Bio‐optical and biogeochemical properties of different trophic regimes in oceanic waters
Bio‐optical and biogeochemical properties of different trophic regimes in oceanic waters
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DOI：
10.4319/lo.2005.50.6.1795
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发表时间：
2005-11
影响因子：
4.5
通讯作者：
Kadija Oubelkheir;H. Claustre;A. Sciandra;M. Babin
中科院分区：
文献类型：
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作者：
Kadija Oubelkheir;H. Claustre;A. Sciandra;M. Babin
为了研究公海生物光学特性变异的来源和幅度，我们在夏末同时测量了从摩洛哥上升流富营养化水域到地中海西北部贫营养化水域和地中海东部超贫营养化水域的固有光学特性（IOPs）和生物地球化学数量。利用高分辨率原位分光光度计（WETLabs ac9）测量了光谱吸收系数和衰减系数的垂直分布，以及生物地球化学测量，包括浮游植物色素和颗粒有机碳浓度、粒径分布和浮游生物丰度。研究了特定IOPs（即每单位生物地球化学成分浓度）的变异性，并推导了粒径的光学指数。利用ac9剖面描述了各种生物地球化学性质的细尺度垂直分布。根据光学和生物地球化学测量相结合估计的颗粒衰减和碳收支是海洋水域非藻类种群的主要贡献。我们发现，海洋中IOPs的一级变化可以用营养状态（即叶绿素a浓度）来解释，而二级变化是浮游植物组合组成变化、藻类和非藻类种群之间的平衡以及与光相关的过程（彩色溶解有机物光氧化和藻类光适应）的结果。
To examine the source and magnitude of the variability of bio‐optical properties in open ocean, we simultaneously measured inherent optical properties (IOPs) and biogeochemical quantities during late summer from the eutrophic waters of the Moroccan upwelling to the oligotrophic waters of the northwestern Mediterranean and the ultraoligotrophic waters of the eastern Mediterranean. Vertical distributions of spectral absorption and attenuation coefficients were measured with a high‐resolution in situ spectrophotometer (WETLabs ac9) together with biogeochemical measurements that included phytoplanktonic pigments and particulate organic carbon concentrations, particle size distributions, and picoplankton abundance. The variability in specific IOPs (i.e., per unit of biogeochemical constituent concentration) was examined, and an optical index of particle size was derived. The fine‐scale vertical distributions of various biogeochemical properties were thus described from ac9 profiles. Particle attenuation and carbon budgets, estimated from a combination of optical and biogeochemical measurements, underlie a major contribution of nonalgal stocks in oceanic waters. We show that first‐order variations in IOPs in oceanic waters are explained by the trophic state (i.e., chlorophyll a concentration) and that second‐order variations are the result of changes in the composition of phytoplankton assemblage, the balance between algal and nonalgal stocks, and lightrelated processes (colored dissolved organic material photo‐oxidation and algal photo‐adaptation).