汶川地震极震区泥石流动力特征及参数研究——以安县高川乡为例

2008年汶川8.0级地震发生以来,极震区泥石流爆发频率有增无减且规模越来越大,破坏性越来越强,严重威胁灾区人民生命财产安全。对比采取现场勘查、遥感图像分析、历史资料对比分析等方法,分析了极震区泥石流动力特征受地形、地层、物源等因素的影响,特别是泥石流爆发过程中深侵蚀和溃决对泥石流动力特征的影响。针对四川安县高川乡流域泥石流沟的调查和分析,建立泥石流流量-冲刷模型,分析了常规地区泥石流峰值流量与极震区泥石流峰值流量差别,推导出极震区峰值流量及冲刷深度定量计算公式。通过实例分析,理论与实际具有较好的一致性,对极震区泥石流动力参数计算具有较好适用性和有效性。     

Enhanced U(VI) bioreduction by alginate-immobilized uranium-reducing bacteria in the presence of carbon nanotubes and anthraquinone-2,6-disulfonate

Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2, 6-disulfonate (AQDS), and carbon nanotubes (CNTs). The effects of different AQDS-CNTs contents, U(IV) concentrations, and metal ions on U(IV) reduction by immobilized beads were examined. Over 97.5% U(VI) (20 mg/L) was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U(VI) occurred at initial U(VI) concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe(III), Cu(II) and Mn(II) slightly increased U(VI) reduction, whereas Cr(VI), Ni(II), Pb(II), and Zn(II) significantly inhibited U(VI) reduction. After eight successive incubation-washing cycles or 8 hr of retention time (HRT) for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters.     

极震区震后泥石流物源特征研究

汶川地震后,极震区产生了大量的崩滑堆积体、震裂岩体及震动松弛覆盖层,极震区震后泥石流物源的产生及汇集方式发生了极大的变化,但缺乏震后特殊条件下动储量的计算方法。在实际调查统计"5·12"极震区安县高川乡多条泥石沟物源的基础上,总结了极震区震后泥石流的形成过程及启动方式。分析得出,震后泥石流物源量与沟域面积、高程放大效应、断层运动方式、地质岩性条件及地形条件等因素有关,其中沟域面积、沟顶高程及沟道与发震断裂的距离为主控影响因子。在此基础上,提出了"地震高程指数放大经验模型";通过多元统计拟合法首次得出了震后泥石流动储量与流域面积、高差的计算关系,并通过地震距离修正得出极震区震后泥石流的动储量计算公式,为震后泥石流动储量估算及工程治理提供参考。     

To roll or not to roll: nyctinastic behavior in young leaves of sacred lotus,Nelumbo nucifera

The Science of Nature -     

A novel approach to estimate and control denitrification performance in activated sludge systems with respirogram technology

Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the evaluation of the performance of denitrification. The size distribution of flocs measured at different denitrification moments demonstrated a clear expansion of flocs triggered by denitrification, during which higher specific endogenous and quasi-endogenous respiration rates (SOUR_e and SOUR_q) were also observed. Furthermore, SOUR_q increases exponentially with the specific denitrification rate (SDNR), suggesting that there should be a maximum SDNR in conventional activated sludge systems. Based on these findings, an index R_q/t, defined as the ratio of quasi-endogenous (OUR_q) to maximum respiration rate (OUR_t), is proposed to estimate the denitrification capacity that higher R_q/t indicates higher denitrification potential, which can be readily obtained without complex measurement or analysis, and it offers a novel and promising respirogram-based approach for denitrification estimation and control by taking measures to extend anoxic time to maintain its value at a high level within a certain range.     

