珠江口盆地Site4B柱状沉积物中长链烷基二醇和酮醇类化合物的检出及意义  

The identification of long-chain diols and keto-ols in Site4B sediment from the Pearl River Mouth Basin and its implication

作　　者：朱小畏[1,2,3] 孙永革[4] 茅晟懿[2,5] 管红香[2,5] 吴能友[2,5] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国科学院广州天然气水合物研究中心,广东广州510640 [3]中国科学院大学,北京100049 [4]浙江大学地球科学系,浙江杭州310027 [5]中国科学院广州能源研究所,广东广州510640

出　　处：《地学前缘》2014年第6期321-334,共14页Earth Science Frontiers

基　　金：国家重点基础研究发展计划"973项目"(2009CB219506);国家自然科学基金项目(41103043;41303067);中国科学院广州能源研究所所长基金项目(y107r71001);有机地球化学国家重点实验室开放基金项目(OGL-201209)

摘　　要：珠江口盆地Site4B沉积物中(65~300cm)检出了1,15-C30(ω16)和1,15-C32(ω18)烷基二醇和酮醇,总的长链烷基二醇和酮醇含量分别为0.026~4.373μg/g干沉积物和0.005~1.549μg/g干沉积物。沉积物剖面上检测到的1,15-C30烷基二醇(-26.6‰±0.9‰)相对于来自陆源高等植物的C30直链烷基醇(-32.8‰±1.5‰)较正的碳同位素特征反映了这类化合物可能不是来自陆源高等植物;同时沉积物中未检出在黄绿藻中相对长链烷基二醇和酮醇更丰富的甾醇,且沉积物浅表层中(0~65cm)未检出长链烷基二醇和酮醇类化合物,表明现今沉积物中几乎没有黄绿藻的贡献,和沉积物所处的寡营养盐(不适宜藻类生长发育)的陆坡位置相吻合。沉积物中1,15-C30烷基二醇(-24.6‰^-28.4‰)和海洋细菌来源的短链脂肪酸(-25.5‰^-28.6‰)具有相似的碳同位素组成,表明了海洋细菌是其可靠来源。Site4B沉积物中1,15-C30和1,15-C32烷基酮醇和二醇具有非常好的相关性,表明了它们可能来自相同的生物来源或者来自相关性较好的不同生源,而不是通过对应的二醇氧化生成,因为在65~95cm的氧化环境中酮醇比例没有明显增高。Site4B沉积物中二醇参数和酮醇参数的变化非常相似,结合含量分布特征反映了古海水温度以及淡水入侵的双重影响,即较高的二醇参数及较高的二醇含量和较低的二醇参数及较低的二醇含量都可能反映了古海水温度是主要影响因素;而较低的二醇参数及较高的二醇含量则可能反映了淡水的侵入是主要影响因素。1,15-C30（ω16）and 1,15-C32（ω18）alkyl diols and keto-ols were identified in Site4Bsediment（65-300 cm below the seafloor）from the Pearl River Mouth Basin,and the total contents of diols and keto-ols were distributed from 0.026-4.373μg/g dry sediment and 0.005-1.549μg/g dry sediment,respectively.The carbon isotope compositions were substantially enriched in 13 C for 1,15-C30diol（δ13 C=-26.6‰±0.9‰）relative to the n-C30alkanol（δ13 C=-32.8‰±1.5‰）,suggesting the absence of terrigenous higher plants.Either the absence of high abundance of sedimentary sterols relative to long-chain alkyl diols and keto-diols or the undetectability of these biomarkers in the surface sediment（0-65cm）indicates that eustigmatophyceae was not a potential source,since the location of Site4 Bsediment was on the continental slope where nutrition salinity is so poor that it is not suitable for algae.δ13 C of 1,15-C30diol（-24.6‰--28.4‰）is similar to that of short chain n-fatty acid（-25.5‰--28.6‰）in the sediment and revealed the same source as marine bacteria.In addition,the keto-ols have similar sources as diols or they are produces from different organisms but having strong couplings with each other;the keto-ols were not from the oxidization of the corresponding diols because the keto-ols ratios in the oxidized sediment（65-95cm）showed no significantly high values.The diol indices and keto-ol indices in the sediment having similar patterns,combined with the contents of these biomarkers,suggested the impact of the monsoon climate of South China Sea and the fresh water.Both the high diol indices and high diol concentration and the low diol indices and low diol concentration reflect the dominant impact of sea surface temperature,while the low diol indices and high diol concentration implied the major factor of increased intrusion of fresh water.

关 键 词：珠江口盆地 长链烷基二醇 长链烷基酮醇 二醇参数 酮醇参数 

分 类 号：P599[天文地球—地球化学]