Solubilization of Organic Particles Collected in Sediment Traps: Effect on Export Production Estimates

Abstract

Sinking organic particles may be a source of DOM to subeuphotic zone waters through particle solubilization or via particle grazing. If solubilization is significant, then particulate organic carbon and nitrogen flux into sediment traps could be underestimated, resulting in underestimates of export production. VERTEX-style sediment traps were deployed at 5 depths, ranging from 60 to 210 m, in Monterey Bay, CA, and DOC and DON accumulation in the supernatant of the traps was determined by high-temperature catalytic oxidation techniques. Our results show that by considering accumulated particles only, the export flux of carbon and nitrogen may be significantly underestimated at the. base of the euphotic zone. The increase in the DOC concentration of the trap supernatant was equivalent to a 57% increase in the organic carbon sedimentation flux at 60 m, while nitrogen export increased 94% when DON and NH₄ ⁺ were considered. The contribution of dissolved components to total flux decreased with depth such that the particle flux was a much better indicator of total flux at 210 m.