Abstract
Recent geochemical estimates of N2-fixation in the North Atlantic ocean indicate rates that are significantly higher than those derived from direct observations. In this paper different N2-fixation rate scenarios are explored using a one-dimensional, biogeochemical model that includes an explicit representation of Trichodesmium. This model reproduces most of the observed interannual variability in phytoplankton production and generates seasonal Trichodesmium biomass and N2-fixation cycles similar to those observed at BATS. Two solutions are presented, one where the N2-fixation rate is increased enough to reproduce the observed summertime drawdown of DIC, and a second where it is tuned to reproduce the observed sediment trap fluxes. The high N2-fixation solution reproduces the seasonal and interannual variability in DIC concentrations quite accurately and generates N2-fixation rates that agree with direct rate measurements from 1990 and recent geochemical estimates. However, this solution generates export fluxes that are more than 4 times higher than those observed, and predicts the development of DON and DOC anomalies in late summer/early fall that have not been observed. In contrast, the low N2-fixation solution generates trap fluxes that are approximately correct, but overestimates the summertime DIC concentrations by 20-30 μmol/kg-1. Both solutions indicate that there is significant interannual variability in N2-fixation at BATS and that the rates were much lower in 1995-1996 than in the previous six years. It is suggested that this variability is linked to decadal-scale fluctuations in the North Atlantic climate.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1609-1648 |
| Number of pages | 40 |
| Journal | Deep-Sea Research Part II: Topical Studies in Oceanography |
| Volume | 48 |
| Issue number | 8-9 |
| DOIs | |
| State | Published - May 24 2001 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Oceanography
Cite this
Modeling the effect of nitrogen fixation on carbon and nitrogen fluxes at BATS. / Hood, Raleigh R.; Bates, Nicholas R.; Capone, Douglas G.; Olson, Donald.
In: Deep-Sea Research Part II: Topical Studies in Oceanography, Vol. 48, No. 8-9, 24.05.2001, p. 1609-1648.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Modeling the effect of nitrogen fixation on carbon and nitrogen fluxes at BATS
AU - Hood, Raleigh R.
AU - Bates, Nicholas R.
AU - Capone, Douglas G.
AU - Olson, Donald
PY - 2001/5/24
Y1 - 2001/5/24
N2 - Recent geochemical estimates of N2-fixation in the North Atlantic ocean indicate rates that are significantly higher than those derived from direct observations. In this paper different N2-fixation rate scenarios are explored using a one-dimensional, biogeochemical model that includes an explicit representation of Trichodesmium. This model reproduces most of the observed interannual variability in phytoplankton production and generates seasonal Trichodesmium biomass and N2-fixation cycles similar to those observed at BATS. Two solutions are presented, one where the N2-fixation rate is increased enough to reproduce the observed summertime drawdown of DIC, and a second where it is tuned to reproduce the observed sediment trap fluxes. The high N2-fixation solution reproduces the seasonal and interannual variability in DIC concentrations quite accurately and generates N2-fixation rates that agree with direct rate measurements from 1990 and recent geochemical estimates. However, this solution generates export fluxes that are more than 4 times higher than those observed, and predicts the development of DON and DOC anomalies in late summer/early fall that have not been observed. In contrast, the low N2-fixation solution generates trap fluxes that are approximately correct, but overestimates the summertime DIC concentrations by 20-30 μmol/kg-1. Both solutions indicate that there is significant interannual variability in N2-fixation at BATS and that the rates were much lower in 1995-1996 than in the previous six years. It is suggested that this variability is linked to decadal-scale fluctuations in the North Atlantic climate.
AB - Recent geochemical estimates of N2-fixation in the North Atlantic ocean indicate rates that are significantly higher than those derived from direct observations. In this paper different N2-fixation rate scenarios are explored using a one-dimensional, biogeochemical model that includes an explicit representation of Trichodesmium. This model reproduces most of the observed interannual variability in phytoplankton production and generates seasonal Trichodesmium biomass and N2-fixation cycles similar to those observed at BATS. Two solutions are presented, one where the N2-fixation rate is increased enough to reproduce the observed summertime drawdown of DIC, and a second where it is tuned to reproduce the observed sediment trap fluxes. The high N2-fixation solution reproduces the seasonal and interannual variability in DIC concentrations quite accurately and generates N2-fixation rates that agree with direct rate measurements from 1990 and recent geochemical estimates. However, this solution generates export fluxes that are more than 4 times higher than those observed, and predicts the development of DON and DOC anomalies in late summer/early fall that have not been observed. In contrast, the low N2-fixation solution generates trap fluxes that are approximately correct, but overestimates the summertime DIC concentrations by 20-30 μmol/kg-1. Both solutions indicate that there is significant interannual variability in N2-fixation at BATS and that the rates were much lower in 1995-1996 than in the previous six years. It is suggested that this variability is linked to decadal-scale fluctuations in the North Atlantic climate.
UR - http://www.scopus.com/inward/record.url?scp=0035041549&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035041549&partnerID=8YFLogxK
U2 - 10.1016/S0967-0645(00)00160-0
DO - 10.1016/S0967-0645(00)00160-0
M3 - Article
AN - SCOPUS:0035041549
VL - 48
SP - 1609
EP - 1648
JO - Deep-Sea Research Part II: Topical Studies in Oceanography
JF - Deep-Sea Research Part II: Topical Studies in Oceanography
SN - 0967-0645
IS - 8-9
ER -