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951.
The uptake of 109Cd and 65Zn and their stable isotopes by ryegrass (Lolium multiflorum Lam.), grown on two different soil types, was investigated in climatically controlled growth chambers at 9 and 21 degrees C. The soils were treated with 0 and 4% organic matter (pig [Sus scrofa] manure) and spiked with 109Cd and 65Zn before sowing. The organic matter addition resulted in increased uptake of the 109Cd, Cd, and Zn by ryegrass, but the uptake of 65Zn was decreased. The latter effect was ascribed to isotopic dilution of 65Zn as the amount of stable Zn in the plant tissues increased with the organic matter addition. The effect of temperature was more pronounced than that of organic matter addition, and the uptake of both 109Cd and 65Zn and their stable isotopes was higher in ryegrass grown at 21 degrees C than that grown at 9 degrees C. Results from fractionation and speciation analysis of soil cadmium and zinc were correlated with plant uptake, and there was a good consistency between observed plant uptake and the physico-chemical forms of cadmium and zinc in soil and soil solution presumed to be plant available. 相似文献
952.
2 semiarid irrigated area with salt-affected soils. The available soil map is at 1:100,000 scale and its mapping units are
used for the land evaluation with the FAO framework. These data are then elaborated using the index value method. This procedure
gives a map of land evaluation units and a table that rates the productive potential of these units for six crops: alfalfa,
barley, maize, rice, sunflower, and wheat. 相似文献
953.
The amount of struvite (MgNH4PO4·6H2O) produced by Myxococcus xanthus as well as the culture parameter values (pH, total phosphorus, total Kjeldahl nitrogen) were dependent on the culture medium used. Struvite formation started during the exponential phase and the maximum concentration was observed at the beginning of stationary growth phase. The addition of each medium component to the liquid culture influenced the amount of crystal produced. This amount did not depend on the pH increase during the culture period. The moment of the bacterial growth phase, at which each medium component was added, influenced the struvite formation. 相似文献
954.
Concentrations of Pb in livers of willow grouse (Lagopus lagopus), black grouse (Tetrao tetrix), and hare (Lepus timidus) were determined in samples collected during the period 1990-92 from 77 locations distributed across Norway. Our objective was to elucidate the impact of long-range atmospheric transport on the Pb exposure of the animals. The moss Hylocomium splendens was measured for atmospheric Pb deposition and Pb in soil at 60-cm depth was determined to reflect the natural geochemical background at the study locations. Strong positive relationships were found between Pb in liver and atmospheric deposition of Pb for all species and age groups studied. Results indicate that long-range atmospheric transport was the main source of Pb in the animals studied. This conclusion was supported by Pb analysis of typical food plants for the animals. Correlation between Pb in liver and Pb in soil mineral matter was observed only when considering sites with very low impact of atmospheric deposition. Even though the observed liver Pb concentrations may seem low (< or =12 microg g(-1) dw) they approach levels where sub-lethal effects cannot be ignored. 相似文献
955.
956.
为了反映岩质边坡在节理面注浆后的变形效应,首先,通过室内试验,分析注浆前后岩体变形和破坏的全过程,以探讨其抗剪性能(粘结力c和内摩擦角φ)的变化;然后,基于理想弹塑性本构模型的Mohr-Cou-lomb准则,运用拉格朗日元数值方法(FLAC3D),对岩坡注浆前后变形效应(水平位移、垂直位移、剪应变增量)进行模拟。结果表明:注浆加固后,岩体的位移场变得均匀和连续,节理面处的较大位移受到抑制,边坡的整体性得到提高,有利于边坡的稳定性。 相似文献
957.
玉环电厂1 000 MW机组降低Nox排放的技术分析与环境评价 总被引:1,自引:0,他引:1
介绍了玉环电厂采用PM型燃烧器和MACT分级燃烧技术,降低了NOx生成量.预测不同负荷下的NOx排放浓度,对照《火电厂大气污染物排放标准》,分析玉环电厂的环境性能,为其他电厂降低NOx排放提供借鉴. 相似文献
958.
H. Cornier-Ríos P. A. Sundaram J. T. Celorie 《Journal of Polymers and the Environment》2007,15(1):51-56
Recycled plastics are considered low performance materials because their properties are expected to decrease drastically with
recycling. The objective of this study was to characterize a 15 wt.% glass filled polyethylene terephthalate (rPET-15GF) using
six recycle generations and four recycle ratios. Mechanical properties such as tensile strength, elastic modulus, and percent
elongation to failure of the PET composite were determined for various recycle generations and recycle ratios. Results show
that the mechanical properties of rPET-15GF decrease slightly per recycle generation. In contrast, thermal properties of rPET-15GF
were not at all affected by the recycling process. This data demonstrates that recycled glass filled PET can be used effectively
to fabricate components without significantly affecting their mechanical performance. 相似文献
959.
清代在水土资源、林木资源、矿产资源的保护与利用等方面采取了积极有效的措施,包括开垦土地、兴修水利、发展生态农业、植树造林、加强法制、设立环保机构等。 相似文献
960.
This was a cross-sectional study which looked into the interaction between situational factors, role stressors, hazard exposure and personal factors among 135 nurses in the Philippine General Hospital. More than half (58.5%) of the respondents reported being ill due to work in the past year, and 59.3% missed work because of an illness. Regression showed factors associated with burnout were organizational role stress, hazard exposure, self-efficacy, age, number of working years, illness in the past 12 months, migraine, dizziness, sleep disorder, cough and colds, and diarrhea. After multiple regression analysis, organizational role stress (p = .000), migraine (p = .001), age (p = .018) and illness in the past 12 months (p = .000) were found to be significant predictors of burnout. The contribution of the study is in advancing new concepts in the already existing framework of burnout, and thus, assisting nurses and hospital administration in on controlling this problem. 相似文献