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491.
The photocatalytic disinfection of Escherichia coli K-12 is investigated by the natural sphalerite (NS) under different spectra, wavelengths and intensities of visible light (VL) emitted by light-emitting-diode lamp (LED). The spectrum effect of VL on disinfection efficiency is studied by using white LED, fluorescent tube (FT) and xenon lamp (XE), which indicates that the “discreted peak spectrum” of FT is more effective to inactivate bacteria than “continuous spectrum” of LED and XE. Besides, the photocatalytic disinfection of bacteria is compared under different single spectrum (blue, green, yellow and red color) LEDs. The results show that the most effective wavelength ranges of VL for photocatalytic disinfection with the NS are 440-490 and 570-620 nm. Furthermore, a positive relationship is obtained between the disinfection efficiency and the VL intensity. The experiment shows that NS can completely inactivate 107 cfu mL−1E. coli K-12 within 8 h irradiation by white LED with the intensity of 200 mW cm−2 at pH 8. Moreover, the destruction process of the cell wall and the cell membrane are directly observed by TEM. Finally, no bacterial colony can be detected within a 96 h regrowth test of inactivated bacteria, which reveals that the VL-photocatalytic disinfection leads to an irreversible damage to the bacterial cells. 相似文献
492.
Development of a novel mathematical model using a group contribution method for prediction of ionic liquid toxicities 总被引:2,自引:0,他引:2
Ismail Hossain M Samir BB El-Harbawi M Masri AN Abdul Mutalib MI Hefter G Yin CY 《Chemosphere》2011,85(6):990-994
A new mathematical model has been developed that expresses the toxicities (EC50 values) of a wide variety of ionic liquids (ILs) towards the freshwater flea Daphnia magna by means of a quantitative structure-activity relationship (QSAR). The data were analyzed using summed contributions from the cations, their alkyl substituents and anions. The model employed multiple linear regression analysis with polynomial model using the MATLAB software. The model predicted IL toxicities with R2 = 0.974 and standard error of estimate of 0.028. This model affords a practical, cost-effective and convenient alternative to experimental ecotoxicological assessment of many ILs. 相似文献
493.
China’s Primary Programs of Terrestrial Ecosystem Restoration: Initiation, Implementation, and Challenges 总被引:5,自引:0,他引:5
China has undertaken several major programs of terrestrial ecosystem restoration (ERPs) in recent years, including the Natural
Forest Protection Program (NFPP) and the Sloping Land Conversion Program (SLCP). There have been reports on the implementation
of these programs, their preliminary impacts, and the problems encountered in carrying them out; a great deal has been learned
from these studies. Nonetheless, China’s ERPs are not limited to the NFPP and the SLCP. Because a complete documentation and
a timely update of these major efforts are still missing from the literature, it is difficult to gauge the scope of these
programs and the scale of their impacts. In addition, a more thorough and critical analysis of both the general ERP policy
and the specific technical measures used in implementing the ERPs remains urgently needed. The purpose of this article is
to tackle these tasks. Overall, with the huge government investments in the ERPs, tremendous progress has been made in implementing
them. To complete them successfully and to fundamentally improve the targeted ecosystems, however, it is essential for China
to have a more balanced and comprehensive approach to ecological restoration. This approach must include: adopting better
planning and management practices; strengthening the governance of program implementation; emphasizing the active engagement
of local people; establishing an independent, competent monitoring network; and conducting adequate assessments of program
effectiveness and impact. 相似文献
494.
Quantifying the Effect of Ecological Restoration on Soil Erosion in China’s Loess Plateau Region: An Application of the MMF Approach 总被引:5,自引:0,他引:5
Changbin Li Jiaguo Qi Zhaodong Feng Runsheng Yin Biyun Guo Feng Zhang Songbing Zou 《Environmental management》2010,45(3):476-487
Land degradation due to erosion is one of the most serious environmental problems in China. To reduce land degradation, the
government has taken a number of conservation and restoration measures, including the Sloping Land Conversion Program (SLCP),
which was launched in 1999. A logical question is whether these measures have reduced soil erosion at the regional level.
The objective of this article is to answer this question by assessing soil erosion dynamics in the Zuli River basin in the
Loess Plateau of China from 1999 to 2006. The MMF (Morgan, Morgan and Finney) model was used to simulate changes in runoff
and soil erosion over the period of time during which ecological restoration projects were implemented. Some model variables
were derived from remotely sensed images to provide improved land surface representation. With an overall accuracy rate of
0.67, our simulations show that increased ground vegetation cover, especially in forestlands and grasslands, has reduced soil
erosion by 38.8% on average from 1999 to 2006. During the same time period, however, the change in rainfall pattern has caused
a 13.1% ± 4.3% increase in soil erosion, resulting in a net 25.7% ± 8.5% reduction in soil erosion. This suggests that China’s
various ecological restoration efforts have been effective in reducing soil loss. 相似文献
495.
