Biogeochemical Characteristics of Western Tropical Atlantic Ocean Water Masses
DOI:
https://doi.org/10.11137/1982-3908_2022_45_45732Keywords:
Inorganic nutrients, Antarctic Intermediate Water (AAIW), Antarctic Bottom Water (AABW)Abstract
Water masses are commonly identified according to their conservative parameters. However, there are also studies that use non-conservative parameters, together with the conservative ones, to refine the water masses identification. The aim of this study was to analyze the chemical properties of the water masses in the western tropical Atlantic Ocean (WTAO) according to their inorganic nutrient concentration: nitrate-NO3–, phosphate-PO43–, and silicic acid-Si(OH)4, to set a regional descriptive framework of the water column in view of future comparative studies. We collected full-depth water column samples from 18 oceanographic stations from a latitudinal transect along 38°W, from 02°S to 15°N during the PIRATA-BR XVII and XVIII campaigns, in November 2017 and 2018. We have also used the regional data available from GLODAPv.2 data product to improve the water masses characterization. Six water masses were identified in the region based on their values of potential temperature, salinity, potential density, and neutral density observed in the study area according to the CTD-O2 data: Tropical Surface Water (TSW); South and North Atlantic Central Water (SACW and NACW, respectively); Antarctic Intermediate Water (AAIW); North Atlantic Deep Water (NADW); and Antarctic Bottom Water (AABW). Regarding the nutrient content within each water mass, our results showed that TSW corresponds to a surface oligotrophic water; NACW and SACW have intermediate nutrient concentration values between TSW and AAIW; AAIW showed the highest concentration of phosphate-PO43– (~ 1.35 µmol kg–1) and nitrate-NO3– (~30 µmol kg–1); AABW, on the other hand, was the water mass with the highest silicic acid-Si(OH)4 concentration (~ 80 µmol kg–1), as well as high nitrate-NO3– (~ 25 µmol kg–1) and phosphate-PO43– (~ 1.80 µmol kg–1) concentrations. Additionally, the water column between 300 and 650 m displays an increase in phosphate-PO43– concentrations north of 5oN, associated to a low dissolved oxygen area coupled to the North Equatorial Under Current (NEUC). Long-term, sustained hydrographic and ocean biogeochemistry observations are key to understand how climate change is affecting the ocean, and this study is a contribution to that.
References
Arhan, M., Mercier, H., Bourlès, B. & Gouriou, Y. 1998, ‘Hydrographic sections across the Atlantic at 7°30N and 4°30S’, Deep Sea Research Part I: Oceanographic Research Papers, vol. 45, no. 6, pp. 829–72. https://doi.org/10.1016/S0967-0637(98)00001-6
Azaneu, M., Kerr, R., Mata, M.M. & Garcia, C.A.E. 2013, ‘Trends in the deep Southern Ocean (1958-2010): Implications for Antarctic Bottom Water properties and volume export’, Journal of Geophysical Research: Oceans, vol. 118, no. 9, pp. 4213–27. https://doi.org/10.1002/jgrc.20303
Azar, E., Piñango, A., Wallner-Kersanach, M. & Kerr, R. 2021, ‘Source waters contribution to the tropical Atlantic central layer: New insights on the Indo-Atlantic exchanges’, Deep Sea Research Part I: Oceanographic Research Papers, vol. 168, p. 103450. https://doi.org/10.1016/j.dsr.2020.103450
De Baar, H.J.W., Van Leeuwe, M.A., Scharek, R., Goeyens, L., Bakker, K.M.J. & Fritsche, P. 1997, ‘Nutrient anomalies in Fragilariopsis kerguelensis blooms, iron deficiency and the nitrate/phosphate ratio (A. C. Redfield) of the Antarctic Ocean’, Deep Sea Research Part II: Topical Studies in Oceanography, vol. 44, no. 1–2, pp. 229–60. https://doi.org/10.1016/S0967-0645(96)00102-6
Boswell, S.M., Smythe-Wright, D., Holley, S.E. & Kirkwood, D. 2002, ‘The tracer signature of Antarctic Bottom Water and its spread in the Southwest Indian Ocean: Part II - Dissolution fluxes of dissolved silicate and their impact on its use as a chemical tracer’, Deep-Sea Research Part I-Oceanographic Research Papers, vol. 49, pp. 575-90. https://doi.org/10.1016/S0967-0637(01)00067-X
Bourlès, B., Araujo, M., McPhaden, M.J., Brandt, P., Foltz, G.R., Lumpkin, R., Giordani, H., Hernandez, F., Lefèvre, N., Nobre, P., Campos, E., Saravanan, R., Trotte‐Duhà, J., Dengler, M., Hahn, J., Hummels, R., Lübbecke, J.F., Rouault, M., Cotrim, L., Sutton, A., Jochum, M. & Perez, R.C. 2019, ‘PIRATA: A Sustained Observing System for Tropical Atlantic Climate Research and Forecasting’, Earth and Space Science, vol. 6, no. 4, pp. 577–616. https://doi.org/10.1029/2018EA000428
Braga, E. de S. & Niencheski, L.F.H. 2006, Composição das massas de água e seus potenciais produtivos na área entre o Cabo de São Tomé (RJ) e o Chuí (RS), ambiente oceanográfico da plataforma continental e do talude na região Sudeste-Sul do Brasil., Edusp.
