TOXIC POLLUTANTS 
by 
Dr. James G. Sanders 
Academy of Natural Sciences 
Dr. Sanders: Thank you. Bob. I, too, will be brief. 
Because of time limitations, I can only begin to identify the 
problems that we have with inorganic compounds. Therefore, I will 
focus only on metals and metal loadings. In the next 10 minutes 
I'd like to present three different points: 
1. Anthropogenic inputs of toxic trace metals to the Chesa¬ 
peake Bay equal, and in some cases exceed, natural in¬ 
puts . 
2. A substantial fraction of many of these metals become 
associated with the Bay's sediments, thereby remaining 
and accumulating within the main stem of the Chesapeake 
Bay. 
3. The cause-and-effect relationships between elevated 
metal levels and organism toxicity have not been well 
established. However, there are strong indications that 
sub-lethal impacts currently occur. 
Anthropogenic and Natural Inputs 
Trace metal loadings to rivers are a mixture of both natural 
weathering of rocks and soils plus some man-derived inputs. An 
examination of the major tributaries in the Chesapeake Bay made 
during the Chesapeake Bay Program and comparison with studies 
from the early 1960s have shown that loadings have not changed 
significantly between the mid-1960s and today. 
Indeed, if we compare the metal loadings that we see in the 
major tributaries to what we might call worldwide, "average" 
uncontaminated river water, we see that they compare rather well 
(Table 1). However, the rivers themselves are not the only 
source of toxic metals in the Bay. There are several other 
significant sources. Table 2, which was taken directly from the 
Chesapeake Bay Program's technical synthesis, indicates that 
large quantities of cadmium, copper, chromium, lead, and zinc 
are entering in industrial and waste water effluents and in 
atmospheric emissions. These inputs are approximately equal to 
inputs from rivers (Table 2). 
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