硝酸根对颗粒状铁降解三氯乙烯的影响(英文)

为研究硝酸根对颗粒状铁降解三氯乙烯的影响,进行了柱实验和相应的反应铁腐蚀电位测定。在硝酸根离子存在条件下,铁的腐蚀电位相应升高,系统条件也因之发生变化,导致钝性的铁氧化物在铁表面生成。因而,三氯乙烯和硝酸根离子降解速率明显减小, 并且降解速率减小的程度与硝酸根离子的浓度成比例。当污染液流过反应柱时,硝酸根离子与铁反应, 被还原为氨根离子。该反应造成硝酸根离子的浓度梯度,使钝化区在柱中上移,从而影响了三氯乙烯的降解曲线。与三氯乙烯单独与铁反应相比,当含4 7 mg/L硝酸根的三氯乙烯溶液流经反应柱170 孔隙体积后,降解50% 三氯乙烯所需的时间(t50) 从小于4 h增加到大于10 h;而当三氯乙烯溶液中加入100 mg/L硝酸根离子,仅17 孔隙体积溶液流经反应柱后,三氯乙烯降解t50就已大于14 h。研究结果表明,由于硝酸根离子对铁的腐蚀电位和铁表面氧化膜的不利作用,在处理靶污染物为高浓度硝酸根离子和三氯乙烯共同污染的地下水时,铁渗透反应隔栅不是最佳选择。如果靶污染物中硝酸根离子浓度比较低,则在设计铁隔栅时应考虑到硝酸根离子造成的不利因素,相应增加铁墙的厚度,从而确保三氯乙烯的降解效果。     

Material Composition and Engineering Characteristics of Red Clay in Guigang, Guangxi

Red clay is highly silty clay with red and yellowcolors, formed by the weathering and laterization ocarbonate rocks in hot and wet climate condition(Wiesner, 1999; The Committee of the Handbook oGeological Engineering, 1993). Guigang in Guangxis in a low latitude, sub tropical climate, so its sum mer is long and its winter is short, and heat and pre cipitation are profuse. Carbonate rocks are wideldistributed. Given such a geological environment anweathering conditions, …     

显生宙海水成分、碳酸盐沉积和生物演化系统研究进展

简述了显生宙海水成分演化的特征、识别标志和成因解释模型以及存在的问题和今后研究的方向.不同时期海水的成分的差异,特别是海水的x(Mg)/x(Ca)值,导致了文石海、方解石海时期的碳酸盐沉积和早期成岩作用均存在差异,甚至影响了盆地深部成岩流体的特征.显生宙海生生物的演替和盛衰,特别是简单生物(如钙藻和海绵)和高产率生物(如造礁生物和碳酸盐沉积物主要生产者),明显体现了海水的x(Mg)/x(Ca)值周期性变化对海生生物的影响.这种影响也同样体现在古生代末期的生物大绝灭及随后的生物复苏样式上,在生物更替事件研究中应引起重视.因此,生物与环境的协同演化研究必须从地球系统科学的角度展开.     

非饱和黄土渗透性的试验研究

通过对甘肃陇西地区的湿陷性黄土做现场浸水试验和室内渗透试验、粒度分析试验，得到了陇西黄土的渗透系数（K20）随孔隙比（e）和吸力（s）的变化规律，为研究黄土浸水入渗规律，求解湿陷性黄土非稳态渗流方程做了必要的准备。     

SPOT5影像纹理特征提取与土地利用信息识别方法

本文以太湖流域西苕溪上游安吉地区SPOT5影像600像元×600像元为试验区,首先采用主成分分析对SPOT5影像进行数据压缩和几何信息增强,再采用小波分析方法对影像进行滤波和噪音处理,利用灰度共生矩阵对高分辨率图像的纹理信息进行分析,以对比度和熵为统计指标,确定对比度和熵的最佳阈值,进行边界匹配和图像的分割,将此分割结果与NDVI阈值法分类结果进行叠合,得到最终的分类结果。试验结果表明:将纹理分析方法应用于图像分类中可区分光谱混淆的地物,光谱与纹理特征结合得到的分类精度高于单纯依靠光谱特征进行分类和单纯依靠纹理分类的分类精度。     

Estimating contributions of sources of soil CO2 at the shallower layer in a Japanese larch forest area

Soils contain about twice the amount of carbon presented in the atmosphere, so a small change in the soil carbon will influence atmospheric chemistry and heat balance. The soil carbon ultimately exchanged with the atmospheric CO2 as soil CO2, which mainly exists at the depth of 0-20 cm. The transport of soil CO2 is affected by the sources of soil CO2. Thus, separation of the contributions of sources of soil CO2 is a fundamental need to understand and predict implications of environmental change on soil carbon cycling and sequestration. It is a complicated task, so that a number of different methodological approaches such as component integration, root removal, and gap analyses have been developed. However, these methods could not avoid changing soil characteristics such as air-filled porosity, soil temperature and soil water contents. Consequently, fractional contributions of respiration of living root and decomposition of soil organic matter to the total soil CO2 cannot be estimated correctly. In this study, based on mass balance theory of both concentrations and δ^13C of soil CO2, a trenching method with a stable-isotope technique was used to determine both soil CO2 sources at the depth of 3-13 cm in a Japanese larch forest area during 30 May to 7 October 2005 and fractional contributions of these sources. Experimental results showed that the amount of atmospheric CO2 invaded the soil air was not significantly variable while its percent rate in the total soil CO2 had significantly temporal variations with the lower values between 5 August and 1 September. The litter-layer decomposition was very small. The soil CO2 derived from the respiration of living root and the decomposition of soil organic matter showed significantly temporal variations with increase from 30 May to 5 Aug. and decrease from 1 September to 7 October, 2005; and it accounted for 82%-98% of the total soil CO2 in which the respiration of living root was in the range from 32% to 62%.     

线划地形图影像中的数字检测

纸质线划地形图是GIS数字地图的主要信息和重要数据来源之一,对扫描后的影像图中信息的自动识别一直是地形图自动读取的一个重要研究方向。研究对线划地形图扫描后影像中的数字字符的自动检测技术,通过对连通成分和字符轮廓的判别和实验,对线划图中的数字字符进行提取和检测。     

关于泛珠三角物流现状及构建泛珠三角物流圈的思考

区域物流业的合作日益受到关注,也成为构建泛珠三角经济圈的主要内容之一。对泛珠三角区域物流业发展现状进行定性及定量的分析,得出区域交通网络发达、港口优势明显、市场需求广阔、物流企业众多以及省区间差异较大等结论;在此基础上,从背景、现状及展望等3方面对构建泛珠三角物流圈进行探讨,以期为区域的经济发展与合作提供参考。     

矽线石研究及应用综述

对矽线石的成分,有主邓－无序,结构,热力学行为及应用研究进展作了综述。通过对矽线石的研究,能够为矽线石的合理利用提供理论基础,强调应堤洄强对矽线碱珠杂质成分,结构及其变化的研究。