@article{1006,
  author = {A.N. Knapp and D.M. Sigman and F. Lipschultz},
  title = {N isotopic composition of dissolved organic nitrogen and nitrate at the Bermuda Atlantic Time-series study site},
  abstract = {To better constrain the dynamics of the dissolved organic nitrogen (DON) pool and the role of N2 fixation in the nitrogen cycle at the Bermuda Atlantic Time-series Study (BATS) site, we measured the 15N/14N ratio of total nongaseous nitrogen (TN) in the upper 250 m and of nitrate in the upper 1000 m of monthly water column profiles from June 2000 through May 2001. The annually averaged TN δ15N in the upper 100 m is 3.9{\textperthousand}, which is greater than thermocline nitrate (2-3{\textperthousand} at 250 m) and similar to literature values for shallow sinking nitrogen at BATS (3.7{\textperthousand}). We discern no seasonal variation in TN δ15N, which suggests that most of the DON pool is recalcitrant on this timescale. The TN data require a δ15N for the sinking flux that is similar to previous measurements, suggesting that N2 fixation is a minor component of new nitrogen at BATS. Small but measurable differences in the concentration and 15N/14N of total organic nitrogen (TON) between the surface and subsurface (\~{}250 m) suggest that subsurface remineralization of \~{}0.25 μM of the surface TON acts to lower the 15N/14N of nitrate in the thermocline at BATS. Copyright 2005 by the American Geophysical Union.},
  year = {2005},
  journal = {Global Biogeochemical Cycles},
  volume = {19},
  number = {1},
  pages = {1-15},
  url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-20444376946\&doi=10.1029\%2f2004GB002320\&partnerID=40\&md5=b1e8fbfa79c0ef69617bd39e2251a6db},
  doi = {10.1029/2004GB002320},
  note = {ps_limited_html},
}