Hydroxy acids in Antarctic lake sediments and their geochemical significance

Hydroxy acids in sediments of Lakes Bonney, Fryxell, Joyce and Vanda, and unnamed ponds (B2, NF1, NF2 and L4) as well as in cyanobacterial mats from the McMurdo Sound region of southern Victoria Land in Antarctica have been studied to clarify their features and elucidate their source organisms. Normal and branched (iso and anteiso) 2-hydroxy acids were found in all the samples studied with the predominance of even- and odd-carbon numbers, respectively. The most dominant 2-hydroxy acids in the sediments were mainly short-chain components (<C₂₀). Normal and branched 3-hydroxy acids were detectewith the predominance of even- and odd-carbon numbers, respectively, in total concentrations between 0.48 and 53 μg/g of dry sediment. (ω-1)-Hydroxy acids were all long-chains (C₂₂, C₂₄, C₂₆, C₂₈ and C₃₀). 9,10-Dihydroxyhexadecanoic and/or 9,10-dihydroxyoctadecanoic acids were identified in all the sediments and a cyanobacterial mat. The composition of hydroxy acids differ considerably among the lakes and ponds, suggesting the difference of source organisms. These 2-, 3- and (ω-1)-hydroxy, and 9,10-dihydroxy acids may be derived from cyanobacteria and microalgae, in addition to non-photosynthetic microorganisms. Cyanobacteria and microalgae which are widely distributed in the world, may be important sources of hydroxy acids in the natural environments.     

饲用鱼油脂肪酸营养成分分析

本文应用气相色谱对鱼油的脂肪酸组成进行分析,结果表明:①鱼油中主要脂肪酸含量SFA为C16∶0和C14∶0,MUFA为C16∶1和C18∶1,PUFA为EPA和DHA.②由于产地及加工工艺等原因,鱼油脂肪酸成分含量有较大的差异,但总体上EPA和DHA含量较高,在15.6%~28.3%之间,而C18∶2和C18∶3含量较低,只有0.4%~3.1%.③饲用鱼油的配制应针对不同鱼用饲料中必需脂肪酸的组成进行适当调制,以期达到理想的养殖效果.     

Distribution and seasonal variation of concentrations of particulate carbohydrates and uronic acids in the northern Indian Ocean

Suspended particulate matter (SPM) samples were collected from the surface seawaters at 31 stations, and from various depths (2 to 1000 m) at 9 locations in the northern Indian Ocean during various seasons. SPM samples were analyzed for total particulate carbohydrate (TPCHO), total particulate uronic acid (TPURA) and total particulate neutral carbohydrate (TPNCHO) concentrations and composition. Strong spatial, temporal and depth related variations were evident in the distribution of these compounds. In surface waters, concentrations of TPCHO, TPNCHO, and TPURA varied from 0.57 to 3.58 μM C, 0.11 to 2.34 μM C, and from 0.01 to 0.31 μM C, respectively, and accounted for 2.6 to 34.6%, 2 to 24.5%, and 0.2 to 6.3% of POC, respectively, whereas the TPURA accounted for 4.7 to 22.7% of TPCHO. Concentrations and yields of both TPNCHO and TPURA decreased rapidly in the upper 100 m of the water column suggesting their utilization by heterotrophic organisms. Glucose was the most abundant constituent of the TPNCHO. Glucose mole fraction decreased while that of other monosaccharides, especially galactose, arabinose, mannose, rhamnose and fucose increased in the upper 100 m water. Below this depth, mole fraction of glucose increased while that of other sugars decreased with the increasing water depth. Generally, high C:N ratios were associated with low yields of carbohydrates and uronic acids. Inverse correlation between the mole fractions of arabinose plus xylose and rhamnose plus fucose indicates the importance of biogenic and terrestrial organic matter input to the Bay of Bengal. TPURA are surface-active in nature and thus may play an important role in coagulation of particles and macromolecules. The observed spatial and seasonal variations of these compounds may be due to differences in phytoplankton biomass, nutrient status, and the influence of terrestrial material.     

中华绒螯蟹(Eriocheir sinensis)成熟蟹、抱卵蟹、流产蟹肝胰腺脂肪酸组成的比较研究

采用气相色谱仪测定中华绒螯蟹(Eriocheir sinensis)不同生理阶段(成熟、抱卵、流产)肝胰腺内的脂肪酸组成。结果表明，中华绒螯蟹肝胰腺中含有22种脂肪酸，其中饱和脂肪酸(SFA)5种，单烯酸(MUFA)5种，多烯酸(PUFA)12种；MUFA的含量最高，占52．47％—58．56％。SFA次之，为23．17％—29．20％，PUFA的含量较低，为8．92％—21．11％。SFA、MUFA、PUFA的含量和cn-3／cn-6值在不同生理阶段的中华绒螯蟹肝胰腺中差异极显著，油酸(c18：1)、棕榈酸(C16：0)、棕榈油酸(C16：1)是肝胰腺中的主要脂肪酸，其含量分别为35．2l％—40．49％、17．97％—21．97％和11．69％—14．90％，不同生理阶段的中华绒螯蟹肝胰腺中各脂肪酸的百分含量差异显著。比较研究温州本地抱卵蟹和太湖抱卵蟹肝胰腺中的脂肪酸，发现脂肪酸中SFA、MUFA、PUFA的含量和Cn-3／Cn-6值差异极显著，除C14：1、C18：1、C20：1及C20：5外，其它脂肪酸的百分含量存在极显著的差异。     

