FY 1991

A modeling study of the vertical distribution and transport of manganese in Puget Sound

Cudaback, C.N., A.J. Paulson, and J.W. Lavelle

NOAA Tech. Memo. ERL PMEL-93, NTIS: PB92-128644, 21 pp (1991)

A one-dimensional vertical distribution and transport model tracing the fate of Mn in dissolved and fine particulate forms and Mn associated with rapidly settling aggregates is developed and results are compared with measurements. Those measurements take the form of vertical profiles of dissolved and particulate Mn concentrations measured in the water column at one station in central Puget Sound. The model provides a framework relating sources, sinks, distributions and fluxes of Mn in a quantitative manner. The model accurately reproduces the vertical distributions of dissolved and particulate Mn, but shows excessive vertical flux of Mn. The model suggests that particles in each of two size classes should carry nearly the same loading of Mn, but measurements show significantly less Mn loading on macroaggregates than on fine particles. Mn budgets from model results allow comparison of major Mn fluxes in Puget Sound. The flux of Mn into the central main basin in particulate form is about half the diffusive flux of dissolved Mn from the bottom. A significant fraction of the riverine flux of particulate Mn is advected out of Puget Sound in dissolved form.