| 摘要: |
| 本文以2021年5月长江口南北支采集的表层水为研究对象,通过测定氢、氧同位素,溶解有机碳(DOC)浓度,有色溶解有机质(CDOM)的吸收光谱和荧光光谱参数,探讨了夏季长江口北支、南支(北港、北槽、南槽)水体溶解有机质的组成、分布及其影响因素。沿长江下游到河口近海,南、北支DOC浓度分别为1.68±0.16mg/L和1.46±0.31mg/L,CDOM的吸光系数a350分别为2.37±0.61m-1和1.59±0.24m-1。南支整体具有“高类腐殖质、低类蛋白”的特征,北支则具有“低类腐殖质、低类蛋白”的特征,这可能与南北支的径流量差异有关。在南北支不同分汊河道(北支、南支北港、南支北槽和南支南槽)中,南槽和北支有类似的海水入侵特征,但南槽具有较强的类蛋白组分输入,而南支北港和北槽样品间无显著差异,均表现为河流有机质为主的特征。对比2011年长江南北支DOC和CDOM数据显示,作为长江主河道的南支在2021年无明显变化,而北支有显著的变化。这些结果综合表明长江口DOM的变化格局可能受水动力条件(径流量)、人类活动因素共同作用的影响。比较全球河口DOC和CDOM浓度数据后发现,不同区域的河口具有明显的差异,这可能是因为不同流域在植被覆盖、工农业生产水平、水利工程强度、以及气候变化对土壤侵蚀作用等方面的差异。 |
| 关键词: 长江口 溶解有机质 有色溶解有机质 水动力 海水入侵 人类活动 |
| DOI：10.11759/hykx20220618001 |
| 分类号:P734.5 |
| 基金项目:国家自然科学基金项目(41676058) |
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| Comparative study on dissolved organic matter in the north and south branches of the Changjiang River Estuary in summer |
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GUO Li-xia, WANG Ya-song, QIAO De-hui, HAN Lu-lu, YU Jian-chun, XU Yun-ping
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College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China
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| Abstract: |
| This study measured multiple parameters, such as hydrogen and oxygen isotopes, dissolved organic carbon (DOC) concentration, and the absorption and fluorescence spectra of chromophoric dissolved organic matter (CDOM), in surface water samples collected from the Changjiang River Estuary in May 2021. On the basis of these data, we discuss the composition, distribution, and influencing factors of DOM in the north and south branches (the latter branch is further divided into the North Channel, North Passage, and South Passage). The DOC concentration in the north and south branches is 1.68±0.16 mg/L and 1.46±0.31 mg/L, respectively, whereas the a350 value is 2.37±0.61 m-1and 1.59±0.24 m-1, respectively. The south and north branches are generally characterized by “high humus and low protein” and “low humus and low protein” respectively, which may be related to the difference in the runoff between these branches. Of the four passages, the South Passage and North Channel receive substantial seawater intrusion, but the former has stronger protein-like component inputs reflected by specific fluorescent components, whereas the North Channel and North Passage in the south branch present typical river-dominated DOM characteristics. The comparison of DOC and CDOM in the Changjiang River Estuary between our study (2021) and the literature (2011) reveals much larger amplitude variability in the north branch compared with the south branch. These results are likely attributable to different hydrodynamic conditions (runoff) and human activities. A comparison with published data for global estuaries suggests apparent differences in DOC and CDOM concentrations, which are likely related to differences in vegetation cover, industrial and agricultural production levels, hydraulic engineering intensity, and the impacts of climate change on soil erosion in river basins in different regions. |
| Key words: Changjiang River Estuary dissolved organic matter chromophoric DOM (CDOM) hydrodynamic force seawater intrusion human activity |
