为探究有色溶解有机物 (CDOM)光学性质如何示踪海水中溶解有机物组分的动态信息，实验利用紫外可见吸收光谱手段，分区域测定了桑沟湾春季水体及表层沉积物间隙水中CDOM的吸收光谱特征，探讨了CDOM的来源组成、空间分布特征、迁移转化过程及其与养殖活动的关系。结果显示，①波长为355 nm的吸收系数[a(355)]范围为0.23~9.09 /m，不同水层空间分布差异显著，表层和底层均从近岸区向贝藻区逐渐降低，在海带区升高后向外海逐渐降低；海带区从表层向底层先降低后升高，高密度、规模化的海带养殖释放了大量的CDOM，各区域沉积物间隙水a(355)是其表层、中层和底层之和的1.3~2.5倍，CDOM在沉积物间隙水中富集并逐渐累积。②光谱斜率(S_275~295)范围为0.013~0.036，外海区和海带区S_275~295均值显著高于其他各区，海带区和外海区CDOM中海源有机质占主要成分，而近岸区以陆源有机质为主；近岸区CDOM中的腐殖酸类物质含量从表层到底层逐渐降低，沉积物中积累的富里酸类物质含量较高，海带区和外海区呈相反趋势。③比紫外吸光度(SUVA₂₅₄)范围为4.60~14.10 L/(mg·m)，贝类区、贝藻区和藻类区SUVA₂₅₄均呈现出从表层到底层逐渐增大的趋势，CDOM的芳香性逐渐增强并在沉积物间隙水中达到最大；海带区和外海区沉积物间隙水中的SUVA₂₅₄显著高于其他各区。研究表明，海带区的规模化养殖活动向养殖海区及邻近海域贡献了较多的惰性溶解有机物，暗示着海带养殖活动有较强的碳汇效应，并通过海流作用向外海输送。本研究对桑沟湾海域不同养殖区域的CDOM的吸收特性和空间分布特征进行研究，可为全面了解海水养殖的碳源汇效应提供基础数据。

Colored dissolved organic matter (CDOM) is an important source of carbon in aquatic ecosystems, and the optical properties of dissolved organic matter (DOM) can be used to trace water masses and provide information about the dynamics of the dissolved organic fraction in seawaters. The ultraviolet-visible absorption spectrum was applied to investigate the chemical composition, sources, spatial distribution characteristics and migration and transformation processes of the CDOM in both the water body and interstitial water in Sanggou Bay, a representative semi-enclosed and mariculture bay in Shandong Province, China. The results indicated that, ① the range of absorption coefficient [a(355)] was 0.23-9.09 /m in Sungo Bay, there are significant differences in the spatial distribution of different water layers, both the surface layer and bottom layer gradually decreased from the nearshore zone to the bivalves & kelp zone, then it rose in the kelp zone and gradually decreased towards the outer sea zone. The a(355) in the kelp zone decreased from surface to bottom and then increased, high-density and large-scale kelp mariculture released a large amount of CDOM into the seawater. The a(355) of sediment interstitial water in each region was 1.3-2.5 times of the sum of the surface, middle and bottom layers, and it was enriched and gradually accumulated in the sediment interstitial water. ② The range of spectral slope (S_275-295) was 0.013-0.036 in Sanggou Bay, the mean values of S_275-295 in outer sea zone and kelp zone were significantly higher than that in other zones, the main components of CDOM are marine organic matter in kelp zone and outer sea zone, and terrigenous organic matter is predominant in the nearshore zone. The content of humic acids in CDOM in the nearshore zone was gradually decreased from the surface layer to the bottom layer, the accumulation of fulvic acid in sediments was high, and kelp zone and outer sea zone showed opposite trend. ③ The range of specific UV absorbance (SUVA₂₅₄)was 4.60-14.10 L/(mg·m) in Sanggou Bay, the SUVA₂₅₄ of the shellfish zone, the bivalves & kelp zone and the kelp zone showed a trend of increasing gradually from the surface to the bottom layer, and the aromaticity of CDOM was gradually increased and reached the maximum in the sediment interstitial water. The SUVA₂₅₄ in the sediment interstitial water of kelp zone and outer sea zone were significantly higher than that in other zones. This study showed that large-scale suspended cultivation activities from kelp zone contributed more refractory dissolved organic matter to the mariculture zone and adjacent seawaters, and it implied that kelp mariculture had a strong carbon sink effect and this sequestration was exported to the offshore waters through the current.

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国家重点研发计划(2020YFA0607603)；国家自然科学基金(U1906216，42376160)；山东省自然科学基金(ZR2022QD035)；中国水产科学研究院黄海水产研究所基本科研业务费专项(20603022022012)；中国科学院战略性先导科技专项(A类)“美丽中国生态文明建设科技工程”( XDA23050402)；山东省重大科技创新工程专项-“健康海洋”技术创新工程(2018SDKJ0501-3)