RESUMO
Carbon budgets of hydrothermal plumes result from the balance between carbon sinks through plume chemoautotrophic processes and carbon release via microbial respiration. However, the lack of comprehensive analysis of the metabolic processes and biomass production rates hinders an accurate estimate of their contribution to the deep ocean carbon cycle. Here, we use a biogeochemical model to estimate the autotrophic and heterotrophic production rates of microbial communities in hydrothermal plumes and validate it with in situ data. We show how substrate limitation might prevent net chemolithoautotrophic production in hydrothermal plumes. Elevated prokaryotic heterotrophic production rates (up to 0.9 gCm-2y-1) compared to the surrounding seawater could lead to 0.05 GtCy-1 of C-biomass produced through chemoorganotrophy within hydrothermal plumes, similar to the Particulate Organic Carbon (POC) export fluxes reported in the deep ocean. We conclude that hydrothermal plumes must be accounted for as significant deep sources of POC in ocean carbon budgets.
Assuntos
Biomassa , Processos Heterotróficos/fisiologia , Fontes Hidrotermais/microbiologia , Oceanos e Mares , Ciclo do Carbono , Crescimento Quimioautotrófico/fisiologia , Fontes Hidrotermais/química , Microbiota , Modelos Teóricos , Células Procarióticas/metabolismo , Água do Mar/química , Água do Mar/microbiologiaRESUMO
We address the problem of cyclone-anticyclone asymmetry in geophysical turbulence using a direct numerical simulation with high Reynolds number Reâ¼15,000 that includes an active upper boundary and interior dynamics. The regime, characterized by a finite Rossby number (Roâ¼0.6) strongly departs from the classical quasigeostrophic regime. The numerical resolution is pushed to the limit of today's supercomputer capabilities ensuring more than two decades free of viscous effects. The results show a strong cyclonic dominance in the upper layers that is stronger for filaments than for vortices. This is in contrast with similar studies that have no active upper boundary which reported either anticyclone dominance or a symmetry between cyclones and anticyclones in the upper layers. This highlights the impact of boundary dynamics on geophysical turbulence.
