Ozone Deposition at a Forest Site in NE Bavaria

The dry deposition of ozone to aconiferous forest in northeastern Bavaria(southern Germany) was quantified during 1999with both the eddy correlation method and a bigleaf model. The model included parameterizationsof the atmospheric transfer resistances fromdirect measurements, stomatal resistance from aplant ecological model, and an estimation of thecuticle resistance as function of leaf wetness.Early in the season, the measured and themodelled deposition fluxes were in goodagreement, although the modelled fluxes tended tounderestimate the measured ones. Thisunderestimation was more pronounced in the latesummer, when high nocturnal fluxes werefrequently measured. The model parameterizationof the cuticle and the stomatal resistances didnot allow for such high fluxes. In these cases,the 24 hour average of the measured fluxes wereup to 4.5 times higher than the modelled ones.The reasons for these large discrepancies remainunknown. However, assigning the unaccounted partof the deposition to a nonstomatal surfacedeposition pathway, a new parameterization of therespective resistance yielded an average value of300 s m^-1. It exhibited a decreasing trendthrough the vegetation period.     

UTILIZING INDUCED RECHARGE FOR REGIONAL AQUIFER MANAGEMENT1

ABSTRACT: The deep aquifers of the Portland Basin are used as a regional water supply by at least six municipalities in Oregon and Washington. Maximum continuous use of the aquifers in 1998 was 13 mgd and peak emergency use was 55 mgd. Continuous use of the deep aquifers at a rate of 55 mgd has been proposed and inchoate water rights have been reserved for expansion of pumping to 121 mgd. A study was completed, using a calibrated ground water flow model, to evaluate the role of induced recharge from the Columbia River in mitigating aquifer drawdown from continuous‐use and expanded pumping scenarios in the center and eastern areas of the basin. The absolute average residual was less than 3.6 feet for steady‐state model calibrations, and less than 8.0 feet for transient calibration to a 42 mgd pumping event in 1987 with 170 feet of drawdown. Continuous use of the aquifers at a rate of 55 mgd is predicted to increase drawdown to 210 feet. Expansion of pumping to 121 mgd in the center basin is predicted to cause 400 feet of drawdown. However, expansion of pumping in the east basin is predicted to result in only 220 feet of drawdown because of induced recharge from the Columbia River.     

磁河有机污染物在饱和土壤中迁移转化试验研究

通过静态吸附、静态降解和动态土柱试验,研究了磁河废水中有机污染物在土壤饱水条件下的迁移转化行为.实验结果经线性拟合和参数估算,得到弥散系数D=0.0036m2/d,分配系数K_d=0.19cm3/g,降解系数K=0.68 d-1.表明磁河有机污染物在土壤中有较强的吸附和降解能力.      

Municipal sludge as landfill barrier material

The aim of this research is to find substitute barrier materials for natural clay from two kinds of municipal sludge: waterworks sludge( Sw ) and dredging sludge( Sd ). Laboratory tests were performed firstly to determine their Atterberg limits and hydraulic conductivity.Based on the results, the use of waterworks sludge was recommended. Then, shear strength tests were performed and it was found the shear resistance property of waterworks sludge is strong enough to maintain slope stability. In order to evaluate the possibility of secondary pollution, the heavy metal contents of waterworks sludge was determined and the results indicated that secondary pollution is unlikely happened. Finally, economic analysis proves that reusing waterworks sludge as barrier will reduce the lost a great for both landfill and waterworks. Based on the results, waterworks sludge was proposed to use and a further long-term simulated landfill test was suggested.     

城市生活垃圾渗透系数测试研究

采用常水头测渗实验,对不同压实密度和水力梯度下的新鲜垃圾与陈垃圾的渗透系数进行测试,根据达西定律求得渗透系数值。由于垃圾的不均匀性、小颗粒的运动和大孔隙沟道流的形成和改变,实验初始阶段渗透系数值先增大至峰值,然后缓慢降低直至趋于稳定。实验稳定后,新鲜垃圾压实密度为0.75~0.95 t/m3时,渗透系数值约为1.26E-03~1.43E-03 cm/s。陈垃圾在压实密度分别为1.2和1.4 t/m3时,渗透系数为8.29E-04和1.35E-04 cm/s。     

Fracking the Debate: Frame Shifts and Boundary Work in Dutch Decision Making on Shale Gas

The meaning of hydraulic fracturing for shale gas is contested worldwide: is it an energy game changer, a transition fuel, or a technology that poses severe environmental problems? In the Netherlands, a policy controversy developed in which fracturing was reframed from ‘business as usual’ to a potential environmental risk. This article theoretically and empirically describes this shift by arguing that the technology of hydraulic fracturing for shale gas is a boundary object that created a sphere of engagement for all sorts of actors. In this sphere, they negotiated a common but soft meaning of this technology. These negotiations consisted of frame contests. As part of those contests, the discursive strategies of framing and boundary work enabled opponents to create uncertainty about economic benefits and environmental impact. The shift in meaning transformed the issue from an economic one with standard governmental rules and regulations into a planning issue that needs more precaution.     

