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Результаты 4911-4920 из 6,560
Spatio-temporal characteristics of adaptability between crop water requirements for summer maize and rainfall in Henan Province, China Полный текст
2020
Cao, Yongxiao | Wei, Huaibin
It is very important to master the rainfall utilization efficiency and spatial-temporal distribution characteristics in order to improve the agricultural water resource utilization efficiency. In this study, an adaptability index (AI) was constructed to reflect the relationship between rainfall and crop water demand. Spatial analysis and clustering analysis were used to study the spatial distribution characteristics and evolution rules of the adaptability between water demand and rainfall in the growing period of summer maize in Henan Province of China. The results showed that there were significant spatial differences in the adaptability of different regions, and such differences change with time, indicating that AI has certain uncertainties in the region and growth season. In general, the AI of the whole growth period of summer maize is mainly determined by the AI of tasseling period–milky period, while the multi-year change rate of AI is mainly determined by the emergence period–jointing period, tasseling period–milky period, and milky period–maturity period The adaptability of summer maize to rainfall in the study area can be divided into three categories, among which the one with increased adaptability occupies the main part, and the one with sharply decreased adaptability were also distributed in the study area. The above studies indicate that it is important to pay attention to the adaptability of rainfall to agricultural water management. The complexity division of crop water demand by rainfall adaptability index can guide the establishment of reasonable and accurate irrigation system.
Показать больше [+] Меньше [-]Development, larvicide activity, and toxicity in nontarget species of the Croton linearis Jacq essential oil nanoemulsion Полный текст
2020
Amado, Jesus Rafael Rodriguez | Prada, Ariadna Lafourcade | García Díaz, Jesús | Souto, Raimundo Nonato Picanço | Arranz, Júlio Cesar Escalona | de Souza, Tatiane Pereira
In this study, the essential oil (EO) from leaves of Croton linearis Jacq was extracted and characterized by GC/MS. The EO hydrophilic-lipophilic balance required (rHLB) for nanoemulsion (NE) development was determined by the Griffin’ method. For evaluating the larvicidal effect against Aedes aegypti, the preparation process of NE was optimized, using a central composite design. It was also evaluated the possible toxic effect of NE in nontarget species. The leaves of C. linearis contain 1.50% of EO, enclosing 61 volatile compounds, mainly eucalyptol (26.66%). The best surfactant, oil:water ratio (4.5–5.0-91.5; % w:w:w), allows to achieve the optimal NE, using a stirring speed of 800 rpm, the addition rate of 0.5 ml/min, and a stirring time of 30 min. NE (with particle size = 163 nm) showed a larvicide effect (LC₅₀ = 17.86 μg/mL) more potent than the whole EO (LC₅₀ = 64.24 μg/mL). NE showed neither hemolytic effect nor cytotoxicity, and it was classified as a nontoxic product, according to the OECD class toxicity test (IC₅₀ > 2000 mg/kg). This product arises in a new green bio-larvicide that could be used for mosquito control.
Показать больше [+] Меньше [-]Phytoremediation of heavy metals by four aquatic macrophytes and their potential use as contamination indicators: a comparative assessment Полный текст
2020
Eid, Ebrahem M. | Galal, Tarek M. | Sewelam, Nasser A. | Talha, Nasser I. | Abdallah, Samy M.
