近日，澳大利亚国立大学Udara Amarathunga团队研究了赞克斯特大洪水后地中海的短暂氧合。2025年8月18日出版的《美国科学院院刊》发表了这项成果。

地中海盆地在5.33 Myr之前，在之前的墨西尼亚盐度危机（5.97 ~5.33 Myr）期间部分干燥后，与大西洋重新连接。尽管人们对最终的墨西尼亚下降程度和重新连接的突然性仍有争议，但最近的研究推断，地中海东部一个异常持久的富含有机物的“神秘浅水推进层”是由于灾难性洪水重新填充盆地后的盐度分层和缺氧而沉积的。然而，需要独立的证据来验证这一假设。

研究组提供了大量的代理数据和数值模型结果来表明，无论在墨西尼亚末期提出的高盐或低盐条件如何，东地中海由于约1.5公里高的湍流和加气梯级重新填充盆地而变得含氧，这创造了一个盐度分层但含氧的水柱，只允许保存最顽固的有机成分。接下来，由于下沉的有机物的再矿化作用，氧气在长达12,000年的时间内逐渐耗尽，最终形成分层的缺氧盆地。洪水过后，湍流扩散用了33,000个小时（比先前认为的时间长了7,000个小时）才削弱了分层，并实现对流深水恢复更新，这标志着整个地中海最终恢复了正常的含氧海洋条件。

附：英文原文

Title: Transient oxygenation of the Mediterranean after the Zanclean megaflood

Author: Amarathunga, Udara, Brocks, Jochen J., Meijer, Paul Th., Hope, Janet M., Zachariasse, Willem-Jan, Hennekam, Rick, van der Hoeven, Isabel, Roehl, Ursula, Rule, Susan, Troitzsch, Ulrike, Haberle, Simon, Sluijs, Appy, Grant, Katharine M., Krijgsman, Wout, Garcia-Castellanos, Daniel, Hogg, Andrew McC., Reichart, Gert-Jan, Roberts, Andrew P., Rohling, Eelco J.

Issue&Volume: 2025-8-18

Abstract: The Mediterranean basin reconnected to the Atlantic Ocean ~5.33 Myr ago, following its partial desiccation during the preceding Messinian salinity crisis (5.97 to 5.33 Myr). While the extent of terminal Messinian drawdown and abruptness of reconnection are debated, recent work inferred that an anomalously long-lasting eastern Mediterranean organic-rich “mystery sapropel” layer was deposited due to salinity-stratification and anoxia following catastrophic flooding that refilled the basin. However, independent evidence is required to test this hypothesis. Here, we present extensive proxy data and numerical model results to show that irrespective of the largely hypersaline or oligohaline conditions proposed for the terminal Messinian, the eastern Mediterranean became oxygenated due to the ~1.5-km-high, turbulent and aerated cascade that refilled the basin, which created a salinity-stratified but oxygenated water column that allowed preservation of only the most recalcitrant organic components. Next, oxygen was gradually depleted over a period of up to 12,000 y due to remineralization of sinking organic matter, culminating in a stratified, anoxic basin. It took 33,000 y after flooding (7,000 y longer than suggested previously) for turbulent diffusion to weaken the stratification and allow resumption of convective deep-water renewal, which marked the final return of normal oxygenated marine conditions throughout the Mediterranean.

DOI: 10.1073/pnas.2505429122

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2505429122