nitrogen uptake by phytoplankton in the atlantic sector of the southern ocean during late austral summer

nitrogen uptake by phytoplankton in the atlantic sector of the southern ocean during late austral summer

;W. R. Joubert;S. J. Thomalla;H. N. Waldron;M. I. Lucas;M. Boye;F. A. C. Le Moigne;F. Planchon;S. Speich
tetrahedron letters 2011 Vol. 8 pp. 2947-2959
127
joubert2011biogeosciencesnitrogen

Abstract

As part of the Bonus-GoodHope (BGH) campaign, <sup>15</sup>N-labelled nitrate, ammonium and urea uptake measurements were made along the BGH transect from Cape Town to ~60° S in late austral summer, 2008. Our results are categorised according to distinct hydrographic regions defined by oceanic fronts and open ocean zones. High regenerated nitrate uptake rate in the oligotrophic Subtropical Zone (STZ) resulted in low <i>f</i>-ratios (<i>f</i> = 0.2) with nitrogen uptake being dominated by &rho;urea, which contributed up to 70 % of total nitrogen uptake. Size fractionated chlorophyll data showed that the greatest contribution (>50 %) of picophytoplankton (<2 μm) were found in the STZ, consistent with a community based on regenerated production. The Subantarctic Zone (SAZ) showed the greatest total integrated nitrogen uptake (10.3 mmol m<sup>−2</sup> d<sup>&minus;1</sup>), mainly due to enhanced nutrient supply within an anticyclonic eddy observed in this region. A decrease in the contribution of smaller size classes to the phytoplankton community was observed with increasing latitude, concurrent with a decrease in the contribution of regenerated production. Higher <i>f</i>-ratios observed in the SAZ (<i>f</i> = 0.49), Polar Frontal Zone (<i>f</i>= 0.41) and Antarctic Zone (<i>f</i> = 0.45) relative to the STZ (<i>f</i> = 0.24), indicate a higher contribution of NO<sub>3</sub><sup>&minus;</sup>-uptake relative to total nitrogen and potentially higher export production. High ambient regenerated nutrient concentrations are indicative of active regeneration processes throughout the transect and ascribed to late summer season sampling. Higher depth integrated uptake rates also correspond with higher surface iron concentrations. No clear correlation was observed between carbon export estimates derived from new production and <sup>234</sup>Th flux. In addition, export derived from <sup>15</sup>N estimates were 2–20 times greater than those based on <sup>234</sup>Th flux. Variability in the magnitude of export is likely due to intrinsically different methods, compounded by differences in integration time scales for the two proxies of carbon export.

Citation

ID: 210397
Ref Key: joubert2011biogeosciencesnitrogen
Use this key to autocite in SciMatic or Thesis Manager

References

Blockchain Verification

Account:
NFT Contract Address:
0x95644003c57E6F55A65596E3D9Eac6813e3566dA
Article ID:
210397
Unique Identifier:
10.5194/bg-8-2947-2011
Network:
Scimatic Chain (ID: 481)
Loading...
Blockchain Readiness Checklist
Authors
Abstract
Journal Name
Year
Title
5/5
Creates 1,000,000 NFT tokens for this article
Token Features:
  • ERC-1155 Standard NFT
  • 1 Million Supply per Article
  • Transferable via MetaMask
  • Permanent Blockchain Record
Blockchain QR Code
Scan with Saymatik Web3.0 Wallet

Saymatik Web3.0 Wallet