Industrial and municipal point sources of contaminants are scattered along the shores of Chesapeake Bay and its tributaries, but reach especially high density at Norfolk, Va., and Baltimore, Md. Sedimentation and various chemical processes in many cases conspire to restrict the water-borne transport of contaminant away from point source . Kepone, residual chlorine, volatile halogenated hydrocarbons, and anthropogenic trace metals are well-studied example of point-source contaminants. For the most part, their concentration in water and sediment drop to nearly immeasurable values within a distance of a few kilometers, or sometimes a few tens of kilometers, from their source .
On the other hand, certain contaminants have now been shown to be truly regionally dispersed. Included are polychlorinated biphenyls, phthalate esters, anthropogenic trace metal (Cu, Zn, Pb), polycyclic aromatic hydrocarbons, herbicides and weapon derived radionuclides. Most of these enter the Bay in significant amount from the atmosphere. Thus their dispersion throughout the Bay is not dependent on aquatic tranport processes. Although it is tempting to link the existence of this regional contamination with well publicized regional biological problem , no link has yet been proven.https://scholarworks.wm.edu/vimsbooks/1058/thumbnail.jp
