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941.
942.
稳定性复合高铁酸盐的制备及其在水质净化中的应用 总被引:1,自引:0,他引:1
在复合高铁酸盐溶液的制备过程中投加Ca(ClO) 2,可以提高其稳定性能.通过对Ca(ClO) 2的投加量、Ca(ClO) 2的投加顺序、反应温度及反应时间的考察,确定其对复合高铁酸盐溶液的最佳稳定条件为:在生成复合高铁酸盐溶液后投加0.08 mol/L的Ca(ClO) 2,并在20℃条件下反应10 min.Ca(ClO) 2对复合高铁酸盐溶液的稳定作用,是ClO-缓慢释放的一级动力学反应过程.将复合高铁酸盐溶液与聚合氯化铝(PAC)联合投加,可净化城市生活污水和铜绿微囊藻配制水.研究表明,与PAC单独投加相比,复合高铁酸盐溶液与PAC联合投加对水体中的氨氯、COD、细菌、浊度、藻细胞等的去除效果更好,且达到同样处理效果所需药剂量少. 相似文献
943.
活性污泥总DNA提取方法的比较 总被引:1,自引:0,他引:1
从处理某制药废水的MBR反应器中采集活性污泥,评价不同DNA提取方法对其总DNA提取效率的影响。DNA提取分细胞裂解和DNA纯化2步,对细胞裂解比较了珠磨匀浆法、反复冻融法、十二烷基磺酸钠(sodium dodecyl sulfate,SDS)裂解法等7种方法;对DNA纯化比较了酚/氯仿纯化法和胶回收纯化法。结果表明,SDS裂解法、酚氯仿纯化法最优。通过条件优化实验,确定SDS裂解酚/氯仿纯化法在污泥量1.1 g,10 000 r/min离心5 min的操作条件下,获得的DNA产量(10 774 μg/g泥重)和纯度(OD260∶OD280=1.84)等综合指标最好。 相似文献
944.
Yaohong Zhang Weixin Ding Zucong Cai Phillips Valerie Fengxiang Han 《Atmospheric environment (Oxford, England : 1994)》2010,44(36):4588-4594
Spartina alterniflora exhibits great invading potential in the coastal marsh ecosystems. Also, nitrogen (N) deposition shows an apparent increase in the east of China. To evaluate CH4 emissions in the coastal marsh as affected by the invasion of S. alterniflora and N deposition, we measured CH4 emission from brackish marsh mesocosms vegetated with S. alterniflora and a native plant, Suaeda salsa, and fertilized with exogenous N at the rates of 0 and 2.7 g N m?2, respectively. Dissolved porewater CH4 concentration and redox potentials in soils as well as aboveground biomass and stem density of plants were also monitored. The averaged rate of CH4 emission during the growing season in the S. alterniflora and S. salsa mesocosms without N application was 0.88 and 0.54 mg CH4 m?2 h?1, respectively, suggesting that S. alterniflora plants significantly increased CH4 emission mainly because of higher plant biomass rather than stem density compared to S. salsa, which delivered more substrates to the soil for methanogenesis. Exogenous N input dramatically stimulated CH4 emission by 71.7% in the S. alterniflora mesocosm. This increase was attributable to enhancement in biomass and particularly stem density of S. alterniflora driven by N application, which transported greater photosynthesis products than oxygen into soils for CH4 production and provided more pathways for CH4 emission. In contrast, there was no significant effect of N fertilization on CH4 emission in the S. salsa mesocosm. Although N fertilization significantly stimulated CH4 production by increasing S. salsa biomass, no significant increase in stem density was observed. This fact, along with the low gas transport capacity of S. salsa, failed to efficiently transport CH4 from wetlands into the atmosphere. Thus we argue that the stimulatory or inhibitory effect of N fertilization on CH4 emission from wetlands might depend on the gas transport capacity of plants and their relative contribution to substrates for CH4 production and oxygen for CH4 oxidation in soil. 相似文献
945.
