Nutrient Cycles during the Permian-Triassic transition (NUC)

人为的海洋变暖预计将导致海洋分层增加和海洋内部溶解氧的减少，对营养循环、初级生产力、碳循环和海洋生物栖息地产生影响。二叠纪-三叠纪(P-T)时间间隔可以被视为现代气候变化的极端情况。它不仅见证了显生界最灾难性的大规模灭绝，而且伴随着8至10°C的低纬变暖和全球广泛的海洋缺氧。该项目旨在重建全球变暖对二叠纪末期至三叠纪早期海洋的营养循环和初级生产力的影响，并记录这些变化是否对动物群的灭绝/恢复产生了影响。氮、磷和硅的循环将通过将地球化学代理重建与最先进的地球系统模拟相结合来研究。我们将检验以下假设：(I)早三叠世的生产力不受磷酸盐的限制，(Ii)铵是早三叠世海洋中营养氮的主要形式，以及(Iii)较高的海洋温度导致了早三叠世的硅质岩缺口。虽然生成的替代记录将代表海洋特定部分的条件，但全球生物地球化学模拟将以相对较高的空间分辨率提供关于营养物质分布和有效性的全球视角。其他Tersane 2.0项目将使用替代记录和时空营养重建来测试营养水平的变化是否会影响生物的灭绝风险、特定生物的身体大小或导致P-T危机期间的纬向灭绝模式。

Anthropogenic ocean warming is expected to result in increased ocean stratification and a decline in dissolved O2 in the ocean interior with implications for nutrient cycling, primary productivity, carbon cycling and marine habitats. The Permian–Triassic (P-T) time interval can be seen as an extreme case analogue to the modern climate change. It not only witnessed the most catastrophic mass extinction of the Phanerozoic, but was accompanied by 8 to 10° C low latitudinal warming and extensive global ocean anoxia. The project aims to reconstruct the effect of global warming on nutrient cycles and primary productivity in latest Permian to Early Triassic oceans and to document whether these changes may have had an impact on faunal extinction/recovery. Nitrogen, phosphorus and silicon cycles will be studied by combining geochemical proxy reconstruction with state-of the art Earth System modeling. We will test the hypotheses that (i) Early Triassic productivity was not limited by phosphate, (ii) ammonium was a main form of nutrient-N in Early Triassic oceans, and, (iii) higher ocean temperatures caused the Early Triassic chert gap. While the generated proxy records will represent the conditions in specific parts of the oceans, global biogeochemical modeling will provide a global view on nutrient distribution and availability with a relatively high spatial resolution. The proxy records as well as spatiotemporal nutrient reconstructions will be used by other Tersane 2.0 projects to test whether altered nutrient levels impacted on the extinction risk of organism, the body size of specific organisms or resulted in latitudinal extinction patterns during the P-T crisis.