Exasperated student had a point.

• Author: Hill, Marquita K.
• Position: On the Ecology of Meat, GM Crops, and the Embodied Energy in a Car - Letter to the Editor

In "Ocean Dead Zones Multiplying" (Environmental Intelligence, July/August 2004), you say dead zones "occur when high concentrations of nitrogen build up in marine waters." Several years ago, in a University of Maine class on environmental pollution, I carelessly spoke of the increase of nitrogen in the environment. An exasperated student confronted me, saying, "You can't increase the amount of nitrogen." Of course, he was right. After that I was careful, when speaking of eutrophication, etc., to refer to the increase in fixed or bio-nitrogen. Students knew the difference between the increase in fixed nitrogen...