地质微生物响应地质环境变化的若干问题--兼论环境代用指标的应用

微生物能够通过改变细胞膜脂类成分而灵敏地响应地质环境条件的变化,使得人们建立了一系列微生物的古环境代用指标。应用比较广泛的古温度定量化指标包括藻类的长链烯酮U_(37)~k、古菌甘油二烷基甘油四醚的TEX_(86),以及细菌甘油二烷基甘油四醚的MBT/CBT等。然而,由于缺乏生理学和生态学分析,人们在应用微生物的环境代用指标时不断发现适用性问题。论文重点从微生物对环境响应的化学过程、生理范围和生态效应这三方面分析了一些环境代用指标在应用时需要考虑的多指标相互验证、线性范围和灵敏度,以及地区性差异等问题。微生物通过脂类响应环境变化有多种化学方式和途径可以实现,使得许多代用指标可以相互验证。微生物对地质环境的生理响应是有线性范围的,这决定了微生物脂类的环境代用指标的灵敏度大小。而微生物对环境因子的生态响应则决定了代用指标的应用存在地区性差异。某种环境的微生物活动往往受到一些限制性因子控制,相应地一些微生物脂类的环境代用指标也主要响应这些限制性环境因子的变化。微生物的古环境代用指标的应用不仅需要了解微生物通过脂类响应环境变化的化学机理,更要了解相应微生物的生理学和生态学原理。     

Seasonal and spatial variation in lipid and triacylglycerol levels in juvenile chinook salmon (Oncorhynchus tshawytscha) from the Bridge River, British Columbia

Triacylglycerols (TAGs) are the primary form of energy storage in fish, but little work has been done on the dynamics of TAG storage and use in relation to environmental conditions. We sampled age-0 chinook salmon (Oncorhynchus tshawytscha) in two reaches of a regulated river in British Columbia, Canada that had different discharge regimes. During the summer, fish from the reach with high freshet flows grew more slowly and had lower TAG levels than those from the reach with lower and more stable flows. In addition, smaller individuals had lower TAG levels than larger ones. We suggest that in the reach with higher flows fish were unable to obtain sufficient surplus energy for somatic growth and lipid storage. In the fall, when flows were lower, TAG storage increased and the proportion of total lipids that were TAGs were similar for both small and large fish. The allocation of energy to TAG stores was likely a strategy to ensure individuals had sufficient energy for overwintering. Our results suggest that individual-based variation in TAG levels may be sensitive to environmental factors and can be used as a measure of fish condition and performance, but more work is needed to fully understand lipid dynamics in seasonally and spatially variable rearing environments.     

Effects of natural organic matter from sediments on the growth of marine gas hydrates

Sediments recovered from 0 to 27 + meters below the seafloor (mbsf) of a gas-hydrate and gas-venting active area in the Gulf of Mexico were added to a hydrate growth test cell to determine the influence of the organic and inorganic sedimentary components on hydrate induction times and formation rates. Induction times were sixteen times shorter in the presence of sediment from approximately 18 mbsf (relative to sediment from 1 mbsf), and remained stable in the presence of sediment from 18 to 27 mbsf. Formation rates increased by a factor of 2.5 in the presence of sediments from approximately 18 mbsf and decreased somewhat in the presence of sediment from 18 to 27 mbsf. Selected samples (surface, 18 and 27 mbsf) were density fractionated and subjected to bulk elemental and X-ray photoelectron spectroscopy (XPS) analysis. XPS revealed the presence of iron in various chemical environments at depths of 18 and 27 mbsf. High Resolution Magic Angle Spinning Nuclear Magnetic Resonance (HR-MAS NMR) was used to characterize the organic component of sediments from selected depths. The discovery of intact proteinaceous material in the surface sediment was surprising due to the labile nature of these biopolymers, and potentially reflects microbial activity in these surface layers. This material was less abundant in sediment from increasing depths, where more lipid-like compounds were prominent. The results suggest that hydrate growth is inhibited by the presence of proteinaceous material but enhanced by lipid-like compounds associated with iron-bearing mineral surfaces.     