ABR-MBR工艺处理生活污水实现短程硝化

采用ABR-MBR耦合工艺对MBR反应器中实现短程硝化的运行控制条件进行了研究,并为后续研究系统的反硝化除磷性能打下基础.ABR-MBR耦合工艺在不同条件下的运行研究结果表明,在ABR反应器的水力停留时间(hydraulic retention time,HRT)6 h,污泥回流比100%,硝化液回流比300%,温度30℃±2℃的条件下,通过控制好氧区溶解氧浓度(DO从0.5~1.0 mg·L~(-1)降为0.3~0.7 mg·L~(-1))以及改变MBR反应器有效容积以控制其HRT,最终在MBR反应器HRT从3 h逐步延长至5 h时短程硝化遭到破坏,亚硝酸盐积累率(nitrite accumulation rate,NAR)从60%急剧下降至15%.短程硝化影响因素的分析表明:pH值、游离氨(free ammonia,FA)和游离亚硝酸(free nitrous acid,FNA)对本试验实现短程硝化无显著影响,维持低DO浓度(0.3~0.7 mg·L~(-1))并逐步缩短HRT是本试验实现短程硝化的关键控制因素,温度和污泥停留时间(sludge retention time,SRT)可作为辅助因素与之共同调控.短程硝化期间,系统获得了高效且稳定的COD和NH_4~+-N去除效果,平均出水浓度分别低于50 mg·L~(-1)和2 mg·L~(-1),去除率均在90%以上,TN平均去除率高达72%.     

上向流厌氧滤池(UAF)处理城市生活污水的运行效能

采用上向流厌氧滤池(UAF)处理实际生活污水,研究中温条件下水力停留时间(hydraulic retention time,HRT)对系统运行效果及优势产甲烷菌群的影响.结果表明,在35℃,HRT为24 h条件下,系统启动28 d后化学需氧量(chemical oxygen demand,COD)去除率可达75%以上. HRT由24 h降至2. 5 h的过程中,COD去除率呈现先上升后下降的趋势,在HRT为5h时最高,平均去除率为81. 71%,最高可达87. 18%,当降至2. 5 h后,COD去除率降至75. 12%.甲烷产率(每消耗单位质量底物产生的甲烷的量,以CH4/CODre计)及甲烷体积分数随HRT的降低而增高,HRT为2. 5h时为0. 30 L·g-1,甲烷体积分数维持在73%左右,经能耗核算后可得系统产能可满足蠕动泵能耗需求.对系统内主要的产甲烷菌进行定量分析表明,乙酸营养型产甲烷菌Methanosarcinales丰度最高,为优势菌群,随着HRT的逐渐降低,乙酸营养型和氢营养型产甲烷菌的丰度都有大幅度提高.     

反应堆压力容器主螺栓水压试验拉伸量调整力学分析评价

目的针对某核电站反应堆压力容器主螺栓残余拉伸量与设计要求(1.63±0.03) mm有出入,个别测试数据不在设计要求范围内的情况,对出厂水压试验工况拉伸量验收值进行调整。方法考虑上述拉伸量偏差对螺栓载荷的影响,从应力、疲劳和密封角度展开系统分析,对螺栓、螺纹、连接法兰及反应堆压力容器密封性能分别进行详细的力学评价。结果根据评价结果,对出厂水压试验工况拉伸量验收值进行两次调整,最终确定为(1.68±0.03) mm。结论该机组反应堆压力容器出厂水压试验各项指标满足要求,针对上述拉伸量调整的力学评价合理性得到有效验证。     

水力负荷对生物沉淀池污染物净化性能的影响特性

本研究将生物转盘和平流式沉淀池设计理念相结合,开发出对水中致浊物质、有机组分、氨氮和总磷具有同步去除性能的一体式生物净化-沉淀池,考察了进水水力负荷对其污染物净化性能的影响规律.结果表明,在特定转盘转速和水质条件下,浊度、有机组分和氨氮的平均去除率随水力负荷的增大均呈先相对稳定后下降趋势,浊度和有机组分与氨氮平均去除率分别在0.036 g·(m~2·d)~(-1)与0.064 g·(m~2·d)~(-1)时达到最大.与浊度、有机组分和氨氮不同,水力负荷对总磷的去除效果影响较大,进水水力负荷在0.064 m~3·(m~2·d)~(-1)时,总磷平均去除率最差,适当减小或增大水力负荷,均有助于除磷过程的进行.进一步研究发现,硝化和除磷过程对水相中的有限碳源及溶解氧存在竞争关系.沿水流方向,盘片表面的微生物具有良好的种群配合和沿程分布特点,保证了在不利水力负荷条件下,工艺仍具有一定的去污效果,在微污染水体的强化净化处理中具有一定的应用前景.