Deciphering riverine CO2 dynamics and driving factors coupled with dissolved organic carbon and nutrient status

被引：0
|
作者：
Zhang Y. [1 ]
Wang H. [1 ,2 ]
Ma Y. [3 ]
Du J. [1 ]
Long J. [1 ]
Lang J. [1 ]
Ni M. [1 ,2 ]
机构：
[1] College of Eco-Environmental Engineering, Guizhou Minzu University, Guiyang
[2] Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing
[3] Guizhou Provincial Engineering Geological Disaster Prevention and Control Engineering Research Center of Guizhou Minzu University, Guiyang
来源：
Hupo Kexue/Journal of Lake Sciences | 2024年 / 36卷 / 03期
关键词：
fluorescence peaks; nutrient elements; Pengxi River; principal component analysis; riverine carbon dioxide; Three Gorges Reservoir area;
D O I：
10.18307/2024.0326
中图分类号：
学科分类号：
摘要：
This study focused on the Pengxi River in the Three Gorges Reservoir area of China to comprehensively explore the correlation between dissolved organic carbon (DOC) and carbon dioxide (CO2) dynamics and their driving factors in rivers. Surface water samples were collected during the rainy and dry seasons. The parameters such as water temperature, pH, alkalinity and flow velocity, along with DOC concentration and nutrients (total nitrogen (TN) and total phosphorus (TP)) concentrations, were determined both in-situ and in the laboratory. The partial pressure of CO2 in the water body (/>CO2), CO2 flux across the water-air interface (F), and the stoichiometric ratios of nutrients (DOC -TN, DOC -TP, and TN:TP) were calculated. Based on the dynamics of CO2, DOC, and nulrient status in the river, a multidimensional analysis was conducted to establish and evaluate potential coupling relationships between DOC, TN, TP, nutrient stoichiometric ratios, and fluorescence peaks (B, T, A, M, C, D, and N) with river /)CO2. This approach aimed to reveal the characteristics of CO2 sources and driving factors in specific regional rivers. We showed that gas transfer velocity of CO2 ranged from 3.75 to 22.9 m/d, which was higher in the wet season ((9.91 ± 4.93) m/d) than that in the dry season ((6.69±4.30) m/d). RiverpC02 varied between 65.95-20642.41 jjiatni, yield an overall CO2 flux of (629.4±1426.8) mmol/(m *d). Aquatic DOC ranged within 1.42-7.88 mg/L, with a higher concentration in the dry season ((4.50+0.17) mg/L) in comparison to the wet season ((2.87±0.18) mg/L). Similarly, TN ranged from 0.176 to 1.917 mg/L, with a higher concentration in the dry season ((1.205±0.353) mg/L) compared to the wet season ((0.665±0.306) mg/L) . The overall TP concentrations were in the range of 0.0003-0.169 mg/L. The proportions of lyrosine-like compounds, tryp-lophan-like compounds, and fulvic acids were significantly higher in the wet season than in the dry season, while we observed the higher humic acids, microbial-derived humic acids and biological productivity in the dry season compared to wet season. During the dry season, />CO2 showed a significant positive correlation with TP, and a significant negative correlation with the stoichiometric ratios of nutrients (TN:TP and DOC:TP) . In contrast, during the rainy season, there was a significant negative correlation with biological productivity. This indicated a seasonal coupling relationship between nutrient status andpC02- These observations highlight that biological metabolism highly constrain CO2 supersaluration in the river, and seasonal rainfall modulate the causal relationship. © 2024 by Journal of Lake Sciences.
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页码：794 / 806
页数：12
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