Variation of crack intensity factor in three compacted clay liners exposed to annual cycle of atmospheric conditions with and without geotextile cover

Performance of compacted clay liners commonly used as landfill barrier systems can be subject to decline in terms of hydraulic conductivity if left exposed to atmospheric conditions for an extended period of time prior to placement of overlaying layers. The resulting desiccation cracking can lead to increased hydraulic conductivity. Desiccation crack intensity was studied for three clayey soils commonly used for construction of landfill barrier system in a relatively large scale test setup exposed to real time atmospheric conditions over a complete annual cycle. A white separator geotextile cover was presumed to be capable of reducing the intensity of desiccation cracking through absorbing and maintaining higher amounts of moisture and reducing the temperature of the soil surface in comparison to a directly exposed soil surface. Desiccation cracking was monitored using a digital imaging technique for three compacted clay liners in two sets, one open to air and the second covered with the white geotextile. Crack intensity factor approached a relatively stable phase after certain cycles corresponding to atmospheric dry wet cycles. The results indicated that the white separator geotextile was capable of reducing the crack intensity factor by 37.4–45.9% throughout the experiment including the cyclic phase of desiccation cracking. During the stable phase, the maximum reduction in crack intensity factor of 90.4% as a result of applying geotextile cover was observed for the soil with the lowest plastic index and clay content and therefore the lowest magnitude of crack intensity factor. The other two soils with similar clay content but different plastic index showed 23.6% and 52.2% reductions in crack intensity factor after cyclic phase when covered with geotextile.     

鲁甸6.5级地震地质灾害调查分析

2014年8月3日云南鲁甸发生6.5级地震,震级不大、灾情较重。震后排查和地震震前后对比显示,滑坡崩塌灾害是加剧灾情的关键因素之一;震后新增隐患沿河谷岸坡脊线、公路边坡开挖线、断裂带"三线耦合"部位集中分布的特征;中小型滑坡主要由地震动触发,大规模滑坡是由断裂活动和地震动联合触发。研究建议在西南山区的应急减灾能力建设中应综合考虑地震和地质灾害,分阶段规划。     

Changes in nitrogen budget and potential risk to the environment over 20 years(1990–2010) in the agroecosystems of the Haihe Basin,China

The nitrogen balance can serve as an indicator of the risk to the environment of nitrogen loss from agricultural land. To investigate the temporal and spatial changes in agricultural nitrogen application and its potential threat to the environment of the Haihe Basin in China, we used a database of county-level agricultural statistics to calculate agricultural nitrogen input, output,surplus intensity, and use efficiency. Chemical fertilizer nitrogen input increased by 51.7% from1990 to 2000 and by 37.2% from 2000 to 2010, concomitant with increasing crop yields.Simultaneously, the nitrogen surplus intensity increased by 53.5% from 1990 to 2000 and by16.5% from 2000 to 2010, presenting a continuously increased environmental risk. Nitrogen use efficiency decreased from 0.46 in 1990 to 0.42 in 2000 and remained constant at 0.42 in 2010,partly due to fertilizer composition and type improvement. This level indicates that more than half of nitrogen inputs are lost in agroecosystems. Our results suggest that although the improvement in fertilizer composition and types has partially offset the decrease in nitrogen use efficiency, the environmental risk has still increased gradually over the past 20 years, along with the increase in crop yields and nitrogen application. It is important to achieve a better nitrogen balance through more effective management to significantly reduce the environmental risk,decrease nitrogen surplus intensity, and increase nitrogen use efficiency without sacrificing crop yields.     

苏州市主要工业污染物排放强度研究

污染物排放强度反映单位新创造经济价值的环境负荷大小.运用均方差赋权法对苏州市各地区的工业废水量、工业化学需氧量、工业氨氮、工业二氧化硫、工业氮氧化物、工业烟(粉)尘等6种主要污染物排放强度进行评价,结果表明,六种主要污染物排放强度综合评价的全市平均水平为15.08.然后分别计算各地区的污染物排放强度降低潜力,结果表明,主要污染物排放强度减排潜力存在区域间差异.最后提出促进污染物排放强度降低的一些建议.     

