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91.
Mingyi WANG Xiaobing LIANG Yaping ZHENG Youzhi ZHAO Zhongqing WEI 《中国地球化学学报》2006,25(B08):65-66
The purpose of the thesis is to analyze the temporal and dimensional distribution of sulfate-reducing bacteria (SRB) groups and quantity in Lake Erhai. In April and September 2005, two sediment cores were collected from Lake Erhai. SRB groups were analyzed by PCR with six-groups primers designed according to the specific 16SrDNA sequence. FISH (fluorescence in-situ hybridization) was established with the oligonucleotide probe (SRB385) and utilized to analyze SRB quantity in the sediments. The results showed that in the sediments of Lake Erhai four SRB groups were detected except Desulfobacterium and Desulfobacter, meanwhile Desulfovibrio-Desulfomicrobium were detected only in autumn; different SRB groups had different temporal and dimensional distribution, and each group in autumn is distributed more widely than in spring; FISH used to count SRB in the sediments of fresh lake was set up successfully; the analysis of correlation between the sediment's depth and SRB quantity had statistical meaning (P〈0.05) . The result showed that SRB quantity showed a decreasing trend with increasing depth. Through the analysis of randomized block designed analysis of variance, the difference in SRB quantity between spring and autumn also had statistical meaning (P〈0.001), which revealed SRB quantity in autumn was larger than in spring; the result of FISH showed that there were some SRB in the deeper sediments in which no above-mentioned six SRB groups were detected by PCR. SRB groups in the sediments of Lake Erhai were rich, and the quantities of SRB groups in autumn were larger than in spring; possibly there were uncultivable SRB groups in the sediments of Lake Erhai. 相似文献
92.
Lichun LIU Yuting CHEN Kuanyu CHEN Jyhyih LEU Tsungkwei LIU 《中国地球化学学报》2006,25(B08):67-67
High concentrations of arsenic and humic substances in groundwater from the southwestern coastal plain of Taiwan were well known for their probable relationships with black-foot disease. In order to realize the relationships between the concentrations of humic substances and arsenic in this area, 24 well water samples were analyzed. After filtered through 0.45 μm glass fiber membrane in the field, samples were kept in the dark at 4℃ and then separated into six fractions with varying range of molecular weight (〈0.5, 0.5-1, 1-5, 5-10, 10-50 and 〉50 k Da) by ultrafiltration apparatus (Molecular/Por Stirred Cell system) in the lab. Concentrations of humic substances were measured by fluorescence spectrometer (HITACHI F-2000, ex=370, em=445) and arsenic by FIAS-AA (Perkin Elmer AAnalyst 100, FIAS-400). On average, only 6.2% of the total arsenic in water existed in the fraction of 〉0.5 k Da. and the others were complexed with humic substances (including humic acid and fulvic acid). The results demonstrated a distinct positive correlation between the concentrations of humic substances and arsenic. 相似文献
93.
Zhengji YI Kaixuan TAN Zhenxun YU Aili TAN Shiqiang WANG 《中国地球化学学报》2006,25(B08):125-126
Uranium processing and mining activities that generate many contaminants, such as high concentrations of U (VI), sulfate and heavy metals (Zn, Cu, Ni, etc), may pose a serious threat to the groundwater resources. In recent years, considerable research has been conducted respectively on two kinds of permeable reactive barriers (PRB), including zerovalent iron (ZVI) and sulfate reducing bacteria (SRB), for in-situ removal of these pollutants from groundwater. However, little investigation has been carried out on the potential benefits of bioaugmenting ZVI barriers to enhance the elimination of the pollutants by combining ZVI with SRB systems. The main goal of this study was to conduct batch and column experiments to determine whether the combination of SRB and ZVI can function synergistically and accelerate the rate of pollutant removal. The results of anaerobic batch experiments demonstrated that although the integrated ZVI/PRB system itself has no ability to reduce and remove sulfate directly, SRB can utilize hydrogen gas produced during the slow process of ZVI corrosion as an electron donor to raise biomass yields significantly and accelerate reductive sulfate removal. In particular, ferrous cations produced as the byproduct of ZVI corrosion process reacted with hydrogen sulfide from sulfate reduction and formed iron-bearing sulfide precipitates, which can stimulate the growth of SRB and promote sulfate removal activity by eliminating the biotoxicity of hydrogen sulfide. It was also shown that secondary mineral products (pyrite/ferrous sulfide) formed as a consequence of microbial sulfate reduction and ZVI corrosion process can enhance the microbial precipitation of soluble U (VI) as insoluble uraninite(uranium dioxide). 相似文献
94.
