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61.
62.
Manganese uptake and accumulation by the hyperaccumulator plant Phytolacca acinosa Roxb. (Phytolaccaceae) 总被引:9,自引:0,他引:9
Xue SG Chen YX Reeves RD Baker AJ Lin Q Fernando DR 《Environmental pollution (Barking, Essex : 1987)》2004,131(3):393-399
The perennial herb Phytolacca acinosa Roxb. (Phytolaccaceae), which occurs in Southern China, has been found to be a new manganese hyperaccumulator by means of field surveys on Mn-rich soils and by glasshouse experiments. This species not only has remarkable tolerance to Mn but also has extraordinary uptake and accumulation capacity for this element. The maximum Mn concentration in the leaf dry matter was 19,300 microg/g on Xiangtan Mn tailings wastelands, with a mean of 14,480 microg/g. Under nutrient solution culture conditions, P. acinosa could grow normally with Mn supplied at a concentration of 8000 micromol/l, although with less biomass than in control samples supplied with Mn at 5 micromol/l. Manganese concentration in the shoots increased with increasing external Mn levels, but the total mass of Mn accumulated in the shoots first increased and then decreased. At an Mn concentration of 5000 micromol/l in the culture solution, the Mn accumulation in the shoot dry matter was highest (258 mg/plant). However, the Mn concentration in the leaves reached its highest value (36,380 microg/g) at an Mn supply level of 12,000 micromol/l. These results confirm that P. acinosa is an Mn hyperaccumulator which grows rapidly, has substantial biomass, wide distribution and a broad ecological amplitude. This species provides a new plant resource for exploring the mechanism of Mn hyperaccumulation, and has potential for use in the phytoremediation of Mn-contaminated soils. 相似文献
63.
López-Ovejero RF y Garcia AG de Carvalho SJ Christoffoleti PJ Neto DD Martins F Nicolai M 《Journal of environmental science and health. Part. B》2005,40(1):1-11
Brazilian off-season maize production is characterized by low yield due to several factors, such as climate variability and inadequate management practices, specifically weed management. Thus, the goal of this study was to determinate the critical period of weed competition in off-season maize (Zea mays L.) crop using thermal units or growing degree days (GDD) approach to characterize crop growth and development. The study was carried out in experimental area of the University of S?o Paulo, Brazil, with weed control (C), as well as seven coexistence periods, 2, 4, 6, 8, and 12 leaves, flowering, and all crop cycle; fourteen treatments were done. Climate data were obtained from a weather station located close to the experimental area. To determine the critical period for weed control (CPWC) logistic models were fitted to yield data obtained in both W and C, as a function of GDD. For an arbitrary maximum yield loss fixed in 2.5%, the CPWC was found between 301 and 484 GDD (7-8 leaves). Also, when the arbitrary loss yield was fixed in 5 and 10%, the period before interference (PBI) was higher than the critical weed-free period (CWFP), suggesting that the weeds control can be done with only one application, between 144 and 410 GDD and 131 and 444 GDD (3-8 leaves), respectively. The GDD approach to characterize crop growth and development was successfully used to determine the critical period of weeds control in maize sown off-season. Further works will be necessary to better characterize the interaction and complexity of maize sown off-season with weeds. However, these results are encouraging because the possibility of the results to be extrapolated and because the potential of the method on providing important results to researchers, specifically crop modelers. 相似文献
64.
Bortagaray Viviana Girardi Viviane Pou Sonia Lizasoain Andrés Tort Luis Fernando López Spilki Fernando R. Colina Rodney Victoria Matias 《Food and environmental virology》2020,12(2):89-98
Food and Environmental Virology - The aim of this study was to detect, quantify, and assess the risk of infection and illness for Group A Rotavirus (RVA) in the watersheds of the Santa Lucia and... 相似文献
65.
José A. Donázar Alejandro Travaini Olga Ceballos Alejandro Rodríguez Miguel Delibes Fernando Hiraldo 《Behavioral ecology and sociobiology》1999,45(1):55-65
Phenotype-limited interference models assume competitive asymmetries among conspecifics and unequal sharing of resources.