The present study estimated the ability of four aquatic macrophytes (Eichhornia crassipes (Mart.) Solms, Ludwigia stolonifera (Guill. & Perr.) P.H. Raven, Echinochloa stagnina (Retz.) P. Beauv. and Phragmites australis (Cav.) Trin. ex Steud.) to accumulate Cd, Ni and Pb and their use for indicating and phytoremediating these metals in contaminated wetlands. Three sites at five locations in the Kitchener Drain in Gharbia and Kafr El-Sheikh Governorates (Egypt) were selected for plant, water and sediment sampling. The water in the Kitchener Drain was polluted with Cd, while Pb and Ni were far below the maximum level of Pb and Ni in the irrigation water. In comparison to the other species, P. australis accumulated the highest concentrations of Cd and Ni, while E. crassipes accumulated the highest concentration of Pb in its tissues. The four species had bioaccumulation factors (BAFs) greater than one, while their translocation factors (TFs) were less than 1 for most heavy metals, except Cd in the leaf and stem of E. stagnina and L. stolonifera, respectively, and Ni in the stem and leaf of E. stagnina. The BAF and TF results indicated that the studied species are suitable for phytostabilizing the studied heavy metals, except Ni in E. stagnina and Cd in L. stolonifera, which are suitable for phytoextracting these metals. Significant positive correlations were found between the investigated heavy metals in the water or sediment and the plant tissues. Their high BAFs, with significant proportional correlations, supported the potential of these species to serve as bioindicators and biomonitors of heavy metals in general and in the investigated metals specifically.
Показать больше [+] Меньше [-]Investigation of antioxidant responses in Gammarus pulex exposed to Bisphenol A Полный текст
2020
Tatar, Şule | Türkmenoğlu, Yener
One of the most important environmental problems in the world is micro-pollutants. The aim of this study was to investigate the antioxidant responses of Gammarus pulex to Bisphenol A (BPA), an endocrine-disrupting agent. For this purpose, sublethal concentrations of BPA were applied to G. pulex and biochemical responses were studied. Enzymatic antioxidants superoxide dismutase (SOD) and catalase (CAT) activities and nonenzymatic antioxidants glutathione (GSH) and thiobarbituric acid reagents (TBARS) levels in G. pulex were determined in four different groups during 24 and 96 h. Biochemical biomarkers were measured using commercial kits in a microplate reader. When we compared with control, SOD enzyme activity increased in all groups during both administration periods and CAT enzyme activity decreased in all groups. GSH and TBARS levels were increased after 24 and 96 h of application periods in all groups when compared with control. For changes in SOD and CAT activities and GSH, TBARS levels have been determined to be useful as biomarkers against BPA in G. pulex tissues. It has also been proven that G. pulex is an effective bioindicator that shows BPA pollution in water. The different results of biochemical biomarkers can be evaluated as a marker of possible metabolic processes, and the biochemical response of G. pulex can reveal to some extent the environmental consequences of BPA pollution resulting from industrial waters.
Показать больше [+] Меньше [-]Copper oxychloride–induced testicular damage of adult albino rats and the possible role of curcumin in healing the damage Полный текст
2020
Gad El-Hak, Heba Nageh | Mobarak, Yomn Mohammed
The current research study investigated the effect of 80 mg/kg b.wt./day curcumin (cur) against 50, 100, and 200 mg/kg copper oxychloride (COC) for 90 days induced testicular damage using histological, ultrastructural, and biochemical techniques. Histological and cellular abnormalities have been noted in seminiferous tubules of COC-treated group and treated group with Cur- and COC-treated group. The biochemical result showed that serum testosterone was significantly decreased in COC-treated rats and Cur COC-treated rats compared with the control groups. Testes copper content and malondialdehyde was increased, whereas the testes total antioxidant, manganese, ferrous, and zinc levels were decreased (p ≥ 0.05) compared to the control groups. In conclusion, the present work reported that the treatment of rats with 80 mg/kg body weight curcumin prior to treatment with COC did not mitigate the deleterious effects of COC and manifested no signs of protection.
