<br>洪泛区的连通性影响河流碳逸出和溶解碳迁移,Science of the Total Environment

当前位置： X-MOL 学术 › Sci. Total Environ. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

洪泛区的连通性影响河流碳逸出和溶解碳迁移
Science of the Total Environment ( IF 8.2 ) Pub Date : 2024-03-08 , DOI: 10.1016/j.scitotenv.2024.171604
Y Jun Xu ₁ , Zhen Xu ₂ , Lee Potter ₃

Affiliation

河流不仅充当将陆地成分输送到海洋的渠道，而且还充当成分生物地球化学处理的重要介质。尽管人们对许多河流的碳迁移进行了广泛的研究，但人们对工程河流与洪泛区网络重新连接的碳转化知之甚少。作为堤坝封闭的密西西比河 (MR) 的最大支流，阿查法拉亚河 (AR) 承载着密西西比河 25% 的水量，流经北美最大的淡水沼泽盆地，最终注入墨西哥湾。此前的研究表明，这个长200公里、宽5-30公里的流域可以去除大量的河流营养物和有机碳。本研究旨在检验以下假设：当 AR 流经其广阔的洪泛区网络时，其向大气中排放的二氧化碳量明显高于堤坝限制的 MR。从 2019 年 1 月到 2021 年 12 月，我们在摩根城的 AR 下游和巴吞鲁日的密西西比河下游进行了每两周一次的现场测量。现场测量包括溶解二氧化碳 (CO) 分压、水温、叶绿素、有色溶解有机物、溶解氧、pH 值和浊度。在每次现场采样期间，收集水样并分析溶解的有机碳和无机碳（DOC 和 DIC）的浓度。对两条河流的 DOC 和 DIC 质量传输以及 CO 释放进行了量化。我们发现，AR 中的 CO 水平（平均值：3563 μatm；最小值-最大值：1130–8650 μatm）显着高于 MR 中的水平（1931 μatm，836–3501 μatm），导致 AR 中的 CO 释气率加倍。 AR (486 mmol md) 高于 MR (241 mmol md)。 AR 具有更高的 DOC（8.5 mg L），但与 MR（7.5 mg L 和 164.0 AFU）相比，叶绿素含量较低（153.9 AFU）。 AR 区的水温始终高于 MR 区，尤其是在冬季。由于密西西比-阿查法拉亚河系统是世界上最大、工程设计最完善的河流系统之一，我们的评估提供了实地案例研究，以了解重新连接河流与其洪泛区网络的潜在影响。

"点击查看英文标题和摘要"

Connectivity of floodplain influences riverine carbon outgassing and dissolved carbon transport

Rivers not only function as a conduit for the delivery of terrestrial constituents to oceans, but they also serve as an essential medium for biogeochemical processing of the constituents. While extensive research has been conducted on carbon transport in many rivers, little is known about carbon transformation in engineered rivers reconnected with their floodplain network. Being the largest distributary of the levee-confined Mississippi River (MR), the Atchafalaya River (AR) carries 25 % of the MR water, flowing through North America's largest freshwater swamp basin and emptying into the Gulf of Mexico. Previous studies reported that this 200-km long, 5–30-km wide river basin can remove a substantial amount of riverine nutrients and organic carbon. This study aimed to test the hypothesis that the AR emits significantly higher CO into the atmosphere as it flows through its extensive floodplain network than the levee-confined MR does. From January 2019 to December 2021, we conducted biweekly – monthly in-situ measurements in the lower AR at Morgan City and in the lower Mississippi River at Baton Rouge. Field measurements included partial pressure of dissolved CO (CO), water temperature, chlorophyll , colored dissolved organic matter, dissolved oxygen, pH, and turbidity. During each field sampling, water samples were collected and analyzed for concentrations of dissolved organic and inorganic carbon (DOC and DIC). Mass transport of DOC and DIC and outgassing of CO were quantified for the two rivers. We found that CO levels were significantly higher in the AR (mean: 3563 μatm; min-max: 1130–8650 μatm) than those in the MR (1931 μatm, 836–3501 μatm), resulting in a doubled CO outgassing rate in the AR (486 mmol m d) than in the MR (241 mmol m d). The AR had higher DOC (8.5 mg L) but lower chlorophyll (153.9 AFU) when compared with the MR (7.5 mg L and 164.0 AFU). Water temperature was constantly higher in the AR than in the MR, especially during the wintertime. Since the Mississippi-Atchafalaya River system is among the world's largest and most engineered river systems, our assessment offers a field case study to inform on the potential implications of reconnecting rivers with their floodplains networks.

更新日期：2024-03-08

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南