Fluxes of particulate organic carbon in the East China Sea in summer

[摘要] To understand carbon cycling in marginal seas better, particulate organiccarbon (POC) concentrations, POC fluxes and primary production (PP) weremeasured in the East China Sea (ECS) in summer 2007. Higher concentrations ofPOC were observed in the inner shelf, and lower POC values were found in theouter shelf. Similar to POC concentrations, elevated uncorrected POC fluxes(720–7300 mg C m⁻² d⁻¹) were found in the inner shelf, andlower POC fluxes (80–150 mg C m⁻² d⁻¹) were in the outershelf, respectively. PP values (~ 340–3380 mg C m⁻² d⁻¹)had analogous distribution patterns to POC fluxes, while some of PP valueswere significantly lower than POC fluxes, suggesting that contributions ofresuspended particles to POC fluxes need to be appropriately corrected. Avertical mixing model was used to correct effects of bottom sedimentresuspension, and the lowest and highest corrected POC fluxes were in theouter shelf (58 ± 33 mg C m⁻² d⁻¹) and the inner shelf(785 ± 438 mg C m⁻² d⁻¹), respectively. The corrected POCfluxes (486 to 785 mg C m⁻² d⁻¹) in the inner shelf could be theminimum value because we could not exactly distinguish the effect of POC fluxfrom Changjiang influence with turbid waters. The results suggest that27–93% of the POC flux in the ECS might be from the contribution ofresuspension of bottom sediments rather than from the actual biogenic carbonsinking flux. While the vertical mixing model is not a perfect model to solvesediment resuspension because it ignores biological degradation of sinkingparticles, Changjiang plume (or terrestrial) inputs and lateral transport,it makes significant progress in both correcting the resuspension problemand in assessing a reasonable quantitative estimate of POC flux in a marginalsea.

[学科分类] 地球化学与岩石