characterized for the removal of two model water-soluble dyes (i.e., the cation methylene blue and the zwitterion rhodamine B). Adsorption is very rapid and controlled by intra-particle and/or film diffusion, depending on dye concentration. Among the nanocomposites studied, the SiOC aerogel (total capacity about 45 mg/g, is easily regenerated under mild treatment (250 °C, 2 h). Adsorption of dyes is not affected by the matrix composition: removals of 150 mg/L methylene blue from river water and simulated textile wastewater with high content of metal ions (2–50 mg/L) and chemical oxygen demand (800 mg/L) were higher than 92% and quantitative for a dye concentration of 1 mg/L.
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