Large-scale mass balance for lead in southern Lake Michigan

Abstract

A large-scale, order-of-magnitude mass balance for lead in the near field of Chicago (the source) is presented. Both experimental data and simple physical modeling are used to estimate the transport of lead from the major sources to the near-field sinks of Southern Lake Michigan, its watershed soil, and the surroundings (losses from the system under question). The results show that atmospheric transport of lead aerosols to a sink like Lake Michigan is about two orders of magnitude greater than other transport mechanisms. To perform a detailed (small-scale) mass balance for lead, in support of the large-scale results, a complete model of atmospheric, aerosol transport and deposition is necessary and dominant. Although much work has been done on (free) turbulent dispersion of aerosols and aerosol deposition through precipitation, little is known about the dry deposition of aerosols from a turbulent boundary layer. An aerosol, turbulent dispersion model with a realistic boundary condition at the fluid-ground interface needs to be developed. A coordinated experimental program for measuring (dry) aerosol flux to the ground (and Lake) should be initiated.