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Resultados 4121-4130 de 5,153
Effect of water motion and microhabitat preferences on spatio-temporal variation of epiphytic communities: a case study in an artificial rocky reef system, Laoshan Bay, China Texto completo
2018
Yang, Xiaolong | Lv, Hongbin | Li, Wentao | Guo, Meiyu | Zhang, Xiumei
Epiphytic fauna community structure is mainly determined by macro-scale environmental characteristics (e.g., water motion), whereas the influences of, and interaction with, micro-scale habitat-forming species are not well known. In order to explore the effects of water motion and functional macroalgal group on the community structure of epiphytic faunas, macroalgae and epiphytic faunas from four isolated artificial rocky reefs with different levels of hydrodynamic conditions were investigated in Laoshan Bay of China. A total of 32 macroalgal species and 22 faunal species were recorded on the surveys. The biomass and abundance of macroalgae and epiphytic faunas showed significant variations among stations and months. The biomass and abundance of epiphytic faunas were highest at outer Huangshankou station (H1) with medium hydrodynamic force. The lowest biomass of epiphytic faunas occurred at inner Huangshankou station (H3) with highest level of water motion, while the lowest abundance of epiphytic faunas occurred at Liepo station (L) with lowest level of water motion. Results showed that medium water motion level contributed to increasing biodiversity of epiphytic faunas. Epiphytic communities generally presented higher biomass and abundance in summer than in spring or autumn, which indicated temperature could be the ecological driver for temporal variation of epiphytic communities. The epiphytic faunas showed distinct preferences to structural morphology of macroalgae which forms suitable habitat for these organisms. This study suggests that artificial rocky reefs are of great significance to restore and maintain coastal biodiversity, and appropriate physical disturbance promote community reestablishment.
Mostrar más [+] Menos [-]Improving growth performance and health status of meat-type quail by supplementing the diet with black cumin cold-pressed oil as a natural alternative for antibiotics Texto completo
2018
Abd El-Hack, MohamedE. | Mahgoub, SamirA. | Hussein, MohamedM. A. | Saadeldin, IslamM.
Using antibiotics in poultry diets as growth promoters was reported to have harmful effects on consumers, so the current study was done to monitor the impact of dietary supplementation of antimicrobial black cumin oil (BCO) on carcass traits, growth performance, biochemical components, and ileal microbial populations of growing Japanese quails. Three hundred growing Japanese quails were used with three different treatments (0, 0.50, and 1.0 g BCO/g diet). Birds fed diet supplemented with 0.5 g BCO/kg diet showed significant increase in body weight comparing with the control and other treatment group. The daily feed intake and feed conversion ratio were significantly increased side by side with increasing BCO level in the diet. The majority of carcass characteristics were maximized by supplementing the quail diet with 0.5 g BCO/kg. Moreover, liver functions, anti-oxidative capacity, lipid profile and anabolic hormones showed significant improvement in BCO-treated diets in a dose-dependent manner. The BCO showed highest antibacterial effect against Escherichia coli and Salmonella enterica. The ileal bacterial populations, i.e., total bacterial count (TBC), coliform, Salmonella species, and Escherichia coli were decreased in birds supplemented with BCO 0.5 and 1.0 BCO g/kg compared with the control diet. Based on the aforementioned results, conclusion could be drawn that supplementing quail with BCO in their diet could improve productive performance traits and enhance health aspect of the birds.
Mostrar más [+] Menos [-]Economic growth and CO2 emissions: an investigation with smooth transition autoregressive distributed lag models for the 1800–2014 period in the USA Texto completo
2018
Bildirici, Melike | Ersin, ÖzgürÖmer
The study aims to combine the autoregressive distributed lag (ARDL) cointegration framework with smooth transition autoregressive (STAR)-type nonlinear econometric models for causal inference. Further, the proposed STAR distributed lag (STARDL) models offer new insights in terms of modeling nonlinearity in the long- and short-run relations between analyzed variables. The STARDL method allows modeling and testing nonlinearity in the short-run and long-run parameters or both in the short- and long-run relations. To this aim, the relation between CO₂ emissions and economic growth rates in the USA is investigated for the 1800–2014 period, which is one of the largest data sets available. The proposed hybrid models are the logistic, exponential, and second-order logistic smooth transition autoregressive distributed lag (LSTARDL, ESTARDL, and LSTAR2DL) models combine the STAR framework with nonlinear ARDL-type cointegration to augment the linear ARDL approach with smooth transitional nonlinearity. The proposed models provide a new approach to the relevant econometrics and environmental economics literature. Our results indicated the presence of asymmetric long-run and short-run relations between the analyzed variables that are from the GDP towards CO₂ emissions. By the use of newly proposed STARDL models, the results are in favor of important differences in terms of the response of CO₂ emissions in regimes 1 and 2 for the estimated LSTAR2DL and LSTARDL models.
