Trace element inventory for the northern Chesapeake Bay with emphasis on the influence of man

For the northern half of the Chesapeake Bay. Maryland, an evaluation has been made of the relative importance of various human and natural sources of Cr, Mn, Fe, Co, Ni, Cu, Cd, Zn, and Pb. For rive of these (Mn, Fe, Co, Ni, and Zn) river discharge, shore erosion and salt water advection from the oceans account for more than half of the total input. On the other hand, the principal source for Cr and Cu is direct industrial discharge, for Cd is municipal wastewater, and for Pb is atmospheric dust and rain. In the subestuary of Baltimore Harbor, industry is the major contributor of all the elements except Cd and Pb, which again come mostly from wastewater and the atmosphere, respectively. Estimates of the removal of these elements by sedimentation suggest that less than $\text{1}\text{3}$ of the annual input of each metal is removed, except in the case of Cr and Fe where more than $\text{2}\text{3}$ is removed. These results suggest that human enhancement of normal input rates for these elements has the potential to produce a regional rather than merely a local biologic impact. It is of interest that for most of the elements, the percentage of the total input that is retained in the sediments is similar for heavily stressed Baltimore Harbor as it is for the northern Bay system as a whole.