Hostname: page-component-745bb68f8f-v2bm5 Total loading time: 0 Render date: 2025-01-08T07:52:10.709Z Has data issue: false hasContentIssue false
  • English
  • Français

Coastal Upwelling and Radiocarbon—Evidence for Temporal Fluctuations in Ocean Reservoir Effect off Portugal During the Holocene

Published online by Cambridge University Press:  18 July 2016

António M Monge Soares  and
João M Alveirinho Dias
António M Monge Soares*
Affiliation:
Departamento de Química, Instituto Tecnológico e Nuclear, Estrada Nacional 10, 2685-953 Sacavém, Portugal
João M Alveirinho Dias
Affiliation:
Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve, Campus de Gambelas, 8000–117 Faro, Portugal. Email: [email protected]
*
Corresponding author. Email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

This paper focuses on the use of the radiocarbon content of marine shells collected along the Portuguese coast as a proxy for the intensity of coastal upwelling off of Portugal. Differences in the 14C ages of closely associated marine mollusk shells and terrestrial material (charcoal or bones) from several Portuguese archaeological contexts seem to be significant throughout the Holocene. ΔR values range from 940 ± 50 to −160 ± 40 14C yr. Five of these values are significantly higher than the modern value (250 ± 25 14C yr), while the remaining values are lower. The modern value was calculated by measuring the 14C content of live-collected, pre-bomb marine mollusk shells. This value is in accordance with an active upwelling of strong intensity that currently occurs off of Portugal. Some primary observations based on data presented here can be made: i) during the Holocene important changes have occurred in the ocean reservoir effect off the Portuguese coast; ii) these fluctuations may be correlated with regional oceanographic changes, namely with changes in the strength of coastal upwelling; and iii) these changes suggest some sort of variability of the climatic factors forcing coastal upwelling off of Portugal.

Type
Articles
Information
Radiocarbon , Volume 48 , Issue 1 , 2006 , pp. 45 - 60
Copyright
Copyright © 2006 by the Arizona Board of Regents on behalf of the University of Arizona 

