NITROGEN VS. PHOSPHORUS 
by 
Dr. Christopher D'Elia 
Chesapeake Biological Laboratory 
Dr. D'Elia: Before I begin, I have two comments. Dr. Eric 
Schneider, being concerned about the limited time available, put 
this big alarm clock in front of me figuring I could look at it and 
keep on schedule. 
Secondly, I hope everyone who is not a scientist understands 
that scientific controversies play an important role in science. 
We scientists are often perceived as being a contentious, 
disagreeable lot who can't really agree with each other, much less 
anybody who has any decisions to make. 
When I put today's program together and planned a session on 
scientific controversies, I wasn't doing so with a mind to showing 
people the disagreeable side of us scientists, but to show people 
that there are many things that we scientists don't know much about 
and that we need to understand more fully to be able to make 
informed decisions. So if we have arguments at all today, consider 
them friendly and constructive discussions among ourselves toward 
the goal of understanding things better. 
With that. I'll launch into my talk on the nitrogen-versus- 
phosphorus controversy, a very important one, I feel. 
I want to talk about the Patuxent River, which is merely a 
little tributary on the Western Shore of the Chesapeake. It is 
very far down on the list of tributaries in terms of its volume of 
flow. However, it has one very important characteristic; it is 
between two pretty big and important cities, Washington and 
Baltimore, and these cities represent the boundaries of a very 
expanding population center. As a result, there are all kinds of 
things happening in the Patuxent Basin that are indications of what 
might be happening to the rest of the Chesapeake. In fact, on a 
flow-weighted basis we're seeing an impact with sewage effluent 
that approximates what we've seen on the Potomac River. 
Figure 1 shows a trend that is not a very encouraging one. It 
depicts the daily rate of discharge of sewage effluent being 
discharged into the Patuxent River. Presently, it's a trickle 
relative to the Blue Plains effluent being discharged into the 
69 
