週二, 08 十一月 2022 15:29

[榮耀] 恭喜本系任昊佳教授榮登《PNAS》

Oceanic nutrient rise and the late Miocene inception of Pacific oxygen-deficient zones

Xingchen Tony Wang https://orcid.org/0000-0001-5316-789X Email住址會使用灌水程式保護機制。你需要啟動Javascript才能觀看它Yuwei WangAlexandra Auderset https://orcid.org/0000-0002-6316-4980, +8, and Woodward W. Fischer https://orcid.org/0000-0002-8836-3054Authors Info & Affiliations


Oxygen is critical to marine ecosystems. The ocean contains oxygen-deficient zones (ODZs) that have been expanding over the past several decades. Predicting future changes in ocean deoxygenation is important for marine ecosystems and human societies that rely on fisheries. Understanding the history of the ocean's oxygen content can provide important insights into how ODZs will behave in the future with climate change and increasing anthropogenic nutrient inputs. In this study, we found that the largest ODZs on our planet were much smaller eight million years ago than they are today. Furthermore, our observations revealed that the expansion of the ODZs was mainly driven by increasing oceanic nutrient content and primary productivity. This finding provides valuable context for ocean deoxygenation processes in the modern and future ocean.



The modern Pacific Ocean hosts the largest oxygen-deficient zones (ODZs), where oxygen concentrations are so low that nitrate is used to respire organic matter. The history of the ODZs may offer key insights into ocean deoxygenation under future global warming. In a 12-My record from the southeastern Pacific, we observe a >10‰ increase in foraminifera-bound nitrogen isotopes (15N/14N) since the late Miocene (8 to 9 Mya), indicating large ODZs expansion. Coinciding with this change, we find a major increase in the nutrient content of the ocean, reconstructed from phosphorus and iron measurements of hydrothermal sediments at the same site. Whereas global warming studies cast seawater oxygen concentrations as mainly dependent on climate and ocean circulation, our findings indicate that modern ODZs are underpinned by historically high concentrations of seawater phosphate.