Marine scavenging: The relative importance of mass transfer and reaction rates

We present an analysis of factors regulating the scavenging rate of trace elements and nutrients by settling particles in the ocean. The overall process limiting marine scavenging rates is determined by comparing the relative kinetics of dissolved phase mass transfer and particle‐associated sorption rates. Measured scavenging and uptake rates of a variety of marine particle types are then compared to theoretically calculated mass transfer rate constants. Our calculations show that for most marine environments, sorption rates arc much slower than external mass transfer of dissolved species. External mass transfer is therefore not the limiting process. Particle‐associated processes such as adsorption, intraparticle reactions, and particle repackaging must control the overall scavenging rates observed in the ocean.