Bristow, L.A., Mohr, W., Ahmerkamp, S. & Kuypers, M.M.M. 2017, ‘Nutrients that limit growth in the ocean’, Current Biology, vol. 27, no. 11, pp. R474–8. https://doi.org/10.1016/j.cub.2017.03.030
Chapman, P. 1998, ‘The WOCE Data Resource’, Bulletin of the American Meteorological Society, vol. 79, no. 6, pp. 1037–42. https://doi.org/10.1175/1520-0477(1998)079<1037:TWDR>2.0.CO;2
Dickson, R.R. & Brown, J. 1994, ‘The production of North Atlantic Deep Water: Sources, rates, and pathways’, Journal of Geophysical Research, vol. 99, no. C6, p. 12319. https://doi.org/10.1029/94JC00530
Emery, W.J. 2001, ‘Water Types And Water Masses’, Encyclopedia of Ocean Sciences, Elsevier, pp. 3179–87. https://doi.org/10.1006/rwos.2001.0108
Emery, W.J. 2019, ‘Water Types and Water Masses’, Encyclopedia of Ocean Sciences, Elsevier, pp. 169–79. https://doi.org/10.1016/B978-0-12-409548-9.04426-2
Fay, M.P. & Proschan, M.A. 2010, ‘Wilcoxon-Mann-Whitney or t-test? On assumptions for hypothesis tests and multiple interpretations of decision rules’, Statistics Surveys, vol. 4, pp. 1–39. https://doi.org/10.1214/09-SS051
Ferreira, M.L.C. & Kerr, R. 2017, ‘Source water distribution and quantification of North Atlantic Deep Water and Antarctic Bottom Water in the Atlantic Ocean’, Progress in Oceanography, vol. 153, pp. 66–83. https://doi.org/10.1016/j.pocean.2017.04.003
Hammer, Ø., Harper, D.A.T. & Ryan, P.D. 2001, ‘Past: Paleontological Statistics Software Package for Education and Data Analysis’, Palaentologia Electronica, vol. 4, pp 1-9.
Hansen, H.P. & Koroleff, F. 1999, ‘Determination of nutrients’, Methods of Seawater Analysis, Wiley-VCH Verlag GmbH, pp. 159–228. https://doi.org/10.1002/9783527613984.ch10
Herrford, J., Brandt, P. & Zenk, W. 2017, ‘Property changes of deep and bottom waters in the Western Tropical Atlantic’, Deep Sea Research Part I: Oceanographic Research Papers, vol. 124, pp. 103–25. https://doi.org/10.1016/j.dsr.2017.04.007
IPCC 2021, ‘Summary for Policymakers’, in V. Masson-Delmotte, P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu & B. Zhou (eds), Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, p. in press.
