Thermal stability of soil organic carbon subjected to water erosion as a function of edaphic factors

The stability of soil organic carbon （SOC）,as it relates to resistance to decomposition,is important for greenhouse gas emission and climate change.However,the SOC stabilization and its related influencing factors subjected to water erosion remain uncertain.The objective of the current study was to determine the SOC stability under long-term water erosion and to investigate the link between SOC stability and edaphic factors.Soil samples from eroded,depositional,and control sites in a closed wate...     

A quantitative study of the degradation of whale bone lipids: Implications for the preservation of fatty acids in marine sediments

The degradation and preservation affecting the biomarker record of ancient metazoa are not fully understood. We report on a five month experiment on the fate of fatty acids (FAs) during the degradation of recent whale vertebrae (Phocoena phocoena). Whale bones were analysed for extractable FAs and macromolecularly bound n-acyl compounds. Fresh bone showed extractable FAs dominated by 16:1ω7c, 16:0, 18:1ω9c and 18:0. Calculated degradation rate constant (k) values showed a rapid decrease in FA concentration, with k values higher for unsaturated than for saturated compounds (0.08/day for 18:1ω9c, 0.05/day for 16:0). The appearance or increased abundance of distinctive methyl branched (e.g. i/ai-15:0 and -17:0, 10Me-16:0) and hydroxy FAs (e.g. 10OH-16:0 and 10OH-18:0) were observed, providing clear evidence for the microbial degradation of bone organic matter and an input of lipids from specialised bacteria. Catalytic hydropyrolysis (HyPy) of demineralised extraction residues released up to 0.13% of the total n-C₁₆ and n-C₁₈ moieties in the degraded bones. This revealed that only a small, yet sizeable, portion of bone-derived fatty acyl units was sequestered into (proto)kerogen during the earliest stages of degradation.     

基于反射地震记录变子波模型提高地震记录分辨率

本文给出了地震记录变子波模型的一种近似数学表达式．基于该表达式研究了反射系数序列不满足白噪假设和子波在地下传播时发生变化这两种情况下地震道谱的组成及结构,讨论了谱白化及反褶积方法在这两种情况下效果不佳的原因．然后基于变子波模型,提出了一种新的提高地震记录分辨率的方法：第一步,用自适应于地震记录的Gabor分子窗把地震记录恰当地划分成若干片断,每段内信号近似平稳,然后将地震记录变换到时间-频率域;第二步,在变换域对每个分子窗内信号的振幅谱进行处理以拓宽频带;最后把处理后的时间-频率域函数反变换回时间域得到提高分辨率后的结果．本文提出的方法具有能较好地适用于反射系数不满足白噪假设的情况及提高分辨率后的地震记录能较好地保持原地震记录的相对能量关系等优点,模型和实际资料算例结果均表明,本文方法在拓宽地震资料频带及保持地震记录局部能量相对关系方面均明显优于谱白化方法．     

用于单一藻细胞PCR扩增反应的样品保存方法比较

用室内培养的塔玛亚历山大藻(Alexandrium tamarense ATHK藻株)作为实验对象,分别选择了5%福尔马林固定后常温保存、95%乙醇固定后常温保存、-20℃冷冻保存、鲁哥氏液(Lugols solution)固定后常温保存等方法,在5,15,30,60 d后对保存的样品进行单细胞PCR反应,并与新鲜样品进行比较。实验结果表明,用95%乙醇保存、-20℃冷冻保存、鲁哥氏液保存的样品在60 d后仍可扩增出目标条带,与新鲜样品没有差别,但是样品中的藻细胞形态有一些改变;而以5%福尔马林固定保存的样品只能在5 d后扩增出目标条带,但藻细胞形态比较完好。因此,对用于单细胞PCR实验的微藻样品,短期内(不多于5 d)可以采用福尔马林保存,而需要长期保存的样品,应当采用乙醇或鲁哥氏液固定,或者采用-20℃冷冻保存的方法。     

软包装即食食品——鲻鱼皮加工工艺

研究了鲻鱼皮的加工工艺 ,筛选出鲻鱼皮加工成软包装即食食品的最佳工艺条件。结果表明 :鲻鱼皮的爽脆性主要与鲻鱼皮的烫煮和冰水浸泡工艺条件有关 ,最佳条件是先用 0 8g/L的保水剂浸泡3h,然后用低浓度的有效氯杀菌 ,再在 90℃中烫煮 60s,最后迅速放进无菌冰水中浸泡。研制出的产品为螺纹状 ,具有鱼皮特有的银灰色 ,爽脆且富有韧性 ,在 0～ 5℃下可保质 45d。     

Discussion on “sandwich” structures and preservation conditions of shale gas in the South Yellow Sea Basin

