珠江口沉积物柱状样的脂肪酸垂向变化特征

THE FATTY ACIDS PROFILE IN CORE SEDIMENT IN THE PEARL RIVER ESTUARY

珠江口3个站位沉积柱的脂肪酸研究结果显示:沉积物中含量最高的脂肪酸是C16:0,其他脂肪酸包括不饱和脂肪酸、单甲基支链脂肪酸和长链脂肪酸。脂肪酸组成表明研究区有机质主要来源于藻类、细菌和陆源有机质。由于横琴岛附近的HQ1031站位靠近外海,初级生产力较高,因而含较多藻类脂肪酸。离淇澳岛较远的QA-B站位处于河口上缘,陆源物质丰富,初级生产力较低,因此该站位含较多陆源脂肪酸。横琴岛附近HQ1031站位的TOC值和总脂肪酸含量均大于QA-B站位,这两个站位的TOC值与总脂肪酸含量在垂向上的相关性差。横琴岛附近HQ1031站位和离淇澳岛较近的QA-A站位分别在20-22cm和16-18cm处藻类脂肪酸突然大量增加,可能与藻类输入突然增多有关。沉积物中所检测到的能指示厌氧微生物或革兰氏阳性菌的脂肪酸含量高于革兰氏阴性菌,表明珠江口沉积物微生物群落中以厌氧微生物为主。

The fatty acid compositions of three sediment cores are analyzed,two of which are collected in the northern of Qi＇ao Island and the third one is collected around Hengqin Island in the Pearl River Estuary.The main fatty acids are C16：0 in sediments.The other detected fatty acids include iso and anteiso fatty acids,long-chain fatty acids and unsaturated fatty acids.The result indicates that the organic matters in this area mainly derive from algae,bacteria and terrestrial organic material.Because the primary production is higher,the site HQ1031 around Hengqin Island has more algal fatty acids.However,due to near river mouth the sediment rate is bigger,the primary production is lower,and the site QA-B far away from Qi＇ao Island has more terrestrial fatty acids.The site HQ1031 has higher TOC than the site QA-B does,so does the total content of fatty acids.It is concluded that the relativity between the vertical profile of TOC and TFA of the two sites is poor.The content of algal fatty acids of the site HQ1031 and the site QA-B increase abruptly relatively at 20cm-22cm and 16cm-18cm,which may associate with the increase of algal input.The content of detected fatty acids biomarker of gram-positive bacteria or anaerobic microbes in the sediment is more than that of gram-negative bacteria,indicating that the main bacterial communities of the Pearl River sediment are anaerobic microbes.