中国南海CDOM三维荧光光谱特征研究

利用三维荧光光谱技术,分析了中国南海有色溶解有机物(CDOM)荧光组分的垂直分布特征.结果表明,中国南海CDOM含有类腐殖质荧光峰M和类蛋白质荧光峰T;CDOM的荧光强度(λEx/λE m:350 nm/450 nm)在表层较低,垂直分布呈现随深度增加而增加,在300 m处达到峰值,然后逐渐下降,在500~600 m间达最小峰值,而后保持相对稳定的分布规律.荧光指数FI均在1.4~2.0间,腐殖化指数HIX值偏低,生物源指数BIX在0.7~1.1之间,T峰为主要贡献者,说明南海CDOM主要为海洋自生来源,受海洋微生物作用过程影响较大.M峰和T峰的荧光强度在垂直分布上具有相似的变化趋势,表层荧光强度都最小,说明南海表层CDOM丰度分布受光降解影响较大.研究表明,南海CDOM的垂直分布受光化学反应、海洋微生物活动及颗粒有机物再矿化的共同影响.

Fluorescence excitation-emission matrix spectroscopy of chromophoric dissolved organic matter in the South China Sea

Fluorescence excitation-emission matrix spectroscopy(EEMs) was used to characterize the chromophoric dissolved organic matter (CDOM) in the South China Sea. The results showed that CDOM included humic-like fluorescence peak M and protein-like fluorescence peak T. The fluorescence of CDOM was low in the surface. The CDOM fluorescence increased steeply to the maximum at 300 m and decreased slightly to the minimum at 500~600 m, then increased slightly and tended to stabilize. The CDOM fluorescence index (FI) varied from 1.4 to 2.0, with a low humidification index (HIX). The index of recent autochthonous contribution (BIX) varied from 0.7 to 1.1, with protein-like fluorescence peak T as a major contributor. This suggested that the CDOM in the South China Sea was mainly from self-generation by marine microorganisms. The fluorescence intensity of peak M and peak T had similar vertical trends and both showed the minimum in the surface layer which suggested that the CDOM in the South China Sea was greatly influenced by the photodegradation. Our results showed that the distribution characteristics of CDOM was commonly affected by the photodegradation, while marine microbial activities and remineralization of particulate organic matter were also played an important role on the biogeochemical cycle in the South China Sea.