Kawase, M. & Sarmiento, J.L. 1985, ‘Nutrients in the Atlantic thermocline’, Journal of Geophysical Research, vol. 90, no. C5, p. 8961. https://doi.org/10.1029/JC090iC05p08961
Kerr, R., Dotto, T.S., Mata, M.M. & Hellmer, H.H. 2018, ‘Three decades of deep water mass investigation in the Weddell Sea (1984–2014): Temporal variability and changes’, Deep Sea Research Part II: Topical Studies in Oceanography, vol. 149, pp. 70–83. https://doi.org/10.1016/j.dsr2.2017.12.002
Kress, N. & Herut, B. 2001, ‘Spatial and seasonal evolution of dissolved oxygen and nutrients in the Southern Levantine Basin (Eastern Mediterranean Sea): chemical characterization of the water masses and inferences on the N:P ratios’, Deep Sea Research Part I: Oceanographic Research Papers, vol. 48, no. 11, pp. 2347–72. https://doi.org/10.1016/S0967-0637(01)00022-X
Kruskal, W.H. & Wallis, W.A. 1952, ‘Use of Ranks in One-Criterion Variance Analysis’, Journal of the American Statistical Association, vol. 47, no. 260, pp. 583–621. https://doi.org/10.1080/01621459.1952.10483441
Levitus, S., Conkright, J.L., Reid, R.G., Najjar, R.G. & Mantyla, A. 1993, ‘Distribution of nitrate, phosphate and silicate in the world oceans’, Progress in Oceanography, vol. 31, pp. 245–73. https://doi.org/10.1016/0079-6611(93)90003-V
Liu, M. & Tanhua, T. 2019a, ‘Characteristics of Water Masses in the Atlantic Ocean based on GLODAPv2 data’, Ocean Science Discussions, no. January, pp. 1–43. https://doi.org/10.5194/os-2018-139
Liu, M. & Tanhua, T. 2019b, ‘Distribution of Water Masses in the Atlantic Ocean based on GLODAPv2’, Ocean Science Discussions, no. January, pp. 1–32. https://doi.org/10.5194/os-2018-140
Lumpkin, R. & Garzoli, S.L. 2005, ‘Near-surface circulation in the Tropical Atlantic Ocean’, Deep Sea Research Part I: Oceanographic Research Papers, vol. 52, no. 3, pp. 495–518. https://doi.org/10.1016/j.dsr.2004.09.001
Mamayev, O.I. 1975, Temperature-Salinity Analysis of World Ocean Waters, Elsevier Science.
Marinov, I., Gnanadesikan, A., Toggweiler, J.R. & Sarmiento, J.L. 2006, ‘The Southern Ocean biogeochemical divide’, Nature, vol. 441, no. 7096, pp. 964–7. https://doi.org/10.1038/nature04883
Mitchell, B.G., Brody, E.A., Holm-Hansen, O., McClain, C. & Bishop, J. 1991, ‘Light limitation of phytoplankton biomass and macronutrient utilization in the Southern Ocean’, Limnology and Oceanography, vol. 36, no. 8, pp. 1662–77. https://doi.org/10.4319/lo.1991.36.8.1662
Nelson, D.M. & Smith, W. 0. 1991, ‘Sverdrup revisited: Critical depths, maximum chlorophyll levels, and the control of Southern Ocean productivity by the irradiance-mixing regime’, Limnology and Oceanography, vol. 36, no. 8, pp. 1650–61. https://doi.org/10.4319/lo.1991.36.8.1650
Olsen, A., Lange, N., Key, R.M., Tanhua, T., Bittig, H.C., Kozyr, A., Álvarez, M., Azetsu-Scott, K., Becker, S., Brown, P.J., Carter, B.R., Cunha, L.C., Feely, R.A., van Heuven, S., Hoppema, M., Ishii, M., Jeansson, E., Jutterström, S., Landa, C.S., Lauvset, S.K., Michaelis, P., Murata, A., Pérez, F.F., Pfeil, B., Schirnick, C., Steinfeldt, R., Suzuki, T., Tilbrook, B., Velo, A., Wanninkhof, R. & Woosley, R.J. 2020, ‘An updated version of the global interior ocean biogeochemical data product, GLODAPv2.2020’, Earth System Science Data, vol. 12, no. 4, pp. 3653–78. https://doi.org/10.5194/essd-12-3653-2020
Oudot, C., Ternon, J.F., Andrié, C., Braga, E.S. & Morin, P. 1999, ‘On the crossing of the equator by intermediate water masses in the western Atlantic ocean: Identification and pathways of Antarctic Intermediate Water and Upper Circumpolar Water’, Journal of Geophysical Research: Oceans, vol. 104, no. C9, pp. 20911–26. https://doi.org/10.1029/1999JC900123
Panassa, E., Santana-Casiano, J.M., González-Dávila, M., Hoppema, M., van Heuven, S.M.A.C., Völker, C., Wolf-Gladrow, D. & Hauck, J. 2018, ‘Variability of nutrients and carbon dioxide in the Antarctic Intermediate Water between 1990 and 2014’, Ocean Dynamics, vol. 68, no. 3, pp. 295–308. https://doi.org/10.1007/s10236-018-1131-2
Peña-Izquierdo, J., van Sebille, E., Pelegrí, J.L., Sprintall, J., Mason, E., Llanillo, P.J. & Machín, F. 2015, ‘Water mass pathways to the North Atlantic oxygen minimum zone’, Journal of Geophysical Research: Oceans, vol. 120, no. 5, pp. 3350–72. https://doi.org/10.1002/2014JC010557
Pérez, F.F., Rı́os, A.F., Castro, C.G. & Fraga, F. 1998, ‘Mixing analysis of nutrients, oxygen and dissolved inorganic carbon in the upper and middle North Atlantic ocean east of the Azores’, Journal of Marine Systems, vol. 16, no. 3–4, pp. 219–33. https://doi.org/10.1016/S0924-7963(97)00108-5
Peterson, R.G. & Whitworth, T. 1989, ‘The subantarctic and polar fronts in relation to deep water masses through the southwestern Atlantic’, Journal of Geophysical Research, vol. 94, no. C8, p. 10817. https://doi.org/10.1029/JC094iC08p10817
Pickard, G.L. & Emery, W. 1990, Descriptive physical oceanography: An introduction, Pergamon Press.
