Basin scale distribution of chromophoric dissolved organic matter in the Pacific Ocean
Basin scale distribution of chromophoric dissolved organic matter in the Pacific Ocean
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DOI：
10.4319/lo.2009.54.2.0598
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发表时间：
2009-03
影响因子：
4.5
通讯作者：
Y. Yamashita;E. Tanoue
中科院分区：
文献类型：
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作者：
Y. Yamashita;E. Tanoue
沿着从赤道到亚北极太平洋的 160°W 断面对有色溶解有机物 (CDOM) 进行了调查。通过测量 320 nm 激发和 420 nm 发射的荧光强度以及 320 nm 的吸收系数 (a) 来评估 CDOM 特性，两者都表明海洋腐殖质类 CDOM。在表层（~200 m），在研究的海洋区域中发现了不同水平但相似光学特征的CDOM。在中层（200-1000 m）和深海层（1000 m-底部）中，荧光强度水平与吸收系数呈线性相关，这些层之间的斜率相似。然而，中深层的两个光学参数之间的线性关系的截距明显低于深海层。截距之间的差异与光学上不同的 CDOM 通过北太平洋中间水 (NPIW) 的形成传输到中深层的情况一致。在波长小于300 nm时，表层CDOM的吸收系数系统地偏离320-350 nm范围内吸收系数与波长之间的自然对数关系。此类 CDOM 使用 275 nm 处的吸收系数进行估计，被定义为表面特异性 CDOM，可能源自生物成分。相对年轻的模式水中的表面特异性 CDOM 高于旧的 NPIW，表明此类 CDOM 是半不稳定的。
Chromophoric dissolved organic matter (CDOM) was surveyed along the 160°W transect from the equatorial to the subarctic Pacific. CDOM characteristics were evaluated through the measurement of fluorescence intensity at 320 nm excitation and 420 nm emission and of absorption coefficient (a) at 320 nm, both indicative of marine humic‐like CDOM. In the surface layer (~200 m), different levels but similar optical characteristics of CDOM were found among the oceanic regions studied. In the mesopelagic (200‐1000 m) and abyssal layers (1000 m‐bottom), levels of fluorescence intensities were linearly correlated to those of absorption coefficients, with a similar slope between these layers. However, the intercept of the linear relationship between the two optical parameters was significantly lower for the mesopelagic layer than for the abyssal layer. Differences between intercepts were consistent with the transport of optically distinct CDOM to the mesopelagic layer through the formation of the North Pacific intermediate water (NPIW). At wavelengths shorter than 300 nm, the absorption coefficients of CDOM in the surface layer systematically deviated from the natural logarithmic relationships between absorption coefficients and wavelengths in the 320‐350 nm range. This class of CDOM, estimated using absorption coefficient at 275 nm, was defined as surface‐specific CDOM and may be derived from biocomponents. Surface‐specific CDOM was higher in the relatively young mode water than in old NPIW, suggesting that this class of CDOM is semi‐labile.