145
Explanations for the apparent imbalance in basin-scale rates were that there were
(1) unidentified sources and organisms, (2) errors in the measurements (e.g. large
overestimates of denitrification), or (3) the budget was indeed unbalanced (Codispoti
et al. 2001; Codispoti 2007). An imbalanced budget has important implications for
contemporary marine productivity and greenhouse gas production and consumption
(Jickells et al. 2017). However, an imbalanced N budget is improbable over long
time scales without major effects on ocean productivity which are not evident from
paleooceanographic studies; recent budgeting exercises indicate a lower imbalance
if any (Gruber 2008).
Table 8.1 (continued)
References
Realm
Approach/notes
Tg N y
−1
Großkopf et al. (2012) N & S Pacific basins SWMAR
63
Indian Ocean
Galloway et al. (2004) Indian
Scaled from BS- DM,
waters >20 °C
19 ± 20
Großkopf et al. (2012) N & S Indian basins SWMAR
26
Arctic
Sipler et al. (2017)
3.5
Benthic
Soderlund and
Svensson (1976)
Benthic
10
Capone and Carpenter
(1982)
Benthic
Scaled from DM
15
Acronyms: BS-DM Basin-specific direct measurements, AMAR Arithmetic mean areal rate, GMAR
Geometric mean areal rate, SWMAR Station-weighted mean areal rates
Fig. 8.1 N fluxes in the marine environment in Tg y
−1
8 N 2 Fixation in Ocean Basins