Mostrar más [+] Menos [-]Fate of triclocarban in agricultural soils after biosolid applications Texto completo
2018
Lozano, Nuria | Rice, CliffordP. | Ramirez, Mark | Torrents, Alba
Triclocarban [N-(4-chlorophenyl)-N-(3,4-dichlorophenyl) urea] (TCC) is an antimicrobial agent utilized in a variety of consumer products. It is commonly released into domestic wastewaters and upon treatment, it is known to accumulate in biosolids. This study examines the occurrence of TCC in biosolids and its long-term fate in biosolid-treated soils. TCC levels in the biosolids from a large waste water treatment plant (WWTP) over 2 years showed little variability at 18,800 ± 700 ng g⁻¹ dry wt. (mean ± SEM). Surface soil samples (top 10 cm) were collected from 26 commercial farms located in northern VA, US that had received biosolid applications from the WWTP. Samples were grouped as farms receiving no biosolids, farms with a single biosolid application, and those receiving multiple biosolid applications from 1992 to 2006. Our results illustrate that TCC soil residues remained years after biosolid application. The two most important parameters controlling TCC topsoil concentrations were the biosolid application rate and the period since the last application. No TCC removal was observed in farms where the time since biosolid application was between 7 and 9 months. TCC concentration analyzed 7 and 8 years after biosolid applications were 45.8 ± 6.1 and 72.4 ± 15.3 ng g⁻¹ dry wt., respectively, showing its persistence in soils and build-up upon multiple biosolid applications. A soil TCC half-life of 287.5 ± 45.5 days was estimated.
Mostrar más [+] Menos [-]A bionanohybrid ZnAl-NADS ecological pesticide as a treatment for soft rot disease in potato (Solanum tuberosum L.) Texto completo
2018
Morales-Irigoyen, Erika Elizabeth | de las Mercedes Gómez-y-Gómez, Yolanda | Flores-Moreno, Jorge Luis | Franco-Hernández, Marina Olivia
Pectobacterium carotovorum (Pc) is a phytopathogenic strain that causes soft rot disease in potato (Solanum tuberosum L.), resulting in postharvest losses. Chemical control is effective for managing this disease, but overdoses cause adverse effects. Because farmers insist on using chemical agents for crop protection, it is necessary to develop more effective pesticides in which the active compound released can be regulated. In this context, we proposed the synthesis of ZnAl-NADS, in which nalidixic acid sodium salt (NADS) is linked to a ZnAl-NO₃ layered double hydroxide (LDH) host as a nanocarrier. XRD, FT-IR, and SEM analyses confirmed the successful intercalation of NADS into the interplanar LDH space. The drug release profile indicated that the maximum release was completed in 70 or 170 min for free NADS (alone) or for NADS released from ZnAl-NADS, respectively. This slow release was attributed to strong electrostatic interactions between the drug and the anion exchanger. A modulated release is preferable to the action of the bulk NADS, showing increased effectiveness and minimizing the amount of the chemical available to pollute the soil and the water. The fitting data from modified Freundlich and parabolic diffusion models explain the release behavior of the NADS, suggesting that the drug released from ZnAl-NADS bionanohybrid was carried out from the interlamellar sites, according to the ion exchange diffusion process also involving intraparticle diffusion (coeffect). ZnAl-NADS was tested in vitro against Escherichia coli (Ec) and Pc and exhibited bacteriostatic and biocidal effects at 0.025 and 0.075 mg mL⁻¹, respectively. ZnAl-NADS was also tested in vivo as an ecological pesticide for combating potato soft rot and was found to delay typical disease symptoms. In conclusion, ZnAl-NADS can potentially be used to control pests, infestation, and plant disease.
