Ecosystem responses of two Permian biocrises modulated by CO2 emission rates
Ecosystem responses of two Permian biocrises modulated by CO2 emission rates
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DOI：
10.1016/j.epsl.2022.117940
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发表时间：
2023-01
影响因子：
5.3
通讯作者：
Wen-qian Wang;Feifei Zhang;Shuangbao Zhang;Ying Cui;Quan‐Feng Zheng;Yi‐chun Zhang;Dong-xun Yuan;Hua Zhang;Yi‐Gang Xu;S. Shen
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作者：
Wen-qian Wang;Feifei Zhang;Shuangbao Zhang;Ying Cui;Quan‐Feng Zheng;Yi‐chun Zhang;Dong-xun Yuan;Hua Zhang;Yi‐Gang Xu;S. Shen
二氧化碳（CO2）的排放和相关的气候变化被认为是造成了许多广泛的海洋缺氧和大规模灭绝事件在地质过去。然而，海洋生态系统如何应对不同的CO2排放模式仍然是一个重要的悬而未决的问题.二叠纪时期的地质记录见证了两次与火山爆发（因此是二氧化碳排放）有关的大规模喷发，但生物反应却截然不同，这为解决这一问题提供了一个独特的窗口。在这里，我们提出了一个长期的铀同位素（δ 238 U）记录使用的海洋石灰岩覆盖最新的早二叠世到中晚二叠世。δ 238 U值在卡匹坦期中期和长兴期晚期出现两次低值，表明二叠纪有两次海洋缺氧扩张期。我们使用铀同位素质量平衡模型来量化缺氧海底区域，我们进一步使用碳循环模型（LOSCAR，长期海洋沉积物碳库），基于观测到的海洋碳酸盐δ 13 C，海洋表面温度记录和海洋表面pH值数据来量化两次生物危机的碳排放率。铀同位素质量平衡模型显示，二叠纪末生物大灭绝（EPME）期间的缺氧海底面积是瓜达卢佩事件（EGE）期间的3倍，占海底面积的10%。LOSCAR模型模拟的两次生物危机的CO2排放速率表明，EPME期间的碳排放速率至少比EGE期间快5倍，输入源的最佳拟合δ 13 C值介于− 8 ‰至− 12‰之间，表明EPME期间的主要火山CO2源，EGE期间接近− 25‰。比较模型结果和观察到的代理数据导致的建议，更严重的生态系统的反应，在EPME期间，包括更高的灭绝率和更大程度的海底缺氧，是密切相关的更快的碳排放率相比，EGE。
Carbon dioxide (CO 2) emissions and associated climate change are thought to have caused a number of widespread marine anoxia and mass extinction events in the geologic past. However, how marine ecosystems respond to different CO 2 emission patterns remains an important unresolved question. The geologic records of the Permian Period, which witnessed two mass extinctions associated with volcanic eruption (thus CO 2 emissions) but with vastly different biological responses, provide a unique window to address this issue. Here, we present a long-term uranium isotope (δ 238 U) record using marine limestones covering the latest Early Permian through Middle to Late Permian. The δ 238 U values show two episodes of low values in the middle Capitanian and late Changhsingian, indicating two periods of expansion of marine anoxia during the Permian Period. We use a uranium isotope mass balance model to quantify the anoxic seafloor areas, and we further use a carbon cycle model (LOSCAR, Long-term Ocean Sediment Carbon Reservoir) based on observed δ 13 C of marine carbonates, sea surface temperature records, and ocean surface pH data to quantify the carbon emission rates across the two biocrises. The uranium isotope mass balance model reveals that the anoxic seafloor area is three times larger during the end-Permian mass extinction (EPME, covering∼ 35% of the seafloor areas) than that during the end-Guadalupian event (EGE, covering∼ 10% of the seafloor areas). The CO 2 emission rates across the two biocrises modeled from the LOSCAR model show that the carbon emission rate across the EPME was at least five times faster than that during the EGE, with the best-fit δ 13 C values of the input sources ranging from− 8 to− 12‰, indicating a predominant volcanic CO 2 source during the EPME, and close to− 25‰ during the EGE. Comparing model results and observed proxy data led to the suggestion that the more severe ecosystem responses during the EPME, including higher extinction rate and larger extent of seafloor anoxia, are closely linked to the faster carbon emission rates compared to the EGE.