In order to make a breakthrough in Mesozoic-Paleozoic shale gas exploration in the South Yellow Sea Basin, a comparison of the preservation conditions was made within the Barnett shale gas reservoirs in the Fortworth Basin, the Jiaoshiba shale gas reservoirs in Sichuan Basin and potential shale gas reservoirs in Guizhou Province. The results show that the “Sandwich” structure is of great importance for shale gas accumulation. Therein to, the “Sandwich” structure is a kind of special reservoir-cap rock assemblage which consist of limestone or dolomite on the top, mudstone or shale layer in the middle and limestone or dolomite at the bottom. In consideration of the Mesozoic-Paleozoic in the Lower Yangtze, and Laoshan Uplift with weak Paleozoic deformation and thrust fault sealing on both flanks of the Laoshan Uplift, a conclusion can be drawn that the preservation conditions of shale gas probably developed “Sandwich” structures in the Lower Cambrian and Permian, which are key layers for the breakthrough of shale gas in the South Yellow Sea. Moreover, the preferred targets for shale gas drilling probably locate at both flanks of the Laoshan Uplift.     

湘中南大庙口地区构造变形特征及其对区域页岩气构造保存条件的启示

近几年来对湖南省页岩气地质条件进行了大量调查研究,但对页岩气的构造保存条件研究和评价很少,因而影响了区域页岩气勘查工作的科学部署。笔者在湘中南永州凹陷西北缘的水岭-大庙口地区开展了1∶50 000页岩气地质调查,对该地区构造特征和构造演化过程进行了研究,在此基础上探讨了页岩气保存和富集的构造条件。调查区构造变形强烈,主要构造类型有：上古生界盖层中发育的NNW-近SN向（主）褶皱和EW向（次）褶皱,下古生界中发育的NNE向和NE向膝折,切割上古生界和下古生界的NNW-SN向、NE向、NW向等3组断裂（主要为逆断裂、正断裂,少量为走滑断裂）,下古生界中极为发育的NNW向板劈理以及泥盆系跳马涧组中发育的SN向、NNE向破劈理等。结合区域构造背景,初步确定上述构造主要形成于早古生代以来的8期构造变形事件,其中以加里东运动、印支运动和早燕山运动的挤压事件以及白垩纪区域伸展事件等最为重要。奥陶系烟溪组和天马山组底部的黑色页岩为调查区页岩气勘探目标层,但钻孔岩心页岩气解吸实验表明含气性极差。分析认为,多期构造运动造成的抬升和剥蚀及形成的断裂、劈理,既导致页岩气的散逸,也使得目标层仅局部有保存;多期构造运动形成的复杂构造样式,使得上古生界之下目标层的空间展布特征难以探明;加里东运动和印支运动所诱发花岗质岩浆活动相关的高地热场区会显著增高有机质热演化程度,总体不利于页岩气的保存。调查区对页岩气富集和保存不利的构造条件基本适用于永州凹陷及周缘其它地区,因此认为永州凹陷及周缘页岩气成藏潜力非常有限。本研究成果对区域页岩气成藏条件的客观认识以及页岩气勘查工作的合理部署具有重要的启示意义。     

四川盆地天然气成藏条件及其勘探方向

四川盆地系在刚性结晶基底上由克拉通海相原型盆地同造山前陆盆地和后造山前陆盆地先后演化而成的克拉通前陆盆地。整体封存构造保存条件是该盆地天然气成藏的主体地质背景和晚期成藏保存的主要条件。加里东和印支两期的古隆起对油气的早期聚集和破坏具有双重作用,但有利于晚期成藏。盆地的保存条件可划分为整体封存、残留封存和缺乏封存三类构造保存单元,并由此可划分出三个相应的构造保存单元组合区。盆地的天然气成藏条件总体良好,影响因素主要是水动力条件和断层。该盆地有T_3,P_2~1,P_1~(1+2),S_1,∈_1和 Z_2六套主力烃源岩和 Z_2—∈_1,∈_1—S,S—P_1,p—T_2,T_3—J 五套成油气体系。今后深化勘探的方向为:(1)川东石炭系向斜带的低缓构造、潜伏构造、高陡背斜带两翼的高陡潜伏构造,特别是构造复合圈闭;(2)川东北—川北开江—梁平、城口—鄂西等海槽为中心的以陆棚边缘滩、碳酸盐岩深缓坡台地;(3)川西—川中的须家沟组原生气藏和侏罗系次生气藏。评价该盆地可以从反向思维入手,即对油气藏破坏条件进行区域和目标评价。     

南方海相地层油气评价及勘探建议

南方海相沉积岩可分上古生界（含三叠系）和下古生界（含上震旦统）两大套生储盖组合。两个成油组合在地史中都发生过大规模油气聚集，形成过许多油藏（已发现１２个古油藏）。由于印支、燕山、喜马拉雅斯构造运动的影响，原始海盆已被强烈改造，有些隆升成山，有些被中、新生界履盖，地下水自由交替带影响深度大，因此保存条件是找油的关键。选区首先要有区域盖层分布，其次目的层要全。已有资料表明，具备保存条件的有利地区为对冲