Quantifying Terrestrial Ecosystem Carbon Dynamics in the Jinsha Watershed, Upper Yangtze, China from 1975 to 2000 总被引:1,自引:0,他引:1
Shuqing Zhao Shuguang Liu Runsheng Yin Zhengpeng Li Yulin Deng Kun Tan Xiangzheng Deng David Rothstein Jiaguo Qi 《Environmental management》2010,45(3):466-475
Quantifying the spatial and temporal dynamics of carbon stocks in terrestrial ecosystems and carbon fluxes between the terrestrial
biosphere and the atmosphere is critical to our understanding of regional patterns of carbon budgets. Here we use the General
Ensemble biogeochemical Modeling System to simulate the terrestrial ecosystem carbon dynamics in the Jinsha watershed of China’s
upper Yangtze basin from 1975 to 2000, based on unique combinations of spatial and temporal dynamics of major driving forces,
such as climate, soil properties, nitrogen deposition, and land use and land cover changes. Our analysis demonstrates that
the Jinsha watershed ecosystems acted as a carbon sink during the period of 1975–2000, with an average rate of 0.36 Mg/ha/yr,
primarily resulting from regional climate variation and local land use and land cover change. Vegetation biomass accumulation
accounted for 90.6% of the sink, while soil organic carbon loss before 1992 led to a lower net gain of carbon in the watershed,
and after that soils became a small sink. Ecosystem carbon sink/source patterns showed a high degree of spatial heterogeneity.
Carbon sinks were associated with forest areas without disturbances, whereas carbon sources were primarily caused by stand-replacing
disturbances. It is critical to adequately represent the detailed fast-changing dynamics of land use activities in regional
biogeochemical models to determine the spatial and temporal evolution of regional carbon sink/source patterns. 相似文献
496.
497.
Yuxiang Mao Yongguang Yin Guangliang Liu Guibin Jiang 《Environmental pollution (Barking, Essex : 1987)》2010,158(11):3378-950
A few studies have reported the occurrence of monoethylmercury (CH3CH2Hg+) in the natural environment, but further verification is needed due to the lack of direct evidence and/or uncertainty in analytical procedures. Various analytical techniques were employed to verify the occurrence of CH3CH2Hg+ in soil of the Florida Everglades. The identity of CH3CH2Hg+ in Everglades soil was clarified, for the first time, by GC/MS. The employment of the recently developed aqueous phenylation-purge-and-trap-GC coupled with ICPMS confirmed that the detected CH3CH2Hg+ was not a misidentification of CH3SHg+. Stable isotope-tracer experiments further indicated that the detected CH3CH2Hg+ indeed originated from Everglades soil and was not an analytical artifact. All these evidence clearly confirmed the occurrence of CH3CH2Hg+ in Everglades soil, presumably as a consequence of ethylation occurring in this wetland. The prevalence of CH3CH2Hg+ in Everglades soil suggests that ethylation could play an important role in the biogeochemical cycling of Hg. 相似文献
498.
通过对反向传播人工神经网络的算法和网络结构的研究,发现拟牛顿算法训练速度较快,能够较好地接近误差目标值,同时建立了包括输入层、隐含层、输出层的人工神经网络三层拓扑结构。通过对街道峡谷人工神经网络的训练,模拟计算了街道峡谷NOx浓度分布值。结果显示,训练误差和测试误差比为1.11,训练样本的模拟值与实测值的相关系数为0.93,测试样本的模拟值与实测值的相关系数为0.87,模拟值与实测值的相关系数均高于显著水平为α=0.05与α=0.01所对应检验性表的相关系数临界值。该模型能够用于街道峡谷污染物浓度的模拟计算,具有较好的泛化能力。 相似文献
499.
纳米Bi2O3/TiO2复合光催化剂的制备及性能研究 总被引:1,自引:1,他引:0
以光催化效果为评价标准,采用超声波作用下水解法制备Bi2O3/TiO2复合光催化剂,考察了水解条件和Bi2O3掺入量等制备条件对复合光催化剂性能的影响。结果表明,与传统制备方法相比,该方法操作简单、快速;当水和乙醇的比例为4∶1时所得样品的光催化活性最好;Bi2O3的掺入拓宽了TiO2对光的吸收范围,提高了TiO2的光催化活性,掺入量(Bi2O3)为0.25%复合光催化剂催化活性最高;复合光催化剂对多种水溶性染料均具有较好的处理效果。 相似文献
500.
自然灾害风险评估国际计划述评Ⅰ——指标体系 总被引:3,自引:0,他引:3
自然灾害风险评估是综合灾害风险管理的关键途径。概述了近年来3个重要的自然灾害风险评估国际计划:灾害风险指标计划(Din)、多发区指标计划(Hotspots)和美洲计划(American Programme)的目标与成果。重点介绍了3个国际计划选取的指标:DRI首次开发了2个脆弱性全球指标;Hotspots发展了3个灾害风险指数;美洲计划开发了4个独立的指标体系,用于描述国家级的灾害风险构成要素,同时,提出城市级的风险评估指标。通过比较3个国际计划选择的指标体系的优缺点,提出选择能全面反映脆弱性和风险特征、计算简便的指标是今后灾害风险评估的关键和重点。 相似文献