Effect of Different Leachate/Acetate Ratios in a Submerged Anaerobic Membrane Bioreactor (SAnMBR)

Leachate treatment using a membrane bioreactor is an effective method. This study presents a configuration including an anaerobic bioreactor and a membrane module, called submerged anaerobic membrane bioreactor (SAnMBR), for treating influent with leachate/acetate rations (L/A), that were kept to be 10, 25, 50, 75, and 100% at a constant SRT (100 days). COD removal decreased from 85 to 75% when the L/A ratio increased from 10 to 100. To prevent membrane fouling, a SAnMBR was operated in the case of circulation of mixed liquor under continuous and intermittent suction. The average fluxes were 2.60 and 0.40 L/m² h at the periods of intermittent and continuous suction, respectively. The methane production varied between 0.25 and 0.32 L CH₄/g COD_removed.     

11种微藻脂类和EPA/DHA组成的研究

研究了11种微藻在可比较的条件下,其生物量、总脂含量和多不饱和脂肪酸(EPA/DHA)的组成.结果表明:卡德藻(Tetraselmissp.)的生物量最大,细胞干重可达0.140g/(L·d);南极冰藻(Berkeleyarutdans)次之,可达0.0748/(L·d).以叉鞭金藻(Dicrateriainornata)和球等鞭金藻(Isochrysisgalbana)的总酯含量最高,分别占细胞干重的13.1%和12.1%.在绿色巴夫藻(Pavlovaviridis)中,EPA和DHA分别占总脂肪酸(TFA)的25%和6%;小球藻(Chlorellasp.)的EPA含量为28%;南极冰藻的EPA含量为19%.     

仿生人工贻贝在筼筜湖海水石油烃污染监测上的应用

仿生人工贻贝（Ｓｅｍｉ－Ｐｅｒｍｅａｂｌｅ Ｍｅｍｂｒａｎｅ Ｄｅｖｉｃｅｓ）是近年来海洋污染监测中新技术,其制作简单,吊挂取样方便,在筼筜湖纳潮进水渠和排污出水口进行夏、冬应用实验,结果显示筼筜湖内石油烃污染仍然较严重,其每ｇ甘油三油酸酯中石油烃浓度夏季可达２．１～７．８ｍｇ。退潮排污出水口人工贻贝石油烃浓度为纳潮进水口的２倍,冬季人工贻贝石油烃浓度又为夏季的１．５倍。同时也说明仿生人工贻贝（ＳＰＭＤ）可克服天然贻贝因性别、生长期、健壮程度和海区条件引起的差异,应用前景良好。     

Performances of Reverse Osmosis Membranes for Treatment of Olive Mill Wastewater

In the following study, two methods were employed in which olive mill wastewaters were treated by using reverse osmosis membranes (BW30 and XLE). In the first, wastewater was centrifuged and then passed through the reverse osmosis whereas in the second, an ultrafiltration was placed between the centrifuge and the reverse osmosis. The reverse osmosis experiments were conducted under 10, 15, 20, and 25 bar. The chemical oxygen demand (COD) removal efficiencies under 25 bar were found to be 97.5% for both BW30 and XLE membranes. The highest conductivity removal rates obtained under 25 bar for BW30 and XLE membranes were found to be 95.6 and 96.2%, respectively. As for the highest permeation flux values obtained under 25 bar, they were separately determined for BW30 and XLE as 15.3 and 21.2 L m^?2 h^?1, respectively. The performances of the membranes were also evaluated in terms of their mass transfer coefficients. According to this, all mass transfer coefficients were found to be <1 and also in proximate to one another; this clearly reflects the results as COD and conductivity removals were approximate and there was a lack of any significant difference, whether ultrafiltration was applied or not.     