钛基改性DSA电极氧化法去除水中全氟化合物

为了提高金属氧化物电极(DSA电极)的稳定性及催化活性,实现全氟化合物(PFCs)的高效降解,分别以溶胶涂覆法和电沉积法制备了改性DSA(Ti/SnO_2-ZnO)电极,并用于全氟辛酸(PFOA)和全氟辛烷磺酸(PFOS)的电化学降解过程研究.实验分别考察了电流密度、溶液初始pH、 PFOA与PFOS初始浓度对PFCs降解效果的影响.结果表明:两种方法制备的改性DSA电极表面均匀负载了SnO_2-ZnO复合涂层.在二维电极体系中,极板面积约为65.0 cm~2,电流密度为20.0 mA·cm~(-2),极板间距为15.0 mm,电解质为1.30 g·L~(-1)次氯酸钠溶液以及电解时间为150 min时,溶胶涂覆法和电沉积法所制备的Ti/SnO_2-ZnO电极对初始浓度为100 mg·L~(-1)的PFOA和PFOS分别在pH为3.50和6.50时去除效果最佳,分别达到了90.6%、94.6%和91.0%、93.7%;循环使用电极3次,其降解过程均符合准一级反应动力学,且电沉积法制备的电极效果优于溶胶涂敷法,表现出对PFCs类污染物稳定、高效的去除能力.     

中国工业污染防治的战略决策——清洁生产

本文简述了清洁生产的概念与国外清洁生产的概况，评述了国内工业生产的现状及推行清洁生产的潜力和前景，并提出了一些有益建议。     

Modeling solute transport in one-dimensional homogeneous and heterogeneous soil columns with continuous time random walk

In this paper, we used the continuous time random walk (CTRW) framework to characterize the transport process in 1250-cm long one-dimensional homogenous and heterogeneous soil columns at the experiments conducted by Huang et al. [Huang, K., Toride, N., van Genuchten, M.Th., 1995. Experimental investigation of solute transport in large, homogeneous and heterogeneous, saturated soil columns. Trans. Porous Media. 18, 283-302]. The transport process was also simulated by using the advection-dispersion equation (ADE) and the spatial fractional advection-dispersion equation (FADE) for comparison. In the homogeneous soil column, the non-Fickian behavior is found at the distances less than 1000cm with beta values larger than 1.60, but less than 2, and Fickian form transport is obtained at distances larger than 1000cm with beta values larger than 2. In the heterogeneous soil column, we found the most anomalous behavior at distances from 200cm to 700cm with beta values ranging from 0.894 to 0.958, and non-Fickian transport process is observed at distances larger than 800cm with beta values in the range between 1 and 1.3. More significant non-Fickian behavior is found for transport in the heterogeneous soil column than that in the homogeneous soil column. The CTRW fits to the breakthrough curves (BTCs) have lower values of root mean square error (RMSE) and higher values of determination coefficient (r(2)), with respect to the fits of ADE and FADE. The CTRW model also is better captures the full evolution of BTCs, and especially their tails.     

单体液压支柱工作面顶板事故的原因与防治

简要地介绍了安徽淮南某矿回采工作面发生的1起重大冒顶事故,从地质、技术、装备、管理以及认识等方面分析r事故发生的原因,并提出了防治顶板事故的6项措施。     

稻田土菌群驯化对稻秆两步发酵产甲烷效果的影响

为提高稻秆的降解率及其厌氧发酵甲烷产量,采用高氨氮畜禽废水作为氮源以驯化稻田土壤微生物,优化其降解稻秆的初始pH值,并评估水解产物液体发酵产甲烷性能.结果表明,混合组驯化的微生物产纤维素酶活性及对稻秆木质素的降解率高于其它组及先前文献报道,分别达到4.01 IU和51.96%,且后期水解液中总有机碳（Total organic carbon, TOC）及还原糖含量最高.随着初始pH值的提高,稻秆中纤维素、半纤维素和木质素的降解率显著增加,稻秆水解液中的挥发性脂肪酸（Volatile fatty acids, VFAs）和TOC含量均显著增加,并在第7 d达到最高值.将水解稻秆7 d的水解液进行厌氧发酵显示,在初始pH=9.0条件下累积甲烷产量达到最大,为37.60 mL·mL^-1水解液.本实验结果表明, 驯化的稻田土微生物在碱性条件下可以更有效地降解稻秆,提高水解液中TOC及VFAs含量,从而提高厌氧发酵的甲烷产量.