Technical Note: A simple method for air–sea gas exchange measurements in mesocosms and its application in carbon budgeting

[摘要] Mesocosms as large experimental units provide the opportunity to performelemental mass balance calculations, e.g. to derive net biological turnoverrates. However, the system is in most cases not closed at the water surfaceand gases exchange with the atmosphere. Previous attempts to budget carbonpools in mesocosms relied on educated guesses concerning the exchange ofCO₂ with the atmosphere. Here, we present a simple method for precisedetermination of air–sea gas exchange in mesocosms using N₂O as adeliberate tracer. Beside the application for carbon budgeting, transfervelocities can be used to calculate exchange rates of any gas of knownconcentration, e.g. to calculate aquatic production rates of climaterelevant trace gases. Using an arctic KOSMOS (Kiel OffShore Mesocosms for future OceanSimulation) experiment as an exemplary dataset, it is shown thatthe presented method improves accuracy of carbon budget estimatessubstantially. Methodology of manipulation, measurement, data processing andconversion to CO₂ fluxes are explained. A theoretical discussion ofprerequisites for precise gas exchange measurements provides a guideline forthe applicability of the method under various experimental conditions.

[学科分类] 地球化学与岩石