Swept under the carpet: organic matter burial decreases global ocean biogeochemical model sensitivity to remineralization length scale

[摘要] Although of substantial importance for marine tracer distributions andeventually global carbon, oxygen, and nitrogen fluxes, the interactionbetween sinking and remineralization of organic matter, benthic fluxes andburial is not always represented consistently in global biogeochemicalmodels. We here aim to investigate the relationships between these processeswith a suite of global biogeochemical models, each simulated over millennia,and compared against observed distributions of pelagic tracers and benthicand pelagic fluxes.

We concentrate on the representation of sediment–water interactions incommon numerical models, and investigate their potential impact on simulatedglobal sediment–water fluxes and nutrient and oxygen distributions. We findthat model configurations with benthic burial simulate global oxygen wellover a wide range of possible sinking flux parameterizations, making themodel more robust with regard to uncertainties about the remineralizationlength scale. On a global scale, burial mostly affects oxygen in the meso- tobathypelagic zone. While all model types show an almost identical fit toobserved pelagic particle flux, and the same sensitivity to particle sinkingspeed, comparison to observational estimates of benthic fluxes reveals a morecomplex pattern, but definite interpretation is not straightforward becauseof heterogeneous data distribution and methodology. Still, evaluating modelresults against observed pelagic and benthic fluxes of organic matter cancomplement model assessments based on more traditional tracers such asnutrients or oxygen. Based on a combined metric of dissolved tracers andbiogeochemical fluxes, we here identify two model descriptions of burial assuitable candidates for further experiments and eventual model refinements.

[学科分类] 地球化学与岩石