Fatty acids and sterols of particulate matter in a brackish and seasonally anoxic coastal salt pond

Particulate matter and interfacial sediment from a seasonally anoxic coastal salt pond were analyzed for fatty acids and sterols to examine variations in organic sources, and compositional changes across the oxic-anoxic interface in the water column and at the sediment-water interface. Fatty acid distributions in suspended particles varied seasonally and as a function of depth. Fatty acids of algal origin (e.g. 16:3, 16:4, 18:3, 18:4) were abundant in particles in oxic surface waters, but these labile components were depleted in particles from the anoxic zone which instead were enriched in bacterial fatty acids (e.g. 16:1Δ⁹, 18:1Δ¹¹, anteiso-C₁₅). Sterol distributionsvaried less than fatty acid distributions and particles throughout the water column reflected an upper water algal source with little in situ alteration. There was evidence for an in situ conversion of Δ⁵-stenols to 5(α)H-stanols in suspended particles in the anoxic zone. Sinking particles and the interfacial sediment were compositionally similar to each other, but different from suspended particles. These data reflect differences in particle source, transport and transformation processes occuring in the water column.     

塔里木沙漠公路防护林土壤水分特征曲线模型分析与比较

应用压力膜仪对塔里木沙漠公路防护林地0~150 cm范围的土层进行土壤水分特征曲线的脱水试验,并选取Gardner模型和VG模型对实测数据进行了拟合分析与比较。结果表明:(1)实测的土壤水分特征曲线可准确地反映土壤结构的差异性,各土层的曲线特征与其基本物理性质一一对应,即容重较小、粉粘粒含量较多的土层其持水性较强,饱和含水率和凋萎含水率也较高;物理性差异小的土层间,其土壤水力性质接近。(2)由VG模型得到的土壤饱和含水率均值为0.429 cm³· cm^-3,凋萎含水率均值为0.040 cm³· cm^-3。由Gardner模型得到的各土层由于各层的物理性状差异造成持水性由强到弱,依次为0~5 cm, 40~60 cm, 100~150 cm, 60~100 cm, 5~40 cm;土壤易效水与难效水的平均临界点水势值为1.5×10⁵ Pa,均值凋萎含水率对应的水势值为15.0×10⁵ Pa。以上结果均较符合砂质土地的实际情况。(3)两种模型均可用于拟合防护林沙质土的土壤水分特征曲线,但VG模型在低吸力段的拟合精度较高, Gardner模型在中吸力段的拟合精度稍高,整体上, VG模型的模拟效果优于Gardner模型。旨在揭示高矿化度咸水滴灌条件下塔里木沙漠公路防护林不同土层的土壤水分曲线特征及其最优拟合模型,为之后开展区域水盐运移数值模拟等研究提供理论依据。     

Distribution of glycerol ether lipids in halophilic,methanogenic and hyperthermophilic archaea

Four representatives of methanogenic Euryarchaeota (Methanosarcina mazei strain Gö1, Methanosphaera stadtmanae, Methanobrevibacter smithii and Methanosaeta thermophila), the hyperthermophilic euryarchaeon Thermococcus kodakarensis and the halophilic euryarchaeon Haloferax volcanii were studied for their glycerol ether lipid composition. The predominant core membrane lipid in all of them was archaeol, which was accompanied by variable quantities of sn-2-hydroxyarchaeol in the methanogens M. mazei (Methanosarcinales) and M. stadtmanae (Methanobacteriales). All methanogenic and hyperthermophilic Euryarchaeota also contained comparatively high abundances of the glycerol dialkyl glycerol tetraether without a cyclopentane moiety (GDGT-0). The methanoarchaeon M. stadtmanae, in addition to GDGT-0, contained GDGT core lipid structures with 1–4 cyclopentane moieties (GDGTs 1–4). We also found minor amounts of a glycerol trialkyl glycerol tetraether (GTGT) and a glycerol dialkanol diether (GDD), both of which did not contain cyclopentane moieties, as well as methylated and dimethylated GDGT-0 in all the archaea with the exception of H. volcanii. Like its GDGT distribution, M. stadtmanae showed an extended range of GDD structures with up to two cyclopentane ring systems. Our results thus indicate that both methanogenic and hyperthermophilic Euryarchaeota may represent source organisms of GTGT-0, GDDs and methylated-GDGTs in natural environments. All the latter components have recently been reported to be ubiquitously distributed in marine sediments but their biological origin is largely unknown. Moreover, a suite of unsaturated GDGTs without a cyclopentane moiety and up to four double bonds in the hyperthermophile T. kodakarensis was tentatively assigned.