Mostrar más [+] Menos [-]Effects of lanthanum and silicon stress on bio-sequestration of lanthanum in phytoliths in rice seedlings Texto completo
2018
Si, Yong | Wang, Lihong | Zhou, Qing | Huang, Xiaohua
Plant phytoliths are important for silicon (Si) cycling in natural ecosystems; however, their role in lanthanum (La) sequestration in plants is still unclear. In the present study, we elucidated the mechanism of La-induced damage to the growth of rice (Oryza sativa L.) seedling from the viewpoint of the La sequestration by phytoliths (PhytLa). The phytoliths were extracted by using the microwave digestion method. La concentrations within the plants and phytoliths were determined by a modified lithium metaborate fusion method. Analysis showed that pretreatment with low La concentration not only promoted photosynthesis and transpiration in rice but also enhanced the sequestration ability of phytoliths on La. Conversely, high La concentration inhibited photosynthesis and transpiration in rice and the ability of phytoliths to sequester La. Moreover, high Si concentrations promoted the sequestration ability of phytoliths during these processes. Promotion of combined stress of La and Si on the ability of rice seedling was stronger than that of the single La stress. The sequestration ability of phytoliths in different parts of rice varied significantly, following the order: stem > leaf > root. This pattern could be attributed to factors such as the production of various phytolith morphotypes (such as tubes) and PhytLa, PhytLa efficiency, La accumulation, and the rate of photosynthesis and transpiration in different parts of rice seedlings. This study demonstrated that La uptake in rice seedlings was affected by the presence of Si in the medium, and phytolith played a crucial role in the bio-sequestration of La and assuaged the damage caused by La in rice seedlings. Graphical abstract ᅟ
Mostrar más [+] Menos [-]Management of tannery wastewater for improving growth attributes and reducing chromium uptake in spinach through citric acid application Texto completo
2018
Maqbool, Arosha | Ali, Shafaqat | Rizwan, Muhammad | Ishaque, Wajid | Rasool, Nasir | Rehman, MuhammadZia ur | Bashir, Arooj | Abid, Mohamed | Wu, Longhua
The use of chromium (Cr)-contaminated tannery wastewater for irrigation is a common practice, especially in developing countries like Pakistan. This practice is due to the shortage of good quality irrigation water for crop growth as well as the issue of tannery wastewater disposal. The current study was done to evaluate the effect of citric acid (CA) (0, 1.0, and 2.0 mM) on the growth and Cr uptake by spinach irrigated with different mixtures of tap water and tannery wastewater (100:0, 50:50, and 0:100 tap water to wastewater ratio). Plants were grown for 8 weeks under ambient conditions. Results showed that 50:50% tap water and wastewater increased plant height, dry weights of shoots and roots, total chlorophyll contents, and gas exchange attributes than the plants treated with only tap water or only wastewater. Increasing wastewater ratio increased electrolyte leakage (EL) in plants and enhanced the leaf key antioxidant enzyme activities as well as increased Cr contents. Foliar application of CA increased the plant dry weights, photosynthesis, and enzyme activities, whereas reduced the EL and Cr concentrations in plants than respective treatments without CA application. It can be concluded that 50:50 tap water and wastewater irrigation along with foliar CA application might be an effective strategy for increasing vegetable growth with reduced metal concentrations.
