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641.
This paper presents a large-scale modeling study characterizing fluid flow and tracer transport in the unsaturated zone of Yucca Mountain, Nevada, a potential repository site for storing high-level radioactive waste. The study has been conducted using a three-dimensional numerical model, which incorporates a wide variety of field data and takes into account the coupled processes of flow and transport in the highly heterogeneous, unsaturated fractured porous rock. The modeling approach is based on a dual-continuum formulation of coupled multiphase fluid and tracer transport through fractured porous rock. Various scenarios of current and future climate conditions and their effects on the unsaturated zone are evaluated to aid in the assessment of the proposed repository's system performance using different conceptual models. These models are calibrated against field-measured data. Model-predicted flow and transport processes under current and future climates are discussed. 相似文献
642.
均相Fenton法深度处理丙烯腈生化尾水 总被引:2,自引:1,他引:1
采用均相Fenton法深度处理丙烯腈生化处理工艺尾水,通过单因素法分析了H_2O_2投加量、Fe~(2+)投加量、初始p H值和反应时间对尾水COD去除率的影响;并采用中心响应曲面法优化Fenton处理的工艺参数,得到最佳反应条件为:Fe~(2+)投加量为1.02 mmol·L-1,H_2O_2投加量为11.13 mmol·L~(-1),初始pH值为3.66,反应时间为105 min,COD去除率达到61.1%.处理后尾水COD值低于50 mg·L~(-1),可满足石化行业一级排放标准.Fenton工艺对尾水中特征污染物均有较好的去除效果,最佳反应条件下丙烯腈、间苯二甲腈、3-氰基吡啶的去除率分别为99.5%、97.6%、73.7%;Fenton法对3种特征污染物的降解能力从大到小依次为:丙烯腈间苯二甲腈3-氰基吡啶.三维荧光光谱分析表明,尾水中存在大量类富里酸荧光物质,其中,紫外区类富里酸含量最高,Fenton工艺在较短反应时间和较少的试剂投加量条件下,便可有效地去除这类难降解物质. 相似文献
643.
城镇化河流DOM组成结构及与水质相关性研究 总被引:6,自引:0,他引:6
应用三维荧光技术和多元统计方法,分析城镇化河流水溶性有机物(DOM)组成结构特征,研究其与河水水质的相关性.根据人类活动对沈阳市白塔堡河影响程度的不同,分别在农村、城镇与城市河段设置3个采样点,采集水样.结果发现,河水营养水平由高到低的顺序为城市河段城镇河段农村河段,而水质由好变差的顺序为农村河段城镇河段城市河段.河水DOM由类酪氨酸、类色氨酸、类糖化蛋白、微生物代谢产物、类富里酸和类胡敏酸组成,主要成分为类蛋白,类蛋白含量由高到低的顺序为城市河段城镇河段农村河段.从源头到入浑河口,类蛋白丰度增长最大,类胡敏酸丰度增长最小,类富里酸介于两者之间.DOM的腐殖化程度由强到弱的顺序为城市河段城镇河段农村河段.影响河水营养状态的潜在因子包括COD、NH3-N、BOD5、DO和类蛋白,农村河段主要污染物来源于农村生活污水及养殖废水,城镇河段污染物来源于生活废水与工业园排水,城市河段污染物来源于处理和未处理的生活污水及工业废水.河水受人类活动影响由大到小的顺序为城市河段城镇河段农村河段. 相似文献
644.
645.
通过检测有机质含量和三维荧光光谱研究了霍州煤矿区地下水中溶解性有机质的垂向分布特征.结果表明,硝酸盐质量浓度在地表水和第四系水中较高(> 37.41 mg/L),而在深部含水层(太灰和奥灰)基本未检出.地表水中TOC(总有机碳)质量浓度和UV254分别大于5.11 mg/L和0.146 cm-1;氧化还原作用下,第四系水中TOC质量浓度和UV254分别减小82.23%和97.96%,而深部含水层中TOC质量浓度也有降低.人类活动污水的大量排放导致地表水中Ⅱ区和Ⅳ区的荧光峰强度异常高,均大于等于8 245 QSU,Ⅲ区的荧光峰强度大于3 419 QSU;进入第四系含水层,Ⅱ区、Ⅲ区和Ⅳ区荧光峰强度均减少至216 QSU以下;太灰水和奥灰水中只Ⅱ区和Ⅳ区出现荧光峰,且荧光峰强度与TOC相关性不大;溶解性有机质(DOM)荧光峰强度与地下水流向呈负相关,同一煤矿区奥灰水中Ⅳ区的荧光峰强度比太灰水高.总体上,分析溶解性有机质含量和荧光特性、硝酸盐含量,可以从垂向上建立霍州矿区各含水层(体)的水化学特征. 相似文献
646.
