Turbidity Currents Can Dictate Organic Carbon Fluxes Across River-Fed Fjords: An Example From Bute Inlet (BC, Canada)
Turbidity Currents Can Dictate Organic Carbon Fluxes Across River-Fed Fjords: An Example From Bute Inlet (BC, Canada)
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浊流可以决定跨河流供水峡湾的有机碳通量：来自布特湾（加拿大不列颠哥伦比亚省）的一个例子
DOI：
10.1029/2022jg006824
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发表时间：
2022
期刊：
影响因子：
4.9
通讯作者：
Hage S
中科院分区：
文献类型：
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作者：
Hage S
海洋沉积物中陆地颗粒有机碳 (OC) 的输送和埋藏对于量化非常重要，因为这种 OC 是底栖生物群落的食物资源，如果埋藏，可能会降低地质时间尺度上大气二氧化碳的浓度。之前对沉积物岩心的分析表明，峡湾是有机碳埋藏的热点地区。峡湾可能包含由海底沉积物流（称为浊流）形成的复杂海底通道网络。然而，以前从未研究过河流供水峡湾中浊流的埋藏效率和 OC 分布。在这里，我们确定了加拿大西部峡湾布特湾内浊流系统的有机碳分布和埋藏效率。我们发现，两条河源提供的 OC 的 62% ± 10% 埋藏在峡湾表层（30-200 厘米）沉积物中。沙质亚环境（河道和波瓣）包含峡湾中年度陆地 OC 埋藏量的 63% ± 14%。相比之下，泥泞的子环境（河岸和远端盆地）包含剩余的 37% ± 14%。河道、波瓣和漫滩中的有机碳完全包括来自河流的陆地有机碳。当按峡湾表面积进行归一化时，与之前研究的其他峡湾的泥泞部分相比，布特湾埋藏的陆地有机碳至少多出三倍。尽管这种有机碳的长期（>100年）保存仍有待充分了解，但峡湾中的浊流似乎能够有效地将河流提供的有机碳储存在其近地表沉积物中。
The delivery and burial of terrestrial particulate organic carbon (OC) in marine sediments is important to quantify, because this OC is a food resource for benthic communities, and if buried it may lower the concentrations of atmospheric CO2over geologic timescales. Analysis of sediment cores has previously shown that fjords are hotspots for OC burial. Fjords can contain complex networks of submarine channels formed by seafloor sediment flows, called turbidity currents. However, the burial efficiency and distribution of OC by turbidity currents in river‐fed fjords had not been investigated previously. Here, we determine OC distribution and burial efficiency across a turbidity current system within Bute Inlet, a fjord in western Canada. We show that 62% ± 10% of the OC supplied by the two river sources is buried across the fjord surficial (30–200 cm) sediment. The sandy subenvironments (channel and lobe) contain 63% ± 14% of the annual terrestrial OC burial in the fjord. In contrast, the muddy subenvironments (overbank and distal basin) contain the remaining 37% ± 14%. OC in the channel, lobe, and overbank exclusively comprises terrestrial OC sourced from rivers. When normalized by the fjord’s surface area, at least 3 times more terrestrial OC is buried in Bute Inlet, compared to the muddy parts of other fjords previously studied. Although the long‐term (>100 years) preservation of this OC is still to be fully understood, turbidity currents in fjords appear to be efficient at storing OC supplied by rivers in their near‐surface deposits.