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121.
河道溢油事故已成为内河道突发性水环境污染的主要问题之一,尤其水源地突发性污染事件日益增多,对社会、经济和河道生态环境造成严重的不良影响。新建的水上项目必须通过溢油风险评价来分析项目建设投产后对周边的环境影响,目前溢油风险评价尚无统一的方法,且风险分析不够深入。本文基于国内外经典的油膜动力学模型及统计学等理论,明确溢油事故环境风险评价中事故源强、事故概率、溢油油膜影响范围、风险应急时间以及水厂吸水口关闭时间等几个关键问题的分析方法,以期进一步提高河道溢油事故的环境风险评价水平。 相似文献
122.
民国初年我国救灾的主要特征有三:一是救灾主体多元化,这可从阶层、国籍、职业、身份等方面看出,总体上又可划分为政府和社会力量两个方面。至于救灾效能,无论是政府还是社会救济力量均存在着或多或少的局限性。二是短效机制占主导,这可从救灾因素之临设性、救灾甚于防灾两点看出。三是社会过渡性彰显,无论是思想,还是机构、制度,都呈现出明显的新旧交错性,即社会过渡性。 相似文献
123.
124.
电催化氧化法处理阳离子染料废水的试验研究 总被引:2,自引:0,他引:2
以结晶紫作为阳离子染料,采用电催化氧化法对阳离子染料溶液进行了电解脱色处理试验,研究了电流密度、电解质种类、电解质浓度、pH值等对该溶液脱色率的影响,测定了电解时溶液中生成的余氯浓度和溶液的紫外-可见吸收光谱曲线,并对不同电解时间的溶液的吸光度进行了归一化计算。结果表明:随着电解时间的延长,水溶液中活性氯浓度不断上升,经一定时间后达到最大值;在电催化和活性氯的协同作用下,阳离子染料结晶紫分子中的大π共轭体系被破坏、苯环结构基本瓦解,溶液快速脱色;在电流密度为5.1mA/cm2、NaCl浓度为4g/L、pH值为9.41的条件下,初始浓度为100mg/L的结晶紫溶液经过20min的电解,其脱色率可高达98.31%。 相似文献
125.
Recruitment precision, i.e. the proportion of recruits that reach an advertised food source, is a crucial adaptation of social
bees to their environment. Studies with honeybees showed that recruitment precision is not a fixed feature, but it may be
enhanced by factors like experience and distance. However, little is known regarding the recruitment precision of stingless
bees. Hence, in this study, we examined the effects of experience and spatial distance on the precision of the food communication
system of the stingless bee Scaptotrigona mexicana. We conducted the experiments by training bees to a three-dimensional artificial patch at several distances from the colony.
We recorded the choices of individual recruited foragers, either being newcomers (foragers without experience with the advertised
food source) or experienced (foragers that had previously visited the feeder). We found that the average precision of newcomers
(95.6 ± 2.61%) was significantly higher than that of experienced bees (80.2 ± 1.12%). While this might seem counter-intuitive
on first sight, this “loss” of precision can be explained by the tendency of experienced recruits to explore nearby areas
to find new rewarding food sources after they had initially learned the exact location of the food source. Increasing the
distance from the colony had no significant effect on the precision of the foraging bees. Thus, our data show that experience,
but not the distance of the food source, affected the patch precision of S. mexicana foragers. 相似文献
126.
Evidence of rich microbial communities in the subsoil of a boreal acid sulphate soil conducive to greenhouse gas emissions 总被引:1,自引:0,他引:1
Miloslav Šimek Seija Virtanen Václav Krištůfek Asko Simojoki Markku Yli-Halla 《Agriculture, ecosystems & environment》2011,140(1-2):113-122
The largest areas of acid sulphate (AS) soils in Europe are located in Finland, where 67,000–130,000 ha of AS soils are in agricultural use. In addition to their acidifying effects on waters, AS soils might be a significant source of greenhouse gases. In this pilot research, carbon and nitrogen content and microbial activity were studied in an AS and a non-AS soil. Large carbon and nitrogen stocks (110 Mg Corg ha?1 and 15 Mg Ntot ha?1) as well as high substrate induced respiration (33 μg CO2–C g?1h?1) were found in the C horizons of the AS soil but not in the non-AS soil. High microbial activity in these horizons of the AS soil was further confirmed by the measurement of dehydrogenase activity, basal respiration, the numbers of culturable bacterial cells, and the ratio of culturable to total numbers of cells. Still, the denitrifying enzyme activity was very low in the anaerobic horizons of the AS soil, indicating the prevalence of microbes other than denitrifiers. We suspect that the microbial community originated with the genesis of AS soil and has been supported by the large stocks of accumulated carbon and mineral nitrogen in the C horizons. If these permanently water-saturated subsoils are exposed to oxygen and their microbial activity consequently increases, large carbon and nitrogen stocks are likely to be mobilised, resulting in increased emission of greenhouse gases. Additional studies of boreal AS soils are needed to assess their potential contribution to increases in greenhouse gas fluxes at the local, regional, and global scales. 相似文献
127.
This paper performs a cost-effectiveness analysis of some of the best available technologies (BAT) that can contribute to decreasing the energy consumption and CO2 emissions in the European Union’s (EU27) cement industry. Several capital budgeting decision criteria have been used (the payback period, the net present value and the internal rate of return) to study whether or not an investment should be considered worthwhile. The results show that, independent of the capital budgeting decision criteria used, the number of cost-effective retrofitting possibilities available is large compared to the rate of improvements that the industry undertakes annually. This shows the insensitivity of the industry to financial criteria when it comes to making their investment decisions. The possible thermal energy improvement in the clinker production, if all these BATs were implemented, has been quantified to be around 10%. This achievement would place the cement industry in the upper bound of the benchmark range for clinker manufacture. However considering the delays observed nowadays in terms of diffusion of BATs in the cement industry, it requires a conducive policy environment that combines support for both technology development and to their deployment. 相似文献
128.
129.
Chih Ming M Ya Wen Lee Gui Bing Hong Te Li Su Je Lueng Shie Chang Tang Chang 《环境科学学报(英文版)》2011,23(4):687-692
TiO2 nanoparticles, doped with di erent Pt contents, were prepared by a modified photodeposition method using Degussa P-25 TiO2,
H2PtCl6 6H2O and methanol as the solvents. The physicochemical properties of Pt/TiO2 were investigated by the nitrogen adsorption
and desorption isotherm measurement technique, X-ray di raction analysis and photoluminescence spectra, respectively. Reaction rates
from photocatalytic removal of dichloromethane over Degussa P-25 TiO2 and Pt/TiO2 were evaluated. The average diameter and BET
surface area of the TiO2 catalyst particles were 300 nm and 50 m2/g, respectively. The degradation e ciency was 99.0%, 82.7%, 55.2%,
and 57.9% with TiO2 at inlet concentrations of 50, 100, 200, and 300 ppm, respectively. And the degradation e ciency was 99.3%,
79.7%, 76.5%, and 73.4% with a 0.005 wt.% Pt/TiO2 at inlet concentrations of 50, 100, 200, and 300 ppm, respectively. In addition, we
found that the photoluminescence emission peak intensities decreased with increases in the doping amount of Pt, which indicates that
the irradiative recombination was weakened. Furthermore, the results showed that the UV/0.005 wt.% Pt/TiO2 process was capable of
e ciently decomposing gaseous DCM in air. 相似文献
130.
The Cu2+-loaded montmorillonite clays (MMT-Cu) may be a good material for the adsorbed and eliminated pathogenic bacteria from aqueous solution. 相似文献