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191.
Morrill PL Lacrampe-Couloume G Slater GF Sleep BE Edwards EA McMaster ML Major DW Sherwood Lollar B 《Journal of contaminant hydrology》2005,76(3-4):279-293
Stable isotope analysis of chlorinated ethene contaminants was carried out during a bioaugmentation pilot test at Kelly Air Force Base (AFB) in San Antonio Texas. In this pilot test, cis-1,2-dichloroethene (cDCE) was the primary volatile organic compound. A mixed microbial enrichment culture, KB-1, shown in laboratory experiments to reduce chlorinated ethenes to non-toxic ethene, was added to the pilot test area. Following bioaugmentation with KB-1, perchloroethene (PCE), trichloroethene (TCE) and cDCE concentrations declined, while vinyl chloride (VC) concentrations increased and subsequently decreased as ethene became the dominant transformation product. Shifts in carbon isotopic values up to 2.7 per thousand, 6.4 per thousand, 10.9 per thousand and 10.6 per thousand were observed for PCE, TCE, cDCE and VC, respectively, after bioaugmentation, consistent with the effects of biodegradation. While a rising trend of VC concentrations and the first appearance of ethene were indicative of biodegradation by 72 days post-bioaugmentation, the most compelling evidence of biodegradation was the substantial carbon isotope enrichment (2.0 per thousand to 5.0 per thousand) in ?13C(cDCE). Fractionation factors obtained in previous laboratory studies were used with isotope field measurements to estimate first-order cDCE degradation rate constants of 0.12 h(-1) and 0.17 h(-1) at 115 days post-bioaugmentation. These isotope-derived rate constants were clearly lower than, but within a factor of 2-4 of the previously published rate constant calculated in a parallel study at Kelly AFB using chlorinated ethene concentrations. Stable carbon isotopes can provide not only a sensitive means for early identification of the effects of biodegradation, but an additional means to quantify the rates of biodegradation in the field. 相似文献
192.
In the United States, the newly promulgateddisinfectant/disinfection by-product (D/DBP) regulationsforce water treatment utilities to be more concerned withfinished and distributed water qualities. In this study,monitoring of DBP formation was conducted from three Frenchwater treatment plants trying to assess DBP variationsthrough time and space. Compared to the in-plant totaltrihalomethanes (TTHM) levels, TTHM levels in thedistribution system increased from less than 150% to morethan 300%. Significant variations for TTHM and bromate(BrO3
-) levels throughout the seasons were alsoobserved; generally higher levels in the summer and lowerlevels in the winter. Combining chemical DBP models(empirical power functional models) and hydraulicsimulations, DBPs including TTHM and BrO3
- weresuccessfully simulated from the full-scale monitoring data,indicating that empirical DBP model can be a potential toolto access DBP formation in actual plants. This study alsoprovides the protocols to assess DBP simulations in thewater treatment systems. 相似文献
193.
Environmental impact of two successive chemical treatments in a small shallow eutrophied lake: Part II. Case of copper sulfate 总被引:3,自引:0,他引:3
Van Hullebusch E Deluchat V Chazal PM Baudu M 《Environmental pollution (Barking, Essex : 1987)》2002,120(3):22-634
The appearance of cyanobacteria ( > 10 colony per ml) was not prevented after alum treatment. In order to prevent cyanobacteria efflorescences in a small shallow polymictic lake (Courtille, France), copper sulfate was applied. Treatment level was 63 microg 1(-1) as Cu2+ from CUSO4, 5 H2O. Cyanobacteria were kept under control during the summer. Microcystis sp. completely disappeared, which allowed swimming in the lake throughout the tourist season. Microcystis only reappeared 2 months after the treatment. Copper content in the water column only returned to its background level 2 months after copper addition. This high residence time of copper in the water might have been caused by complexation and adsorption of copper on natural organic matter, whose level was high in the ecosystem studied. A mechanism of transfer of 'truly' dissolved copper towards particulate copper has been underlined and explains the disappearance of this fraction of copper in the water column. 相似文献
194.
195.
以中国南方著名的滇中和会理盆地砂页岩铜矿床宏观地质特征和硫同位素分析数据为基础,系统地研究了我国南方砂页岩铜矿床硫同位素组成特征。首次用筛分模式、分馏效应对硫同位素总体进行评分,结果表明硫主要有三个来源:有机质分解或还原流酸盐,占11.3%;地下水,占42.5%;热卤水,占46.2%。本研究为该类型矿床的成因、成矿地球化学环境及指导区域找矿勘探等提供了重要依据。 相似文献
196.
