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131.
The identities and concentrations of low-molecular-weight organic acids (LMWOAs) were determined by ion chromatography throughout a 20-m water column in Hongfeng Lake, China. The spatiotemporal variations of LMWOAs and their contributions to dissolved organic matter (DOM) in a research period of 24 hr were also investigated. The results demonstrated that five LMWOAs (lactic, acetic, pyruvic, sorbic, oxalic acid) were detected, and their total concentration and proportion in DOC were 6.55 μmol/L and 7.47%. Their average levels were 2.50, 0.65, 2.35, 0.96 and 0.09 μmol/L, respectively. LMWOAs were higher during daytime (10:00-18:00 on Jun 13, 2008) than nighttime (21:00-6:00 the next morning), in particular 4.99 μmol/L high in the epilimnion ( 1 m water depth), reflecting the fact that direct import from terrigenous sources and photochemical production from humic materials were dominant during LMWOAs’ origin and accumulation. The same factors caused LMWOAs to be 0.63 μmol/L in the epilimnion higher than in the hypolimnion. The rapid decrease of total organic acid (TOA) up until 18:00 mainly resulted from bio-uptake and mineralization in the hypolimnion (>1 m water depth). Pyruvic acid increased with time in the epilimnion and decreased in the hypolimnion, largely related to the two contrary processes of continuous degradation and synthesis of macromolecular organic matter during life materials’ cycle mediated by organisms. Simultaneously, plankton behavior and thermal stratification played a pivotal role in LMWOAs’ behavior in the water column, causing decreasing and increasing profiles. The distribution of LMWOAs represents an interesting resource for biogeochemical research of DOM in aquatic ecosystems. 相似文献
132.
废弃SCR脱硝催化剂的再生及其脱硝性能研究 总被引:1,自引:1,他引:0
对废弃脱硝催化剂处理后重新加工再生,研究了添加剂对其粉体成型和再生催化剂脱硝活性的影响,探讨了反应温度、空速、n(NH3)∶n(NO)摩尔比、氧含量、H2O和SO2对再生催化剂NH3选择性催化还原(SCR)NO的影响。结果表明:最佳再生条件是使用5%羧甲基纤维素和10%无机粘结剂辅助成型;废弃催化剂再生利用率高达90%;再生催化剂抗压强度为4.73 MPa,优于商用催化剂;空速5 000 h-1、氨氮摩尔比1、氧含量6%时,脱硝活性温度窗口为310450℃,350℃时活性最高为94%;350℃时,单独通入1 000×10-6SO2或10%H2O对再生催化剂活性均有一定抑制作用,最低活性分别为70%和81%,停止通入SO2或H2O后其活性逐渐恢复;同时通入1 000×10-6SO2和10%H2O,再生催化剂活性下降至63%并于1 h内保持相对稳定,停止通入SO2和H2O 2 h后,活性逐渐恢复到73%。 相似文献
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描述了安徽省地震局"十一五"期间安装的5套钻孔体应变仪的地质构造特点与钻孔岩芯物理特性,介绍了TJ-Ⅱ体应变仪的运行情况。通过对两次强震活动的同震效应分析,初步探讨了地理、地质构造条件不同的情况下,各观测井对记录应力活动能力强弱的反映。 相似文献
138.
镍掺杂二氧化钛光催化剂的制备与光催化性能研究 总被引:1,自引:0,他引:1
利用溶胶-凝胶法制备了镍掺杂的二氧化钛,采用紫外可见分光光度计、傅里叶红外分光光度计、X衍射仪(XRD)、扫描电镜(SEM)等测试手段对结果进行了表征。表征结果表明在550℃下煅烧的产物主要是锐钛型二氧化钛,镍的掺杂使得二氧化钛的紫外可见反射光谱明显红移,且镍掺杂二氧化钛的粒度减小,团聚程度下降。以活性艳蓝KN-R为模型降解目标物,通过比较镍掺杂二氧化钛、纯二氧化钛以及标准P25二氧化钛的光催化性能发现镍掺杂二氧化钛的光催化活性最好。当钛酸正丁酯/乙醇比为1:25;钛酸正丁酯/冰乙酸比为1:1;钛酸正丁酯/硝酸镍比为1 000:3;煅烧温度为550℃,煅烧时间为2 h时,镍掺杂二氧化钛的光催化效率最高,达到73.3%。 相似文献
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Aerobic degradation of methyl tert-butyl ether by a Proteobacteria strain in a closed culture system 总被引:4,自引:0,他引:4
The contamination of methyl ten-butyl ether (MTBE) in underground waters has become a widely concerned problem all over the world. In this study, a novel dosed culture system with oxygen supplied by H2O2 was introduced for MTBE aerobic biodegradation. After 7 d, almost all MTBE was degraded by a pure culture, a member of β-Proteobacteria named as PMI, in a closed system with oxygen supply, while only 40% MTBE was degraded in one without oxygen supply. Dissolved oxygen (DO) levels of the broth in closed systems respectively with and without H2O2 were about 5-6 and 4 mg/L. Higher DO may improve the activity of monooxygemase, which is the key enzyme of metabolic pathway from MTBE to tert-butyl alcohol and finally to CO2, and may result in the increase of the degrading activity of PM1 cell. The purge and trap GC-MS result of the broth in closed systems showed that tea-butyl alcohol, isopronol and acetone were the main intermediate products. 相似文献