层次分析法作为一种常用的安全评价方法,针对其中的两两比较这一环节,由于专家的自身原因,做出的评价与实际情况可能存在一定的误差。该研究借用信息论的理论,将群组层次分析法(GAHP)中的两两比较的实际情况看作信源,将专家看做信道,将得出的判断矩阵看做信息,从而使因为专家的差异而导致的判断矩阵的误差转变为信息在传播过程中的失真;通过分析其失真与信源类型并且计算其中的平均失真度和率失真函数,从而针对基于率失真函数的群组层次分析法的修正进行进一步的研究。最后以某一使用层次分析法的鞭炮厂的评价作为实例,对于率失真函数在判断矩阵的修正中的准确性与可行性进行验证。 相似文献
647.
648.
Daniele Contini Franco Belosi Andrea Gambaro Daniela Cesari Angela Maria Stortini Maria Chiara Bove 《环境科学学报(英文版)》2012,24(11):1954-1965
The Venice Lagoon is exposed to atmospheric pollutants from industrial activities, thermoelectric power plants, petrochemical plants, incinerator, domestic heating, ship traffic, glass factories and vehicular emissions on the mainland. In 2005, construction began on the mobile dams (MOSE), one dam for each channel connecting the lagoon to the Adriatic Sea as a barrier against high tide. These construction works could represent an additional source of pollutants. PM10 samples were taken on random days between 2007 and 2010 at three different sites: Punta Sabbioni, Chioggia and Malamocco, located near the respective dam construction worksites. Chemical analyses of V, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Tl and Pb in PM10 samples were performed by Inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) and results were used to identify the main aerosol sources. The correlation of measured data with meteorology, and source apportionment, failed to highlight a contribution specifically associated to the emissions of the MOSE construction works. The comparison of the measurements at the three sites showed a substantial homogeneity of metal concentrations in the area. Source apportionment with principal component analysis (PCA) and positive matrix factorization (PMF) showed that a four principal factors model could describe the sources of metals in PM10. Three of them were assigned to specific sources in the area and one was characterised as a source of mixed origin (anthropogenic and crustal). A specific anthropogenic source of PM10 rich in Ni and Cr, active at the Chioggia site, was also identified. 相似文献
649.
Endogenous nitric oxide mediates alleviation of cadmium toxicity induced by calcium in rice seedlings 总被引:2,自引:0,他引:2
The effect of calcium chloride (CaCl2) on rice seedling growth under cadmium chloride (CdCl2) stress, as well as the possible role of endogenous nitric oxide (NO) in this process, was studied. The growth of rice seedlings was seriously inhibited by CdCl2, and the inhibition was significantly mitigated by CaCl2. However, hemoglobin (Hb) and 2-(4-carboxyphenyl)-4, 4,5,5-tetramethylimidazolinel- oxyl-3-oxide (cPTIO) weakened the promotion effect of CaCl2. The results of NO fluorescence localization suggest that growth accelerated by CaCl2 might be associated with elevated NO levels. The content of Cd, protein thiols (PBT), and nonprotein thiols (NPT) in cell walls, cell organelles, and soluble fractions, respectively, of rice seedlings decreased considerably in the presence of CaCl2, whereas the content of pectin, hemicellulose 1 (HC1), and hemicellulose 2 (HC2) increased significantly. Elimination of endogenous NO in Cd+Ca treatment could promote the transportation of Cd2+ to cell organelles and soluble fractions and increase the content of NPT and PBT in leaves. In addition, transportation of Cd2+ to cell organelles and soluble fractions was retarded in roots, the content of NPT increased, and the content of PBT decreased. With elimination of endogenous NO in Cd+Ca treatment, the content of pectin, HC1, and HC2 decreased significantly. Thus, Ca may alleviate Cd toxicity via endogenous NO with variation in the levels of NPT, PBT, and matrix polysaccharides. 相似文献
650.
张玲 《安全.健康和环境》2007,7(6):39-42
以炼焦炉的化产系统为例,使用相互矩阵方法分析化学物质相互间的影响、与外部因素的关系及可能发生事故类型,并制定对策措施. 相似文献