厦门湾有色溶解有机物的光吸收特性研究

研究了厦门湾九龙江河口区、西海域、同安湾及东侧水道海水中有色溶解有机物(CDOM)的光吸收特性,分析了CDOM的河口行为,并讨论了CDOM光吸收特性与其荧光性质之间的关系。结果表明,厦门湾表层海水CDOM光吸收系数a(355)的水平分布表现为河口区最高、东侧水道最低、西海域和同安湾介于两者之间,底层水a(355)的分布与表层基本相似,表明陆源河流输入是厦门湾CDOM的主要来源;a(355)的垂直分布为表层高于底层,主要受水文和生物因素控制。厦门湾表层水CDOM光谱斜率S的平均值介于0.014—0.018nm-1,但河口低盐度区S值较小,反映陆源腐殖质的影响。a(355)在河口混合中呈保守行为,表明CDOM具有良好的保守性质。CDOM的吸收系数a(355)与其荧光强度之间表现为较好的相关关系,指示可以用灵敏度更高的荧光方法来研究CDOM的分布和行为。

A study on optical absorption properties of chromophoric dissolved organic matter in Xiamen Bay

Optical absorption properties of chromophoric dissolved organic matter (CDOM) in seawater from the Xiamen Bay in April and May of 2003 were studied, including the Jiulong River estuary, the western Xiamen Harbour, the Tong'an Bay and the eastern sea area of Xiamen. Based on the experimental results, the mixing behavior of CDOM in the estuary was analyzed and the relationships between absorption and fluorescence characteristics of CDOM were discussed. The highest CDOM spectral absorption coefficient a(355) of surface water was observed in the Jiulong River estuary, the western Xiamen Harbour and the Tong'an Bay were next; and the lowest value was found in the eastern sea area of Xiamen. The distribution of CDOM spectral absorption coefficient in bottom water was similar to that in surface water, indicating that the terrestrial river input was the main resource of CDOM in the Xiamen Bay. The vertical distribution showed higher a(355) values in surface water than in bottom water, which was controlled by hydrological and biological factors. The average value of the spectral slope S of CDOM in surface water varied from 0.014 to 0.018nm -1, while it showed a lower value in the lower salinity areas of the estuary, reflecting the influence of terrestrial humic sources. The a(355) in the estuary showed conservative behavior, indicating a good conservative characteristic of the CDOM it reflected. There was a good correlative relationship between a(355) and the fluorescence intensity of CDOM, meaning that more sensitive fluorescence technique can be used to study the distribution and behavior of CDOM.