The Influence of Tides on the Content and Spectral Characteristics of Dissolved Organic Matter in the Tidal Section of the Minjiang River
Dissolved Organic Matter(DOM)only accounts for a small portion of organic matter in ecosystems,while it is easily utilized by microorganisms and plays a crucial role in nutrient supply and material cycling in river ecosystems.The dissolved organic matter in the water of tidal river sections is highly susceptible to the impact of tidal runoff changes,however there is still a lack of necessary un-derstandings.Taking the tidal section of the Minjiang River(117 km)as the research object,the con-tent and spectral characteristics of dissolved organic matter in the water during the rising and falling tide processes were analyzed on giant tide days.The results show that tidal effects significantly affect the content,structure,composition,and source of dissolved organic matter in water within a range of 20 km from the estuary.The increase in DOC content during the rising tide stage is 35.9%higher than that during the falling tide stage,and the decrease in CDOM concentration is 26.2%higher than that during the falling tide stage.During the rising tide stage,the molecular weight of dissolved organic matter near the estuary increases,while the degree of aromatization decreases and endogenous enhancement occurs.Comprehensive analysis suggests that tides mainly promote the physical process of mixing river water and seawater,affecting the water environment,dissolved organic matter content and stability,enhancing the correlation between pH,conductivity,salinity,dissolved oxygen and dissolved organic matter,but weakening the correlation between water temperature and dissolved organic matter.These results have certain scientific significance for a deeper understanding of the impact of tidal processes on river ecosystems and for understanding the material cycling laws of tidal river sections.
tidal effectsMinjiang Rivertide river sectiondissolved organic matterUV-visible spectrum
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NSTL
万方数据