基于脂肪酸组成的海洋微藻化学计量学分类研究

运用平方欧氏距离为相似性测度、方差平方和为类间距，对海洋微藻进行基于脂肪酸组成的数值分类研究。20种微藻聚类分析的结果是将其分为4类：类I由6种金藻(a10-a15)组成；类Ⅱ由2种绿藻(a1，a3)、1种金藻(a16)和所有3种甲藻(a17—a19)组成；类Ⅲ由1种绿藻(a2)、1种红藻(a20)组成；类Ⅳ由2种绿藻(a4，a5)和全部4种硅藻(a6-a9)组成。这种化学计量学数值分类方法，不同于传统分类学、化学分类学方法，可帮助量化评价各种微藻的营养价值。     

压力对未熟烃源岩低温催化脂肪酸酯水解的影响

选择十八烷酸甲酯为模型化合物,以 7种抽提有机质的未熟烃源岩为载体考察了压力对未熟烃源岩矿物催化脂肪酸酯水解反应的影响。结果表明,在未熟烃源岩低温催化脂肪酸酯的水解反应中,压力是重要的影响因素,压力效应不可忽视。7种未熟烃源岩产生了不同的压力效应,并因此引起了水解率的升高或降低。文中对压力效应产生的原因进行了探讨,认为观测到的压力效应是压力对反应促进和抑制作用共同作用的结果。     

铀有机地球化学研究进展

与铀矿有密切关系的有机质主要是腐殖酸(HAs)、富里酸(FAs)、微生物及细菌.腐殖酸与铀酰存在着强烈的吸附、络合及还原作用关系.微生物和细菌在铀矿形成过程中也起到很微妙的作用.在研究手段上包括试验、计算、热解分析、X射线分析、裂变径迹分析、电子探针、红外光谱、紫外光谱、荧光光谱、顺磁共振、色谱质谱联用等方法.     

水体溶解态黑碳的分子标志物苯多羧酸的气相色谱-质谱分析

苯多羧酸分子标志物法是定量水体中溶解态黑碳的常用方法,然而由于部分苯多羧酸,尤其是硝基苯多羧酸商业化标准品的缺失,采用该方法定量溶解态黑碳仍需进一步完善和优化。本文通过已有的苯多羧酸商业化标准品,建立了气相色谱-质谱联用仪(GC-MS)分离和定量 9 种缺少商业化标准品苯多羧酸的分析方法。并首次将菲-D10 作为溶解态黑碳的替代物,指示苯多羧酸法定量溶解态黑碳过程中的损失率。结果表明,该方法具有良好的重现性(RSD=10.34%),方法检出限为 0.67~5.38 ng/L。本文采用该方法分析了大亚湾表层水体溶解态黑碳的分布特征,其浓度范围为 30.38~46.19 μg/L,平均值为(38.93±6.17)μg/L,空间分布表现为从湾内到外海递减的趋势。     

流沙区不同立地条件下防护林土壤微生物多样性分析

土壤微生物在极端干旱区土壤发育过程中至关重要。结合传统培养、PLFA和PCR-DGGE 3种方法,研究了塔里木沙漠公路防护林不同立地条件下土壤微生物数量、脂肪酸种类和DNA片段多样性。结果表明,不同立地条件下土壤微生物数量明显不同,脂肪酸种类和DNA片段多样性指数亦有显著差异 （F84%）,放线菌次之,真菌很少（<0.05%）;0～35 cm采样范围内,土壤微生物多样性垂直差异不明显;相关分析表明,土壤微生物多样性指数高时林木生长也较好。说明塔里木沙漠公路防护林建设后土壤生物活性明显增强,但在防护林生态工程的营造、恢复与重建实践中需考虑地形地貌因素,以充分发挥防护林防风固沙效益,有效促进流沙地土壤的发育。     

盐度变化对杜氏盐藻的游离氨基酸和脂肪酸含量的影响

研究了盐度对杜氏盐藻(Dunaliella salina)的生理生化效应。结果表明该藻适于生活在盐度为6-7倍海水的试验水中(海水盐度为33．5)。在此盐度中其光合速率、细胞增长速率、光合色素增长速率,游离氨基酸总量及多聚不饱和脂肪酸总量均高于生活在其它盐度的藻。