References

Abrantes, F. 2000. 200 000 yr diatom records from Atlantic upwelling sites reveal maximum productivity during LGM and a shift in phytoplankton community structure at 185 000 yr. Earth and Planetary Science Letters 176:7–16.CrossRefGoogle Scholar
Abrantes, F, Loncaric, N, Moreno, J, Mil-Homens, M, Pflauman, U. 2001. Paleoceanographic conditions along the Portuguese Margin during the last 30 ka: a multiple proxy study. Comunicações do Instituto Geológico e Mineiro 88:161–84.Google Scholar
Bond, G, Showers, W, Cheseby, M, Lotti, R, Almasi, P, deMenocal, P, Priore, P, Cullen, H, Hadjas, I, Bonani, G. 1997. A pervasive millennial-scale cycle in North Atlantic Holocene and glacial climates. Science 278:1257–66.CrossRefGoogle Scholar
Bond, G, Kromer, B, Beer, J, Muscheler, R, Evans, MN, Showers, W, Hoffmann, S, Lotti-Bond, R, Hajdas, I, Bonani, G. 2001. Persistent solar influence on North Atlantic climate during the Holocene. Science 294:2130–6.CrossRefGoogle ScholarPubMed
Broecker, WS. 2000. Abrupt climate change: causal constraints provided by the paleoclimate record. Earth-Science Reviews 51:137–54.Google Scholar
Diffenbaugh, NS, Sloan, LC, Snyder, MA. 2003. Orbital suppression of wind-driven upwelling in the California Current at 6 ka. Paleoceanography 18:1051, doi: 10.1029/2002PA000865.CrossRefGoogle Scholar
Ferreira, DB. 1984. Le systeme climatique de l'upwelling Ouest Ibérique [report #19 of the Linha de Acção de Geografia Física]. Lisbon: Centro de Estudos Geográficos. INIC. 92 p.Google Scholar
Fiúza, AFG. 1982. The Portuguese coastal upwelling system. In: Actual Problems of Oceanography in Portugal. Lisbon: Junta Nacional de Investigaçao Cientifica e Tecnológia. p 45–71.Google Scholar
Fiúza, AFG. 1983. Upwelling patterns off Portugal. In: Suess, E, Thiede, J, editors. Coastal Upwelling, Its Sediment Record. New York: Plenum. p 85–98.CrossRefGoogle Scholar
Fiúza, AFG, Macedo, ME, Guerreiro, MR. 1982. Climatological space and time variation of the Portuguese coastal upwelling. Oceanologica Acta 5:31–40.Google Scholar
Ingram, BL. 1998. Differences in radiocarbon age between shell and charcoal from a Holocene shellmound in northern California. Quaternary Research 49(1):102–10.Google Scholar
Keith, ML, Anderson, GM. 1963. Radiocarbon dating: fictitious results with mollusk shells. Science 141:634–7.Google Scholar
Lemos, RT, Pires, HO. 2004. The upwelling regime off the west Portuguese coast. International Journal of Climatotology 24:511–24.Google Scholar
Longin, R. 1970. Extraction du collagene des os fossils pour leur datation par la methode du Carbone 14. [Thesis 3e cycle]. Lyon: Faculté des Sciences de l'Université de Lyon. 70 p. In French.Google Scholar
Mateus, JE. 1992. Holocene and present-day ecosystems of the Carvalhal Region, southwest Portugal [PhD dissertation]. Utrecht: University of Utrecht. 184 p.Google Scholar
Mateus, JE, Queiroz, PF. 1993. Os estudos de vegetação quaternária em Portugal; contextos, balanço de resultados, perspectivas. In: Carvalho, GS, Ferreira, A, Senna-Martínez, JC, editors. O Quaternário em Portugal. Balanço e Perspectivas. Lisbon: Colibri. p 105–31. In Portuguese.Google Scholar
McDermott, F, Mattey, DP, Hawkesworth, C. 2001. Centennial-scale Holocene climate variability revealed by a high-resolution speleothem δ18O record from SW Ireland. Science 294:1328–31.CrossRefGoogle ScholarPubMed
deMenocal, P, Ortiz, J, Guilderson, T, Sarnthein, M. 2000. Coherent high- and low-latitude climate variability during the Holocene warm period. Science 288:2198–202.Google Scholar
Peliz, Á, Rosa, TL, Santos, AMP, Pissarra, JL. 2002. Fronts, jets, and counter-flows in the Western Iberian upwelling system. Journal of Marine Systems 35(1–2):61–77.CrossRefGoogle Scholar
Reimer, PJ, Baillie, MGL, Bard, E, Bayliss, A, Beck, JW, Bertrand, CJH, Blackwell, PG, Buck, CE, Burr, GS, Cutler, KB, Damon, PE, Edwards, RL, Fairbanks, R, Friedrich, M, Guilderson, TP, Hogg, AG, Hughen, KA, Kromer, B, McCormac, G, Manning, S, Ramsey, CB, Reimer, RW, Remmele, S, Southon, JR, Stuiver, M, Talamo, S, Taylor, FW, van der Plicht, J, Weyhenmeyer, CE. 2005. IntCa104 terrestrial radiocarbon age calibration, 0–26 cal kyr BP. Radiocarbon 46(3):1029–58.Google Scholar
Relvas, P, Barton, ED. 2000. Surface structure of the coastal ocean off SW Iberia during an upwelling relaxation. In: Proceedings of the 3rd Symposium on the Iberian Atlantic Margin. 25–27 September 2000. p 177–8.Google Scholar
Sánchez, R, Relvas, P. 2003. Breakup of the upwelling circulation off Cape St Vincent, SW Portugal. Thalassas 19:125–6.Google Scholar
Soares, AMM. 1989. O efeito de reservatório oceânico nas aguas costeiras de Portugal continental. Sacavém: Instituto de Ciências e Engenharia Nucleares (Instituto Nacional de Engenharia e Tecnologia Industrial). 135 p. In Portuguese.Google Scholar
Soares, AMM. 1993. The 14C content of marine shells: evidence for variability in coastal upwelling off Portugal during the Holocene. In: Isotope Techniques in the Study of Past and Current Environmental Changes in the Hydrosphere and the Atmosphere. Vienna: International Atomic Energy Agency (IAEA). p 471–85.Google Scholar
Soares, AMM. 2005. Variabilidade do “Upwelling” costeiro durante o Holocénico nas Margens Atlânticas Ocidental e Meridional da Península Ibérica [PhD dissertation]. Faro: Faculdade de Ciências do Mar e do Ambiente, Universidade do Algarve.Google Scholar
Stuiver, M, Braziunas, TF. 1993. Modeling atmospheric 14C influences and 14C ages of marine samples to 10,000 BC. Radiocarbon 35(1):137–89.Google Scholar
Stuiver, M, Polach, HA. 1977. Discussion: reporting of 14C data. Radiocarbon 19(3):355–63.Google Scholar
Stuiver, M, Reimer, PJ. 1993. Extended 14C database and revised CALIB 3.0 14C age calibration. Radiocarbon 35(1):215–30.Google Scholar
Stuiver, M, Pearson, GW, Braziunas, T. 1986. Radiocarbon age calibration of marine samples back to 9000 cal yr BP. Radiocarbon 28(2B):980–1021.Google Scholar
Teller, JT, Leverington, DW, Mann, JD. 2002. Freshwater outbursts to the oceans from glacial Lake Agassiz and their role in climate change during the last deglaciation. Quaternary Science Reviews 21:879–87.CrossRefGoogle Scholar
Vargas, JM, García-Lafuente, J, Delgado, J, Criado, F. 2003. Seasonal and wind-induced variability of sea surface temperature patterns in the Gulf of Cádiz. Journal of Marine Systems 38:205–19.Google Scholar
Wooster, WS, Bakun, A, McClain, DR. 1976. The seasonal upwelling cycle along the eastern boundary of the North Atlantic. Journal of Marine Research 34:131–41.Google Scholar