| microbiological, molecular biological and stable isotopic evidence for nitrogen fixation in the open waters of lake michigan. | we have used a combination of microbiological, molecular biological and stable isotope methods to relate specific microbial populations to elemental cycling at an offshore site in lake michigan. several lines of evidence suggest that atmospheric n2 may be a significant source of nitrogen to the lake. particulate organic nitrogen (pon) at approximately equals 10-15m depth in july and october had a delta15n of 0.5-1.5%o. these values closely reflect the 15n composition of atmospheric n2, suggestin ... | 2001 | 11321537 |