80
deep ocean water is isotopically enriched and averages δ
15
N of about +4.5–5‰.
This average represents the balance between the isotopic signatures of N input
(e.g. N 2 fixation) and removal (e.g. denitrification) terms. Estimates of basin scale
and global rates of N 2 fixation and denitrification have been derived by box models
of mixing for these sources (Brandes and Devol 2002).
Fig. 5.6 Shifts in isotope signatures in the food web based on deep nitrate versus N 2 fixation.
(Figure from J. Montoya with permission)
5 Measurements of Organism Abundances and Activities
deep ocean water is isotopically enriched and averages δ
15
N of about +4.5–5‰.
This average represents the balance between the isotopic signatures of N input
(e.g. N 2 fixation) and removal (e.g. denitrification) terms. Estimates of basin scale
and global rates of N 2 fixation and denitrification have been derived by box models
of mixing for these sources (Brandes and Devol 2002).
Fig. 5.6 Shifts in isotope signatures in the food web based on deep nitrate versus N 2 fixation.
(Figure from J. Montoya with permission)
5 Measurements of Organism Abundances and Activities