环胶州湾河流入海口CDOM吸收光谱特征

为深入认识河流对胶州湾水体有机碳的贡献，于2016年4月-2017年2月对环胶州湾河流入海口进行双月采样，通过分析水体中DOC（溶解有机碳）和POC（颗粒有机碳）质量浓度及CDOM（有色溶解有机物）的吸收光谱特征，揭示环胶州湾入海口有机碳的分布特征，辨析CDOM的组成和来源，探讨其与主要环境因素的关系.结果表明:①环胶州湾河流入海口DOC和POC质量浓度范围分别为0.98~32.75和0.13~22.40 mg/L，其中李村河口最高，轮渡和大港相对较小.②a（355）（CDOM的吸收系数）变化范围为0.23~16.35 m-1，存在明显的季节性差异，与盐度成反比，其分布与DOC和POC基本一致.③研究区域水体中，表征CDOM分子组成、来源及芳香化程度的S_R光谱斜率比，S_g（275~295 nm）/S_g（350~400 nm）]和A_{250 nm}/A_{365 nm}存在显著的时空差异.④夏季、秋季CDOM的整体分子量水平高于春季、冬季；轮渡、大港、板桥坊河和娄山河S_R相对较高，CDOM组成趋向于蛋白类或富里酸类物质.⑤轮渡、大港和镰湾河A_{250 nm}/A_{365 nm}相对较高，类腐殖质的芳香化程度较低，受海源控制；其他河口A_{250 nm}/A_{365 nm}相对较低，CDOM以陆源输入为主，其类腐殖质的芳香化程度较高，结构相对稳定而不易降解.⑥CCA（Canonical Correspond Analysis，典范对应分析）结果表明，DOC与CDOM吸收特性存在较好的相关性，河口CDOM主要来自地表径流，温度和DO是影响CDOM时空分布的主要因素.研究显示，CDOM的组成、降解的难易程度与来源密切相关，秋季生物量丰富，水体中腐殖酸所占比例增大，CDOM芳香度较高，不容易被降解. 

Optical Absorption Properties of CDOM at the Estuaries of Jiaozhou Bay

In order to demonstrate the relative contribution of organic carbon from rivers to the Jiaozhou Bay and associated environmental factors, water samples were collected in each two months, and dissolved organic carbon (DOC), particle organic carbon (POC) and UV-vis absorption of chromophoric dissolved organic matter (CDOM) were analyzed from April 2016 to February 2017 at the estuaries of Jiaozhou Bay. The results showed that:(1) DOC and POC ranged at 0.98-32.75 and 0.13-22.40 mg/L at the estuaries of Jiaozhou Bay, respectively, in which higher contents were located in Licun estuary and lower contents in Lundu and Dagang areas. (2) The absorption coefficient (a(355)) is between 0.23 and 16.35 m^-1, obvious seasonal differences among them, and negatively related with salinity, which presented similar patterns with those of DOC and POC. (3) Being used to indicate the molecular compositions, sources and aromatization degree of CDOM, the parameters of spectral slope ratio S_R(S_g(275-295 nm)/S_g(350-400 nm)) and absorbance ratio A_{250 nm}/A_{365 nm} significantly varied in space and time. (4) S_R values were relative higher in Lundu, Dagang, Banqiaofang estuary and Loushan estuary, where CDOM tended to be composed by protein or fulvic acid substances. Meanwhile, the whole molecular weight of CDOM in summer and autumn is higher than that in spring and winter. (5) A_{250 nm}/A_{365 nm} ratios stayed higher in Lundu, Dagang and Lianwan estuary, where like-humus presented in lower aromatization degrees and CDOM compositions were primarily controlled by production in situ in seawaters. A_{250 nm}/A_{365 nm} at the other estuaries were relative low, where CDOM compositions were mostly contributed by the terrestrial input with higher aromatization degrees, implying that CDOM were more stable and hard to be degraded. (6) CCA analysis show that CDOM absorption closely correlated with environmental factors. It was suggested that, CDOM at the estuaries of Jiaozhou Bay were significantly contributed by riverine input, and temperature and DO greatly impacted on the CDOM special and temporal distributions. The research shows, it existed closely relationship among the composition and degradation degree and sources of CDOM. In autumn, the proportion of humic acid in water increased because of abundant biomass, and the aromaticity of CDOM increased, and not easy to be degraded.