The Disparity of Chain Length Distribution Patterns and Carbon Isotopic Compositions between Different Fatty Acid Purification Procedures
-
摘要: 饱和脂肪酸及其同位素组成是重建古环境和古气候的重要代用指标，目前存在多种提取及纯化流程。在全球变化研究中，基于不同原理的纯化流程得到的脂肪酸含量及其同位素组成是否一致，直接影响着该指标应用于不同区域重建结果的对比。本文用两种常见的脂肪酸纯化流程提取脂肪酸标准、现生植物和泥炭样品类脂物，通过对比发现：对脂肪酸标准两种流程都可以得到纯净的单体脂肪酸，而且回收率均较高(85%以上)，都是较为可靠的脂肪酸纯化流程；然而对于天然样品，虽然高碳数脂肪酸(碳数 > C24)的回收率相近，流程1却能够获得相对较多的低碳数饱和脂肪酸，如泥炭样品中该流程获得的n-C22脂肪酸是流程2的3倍；两种流程纯化狗尾草(Setaira viridis)和三叶草(Trifolium repens)得到n-C16脂肪酸的δ13C不同，流程1分别为-21.1‰和-36.2‰；流程2分别为-23.3‰和-34.9‰，表明两个实验流程得到的低碳数脂肪酸的含量、脂肪酸链长分布模式以及碳同位素组成均存在明显的差异。实验结果显示，流程2分离纯化样品可得到几乎全部的游离态脂肪酸，而流程1可提纯样品中游离态和酯态存在的总脂肪酸。由于在沉积物中游离态脂肪酸和酯态脂肪酸可以相互转化，因此使用流程1分析样品中的总脂肪酸更为合适，也可以将类脂物皂化使酯态脂肪酸释放为游离态，然后使用流程2。Abstract: Saturated fatty acids and their isotopic composition are important proxies to reconstruct paleoenvironment and paleoclimate. There are several extraction and purification procedures of n-fatty acids based on different principles. However, a comparison test between different processes has not been reported. In this article, the agreement of fatty acid and its isotope compositions purified by different processes directly impacted on the proxies′ application, especially on the comparison of reconstruction results from different regions in global change research. Two common fatty acid purification procedures were used to purify lipids of fatty acid standards, plant and peat samples. For the standards, the recovery rates of these two procedures were all greater than 85%, which indicates that these two methods are reliable to process the n-fatty acids. However, for the plants and peats samples, Procedure 1 obtained a relatively large amount of shorter chain length n-fatty acids. According to our results, Procedure 2 obtained almost all of the free fatty acids, while Procedure 1 can obtain both the free and ester state n-fatty acids in the samples. Since the free state fatty acids and esters state fatty acids in the sediment can be transformed into each other, using Procedure 1 to analyze the total fatty acids in the sediment sample was more appropriate. Alternatively, we can also use the Procedure 2 after the ester-state fatty acids in the lipids were released as free state acids by saponification.
-
不知你是否有过这样的经历，终于得到那本向往已久的好书，或是觅得那张曾经深深触动你的CD，你是即刻拆封？还是放进书包带回家，等外界嘈杂喧嚣退去，静候自己那颗久别重逢的心都准备好了，才打开来细细品读或是聆听？
上大学时，笔者第一次听到了德沃夏克的第九交响曲“自新大陆”。乐中蕴含着一股强大而内敛的力量，气势恢弘，充满自信与自豪，是充满生机的号角和热血生命的召唤，让当时年轻的心澎湃不已，至今不能忘怀。那个时候有年轻的心，有远方的梦，在时间和生命的轨迹上自由地延伸。自那时起，找寻和聆听这首交响曲，就成了心中一份默默的寄托。不知等了多少年，终于觅得了这一珍贵CD。当时拿到CD，真恨不得马上回家就听。然而，真正回到家，却总也不敢拆开那精美的包装，担心里面那颗澎湃的心所掳掠的这么多年的找寻和期待稍纵即逝，或流于指缝，或散于世俗。要重温这张CD，必须有一种“仪式”：最悦耳的音响，最静谧的夜，最清澈的星空……，只有这个时候，再奏响这火红的乐章，才能让心在足够的宁静中再一次澎湃，让灵魂再一次感受久违的呼唤与震撼。穿越这数十年的流觞，与那个年轻的自己一起，坐在大学校园的静夜里，沉醉、省思和积淀。这一等，就又是十年。