Pond, S. & Pickard, G.L. 2013, Introductory Dynamical Oceanography, 2nd edn, Butterworth-Heinemann.
Poole, R. & Tomczak, M. 1999, ‘Optimum multiparameter analysis of the water mass structure in the Atlantic Ocean thermocline’, Deep Sea Research I, vol. 46, no. 11, pp. 1895–921. https://doi.org/10.1016/j.dsr.2020.103450
Santos, G.C., Kerr, R., Azevedo, J.L.L., Mendes, C.R.B. & Cunha, L.C. 2016, ‘Influence of Antarctic Intermediate Water on the deoxygenation of the Atlantic Ocean’, Dynamics of Atmospheres and Oceans, vol. 76, pp. 72–82.
https://doi.org/10.1016/j.dynatmoce.2016.09.002
Sardessai, S., Shetye, S., Maya, M.V., Mangala, K.R. & Prasanna Kumar, S. 2010, ‘Nutrient characteristics of the water masses and their seasonal variability in the eastern equatorial Indian Ocean’, Marine Environmental Research, vol. 70, no. 3–4, pp. 272–82. https://doi.org/10.1016/j.marenvres.2010.05.009
Schlitzer, R. 2017, Ocean Data View, p. Version 4.7.10.
Schmid, C. & Garzoli, S.L. 2009, ‘New observations of the spreading and variability of the Antarctic Intermediate Water in the Atlantic’, Journal of Marine Research, vol. 67, no. 6, pp. 815–43. https://doi.org/10.1357/002224009792006151
Schott, F.A., Dengler, M., Brandt, P., Affler, K., Fischer, J., Bourlès, B., Gouriou, Y., Molinari, R.L. & Rhein, M. 2003, ‘The zonal currents and transports at 35°W in the tropical Atlantic’, Geophysical Research Letters, vol. 30, no. 7. https://doi.org/10.1029/2002GL016849
Schott, F.A., Dengler, M., Zantopp, R., Stramma, L., Fischer, J. & Brandt, P. 2005, ‘The Shallow and Deep Western Boundary Circulation of the South Atlantic at 5°–11°S’, Journal of Physical Oceanography, vol. 35, no. 11, pp. 2031–53. https://doi.org/10.1175/JPO2813.1
Shapiro, S.S. & Wilk, M.B. 1965, ‘An Analysis of Variance Test for Normality (Complete Samples)’, Biometrika, vol. 52, no. 3/4, p. 591. https://doi.org/10.2307/2333709
Shepherd, J.G., Brewer, P.G., Oschlies, A. & Watson, A.J. 2017, ‘Ocean ventilation and deoxygenation in a warming world: introduction and overview’, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 375, no. 2102, p. 20170240. https://doi.org/10.1098/rsta.2017.0241
Sherman, E. 1965, ‘A Note on Multiple Comparisons Using Rank Sums’, Technometrics, vol. 7, no. 2, pp. 255–6. 10.1080/00401706.1965.10490253
Silva, A.C., Grenier, M., Chuchla, R., Grelet, J., Roubaud, F., Hamelin, B., Lyard, F. & Jeandel, C. 2010, ‘Water masses and zonal current in the Western Tropical Atlantic in October 2007 and January 2008 (AMANDES project)’, Ocean Science Discussions, vol. 7, no. 6, pp. 1953–76. https://doi.org/10.5194/osd-7-1953-2010
Souza, A.G.Q., Kerr, R. & Azevedo, J.L.L. 2018, ‘On the influence of Subtropical Mode Water on the South Atlantic Ocean’, Journal of Marine Systems, vol. 185, pp. 13–24. https://doi.org/10.1016/j.jmarsys.2018.04.006
Stramma, L. & England, M. 1999, ‘On the water masses and mean circulation of the South Atlantic Ocean’, Journal of Geophysical Research: Oceans, vol. 104, no. C9, pp. 20863–83. https://doi.org/10.1029/1999JC900139