Mostrar más [+] Menos [-]Growth performance, metal accumulation and biochemical responses of Palak (Beta vulgaris L. var. Allgreen H-1) grown on soil amended with sewage sludge-fly ash mixtures Texto completo
2018
Sharma, Bhavisha | Kothari, Richa | Singh, RajeevPratap
Agricultural utilization of sewage sludge (SS) and fly ash (FA) has become both, a common practice and an alternative disposal method for these wastes all around the world. The present study was conducted to assess the effect and viability of co-application of SS and FA (SLASH) in four mixing ratios denoted as A [4 (SS): 1(FA)], B [4 (SS): 2 (FA)], C [4 (SS): 3 (FA)] and D [4 (SS): 4(FA)] at three application rates viz. 20, 40 and 60% (w/w) with agricultural soil on biochemical, physiological and growth response of Palak (Beta vulgaris L. var. Allgreen H-1), a commonly used green leafy vegetable. SLASH amendment modified the physico-chemical properties of soil and increased the concentration of heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, Zn) in soil and plant parts however, within the Indian permissible limit except for Cr, Cd and Zn in shoot. Experimental results revealed decrease in morphological and growth parameters such as root and shoot length, leaf area, root, shoot biomass etc. Lipid peroxidation, ascorbic acid, proline and protein content increased however, total chlorophyll and carotenoid content decreased indicating towards heavy metal stress induced biochemical and physiological response in Palak plants. Significant increase in yield was seen in some of the treatments viz. three mixing ratios B, C and D, with maximum increment shown by mixture D at 20 and 40% amendment rate. The results of this study suggest that though SLASH amendment for growing Palak improved the physico-chemical properties of soil amended and also the yield of the plants in some treatments, it may not be a good option due to risk of contamination of heavy metals such as Cr, Cd and Zn showing higher accumulation.
Mostrar más [+] Menos [-]Impacts of nutrients and pesticides from small- and large-scale agriculture on the water quality of Lake Ziway, Ethiopia Texto completo
2018
Teklu, BerhanM. | Hailu, Amare | Wiegant, DanielA. | Scholten, BerniceS. | Van den Brink, PaulJ.
The area around Lake Ziway in Ethiopia is going through a major agricultural transformation with both small-scale farmers and large horticultural companies using pesticides and fertilisers at an increased rate. To be able to understand how this influences the water quality of Lake Ziway, water quality data was gathered to study the dynamics of pesticide concentrations and physicochemical parameters for the years from 2009 to 2015. Results indicate that for some physicochemical parameters, including pH, potassium and iron, over 50 % of the values were above the maximum permissible limit of the Ethiopian standard for drinking water. The fungicide spiroxamine poses a high chronic risk when the water is used for drinking water, while the estimated intake of diazinon was approximately 50 % of the acceptable daily intake. Higher-tier risk assessment indicated that the fungicide spiroxamine poses a high acute risk to aquatic organisms, while possible acute risks were indicated for the insecticides deltamethrin and endosulfan. Longer-term monitoring needs to be established to show the water quality changes across time and space, and the current study can be used as a baseline measurement for further research in the area as well as an example for other surface water systems in Ethiopia and Africa.
Mostrar más [+] Menos [-]Two dechlorinated chlordecone derivatives formed by in situ chemical reduction are devoid of genotoxicity and mutagenicity and have lower proangiogenic properties compared to the parent compound Texto completo
2018
Legeay, Samuel | Billat, Pierre-André | Clere, Nicolas | Nesslany, Fabrice | Bristeau, Sébastien | Faure, Sébastien | Mouvet, C. (Christophe)
Chlordecone (CLD) is a chlorinated hydrocarbon insecticide, now classified as a persistent organic pollutant. Several studies have previously reported that chronic exposure to CLD leads to hepatotoxicity, neurotoxicity, raises early child development and pregnancy complications, and increases the risk of liver and prostate cancer. In situ chemical reduction (ISCR) has been identified as a possible way for the remediation of soils contaminated by CLD. In the present study, the objectives were (i) to evaluate the genotoxicity and the mutagenicity of two CLD metabolites formed by ISCR, CLD-5a-hydro, or CLD-5-hydro (5a- or 5- according to CAS nomenclature; CLD-1Cl) and tri-hydroCLD (CLD-3Cl), and (ii) to explore the angiogenic properties of these molecules. Mutagenicity and genotoxicity were investigated using the Ames’s technique on Salmonella typhimurium and the in vitro micronucleus micromethod with TK6 human lymphoblastoid cells. The proangiogenic properties were evaluated on the in vitro capillary network formation of human primary endothelial cells. Like CLD, the dechlorinated derivatives of CLD studied were devoid of genotoxic and mutagenic activity. In the assay targeting angiogenic properties, significantly lower microvessel lengths formed by endothelial cells were observed for the CLD-3Cl-treated cells compared to the CLD-treated cells for two of the three tested concentrations. These results suggest that dechlorinated CLD derivatives are devoid of mutagenicity and genotoxicity and have lower proangiogenic properties than CLD.
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