FYI -- I guess I'm not the only one wondering where the nitrogen went! (See previous posting on the possibility of the Earth losing a significant portion of its atmosphere in the "k-T event" ~60 million years ago.) http://scientistatwork.blogs.nytimes.com/2011/03/23/where-has-all-the-nitrog... Scientist at Work - Notes From the Field March 23, 2011, 2:06 pm Where Has All the Nitrogen Gone? By ALYSON SANTORO Alyson Santoro, a postdoctoral researcher at Woods Hole Oceanographic Institution, writes from off the coast of Chile, where she is studying microbes in the nitrogen cycle. The federal government isnÂt the only group with a problem balancing its budget these days. Oceanographers have a budget problem too. Nitrogen  an essential nutrient for all life on the planet  is at the heart of this budget crisis. Some estimates of the amount of nitrogen leaving the ocean exceed estimates of the amount of nitrogen coming in by several hundred teragrams (thatÂs one billion kilograms) per year. Does this mean that the ocean is actually losing nitrogen? Probably not, but it does mean that we donÂt have a good understanding of where in the ocean nitrogen is coming and going. Over the next five weeks, I will be joining a team of researchers from around the world on a research cruise to the eastern tropical South Pacific off the coast of Chile to see if this could be one area where the Âmissing nitrogen could be entering the ocean. ...