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以香港近岸海域为研究区,基于2009~2012年HJ-1A/B CCD数据和实测数据,建立悬浮固体浓度遥感反演模型,运用地统计学方法对模型反演结果进行分析,探索研究区内悬浮固体浓度空间分布及其变异特征.结果表明:香港近岸海域北部深圳湾附近常年处于悬浮固体浓度的高值区,东北部珠江入海口海域悬浮固体浓度受季节影响明显,大屿山以南的南部海域的浓度值常年处于较低水平,并具有明显的季节特征.2009~2012年的地统计数据表明,香港近岸海域悬浮固体浓度值总体处于较低水平,月均值为12.25mg/L,由北向南递减趋势明显.全年大部分时间空间变异特征明显,空间自相关性较强,其中3月份的块金值/基台值最小,仅约为0.0005. 相似文献
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乌江干流中上游水电梯级开发水温累积效应 总被引:2,自引:0,他引:2
以乌江流域洪家渡库尾至乌江渡坝下的水电工程干扰典型段为研究区域,利用建坝前后的水温实测资料,采用建坝前天然水温和建坝后下泄水温比较法,对乌江干流梯级水库水温时空分布特征进行分析。研究结果表明:对天然水温改变最大的电站为洪家渡和乌江渡,前者是受水库水温结构自身影响,后者是梯级联合运行的结果;梯级联合运行使库区水温分层有所减弱,随着时间的推移或上游梯级电站的建成,电站下泄水温年变化过程趋于均化,与天然水温的延迟也越加明显;不同的水库水温结构对水温累积效应的影响也各不相同,稳定分层型水库对水温累积具有正效应,混合型水库具有负效应,过渡型水库处于两者之间,体现了梯级电站的水温累积影响,为研究减缓下泄低温水的对策措施提供依据和参考。 相似文献
347.
This study was designed to clarify the influence of operating conditions on the formation and emissions of polychlorinated-pdibenzodioxins and dibenzofurans (PCDD/Fs) from a sintering process with hot flue gas recycling. A pilot scale sinter pot with simulated flue gas recycling was developed, and four key operational parameters, including temperature, oxygen content of the simulated waste flue gas, the coke rate of the sintering mixture, and the quicklime quality, were selected for exploring PCDD/Fs formation. The results showed that the temperature of the recycled flue gas had a major affect on PCDD/Fs formation, and a high temperature could significantly increase their formation during sintering. A clear linear correlation between the temperature of recycling flue gas and PCDD/Fs emission (r = 0.93) was found. PCDD/Fs could be reduced to a certain extent by decreasing the level of oxygen in the recycled flue gas, while sintering quality was unchanged. The coke rate had no significant influence on the formation of PCDD/Fs, but the quality of quicklime used in the sintering mixture could affect not only the amount of PCDD/Fs emissions but also the sintering productivity. Compared with a benchmark sinter pot test, PCDD/Fs emissions markedly decreased with improvements to quicklime quality. However, the reduction in PCDD/Fs emissions realized by using high-quality quicklime was limited by the temperature of the inlet gas. The highest reduction achieved was 51% compared with conventional quicklime when the temperature of the inlet gas was 150°C. 相似文献
348.
A GFP-based bacterial biosensor with chromosomally integrated sensing cassette for quantitative detection of Hg(II) in environment 总被引:3,自引:0,他引:3
Himanshu Priyadarshi Absar Alam Gireesh-Babu P Rekha Das Pankaj Kishore Shivendra Kumar Aparna Chaudhari 《环境科学学报(英文版)》2012,24(5):963-968
A mercury biosensor was constructed by integrating biosensor genetic elements into E. coli JM109 chromosome in a single copy number, using the attP/attB recombination mechanism of λphage. The genetic elements used include a regulatory protein gene (merR) along with operator/promoter (O/P) derived from the mercury resistance operon from pDU1358 plasmid of Serratia marcescens. The expression of reporter gene gfp is also controlled by merR/O/P. Integration of the construct into the chromosome was done to increase the stability and precision of the biosensor. This biosensor could detect Hg(II) ions in the concentration range of 100-1700 nmol/L, and manifest the result as the expression of GFP. The GFP expression was significantly different (P ≤ 0.05) for each concentration of inducing Hg(II) ions in the detection range, which reduces the chances of misinterpretation of results. A model using regression method was also derived for the quantification of the concentration of Hg(II) in water samples. 相似文献
349.
pH-dependent leaching behaviour and other performance properties of cement-treated mixed contaminated soil 总被引:2,自引:0,他引:2
Portland cement has been widely used for stabilisation/solidification (S/S) treatment of contaminated soils. However, there is a dearth of literature on pH-dependent leaching of contaminants from cement-treated soils. This study investigates the leachability of Cu, Pb, Ni, Zn and total petroleum hydrocarbons (TPH) from a mixed contaminated soil. A sandy soil was spiked with 3000 mg/kg each of Cd, Cu, Pb, Ni and Zn, and 10,000 mg/kg of diesel, and treated with ordinary Portland cement (CEM I). Four different binder dosages, 5%, 10%, 15% and 20% (m/m) and different water contents ranging from 13%-19% dry weight were used in order to find a safe operating envelope for the treatment process. The pH-dependent leaching behaviour of the treated soil was monitored over an 84-day period using a 3-point acid neutralisation capacity (ANC) test. The monolithic leaching test was also conducted. Geotechnical properties such as unconfined compressive strength (UCS), hydraulic conductivity and porosity were assessed over time. The treated soils recorded lower leachate concentrations of Ni and Zn compared to the untreated soil at the same pH depending on binder dosage. The binder had problems with Pb stabilisation and TPH leachability was independent of pH and binder dosage. The hydraulic conductivity of the mixes was generally of the order, 10-8 m/sec, while the porosity ranged from 26%-44%. The results of selected performance properties are compared with regulatory limits and the range of operating variables that lead to acceptable performance described. 相似文献
350.
Amina Chnirhe Mourad Harir Basem Kanawati Mohammed El Azzouzi Istvan Gebefgi Philippe Schmitt-Kopplin 《环境科学学报(英文版)》2012,24(9):1686-1693
The photodegradation of mefenpyrdiethyl (MFD), an herbicide safener, was investigated in aqueous suspensions by using Degussa P-25 and Hombikat UV100 titanium oxide under simulated sunlight irradiation. The effects of initial concentration of the herbicide, pH, catalysts and hydrogen peroxide doses as well as their combinations were studied and optimized. Accordingly, the kinetic parameters were determined and the effectiveness of the processes was assessed by calculating the rate constants. A pseudo first-order kinetics was observed. Under experimental conditions, the degradation rate constants were strongly influenced using P-25 and no noticeable effect was observed for Hombikat UV100. DFT calculations with B3LYP/6-311+G(2d,p)//B3LYP/6-31+G(d,p) level of theory were performed to check whether significant conformational changes occur when the charge state of the MFD substrate changes and whether these changes could play a role in the dependency of photodegradation rate constant on the studied pH. High resolution mass spectrometry (FT-ICR/MS) was implemented to identify the main degradation products. 相似文献