如果说科学和艺术是一双智慧和反智慧的孪生体，那么这样的“反”中，必然免不去这诸多的“同”。不久前看到一段话，大意是说，只会开卷勤读，不会掩卷悲喜，这一生就算做到中文系教授，也不过是一个文学的绝缘体。对于搞科研的人来说，这掩卷后的触动和省思更为重要。没有这点滴的“省”，你不仅会渐渐绝缘于真正意义上的科研，甚至也绝缘于自己———你永远无法体验多年后与曾经的自己再一次邂逅的快乐。2013年在《岩矿测试》上发表的文字，既有踏雪寻梅，一层一层曲折着向科学深处走去的探索，又有山重水复疑无路的回转，以及攻克了诸多技术难题的实验新作。邈远空茫之处，探寻的精神与攻克难关的乐趣尽显。
“氧同位素在岩石成因研究中的新进展”一文（Vo1.32，No.6，p841－849），初看似如入云山雾海，那些氧同位素组成的变化和分馏效应的差异，如何用来识别不同来源、不同期次岩石的形成、混染和演化？技术手段的改变，又如何否定了前人的假设与假说，导致了多种岩石成因学说的进步？层层叠叠，庐山面目不得识。然而这反倒促使你静下心来，仔细阅读，去理解科学道理与自然规律的天然自成。自然之美在这里一览无余。也不得不使你感受到作者对于该门学科独到的思辨与洞察。
“应用纤维素示踪北京市PM2．5天然植被排放来源的研究”（Vo1.32，No.5，p738－746）实在是一篇需要推荐给大家去读的文章。现在举国上下，直至欧美诸国，都在广泛谈论PM2．5与北京和全国各地的雾霾。当北京重度污染的时候，还会收到国际友人的邮件关注。印象中，我们谈论的雾霾来源都是工业污染、沙尘，甚或汽车尾气。然而，该文作者们通过精巧的设计和实验方法的改进，通过与国外文献的方法及数据对比，表明在北京，天然植被排放量占据了PM2．5质量浓度的1．37％的份额，天然植被排放源对有机碳的最大贡献可达9．2％，天然植被排放成为北京市PM2．5重要来源之一。该研究与我们大家的生活息息相关，其重要性和科学意义不言而喻。
微区定量分析中，标准物质的缺乏是其重要制约因素之一。标准物质与待测样品基体的不一致是分析误差的主要来源。“激光剥蚀电感耦合等离子体质谱分析石笋样品中多元素比值及45种元素含量”（Vo1.32，No.3，p383－391）一文，在实验与方法上，采取了一系列富有创意的、绕口令一般的“桥梁”设计，有效地避免了碳元素无法准确检测的问题，获得了与Ca内标法相匹配的校正结果。“磷灰石Sr－Nd同位素的激光剥蚀－多接收器电感耦合等离子体质谱微区分析”（Vo1.32，No.4，p547－554）研究中，作者们不仅进行了深入的研究，还详尽地进行了国内外方法与数据的比较，佐证了所建方法的先进性和可靠性。这一点十分值得推荐，这样做也需要有渊博的学识、扎实的功底和探求真知的勇气。一年来，这样的研究还有很多……
这些文字，或充满丰富的奇思妙想，或构思着精巧的实验设计，智慧、坚韧与探求，无不浸润在文中的字里行间。
于是，就想，一定要集撰这样一本好书，也一定会有这样一卷好书，在星星聚齐的时候，我们一起开卷细品，掩卷遐思！
主编：罗立强
2013年10月26日
于北京
致谢: 感谢中国科学院地球环境研究所王政助理研究员和曹蕴宁高级工程师在实验过程中提供的帮助。 -
![]()
图 1 脂肪酸标准在不同实验流程中的回收率
Figure 1. The recovery rate of standard fatty acids by different purification procedures
![]()
图 2 不同纯化方法得到的多尔计泥炭样品中单体脂肪酸的链长分布模式
Figure 2. The individual fatty acids distribution patterns of Duoerji peat samples purified by different procedures
![]()
图 3 狗尾草和三叶草通过不同流程纯化得到的各单体脂肪酸含量分布图
Figure 3. The individual fatty acids distribution patterns of Setaira viridis and Trifolium repens purified by different procedures
表 1 不同流程纯化狗尾草、三叶草和多尔计泥炭类脂物得到的各单体脂肪酸含量
Table 1 The individual fatty acid content of Setaira viridis, Trifolium repens and Duoerji peat samples by different purification procedures
样品编号 脂肪酸含量 w/(μg·g-1) ACL16-32 ACL20-32 C16FA
δ13C/‰SD C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C32 GW-SNS 29 0 111 40 2410 56 436 10 431 26 456 36 284 20 96 7 90 12 124 33 82 18.88 23.56 -21.1 0.05 GW-SPE 12 0 12 7 183 6 38 0 24 8 24 6 38 6 49 8 93 16 138 28 90 24.27 28.11 -23.3 0.20 SY-SNS 19 0 150 59 2354 56 699 11 322 23 206 57 202 22 50 14 60 15 65 31 23 18.02 23.15 -36.2 0.02 SY-SPE 10 0 7 7 166 6 40 5 10 5 10 7 17 5 12 7 30 12 60 11 32 21.71 28.11 -34.9 0.19 Sed-SNS - - - - 25 2 31 2 68 7 47 13 86 13 104 5 68 4 20 1 3 23.7 24.65 - - Sed-SPE - - - - 5 0 6 0 10 2 16 8 54 10 91 6 93 6 42 2 8 26.2 26.54 - - 注：样品编号中GW、SY和Sed分别代表狗尾草、三叶草、沉积物； ACL16-32代表C16～C32 脂肪酸的平均链长 (Average chain length,ACL)；SD代表两次测量之间的标准偏差(Standard deviation)。 
下载: 导出CSV
表 2 不同浓度的乙酸洗脱多尔计泥炭样品的各单体脂肪酸相对于C26脂肪酸的含量