Показать больше [+] Меньше [-]Relationships among cigarette smoking, urinary biomarkers, and urothelial carcinoma risk: a case-control study Полный текст
2020
Chung, Chi-Jung | Hsu, Hui-Tsung | Chang, Chao-Hsiang | Li, Sheng-Wei | Liu, Chiu-Shong | Chung, Mu-Chi | Wu, Guo-Wei | Jung, Wei-Ting | Kuo, Yen-Jung | Lee, Hui-Ling
Cigarette smoke is a known risk factor for urothelial carcinoma (UC). However, there is limited information about the distributions and effects of volatile organic compounds (VOCs) on smoking-related UC risk. With this hospital-based case-control study, we explored the associations between urinary levels of cotinine and VOC metabolites (acrylamide, 1,3-butadiene, and benzene) and the risk of UC. Urological examinations and pathological verifications were used to confirm the diagnoses of UC. All study participants provided smoking-related information via questionnaires and face-to-face interviews; they also provided urine samples for the measurement of VOC metabolites, cotinine, and 8-hydroxydeoxyguanosine (8-OHdG), which was used as an indicator of oxidative stress. We applied multiple logistic regression analysis to estimate the risk of UC, and we found that levels of urinary cotinine and 8-OHdG were higher in the UC group than in the control group. Furthermore, urinary levels of VOC metabolites, including N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA), N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine, N-acetyl-S-(4-hydroxy-2-buten-1-yl)-L-cysteine-3, trans,trans-muconic acid (t,t-MA), and S-phenylmercapturic acid (SPMA), increased with increasing levels of urinary cotinine. After adjusting for potential risk factors, dose–response relationships were observed between UC risk and urinary levels of AAMA, t,t-MA, SPMA, and 8-OHdG. Participants with high urinary levels of cotinine, AAMA, t,t-MA, SPMA, and 8-OHdG had risks of UC that were 3.5- to 6-fold higher than those of participants with lower levels. Future, large-scale investigations of the risks of UC should be explored, and repeated measurement of VOC metabolites should be assessed.
Показать больше [+] Меньше [-]Drawing the baseline of trace element levels in the vulnerable Mediterranean osprey Pandion haliaetus: variations by breeding location, habitats, and egg components Полный текст
2020
Monti, Flavio | Bianchi, Nicola | Sforzi, Andrea | Leonzio, Claudio | Ancora, Stefania
Due to its peculiarity to accumulate environmental contaminants, the osprey Pandion haliaetus is a sentinel species for the biomonitoring of contaminants in aquatic ecosystems. Despite this, no information on trace element concentration exists for the Mediterranean area, where relict and vulnerable osprey populations exist. We evaluated the geographical patterns of heavy metals and selenium in osprey eggs from three different populations of the Mediterranean basin (Balearic Islands, Corsica, and Tuscany), to identify any possible contaminant sources. Pattern of metal concentration followed the order: Fe > Zn > Cu > Se > Hg > Pb > Cd. Differences in contaminant concentrations between habitats and among egg components were found. Egg content and inner membrane showed higher mercury levels (1.06 ± 0.89 and 0.67 ± 0.62 mg/kg dw, respectively) than those recorded in the eggshell. Mercury concentration was ca. two times higher in marine than in wetland samples, and even higher (3.6 times) when referred to the eggshell. Cu, Fe, Zn, and Se had higher concentration in the inner membrane. We stress how the choice of the biological material can have significant implications for the correct evaluation of contamination. Our study represents a first regional scale survey for the vulnerable Mediterranean osprey populations and provides baseline data for their long-term biomonitoring.