Christina A. Kellogg 《中国地球化学学报》2006,25(B08):218-219
Desert winds aerosolize several billion tons of soil-derived dust each year, including concentrated seasonal pulses from Africa and Asia. Huge dust events create an atmospheric bridge over continents and oceans, and eject a large pulse of soil-associated microorganisms into the atmosphere. These dust events might therefore have a role in expanding the biogeographical range of some microorganisms by facilitating rare long-distance dispersal events. The goal of this study is to characterize the microbes associated with African dust events and determine if they pose a risk to humans or downwind ecosystems. Air samples were collected by vacuum filtration in a source region (Mali, West Africa) during dust events and plated on R2A media to culture microorganisms. These organisms were compared to those in similar samples collected in the Caribbean during Saharan/Sahelian dust events. A high-volume liquid impinger is currently being tested in Barbados, collecting aerosol samples during African dust events. Over 100 bacteria and fungi (19 genera of bacteria and three genera of fungi) have been characterized from source region dust events. 相似文献
95.
本文对影响南极细菌S-15-13生长和胞外多糖产量的主要环境因子进行了研究,同时采用16S rDNA序列分析及系统发育分析方法对其进行了分子鉴定。结果表明:菌株S-15-13最佳产糖条件为:培养时间,56h;培养温度,8℃;碳源,1.0%葡萄糖;NaCl浓度,3.0%;pH,6.0-7.0。16S rDNA序列分析和系统发育分析表明,菌株S-15-13属于假交替单胞菌属(Pseudoaltero- monas)。 相似文献
96.
许家窑泥河湾河-湖相沉积物磁化率(k)、天然剩磁(NRM)、饱和等温剩磁(SIRM4T)、非磁滞剩磁(ARM)及S比率(IRM-0.3T/IRM4T)等磁学参数与深海氧同位素的对比分析结果显示:1)许家窑泥河湾层从布容/松山界线到氧同位素阶段5(0.13MaB.P.)基本上是连续沉积,沉积速率保持在约2.45cm/103a左右;2)与同期形成的黄土高原黄土-古土壤序列类似,许家窑河-湖相层也很好地记录了当时中国北方的第四纪气候和环境特征,其典型特征为冰期时高矫顽力赤铁矿含量的显著增加,而间冰期则以低矫顽力的磁铁矿及磁赤铁矿为主要载磁矿物;3)由尝试建立的S比率时间标尺所确定的许家窑古人类遗址处的地层年代约0.5MaB.P.,与先前报道的化石的UTh绝对年龄(0.1MaB.P.)不一致;4)与k相比,S比率与SIRM更适合作为河-湖相沉积物的古气候替代性指标;5)以2.45cm/103a的沉积速率来推算,沉积物的主要物质来源为正常的河-湖相沉积,而直接接受的类似于黄土状的粉尘并不占主导地位 相似文献
97.
98.
硅酸盐细菌解钾作用机理的综合效应 总被引:44,自引:5,他引:44
硅酸盐细菌能释放土壤含钾硅酸盐矿物中的磷、钾、硅等元素,直接供给植物生长利用,同时亦具有固氮能力。这为挖掘土壤潜在肥力、发展可持续农业提供了一条新的思路。本文分析了硅酸盐细菌对钾长石、伊利石的解钾作用过程,细菌-矿物复合体的形成,细菌对矿物的溶蚀作用,矿物晶体结构与细菌的解钾作用关系,复合体微环境的变化对细菌解钾作用的影响以及细菌对K^ 的主动吸收等,从微生物矿物学的角度讨论了硅酸盐细菌对含钾硅酸盐矿物解钾作用的机理问题,提出了硅酸盐细菌解钾作用综合效应的看法,并就农业生产上的利用问题指出,应根据当地的土壤环境,选择适宜的生产菌种和吸附剂,并配合使用其它化学肥料和有机肥料。 相似文献
99.
100.