Table 2 The relative content of individual fatty acid of Duoerji peat sample eluted by different concentration of acetic acids
乙酸浓度 脂肪酸相对含量w/%(相对于n-C26FA) ACL16-32 ACL20-32 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C32 2% 5 0 6 2 16 3 21 10 64 6 100 14 96 11 32 8 6 25.85 26.14 4% 4 0 5 0 15 2 20 10 61 11 100 8 102 6 37 3 7 26.08 26.30 10% 5 0 5 1 16 3 21 10 63 11 100 10 98 8 35 8 7 25.95 26.21 20% 5 0 5 2 15 3 21 10 63 6 100 11 99 6 34 1 4 25.90 26.16 平均值/% 5 0 5 1 15 3 21 10 63 8 100 11 99 8 34 5 6 25.95 26.20 标准偏差 0.57 0.00 0.39 0.94 0.63 0.38 0.70 0.33 1.14 3.06 0.00 2.79 2.58 2.40 2.06 3.27 1.40 0.10 0.07
下载: 导出CSV
-
Cranwell P. Lipids of aquatic sediments and sedimenting particulates [J]. Progress in Lipid Research, 1982, 21: 271. doi: 10.1016/0163-7827(82)90012-1
Huang Y, Shuman B, Wang Y, Webb T. Hydrogen isotope ratios of palmitic acid in lacustrine sediments record late Quaternary climate variations [J]. Geology, 2002, 30: 1103. doi: 10.1130/0091-7613(2002)030<1103:HIROPA>2.0.CO;2
Naraoka H, Ishiwatari R. Molecular and isotopic abundances of long-chain n-fatty acids in open marine sediments of the western North Pacific [J].Chemical Geology,2000,165: 23-36. doi: 10.1016/S0009-2541(99)00159-X
Tierney J E, Russell J M, Huang Y, Damst J S, Hopmans E C, Cohen A S. Northern hemisphere controls on tropical southeast African climate during the past 60000 years [J]. Science, 2008, 322: 252-255. doi: 10.1126/science.1160485
Hughen K A, Eglinton T I, Xu L, Makou M. Abrupt tropical vegetation response to rapid climate changes [J]. Science, 2004, 304: 1955. doi: 10.1126/science.1092995
Gao L, Hou J, Toney J, MacDonald D, Huang Y. Mathematical modeling of the aquatic macrophyte inputs of mid-chain n-alkyl lipids to lake sediments: Implications for interpreting compound specific hydrogen isotopic records [J]. Geochimica et Cosmochimica Acta, 2011, 75(13): 3781-3791. doi: 10.1016/j.gca.2011.04.008
Sessions A, Burgoyne T, Schimmelmann A, Hayes J. Fractionation of hydrogen isotopes in lipid biosynthesis [J]. Organic Geochemistry, 1999, 30: 1193-1200. doi: 10.1016/S0146-6380(99)00094-7
Li C, Sessions A L, Valentine D L, Thiagarajan N. D/H variation in terrestrial lipids from Santa Barbara Basin over the past 1400 years: A preliminary assessment of paleoclimatic relevance [J]. Organic Geochemistry, 2011, 42: 15-24. doi: 10.1016/j.orggeochem.2010.09.011
赵江涛,刘卫国,安芷生.贡嘎山现代植物叶蜡脂肪酸氢同位素组成及对海拔变化的响应[J].第四纪研究, 2011, 31(5): 856-863. http://www.cnki.com.cn/Article/CJFDTOTAL-DSJJ201105010.htm Chikaraishi Y, Suzuki Y, Naraoka H. Hydrogen isotopic fractionations during desaturation and elongation associated with polyunsaturated fatty acid biosynthesis in marine macroalgae [J]. Phytochemistry, 2004, 65: 2293-2300. doi: 10.1016/j.phytochem.2004.06.030