Stramma, L., Fischer, J., Brandt, P. & Schott, F. 2003, ‘Circulation, variability and near-equatorial meridional flow in the central tropical Atlantic’, in G.J. Goni & P. Malanotte-Rizzoli (eds), Interhemispheric Water Exchange in the Atlantic Ocean, vol. 68, Elsevier, pp. 1–22. https://doi.org/10.1016/S0422-9894(03)80141-1
Stramma, L. & Schmidtko, S. 2020, ‘Oxygen and nutrient trends in the Tropical Oceans’, Ocean Science Discussions, no. December, pp. 1–25. https://doi.org/10.5194/os-2020-123
Stramma, L. & Schott, F. 1999, ‘The mean flow field of the tropical Atlantic Ocean’, Deep-Sea Research Part Ii-Topical Studies in Oceanography, vol. 46, pp. 279-303. https://doi.org/10.1016/S0967-0645(98)00109-X
Talley, L.D. 1996, ‘Antarctic Intermediate Water in the South Atlantic’, The South Atlantic: Present and Past Circulation, Springer Berlin Heidelberg, pp. 219–38. https://doi.org/10.1007/978-3-642-80353-6_11
Talley, L.D., Pickard, G.L., Emery, W.J. & Swift, J.H. 2011, ‘Typical Distributions of Water Characteristics’, in L.D. Talley, G.L. Pickard, W.J. Emery & J.H. Swift (eds), Descriptive Physical Oceanography, Elsevier, pp. 67–110. https://doi.org/10.1016/B978-0-7506-4552-2.10004-6
Tomczak, M. 1999, ‘Some historical, theoretical and applied aspects of quantitative water mass analysis’, Journal of Marine Research, vol. 57, no. 2, pp. 275–303. https://doi.org/10.1357/002224099321618227
Tomczak, M. & Large, D.G.B. 1989, ‘Optimum multiparameter analysis of mixing in the thermocline of the eastern Indian Ocean’, Journal of Geophysical Research, vol. 94, no. C11, p. 16141.
https://doi.org/10.1029/JC094iC11p16141
Tréguer, P., Nelson, D.M., Van Bennekom, A.J., Demaster, D.J., Leynaert, A. & Quéguiner, B. 1995, ‘The silica balance in the world ocean: a reestimate.’, Science, vol. 268, no. 5209, pp. 375–9. https://doi.org/10.1126/science.268.5209.375
Troupin, C., Barth, A., Sirjacobs, D., Ouberdous, M., Brankart, J.-M., Brasseur, P., Rixen, M., Alvera-Azcárate, A., Belounis, M., Capet, A., Lenartz, F., Toussaint, M.-E. & Beckers, J-M. 2012, ‘Generation of analysis and consistent error fields using the Data Interpolating Variational Analysis (DIVA)’, Ocean Modelling, vol. 52–53, pp. 90–101. https://doi.org/10.1016/j.ocemod.2012.05.002
Whitney, F.A., Bograd, S.J. & Ono, T. 2013, ‘Nutrient enrichment of the subarctic Pacific Ocean pycnocline’, Geophysical Research Letters, vol. 40, no. 10, pp. 2200–5. https://doi.org/10.1002/grl.50439
Zakem, E.J., Al-Haj, A., Church, M.J., van Dijken, G.L., Dutkiewicz, S., Foster, S.Q., Fulweiler, R.W., Mills, M.M. & Follows, M.J. 2018, ‘Ecological control of nitrite in the upper ocean’, Nature Communications, vol. 9, no. 1, p. 1206. https://doi.org/10.1038/s41467-018-03553-w
Additional Files
Published
Issue
Section
License
This journal is licensed under a Creative Commons — Attribution 4.0 International — CC BY 4.0, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.