Their main prediction is a correlation between dominance status and patch quality: dominant individuals should preferentially
exploit better-quality habitats. We tested assumptions and predictions of the phenotype-limited interference model in Andean
condors (Vultur gryphus), a New World vulture with strong sexual size dimorphism (males are 30–40% heavier than females). We recorded searching birds
in habitats differing in quality: mountains and plains. We also observed scavenging behaviour at 20 sheep carcasses, and videotaped
5 of them. Intraspecific hierarchy at carcasses was based on size: males dominated females and, within each sex, older birds
dominated younger ones. Adult males and juvenile females occupied extreme positions in the feeding hierarchy. Aggression was
directed at those individuals belonging to lower hierarchical levels. In high-quality areas (mountains), more condors arrived
at carcasses. Juvenile females were more often observed searching in low-quality areas (plains), far from breeding areas and
main roost sites. GLM analyses of individual behaviour showed that the hierarchy did not influence time of arrival, but low-ranking
individuals spent more time at carcasses, especially if the number of condors at arrival was high. Additionally, low-ranking
condors spent less time feeding at carcasses when individuals of higher hierarchical levels were present. On the other hand,
the number of condors present had a positive effect on feeding rates of dominant individuals, probably because of a reduction
in individual vigilance. These results support most of the assumptions and predictions of the phenotype-limited distribution
model, although a spatial truncated distribution between phenotypes was not observed. Asymmetric feeding pay-off, unequal
parental roles and sexual selection constraints could favour sexual divergence in body size in Andean condors.
Received: 6 April 1998 / Accepted after revision: 11 July 1998 相似文献
66.
Waves and turbulence in katabatic winds 总被引:1,自引:0,他引:1
The measurements taken during the Vertical Transport and Mixing Experiment (VTMX, October, 2000) on a northeastern slope of Salt Lake Valley, Utah, were used to calculate the statistics of velocity fluctuations in a katabatic gravity current in the absence of synoptic forcing. The data from ultrasonic anemometer-thermometers placed at elevations 4.5 and 13.9 m were used. The contributions of small-scale turbulence and waves were isolated by applying a high-pass digital (Elliptical) filter, whereupon the filtered quantities were identified as small-scale turbulence and the rest as internal gravity waves. Internal waves were found to play a role not only at canonical large gradient Richardson numbers $(\overline{\hbox {Ri}_\mathrm{g} } >1)$ , but sometimes at smaller values $(0.1 < \overline{\hbox {Ri}_\mathrm{g}}<1)$ , in contrast to typical observations in flat-terrain stable boundary layers. This may be attributed, at least partly, to (critical) internal waves on the slope, identified by Princevac et al. [1], which degenerate into turbulence and help maintain an active internal wave field. The applicability of both Monin-Obukhov (MO) similarity theory and local scaling to filtered and unfiltered data was tested by analyzing rms velocity fluctuations as a function of the stability parameter z/L, where L is the Obukhov length and z the height above the ground. For weaker stabilities, $\hbox {z/L}<1$ , the MO similarity and local scaling were valid for both filtered and unfiltered data. Conversely, when $\hbox {z/L}>1$ , the use of both scaling types is questionable, although filtered data showed a tendency to follow local scaling. A relationship between z/L and $\overline{\hbox {Ri}_\mathrm{g} }$ was identified. Eddy diffusivities of momentum $\hbox {K}_\mathrm{M}$ and heat $\hbox {K}_\mathrm{H}$ were dependent on wave activities, notably when $\overline{\hbox {Ri}_\mathrm{g} } > 1$ . The ratio $\hbox {K}_{\mathrm{H}}/\hbox {K}_{\mathrm{M}}$ dropped well below unity at high $\overline{\hbox {Ri}_\mathrm{g} }$ , in consonance with previous laboratory stratified shear layer measurements as well as other field observations. 相似文献
67.
