Contribution of nuclear applications to study the effects of reduced oxygen in coastal environments - Peter Swarzenski,

- Reduced penetration of O2 into deeper water due to enhanced stratification 2017 Gulf of Mexico Hypoxic Zone Size Gulf of Oman world’ largest Hypoxic Zone CONTEXT deoxygenation - Reduced oxygen (O2) solubility in warmer water. [...] - Reduced penetration of O2 into deeper water due to enhanced stratification observed in much of the global ocean OM respiration shifts to sp bacteria that use NO3 rather than O2 >> denitrification and N20 (300x) More sinking particles reach the deep ocean >> air / sea CO2 partitioning Warmer water = incr O2 demand CONTEXT deoxygenation increasing in number, volume, and intensity OMZs <2 mg liter−. [...] Science 2018;359:eaam7240 Globally distributed deoxygenation Potential consequences of ocean oxygen loss are profound: • reduced biological productivity and diversity, • altered animal behaviour, • declines in fisheries, redistributions of communities, • altered biogeochemical cycles, including • environmental feedbacks (e.g., increased production of N2O and CH4. [...] Diversity impacts deoxygenation via photosynthesis and respiration So a tracer of rate at which OM is produced, redistributed, and decomposed in the ocean >> biological pump O2 directly linked to carbon Contribution of nuclear applications to deoxygenation studies IAEA’ Radioecology Labs Monaco R A D I O T R A C E R S Contribution of nuclear applications to. [...] aquaria to assess st ress R A D I O T R A C E R S Regulating DO in experimental aquaria to assess s t r e s s R A D I O T R A C E R S Regulating DO in experimental aquaria Oberhänsli et al, in prep to assess s t r e s s R A D I O T R A C E R S .