摘要:
对南海北部神狐海域表层沉积物中脂肪酸组分进行了分析,检测到的总正构脂肪酸含量为1.80~10.16 μg/g(μg脂肪酸/g干沉积物),碳数分布为C12—C32,呈偶奇优势分布,以C16和C18为主峰碳。将90 cm以上层位样品进行归一化,建立加权平均碳同位素讨论正构脂肪酸来源,结果表明,短链脂肪酸(n-C14~18)具有较正的碳同位素组成(加权平均为-26.7‰~-28.2‰),反映了化学自养细菌来源;大部分长链脂肪酸(n-C21~23,n-C25,n-C29~32)具有偏负的碳同位素组成(加权平均为-29.6‰~-34.1‰),反映了陆源C3高等植物来源;而另外的长链脂肪酸(n-C24&n-C26~28)和n-C19~20中链脂肪酸(加权平均碳同位素为-26.1‰~-29.3‰)则可能反映了混合来源输入。沉积物75~80 cm层位陆源输入和海洋输入含量达到最低,可能和Younger Dryas冷期旋回事件有关。
Abstract:
The saturated fatty acids (SaFAs) in the surface sediments from the Shenhu Area, northern South China Sea were examined. The total SaFA concentrations are distributed within a range of 1.80-10.16 μg/g(μg FA/g dry sediment), and the carbon numbers range from C12-32. The SaFAs follow an even-over-odd predominance distribution, with n-C16 and n-C18 being the two major components. In this paper, the samples above 90cm were combined into one sample to discuss the sources of SaFAs by n-average δ13C. The results revealed that short-chain fatty acids (n-C12-18) have relatively positive n-average δ13C values from -26.7‰ to -28.2‰, suggesting the chemical autotrophic bacteria sources, while most long-chain fatty acids (n-C21-23, n-C25, n-C29-32) have relatively negative n-average δ13C values from -29.6‰ to -34.1‰, suggesting the C3 higher plant sources, and the other LcFAs (n-C24 & n-C26-28), as well as n-C19 and n-C20 mid-chain fatty acids have n-average δ13C from -26.1‰ to -29.3‰, suggesting the mixed marine and terrigenous sources. The lowest concentrations of terrigenous and marine inputs at depths of 75-80cm may be related to Younger Dryas event.
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