【作者】 吴璟瑜；

【导师】 洪华生； 商少凌；

【作者基本信息】 厦门大学 ， 环境科学， 2006， 博士

【摘要】 本论文研究中国东南近海几种不同特征水体的光吸收特性及其控制机制,包括河口水体—珠江口、沿岸水体—台湾海峡南部、陆架水体—南海东北部,并探讨浮游植物吸收对浮游植物群落结构的指示作用;另外,追踪厦门西海域两次水华过程水体光吸收特征的变动。就440 nm水体吸收而言,珠江口春、冬季最主要成分是非色素颗粒吸收,南海东北部则是浮游植物吸收;夏季台湾海峡南部也以浮游植物吸收为主,但非色素颗粒与CDOM二者的贡献与之相当。三个海域吸收组成分别体现河口水体、陆架水体和近岸水体的特征。南海东北部、台湾海峡南部的非色素颗粒吸收光谱斜率Sd(350-700 nm)接近,平均分别为0.0099、0.00912 nm-1,和珠江口的差别较大(~0.00126 nm-1)。CDOM的吸收特征与其来源密切相关。冬季珠江口355 nmCDOM吸收ag(355)为0.24-1.93 m-1,低于多数欧美河口水体;与盐度呈线性反相关,在分布上体现珠江口的多口门特征,CDOM主要为陆源。相应的光谱斜率Sg(300-500 nm)为0.0138-0.0184 nm-1,变动小,仅河口与南海陆架间的过渡带低于0.015 nm-1,同时荧光EEMs分析在此发现海源类腐殖质荧光团,过渡带Sg的变动可能是河口水和多个海洋水团的混合及其他因素的综合结果。夏季台湾海峡南部ag(355)为0.033-0.456 m-1,高于一般大洋水体;其分布基本呈表层低、深层高,总体上与温度反相关,与盐度、浮游植物吸收aph(675)正相关,说明CDOM受陆源的影响小,主要来自现场生产,荧光EEMs结果及部分样品在300-350 nm的特殊吸收峰现象与之相符。对应的Sg为0.0101-0.0318 nm-1,平均0.0204 nm-1。浮游植物吸收(aph)在南海和台湾海峡存在时空变动,主要受控于物理过程。在南海东北部位于珠江口外的一垂直岸断面,春季一场暴雨后,由于河口锋外移,内陆架区表层aph(675)由0.002 m-1升高至0.050 m-1,B/R值(aph(440)/aph(675))由3.9降低至2.5;冬季相同站位表层aph(675)比春季高0.002-0.012 m-1,而内陆架区表层B/R值(不超过2.5)低于春季(>3.0),很可能由于强东北季风加强水体垂直混合并驱动粤东沿岸流影响内陆架区。夏季台湾海峡南部沿岸上升流对浮游植物吸收的影响显著:在从南到北的三个沿岸站位,北端较南端表层水温低3.6℃,相应的aph(675)高出一个数量级(0.038 vs. 0.004 m-1 )。更多还原

【Abstract】 Absorption properties off southeastern China were investigated, including several kinds of regimes such as the Pearl River Estuary (PRE), the southern Taiwan Strait (TWS) and the northeastern South China Sea (NSCS)—a continental shelf water. In addition, a time series of absorption properties as well as algal pigments were measured in the western Xiamen Bay in order to assess temporal variations in absorption properties of various constituents associated with bloom development.In general, de-pigmented particles dominate the total absorption at 440 nm both in the spring and the winter in the PRE, while phytoplankton dominate in the NSCS. During summer, phytoplankton are the major absorption component in the southern TWS, but the contributions of de-pigmented particles and CDOM can’t be neglectable.The mean absorption spectral slope of de-pigmented particles (Sd, determined between 350-700 nm) in the NSCS is 0.0099 nm-1, similar to that in the southern TWS (0.00912 nm-1), and much smaller than that in the PRE (~0.00126 nm-1).Absorption properties of CDOM are different in the PRE and the southern TWS, depending on the different sources. Over a 0-33 salinity range, CDOM absorption coefficients at 355 nm, ag(355) decreased from 1.93 to 0.24 m-1 in the PRE in the winter, relatively lower than those in the other American and European estuaries. ag(355) showed a linear, inverse relationship with salinity, suggesting a freshwater source. High ag(355) in the vicinity of four outlets demonstrated multiple sources of CDOM. Absorption spectral slopes (Sg), determined between 300-500 nm, ranged from 0.0138 to 0.0184 nm-1. No apparent pattern of Sg for most stations was observed except lower values in the transition zone between the estuary and the South China Sea shelf, where a marine humic-like fluorophore (M) was encountered by fluorescence EEMs analysis. This phenomenon can be interpreted as a mixing process of involving upstream estuarine water and adjacent seawater with different Sg values. In the southern TWS, ag(355) varied from 0.033 to 0.456 m-1 in the summer, a little更多还原