Weixin Ding Yaohong Zhang Zucong Cai 《Atmospheric environment (Oxford, England : 1994)》2010,44(32):3894-3900
To understand the effect of water level on CH4 emissions from an invasive Spartina alterniflora coastal brackish marsh, we measured CH4 emissions from intermittently and permanently (5 cm water depth) inundated mesocosms with or without N fertilizer added at a rate of 2.7 g N m?2. Dissolved CH4 concentrations in porewater and vertically-profiled sediment redox potential were measured, as were aboveground biomass and stem density of S. alterniflora. Mean CH4 fluxes during the growing season in permanently inundated mesocosms without and with N fertilizer were 1.03 and 1.73 mg CH4 m?2 h?1, respectively, which were significantly higher than in the intermittently inundated mesocosms. This response indicates that prolonged submergence of sediment, up to a water depth of 5 cm, stimulated CH4 release. Inundation did not greatly affect aboveground biomass and stem density, but did significantly reduce redox potential in sediment, which in turn stimulated CH4 production and increased the CH4 concentration of porewater, resulting in higher CH4 emission in the mesocosm. Our data showed that the stimulatory effect of shallow, permanent inundation on CH4 emission in S. alterniflora marsh sediment was due primarily to an improved methanogenic environment rather than an increase in plant-derived substrates and/or the number of gas emission pathways through the plant’s aerenchymal system. 相似文献
946.
高价铬及双酚A在铁-乳酸体系中的同时光处理 总被引:1,自引:0,他引:1
研究了Fe(Ⅲ)-乳酸配合物体系同时对Cr(Ⅵ)的光还原及双酚A(BPA)的光氧化处理,考察了光源、初始pH值、Fe(Ⅲ)、乳酸盐、Cr(Ⅵ)及BPA初始浓度等因素对Cr(Ⅵ)及BPA光处理效率的影响。结果表明:光照条件下,铁-乳酸配合物能有效实现对六价铬及BPA的同时光处理。同一体系中,Cr(Ⅵ)的光还原快于BPA的光氧化,Fe(Ⅲ)初始浓度的增加可同时提高Cr(Ⅵ)的光还原效率和BPA的光氧化效率;Fe(Ⅲ)-乳酸盐配合物光解产生的Fe(Ⅱ)是Cr(Ⅵ)的主要还原剂,其次级光反应中产生的.OH是BPA的氧化剂。 相似文献
947.
微波强化氧化处理垃圾渗滤液工艺研究 总被引:3,自引:1,他引:2
考察了最优作用方式下单独微波、单独氧化剂以及两者的结合工艺对垃圾渗滤液的处理效果。单独微波工艺在功率为700 W,辐射10 min,COD、氨氮、磷和色度去除率分别为37.66%、96.14%、40%和80%,BOD5/COD由0.16增加到0.43。渗滤液先微波再氧化,氨氮去除率增加显著,节省了氧化剂用量。微波后渗滤液在pH=5,T=50℃,NaClO=24 mL/L时COD、氨氮、磷和色度去除率分别为98.63%、99.67%、97.25%和98%,BOD5/COD=0.8。总处理效率:微波-NaClO微波-Fenton微波-KMnO4微波-H2O2,微波-Fenton处理效率低于微波-NaClO主要取决微波后滤液中小表观分子质量增加导致氧化剂的混凝作用减弱,其次受反应后pH值变化的影响。 相似文献
948.
949.
950.
A High‐Resolution National‐Scale Hydrologic Forecast System from a Global Ensemble Land Surface Model
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Alan D. Snow Scott D. Christensen Nathan R. Swain E. James Nelson Daniel P. Ames Norman L. Jones Deng Ding Nawajish S. Noman Cédric H. David Florian Pappenberger Ervin Zsoter 《Journal of the American Water Resources Association》2016,52(4):950-964
Warning systems with the ability to predict floods several days in advance have the potential to benefit tens of millions of people. Accordingly, large‐scale streamflow prediction systems such as the Advanced Hydrologic Prediction Service or the Global Flood Awareness System are limited to coarse resolutions. This article presents a method for routing global runoff ensemble forecasts and global historical runoff generated by the European Centre for Medium‐Range Weather Forecasts model using the Routing Application for Parallel computatIon of Discharge to produce high spatial resolution 15‐day stream forecasts, approximate recurrence intervals, and warning points at locations where streamflow is predicted to exceed the recurrence interval thresholds. The processing method involves distributing the computations using computer clusters to facilitate processing of large watersheds with high‐density stream networks. In addition, the Streamflow Prediction Tool web application was developed for visualizing analyzed results at both the regional level and at the reach level of high‐density stream networks. The application formed part of the base hydrologic forecasting service available to the National Flood Interoperability Experiment and can potentially transform the nation's forecast ability by incorporating ensemble predictions at the nearly 2.7 million reaches of the National Hydrography Plus Version 2 Dataset into the national forecasting system. 相似文献