CuO/BiVO_4催化剂制备及其可见光降解甲苯效果研究

采用水热法和浸渍法制备复合催化剂CuO/BiVO4。利用紫外-可见漫反射光谱(UV-Vis-DRS)和电化学测试手段对样品进行表征。UV-Vis-DRS表征表明,CuO的负载几乎不改变BiVO4的可见光吸收范围;线性扫描伏安法(LSV)和塔菲尔(Tafel)电化学表征说明复合催化剂中异质结的形成促进了光生电子-空穴的分离,提高了催化剂的光催化活性。通过考察CuO负载对该样品在可见光下光催化矿化甲苯效果的影响,结果显示Cu含量为4.0 wt%时BiVO4矿化甲苯效果最佳,光催化降解308 mg/m3的甲苯6 h后,最高矿化率由纯BiVO4的4.1%提高到19.5%。     

深溪沟电站大坝强震监测系统设计及应用

强震监测是大坝安全监测的重要内容之一,强震监测成果对大坝的安全性和稳定性分析有重要作用。本文根据水电站枢纽工程实际对深溪沟水库大坝强震监测系统设计开展研究,并对仪器的性能指标和数据采集处理分析软件进行了全面阐述。通过深溪沟水电站建设大坝强震监测系统的运行实践,大坝强震监测系统可以在地震发生后短时间内自动获取强震动加速度记录,储存地震波数据,并显示大坝坝体各测点的地震反应过程。强震监测结果进一步验证了设计烈度,为判定震后大坝安全性提供了支持。     

低强度超声波强化污水生物处理中超声辐照污泥比例的优化选择

通过超声波的SBR反应器与对照反应器处理人工配制生活污水的对比试验,研究了利用低强度超声波强化污水生物处理的另一个重要工艺参数———超声处理污泥比例(即超声处理污泥量占反应器内总污泥量的百分比).设置超声波反应器采用频率35kHz、声强0.3W/cm²超声波每隔8h取反应器中一定比例的活性污泥辐照10min后再返回反应器.结果表明,超声处理污泥比例为10%时,其COD和NH₃-N去除率可分别提高5%和0.5%左右,以好氧呼吸速率(Oxygen Uptake Rate,OUR)表示的污泥活性可提高12%以上.通过对污泥增长率的研究表明,当超声污泥比例为10%,超声波反应器内污泥的增长率比对照反应器降低了11%左右,减轻了后续污泥处理工序的负荷.随着超声处理污泥比例的增加,污泥体积指数SVI持续增大,但是超声污泥比例不超过10%对污泥沉降性能影响不大.因此,在超声强化污水生物处理工艺中,可采用强度0.3W/cm²超声波每隔8h取反应器中的10%的活性污泥辐照10min后再返回反应器,来提高反应器的生物处理效率.     

Economic Analysis of CO2 Emission Trends in China

Climate change is one of hot spots all around the world. China, the second biggest CO₂ emitter, is facing increasingly severe pressure to reduce CO₂ emission. The article first describes Kaya Identity and its policy implications. Second, it uses the modified Kaya Identity and makes decomposition without residues on CO₂ emission during the period 1971-2005. Taking into account the changes of macroeconomic background, it conducts a detailed analysis in terms of CO₂ emission trend from 4^th Five Year Plan through 10^th Five Year Plan. The decomposition results indicate that economic development and increase in population are major driving forces, and that improvement in energy efficiency contributes to the reduction of CO₂ emission, and that decarbonization in primary energy structure is also an important strategic choice. Finally, the article stresses that in CO₂ order to realize the binding target of 20% reduction in GDP energy intensity during the 11^th Five Year Plan, China should speed up the readjustment of the industrial structure and energetically develop the energy-efficient technologies and clean fuel technology, which will effectively promote the country to reduce CO₂ emission and contribute to the mitigation of climate change.     

石油野外作业工人体力劳动强度分级调查

据ＧＢ３８６９—８３标准对江汉油田测量、地震、钻井、井下四类野外作业３４名工人、２４个工种进行了体力劳动强度分级调查，其结果：测量作业为Ⅰ～Ⅱ级；钻井作业Ⅱ级占５／８，Ⅲ级占１／４；井下作业Ⅲ级占２／３；地震作业Ⅲ、Ⅳ级各占４／９、２／９。说明前两类基本属中等强度劳动，后两类大部分属重强度劳动。     

RUNOFF AND SEDIMENT YIELD UNDER GRAZING IN FOOTHILLS FESCUE GRASSLANDS OF ALBERTA1

ABSTRACT: Grazing can have a profound impact on infiltration and thus runoff and erosion. The objectives of this study were to quantify the effects of select grazing systems on rainfall and snowmelt induced runoff and sediment yield from sloped areas of the foothills fescue grasslands of Alberta, Canada. The effects of two grazing intensities (heavy and very heavy) for two durations (short duration and continuous throughout the growing season) were compared to an ungrazed control between June 1988 and April 1991. Runoff was measured using 1-rn² runoff frames and collection bucket systems. Sediment yields were then determined on samples from the collected runoff. Snowmelt was the dominant source of runoff. Snowmelt runoff was higher from the heavily grazed areas than from the very heavily grazed areas, due to the higher standing vegetation which accumulated snow in the former areas. Sediment yields as a result of snowmelt were generally low in all areas. Only a few summer storms caused runoff. Runoff volumes and sediment yields from summer rainstorms were low, due to low rainfall and to generally dry antecedent soil moisture conditions. The greatest risk of summer runoff, and thus sediment yield, appears to occur in August.