Wang Z, Liu W. Carbon chain length distribution in n-alkyl lipids: A process for evaluating source inputs to Lake Qinghai [J]. Organic Geochemistry, 2012, 50:36-43. doi: 10.1016/j.orggeochem.2012.06.015
Sessions A. Seasonal changes in D/H fractionation ac-companying lipid biosynthesis in Spartina alterniflora [J]. Geochimica et Cosmochimica Acta, 2006, 70: 2153-2162. doi: 10.1016/j.gca.2006.02.003
Hou J Z, D′Andrea W J, Huang Y S. Can sedimentary leaf waxes record D/H ratios of continental precipitation? Field, model, and experimental assessments [J]. Geochimica et Cosmochimica Acta, 2008, 72: 3503-3517. doi: 10.1016/j.gca.2008.04.030
Yang H, Huang Y.Preservation of lipid hydrogen isotope ratios in Miocene lacustrine sediments and plant fossils at Clarkia, northern Idaho, USA [J]. Organic Geochemistry, 2003, 34: 413-423. doi: 10.1016/S0146-6380(02)00212-7
Huang Y, Street-Perrott F A, Perrott R A, Metzger P, Eglinton G. Glacial-interglacial environmental changes inferred from molecular and compound-specific δ13C analyses of sediments from Sacred Lake, Mt. Kenya [J]. Geochimica et Cosmochimica Acta, 1999, 63: 1383-1404. doi: 10.1016/S0016-7037(99)00074-5
Ficken K, Li B, Swain D, Eglinton G. An n-alkane proxy for the sedimentary input of submerged/floating freshwater aquatic macrophytes [J].Organic Geochemistry, 2000, 31: 745-749. doi: 10.1016/S0146-6380(00)00081-4
Simoneit B R T, Sheng G, Chen X, Fu J, Zhang J, Xu Y. Molecular marker study of extractable organic matter in aerosols from urban areas of China [J]. Atmospheric Environment Part A: General Topics,1991,25: 2111-2129. doi: 10.1016/0960-1686(91)90088-O
赵大勇,燕文明,冯景伟,袁守军.磷脂脂肪酸分析在湖泊沉积物微生物生态学研究中的应用[J].化学与生物工程, 2009, 26(12): 17-20. doi: 10.3969/j.issn.1672-5425.2009.12.004 Lewis T, Nichols P D, McMeekin T A. Evaluation of extraction methods for recovery of fatty acids from lipid-producing microheterotrophs [J]. Journal of Microbiological Methods, 2000, 43: 107-116. doi: 10.1016/S0167-7012(00)00217-7
Huang Y, Shuman B, Wang Y, Webb T. Hydrogen isotope ratios of individual lipids in lake sediments as novel tracers of climatic and environmental change: A surface sediment test [J]. Journal of Paleolimno-logy, 2004, 31: 363-375. doi: 10.1023/B:JOPL.0000021855.80535.13
Meyers P A, Eadie B J. Sources, degradation and recycling of organic matter associated with sinking particles in Lake Michigan [J]. Organic Geochemistry, 1993, 20: 47-56. doi: 10.1016/0146-6380(93)90080-U
瞿文川,张平中.太湖沉积物中长链脂肪酸甲酯化合物的检出及意义[J].湖泊科学, 1999(11): 245-250. http://www.cnki.com.cn/Article/CJFDTOTAL-FLKX199903008.htm Diefendorf A F, Freeman K H, Wing S L, Graham H V. Production of n-alkyl lipids in living plants and implications for the geologic past [J]. Geochimica et Cosmochimica Acta, 2011, 75(23): 7422-7485.
计量
- 文章访问数: 1102
- HTML全文浏览量: 334
- PDF下载量: 10
京公网安备 11010202008159号