美国耶鲁大学Mojtaba Fakhraee团队报道了海水硫酸盐动力学和地球系统的新临界点。这一研究成果发表在2024年9月25日出版的国际学术期刊《地质学》上。

据介绍，在整个地球历史中，海水硫酸盐(SO₄^2-)的浓度随着大气和海洋氧化还原动力学的变化，已经发生了数量级的变化。然而，仍然缺乏一个基于质量平衡原理的限制海水SO₄^2-动力学的基本模型。

通过动态系统方法来确定全球源和汇强度对海水SO₄^2-浓度的影响，研究人员对SO₄^2-质量平衡的随机分析揭示了两种最可能的海水SO₄^2-浓度范围：一个是在广泛的海洋缺氧条件下与SO₄^2-浓度为<1000μM，另一个是在广泛充氧的海洋条件下，SO₄^2-浓度在10,000μM左右或以上。

显生宙期间，这两种海水SO₄^2-之间的波动浓度范围非常明显，是对反复发生的海洋缺氧事件的反应。研究还确定了海洋缺氧程度的阈值，超过该阈值的海水SO₄^2-浓度骤降至1000μM，并对全球生物地球化学循环、生物和气候产生相应的影响。

附：英文原文

Title: Seawater sulfate dynamics and a new tipping point in the Earth system

Author: Mojtaba Fakhraee, Kohen W. Bauer, Sean A. Crowe

Issue&Volume: 2024-09-25

Abstract: Seawater sulfate (SO₄^2-) concentrations have changed by orders of magnitude in response to atmospheric and ocean redox dynamics throughout Earth’s history. A fundamental model that constrains seawater SO₄^2- dynamics based on the principles of mass balance, however, is still lacking. Here, we used a dynamical systems approach to determine the effects of global source and sink strengths on seawater SO₄^2- concentrations. Our stochastic analysis of the SO₄^2- mass balance revealed two most probable seawater SO₄^2- concentration ranges: one under widespread oceanic anoxic conditions with SO₄^2- concentrations <1000 μM, and the other with SO₄^2- concentrations around or above 10,000 μM under widely oxygenated ocean conditions. Swings between these two seawater SO₄^2- concentration ranges are notably evident during the Phanerozoic Eon and developed in response to reoccurring oceanic anoxic events. We also identified a threshold for the extent of oceanic anoxia above which seawater SO₄^2- concentrations collapse to <1000 μM, with corresponding impacts on global biogeochemical cycles, biology, and climate.

DOI: 10.1130/G52228.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G52228.1/648694/Seawater-sulfate-dynamics-and-a-new-tipping-pointredirectedFrom=fulltext