研究了重金属Co、Ni、Fe、Mn在长江口及邻近海域悬浮颗粒中的含量、存在形态以及它们在河水与海水混合过程中迁移转化特征,其变化动态特征表明,Co、Ni、Fe以残渣态为主要存在形式;由于Fe-Mn氧化物的形成和吸附作用,使上述金属从水体经过悬浮颗粒转到沉积物中;以Fe-Mn氧化物和碳酸盐形态存在的重金属含量受水体环境的pH和盐度制约。用多元回归分析求得不同形态重金属含量与盐度、pH值和悬浮物含量的变化方程,以及与环境要素间的相互关系。 相似文献
197.
利用泡沫分离技术,对胶团强化超滤(MEUF)工艺处理含SDS和Cd2 所得渗透液中SDS的回收进行了研究,考察了影响表面活性剂SDS(十二烷基硫酸钠)和金属Cd2 去除率,富集率及夹带率的操作参数(空气流速、泡沫高度、液面高度),溶液体系性质(表面活性剂SDS进料浓度、pH值、离子强度和乙醇的添加量)等因素对分离效果的影响.实验结果表明,当胶团强化超滤废水中初始SDS和Cd2 的浓度为1440 mg·L-1和50 mg·L-1时,排出的渗透液中含SDS和Cd2 浓度分别为500 mg·L-1和10 mg·L-1,在最佳的工艺条件下(曝气头孔径为10μm,空气流速为100L·h-1,液体流速为5L·h-1,泡沫高度为66cm,液面高度为45cm),SDS和Cd2 的去除率分别达52%和99.35%,SDS富集比为3.1.Cd2 出水浓度低于0.1 mg·L-1,达到GB8978-1996国家污水排放标准. 相似文献
198.
Sequential fractionation of reactive phosphorus in the sediment of a shallow eutrophic lake——Donghu Lake, China 总被引:4,自引:0,他引:4
IntroductionSedimentphosphorushasbeenthefocusofanumberofstudiesduetoitsroleintheeutrophicationoflakes.Phosphorusfractionsinse?.. 相似文献
199.
从具强烈成分分带的娘娘山碱性火山杂岩中分选出7个全岩。2个基质和8个单矿物,测定了REE含量,验证了矿物学和化学成分研究的结论,即岩浆房内主岩浆体顶部存在一个演化程度较高的粗面——响岩质岩浆层。LREE和HREE与其它不相容元素(如Rb、Zr等)在此岩浆层中强烈富集,而Eu则与Sr、Ba、Sc以及相容元素一样强烈亏损,MREE也显示中等程度的亏损。表明分离结晶是该成分梯度产生的主要原因。 相似文献
200.
Phosphorus (P) is one of the main limiting plant nutrients in most tropical soils. Acquiring quantitative information on soil P status is essential for evaluating its sustainable management in agroecosystems. The objective of this study was to evaluate how land-use shifts from semi-permanent food crop systems (CF) to plantations of tea (Camellia sinensis) (TP) and Eucalyptus grandis (EP) impact on both organic and inorganic P species. Determination of phosphorus status combined a P sequential fractionation procedure and 31P nuclear magnetic resonance (NMR) spectroscopy. Sequentially extracted pools included available P by 0.5 M NaHCO3, Al/Fe-P by 0.1 M NaOH, Ca-P by 0.5 M HCl and residual P by 0.5 M H2SO4 after ignition at 550 °C. Soil total P (STP) varied significantly across land uses (P<0.05) with the lowest mean value (1025.6±23.1 mg kg−1) occurring under CF and the highest (1698.0±86.1 mg kg−1) under TP. The largest P-pools were NaOH-P (47–51% of total soil P) and H2SO4-P (25–32%). NaHCO3-Pi under fertilized land uses (CF and TP) was greater than 12 mg kg−1 indicating that these systems were sustainable. Unfertilized EP was P-deficient, probably as the result of organic-matter accretion and subsequent P immobilization in organic forms. 31P NMR revealed that 88–89% of P compounds in NaOH extract were organic with monoester-P accounting for 59.1–60.8%. This was followed by diester-P (9.8–12.4%), teochoic acid (8.4–10.1%), orthophosphate (8.8–9.7%), unknown compounds (7.4–8.4%), pyrophosphate (1.1–4.6%) and phosphonate (0–1.3%). EP had higher diester-P and no phosphonate compound whereas CF had substantial amount of pyrophosphate (4.6%) and less orthophosphate and teochoic acid. These results indicate that these last P compounds are easily mineralizable P forms participating actively in plant P nutrition. 相似文献