Mitigation of Extreme Ocean Anoxic Event Conditions by Organic Matter Sulfurization
Mitigation of Extreme Ocean Anoxic Event Conditions by Organic Matter Sulfurization
复制标题
DOI：
10.1029/2018pa003470
复制
发表时间：
2019-04-01
影响因子：
3.5
通讯作者：
Ridgwell, A.
中科院分区：
文献类型：
--
作者：
Hulse, D.;Arndt, S.;Ridgwell, A.
过去发生的海洋大面积严重缺氧经常与水体中存在大量游离硫化氢（H2S）的地质证据有关，即所谓的常氧条件。游离的 H2S 可能与通过水柱和海洋沉积物沉降的有机物的化学结构发生反应并改变其化学结构，这对碳封存具有假设的影响。在这里，我们以海洋缺氧事件2为例，通过地球系统建模探讨有机物硫化对海洋碳氧循环的潜在影响。我们的模型实验表明，水体中有机物的快速硫化（k(sulf) >= = 10(5) M-1year(-1)）可以使海洋沉积物中有机碳的保存和埋藏提高30%以上，从而有助于加速气候变冷和海洋缺氧事件2的恢复。由于有机物硫化，我们还发现 H2S 可以被迅速清除，并且常生海洋体积减少高达 80%，有助于海洋再充氧，并减少有毒 H2S 排放到大气中，这对二叠纪末期的杀灭机制具有潜在影响。最后，我们发现，有机物硫化的增加会引起一系列额外的反馈，包括大气中二氧化碳的进一步减少和海洋的再氧化，因为随着硫化氢被清除和埋藏，海洋中产生了以前未被识别的碱度净源。
Past occurrences of widespread and severe anoxia in the ocean have frequently been associated with abundant geological evidence for free hydrogen sulfide (H2S) in the water column, so-called euxinic conditions. Free H2S may react with, and modify, the chemical structure of organic matter settling through the water column and in marine sediments, with hypothesized implications for carbon sequestration. Here, taking the example of Ocean Anoxic Event 2, we explore the potential impact of organic matter sulfurization on marine carbon and oxygen cycling by means of Earth system modeling. Our model experiments demonstrate that rapid sulfurization (k(sulf) >= = 10(5) M-1 year(-1)) of organic matter in the water column can drive a more than 30% enhancement of organic carbon preservation and burial in marine sediments and hence help accelerate climate cooling and Ocean Anoxic Event 2 recovery. As a consequence of organic matter sulfurization, we also find that H2S can be rapidly scavenged and the euxinic ocean volume reduced by up to 80%-helping reoxygenate the ocean as well as reducing toxic H2S emissions to the atmosphere, with potential implications for the kill mechanism at the end-Permian. Finally, we find that the addition of organic matter sulfurization induces a series of additional feedbacks, including further atmospheric CO2 drawdown and ocean reoxygenation by the creation of a previously unrecognized net source of alkalinity to the ocean as H2S is scavenged and buried.