近年来,由于“动物友好”协议的广泛应用,鱼类胚胎实验(Fish Embryo Test, FET)成为了生态毒理学研究的主要方法。OECD 236 FET方法在REACH法规所辖范围内广泛应用,主要针对简单混合物暴露情况(simple mixture exposures),但其还在世界范围内被盲目地用于排放废水综合测试(Whole Effluent Test, WET),这是一种复杂混合物暴露情况。然而,评价FET方法用于WET的有效性的可靠数据几乎没有。本文将OECD 236 FET方法与其他国际通用的标准的和略作改进的生态毒理学研究方案进行了比较,得出了可用于WET的测试方法的总体评价结果。我们使用了未经处理的医院排水,通常认为该排水具有高毒性,且会进入市政污水处理系统。我们选择的毒性测试方法包括OECD 203 (juvenile), USEPA 2000.0 (larva) and OECD 236 (embryo)。值得一提的是,我们还额外测试了3个亚致死指标(不移动性、不孵化率、心包囊肿),这些指标可以提高OECD 236方法的敏感性。我们在所选的8种方法中考察了急性毒性数据,方法的敏感性均有提高且胚胎实验≤仔鱼实验<幼鱼实验(Embryo≤Juvenile
详情请见 https://doi.org/10.1002/etc.4215 相似文献
68.
Gómara B González MJ Baos R Hiraldo F Abad E Rivera J Jiménez B 《Environment international》2008,34(1):73-78
This study provides information on the current status of contamination by organochlorines (DDTs, PCBs, PCDDs and PCDFs) in the declining red kite (Milvus milvus L.) population breeding in the Do?ana National Park (DNP), south-western Spain. Analyses were performed in addled eggs collected between 1999 and 2001. DDE concentrations ranged from 0.1 to 33.5 microg/g ww, representing more than 86% of the total DDTs. Of the samples studied, 50% showed DDE levels above those associated with reproductive impairment in other raptor species. Concentrations of ortho PCBs (average 36.8 microg/g ww+/-37.7) in 50% of the eggs were much higher than levels reported to cause reduced hatching success, embryo mortality, and deformities in birds (>20 microg/g ww). It is remarkable that average ortho PCB and DDE concentrations showed an increase of one order of magnitude compared to previous data for the species during the 80s. Total PCDD/Fs showed levels in the low pg/g range (7.2-42 pg/g ww), having PCDDs and PCDFs similar contributions in most samples. Total mean TEQs were 238 pg/g (ww), being the range 7.02-667 pg/g (ww). Spatial variation within DNP was observed for PCBs, DDTs, as well as for TEQs. Since some eggs exceeded the NOEL (67%) and LOEL (33%) reported for other raptor species, we would expect the red kite to experience detrimental effects to dioxin-like toxicity. Our results suggest that organochlorine contaminants should be regarded as an element of concern in the population under study, in addition to other conservation problems already reported. Further investigations should be undertaken to identify potential sources of these chemicals in DNP, and to find out if organochlorine contamination is present in other predator species in the area, as well as their potential health effects on individuals and/or populations. 相似文献
69.
Rosa María Arnaldo Valdés Fernando Gómez Comendador Luis Mijares Gordún Francisco J. Sáez Nieto 《Safety Science》2011,49(5):633-650
The risks of landing overrun (LDOR – LanDing OverRun), Take-off Overrun (TOOR – Take-Off OverRun) and landing undershoot (LDUS – LanDing UnderShoot) are dependent on multiple factors related to operating conditions. These include wind, runway surface conditions, landing or take-off distances required, the presence of obstacles, runway distance available, the existence and dimensions of runway safety areas.In this paper we propose risk models for runway overrun and landing undershoot, using a probabilistic approach. These models are supported by historical data on accidents in the area around the runway and will enable us to determine if the risk level is acceptable or whether action must be taken to mitigate such risks at a given airport. Furthermore, these models permit comparison of the results of different risk mitigation actions in terms of operational risk and safety.The principal advantage of this method is the high quality results obtained for a limited investment in terms of time, computing power and data. As such the method is extremely practical and easy to apply in aerodrome planning, development and operation. 相似文献
70.
Schirmer Waldir Nagel Stroparo Erivelton César Gueri Matheus Vitor Diniz Capanema Marlon André Mazur Douglas Luiz Jucá José Fernando Thomé Martins Kelly Geronazzo 《Journal of Material Cycles and Waste Management》2022,24(5):2041-2053
Journal of Material Cycles and Waste Management - Biofilters have been recognized as a key technology in the mitigation of greenhouse gases (GHG) emitted by landfills. This study aimed to evaluate... 相似文献