题目 Title

Crucial Role of Tributary Bays in the Carbon Burial of Three Gorges Reservoir

期刊 Journal

ACS ES&T Water (IF=5.3)

作者 Author

Wang, K.; Huang, L.; He, G. J.; Liu, Y.; Xu, S.; He, D.; Bai, S.; Reible, D.; Fang, H. W.

摘要 Abstract

Tributary bays, which are formed in river tributaries for reservoir construction with a relatively lentic environment, have been estimated to hold unique biogeochemical processes and to be involved in ecological issues (e.g., algal bloom). Nevertheless, the role of tributary bays in carbon cycling is unclear, precluding an accurate assessment of the carbon budgets of reservoirs. To fill this knowledge gap, we take the Three Gorges Reservoir (TGR) as an example and assess the carbon budget of a typical tributary bay (Xiangxi River, XXR) of TGR. With laboratory experiments and numerical models, we demonstrate that XXR may be an important carbon sink. This study exhibits that primary productivity enhancement (e.g., algal bloom) in tributary bays plays a critical role in CO₂ sequestration and contributes significantly to carbon burial. Moreover, the organic carbon burial flux of tributary bays in TGR is estimated to be equivalent to (22 ± 9) % of that in the mainstream, demonstrating the crucial role of tributary bays in the carbon burial of TGR. Considering the scientific debate on whether the reservoir is a carbon sink or source, we suggest that the overlooking of tributary bays might lead to a significant error in assessing the reservoir carbon budget.

简介 Brief introduction

支流库湾是为了水库建设而在河流支流中形成的，具有相对静态的环境。支流库湾具有独特的生物地球化学过程，并且涉及生态问题（如：藻华等）。然而，支流库湾在碳循环中的作用尚不明晰，阻碍了对水库碳收支的准确评估。为了填补这一知识空白，我们以三峡库区为例，评估了三峡库区典型支流库湾——香溪河——的碳收支。室内实验和数值模型表明香溪河可能是一个重要的碳汇。

结果表明，支流库湾中的初级生产力增加（如：藻华等）在CO₂封存中起着关键作用，对碳埋藏有重要贡献。此外，据估计，三峡库区支流库湾的有机碳埋藏通量相当于干流的 (22 ± 9) % ，表明支流库湾在三峡库区碳埋藏中起着至关重要的作用。考虑到“水库是碳汇还是碳源”的科学争论，我们认为，忽视支流库湾可能会导致评估水库碳收支时出现重大偏差。

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