Thought this was interesting at the end of page 6 to see the nitrate uptake of Hornwort.
Code:
"In an experiment in which the initial nitrate concentration was 350 ppm, it reduced the concentration to 75 ppm in nine days, corresponding to a half-life of 4-5 days. It removed on average about 2 ppm per day per gram of plant..."
http://www.siu.edu/worda/igc/proceedings/01/larson.pdf