Показать больше [+] Меньше [-]Ceria oxide nanoparticle-based diffusive gradients in thin films for in situ measurement of dissolved reactive phosphorus in waters and sewage sludge Полный текст
2020
Tan, Feng | Wang, Yi | Wang, Yan | Ren, Suyu | Cui, Ying | Xu, Dongyan
A passive sampling method based on diffusive gradients in thin films (DGT) using ceria oxide (CeO₂) binding gel was developed for in situ measurement of dissolved reactive phosphorus (DRP). CeO₂-based DGT showed excellent uptake performance for DRP, and the uptake mass was consistent with the predication by DGT equation. pH (4.2~9.4) and ionic strength (0.01~500 mM) had no effects on the uptake of DRP. Filed deployment of CeO₂-DGT in reservoir water and seawater showed that the measureable concentrations of DRP were comparable to those obtained by grab sampling. CeO₂-DGT was deployed in sewage sludge, and results showed the ratios (RS) between the concentration (CDGT) by CeO₂-DGT and the concentration (CS) obtained by a traditional centrifugation method ranged from 0.23 to 0.58. This result indicated that sludge solid phase was a potential pool of DRP in sludge solution, and the DRP released from sludge solid phase could compensate partly the consumption of DRP at the interface of DGT device during the deployment. The ratios RS had positive correlation with the content of Fe (r = 0.847, p < 0.01) but were reversed with the level of Ca (r = − 0.879, p < 0.01) in sewage sludge. The proposed method provided a powerful tool for in situ measurement of DRP in natural waters and for release behavior of DRP in sludge.
Показать больше [+] Меньше [-]Using graphene quantum dots for treating radioactive liquid waste Полный текст
2020
de Menezes, Frederico Duarte | Alencar, Luciana Magalhães Rebelo | dos Santos, Clenilton Costa | da Silva, Maria Isabel Barbosa | Santos-Oliveira, Ralph
The use of smart materials, especially the carbon-based nanomaterials, is increasing each day. Among the several carbon-based nanomaterials, graphene quantum dots are one of the most impressive ones, not only by its quantum behavior but due to the adsorption quality conferred by electrostatic interactions from the negatively charged groups as the huge surface area (2.630 m2/g). In this study, we developed and tested graphene quantum dots (GQDs) as smart nano-adsorbents of uranium (²³⁸U) from the radioactive industry waste. The GQDs were developed in a size range of 160–220 nm using a totally green route. The results showed that the GQDs were capable to adsorb almost 40% of the uranium (²³⁸U) in alamine 3366 solution. Also, the results demonstrated that using GQDs treatment-like smart nanomaterials for radioactive waste in a volume reduction of almost 90% is achieved, helping the storage process as the final disposal of this material. We may conclude that GQDs may represent a smart device for the treatment of radioactive waste as an alternative of absorbent in the radioactive industry.
Показать больше [+] Меньше [-]Phosphorus homeostasis in Populus alba L. under excess phosphate conditions, assessed by 31P nuclear magnetic resonance spectroscopy and X-ray microfluorescence Полный текст
2020
Zakrzewska, Joanna | Lj. Mitrović, Aleksandra | Mutavdžić, Dragosav | Dučić, Tanja | Radotić, Ksenija
The phosphates (Pi) are nowadays recognized as pollutants. We studied the effect of Pi (0.625–12.500 mM KH₂PO₄) in the culture medium on in vitro grown 2-month-old Populus alba trees. The levels of sugar phosphates and vacuolar and cytoplasmic Pi in cell compartments of roots and stems were determined using ³¹P NMR, while tissue-specific micro- and macroelements mapping on stem cross-sections were performed using synchrotron-based X-ray microfluorescence. Plants grown on 0.625 mM Pi (MS/2 medium) showed a survival rate of 70%. With the increase in Pi concentrations up to 6.250 mM, plant growth and survival increased, without changes in total P content per mass or in the levels of cytoplasmic and vacuolar phosphates, in both stems and roots, while the levels of Fe, Cu, Zn, Ca and Mn in stems increased. Further increase in Pi to 9.375 and 12.500 mM in the medium resulted in inhibited growth comparable with plants grown on MS/2, with the increase in total P content per mass up to 50%, in both stems and roots, but with no changes in cytoplasmic and vacuolar phosphates; 12.500 mM Pi affected even plant survival (70%) and thus might be considered as mildly toxic. ³¹P NMR results indicate that the high tolerance of P. alba to increased Pi could result from its ability to maintain an intracellular P homeostasis, despite P accumulation up to 50%, in both stems and roots, indicating P. alba as a promising wood species for dendroremediation.
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