Hostname: page-component-8448b6f56d-c47g7 Total loading time: 0 Render date: 2024-04-16T11:46:02.840Z Has data issue: false hasContentIssue false

Comparison of Particulate Organic and Dissolved Inorganic Radiocarbon Signatures in the Surface Northeast Pacific Ocean

Published online by Cambridge University Press:  09 February 2016

Chanda Bertrand*
Affiliation:
Department of Earth System Science, University of California Irvine, Irvine, California 92697-3100, USA
Brett Walker
Affiliation:
Department of Earth System Science, University of California Irvine, Irvine, California 92697-3100, USA
Sheila Griffin
Affiliation:
Department of Earth System Science, University of California Irvine, Irvine, California 92697-3100, USA
E R M Druffel
Affiliation:
Department of Earth System Science, University of California Irvine, Irvine, California 92697-3100, USA
*
1Corresponding author. Email: bertranc@uci.edu.

Abstract

It has long been assumed that radiocarbon (Δ14C) content of dissolved inorganic carbon (DIC) is equal to that of particulate organic carbon (POC) in surface seawater; however, little research has been conducted to explicitly test this assumption. Here, we report Δ14C measurements of surface POC samples and compare them with contemporaneous DIC Δ14C measurements from the northeast Pacific Ocean (Hwang et al. 2004; Druffel et al. 2010). Samples were collected from surface waters at Station M off California between 1995 and 2004. The POC Δ14C values decreased 3.2% per year from 1995 to 2004, similar to the decline observed in the DIC Δ14C values during the same period. Overall, our results show no statistical difference between POC and DIC Δ14C—consistent with the assumption that DIC and POC Δ14C values can generally be considered equivalent. However, significant variability was observed for POC Δ14C values during several fall/summer events, where POC Δ14C signatures were lower than DIC Δ14C values. An evaluation of 2 sample pretreatments also suggests that non-homogenized POC samples deviated less from average POC Δ14C values and more closely matched the DIC Δ14C average for the time series. The presence of seasonal POC/DIC Δ14C disagreements, combined with sample processing effects, suggest that infrequent contributions of allochthonous, older carbon may have originated from deeper in the water column, especially during periods when upwelling in this area was prominent.

Type
Oceanic Carbon Cycle
Copyright
Copyright © 2013 by the Arizona Board of Regents on behalf of the University of Arizona 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Alldredge, AL, Silver, MW. 1988. Characteristics, dynamics and significance of marine snow. Progress in Oceanography 20(1):4182.Google Scholar
Alldredge, AL, Passow, U, Logan, BE. 1993. The abundance and significance of a class of large, transparent organic particles in the ocean. Deep-Sea Research I 40(6):1131–40.Google Scholar
Bauer, JE, Druffel, ERM. 1998. Ocean margins as a significant source of organic matter to the deep open ocean. Nature 392(6675):482–5.Google Scholar
Cho, BC, Azam, F. 1990. Biogeochemical significance of bacterial biomass in the oceans euphotic zone. Marine Ecology-Progress 63:253–9.Google Scholar
Druffel, ERM, Williams, PM, Bauer, JE, Ertel, J. 1992. Cycling of dissolved and particulate organic matter in the open ocean. Journal of Geophysical Research 97(C10):15,63959.Google Scholar
Druffel, ERM, Beaupre, SR, Griffin, S, Hwang, J. 2010. Variability of dissolved inorganic radiocarbon at a surface site in the northeast Pacific Ocean. Radiocarbon 52(3):1150–65.Google Scholar
Fowler, SW, Knauer, GA. 1986. Role of large particles in the transport of elements and organic-compounds through the ocean water column. Progress in Oceanography 16(3):147–94.CrossRefGoogle Scholar
Hobson, LA, Menzel, DW, Barber, RT. 1973. Primary productivity and sizes of pools of organic carbon in mixed layer of ocean. Marine Biology 19(4):298306.Google Scholar
Hwang, J, Druffel, ERM, Griffin, S, Smith, KL Jr, Baldwin, RJ, Bauer, JE. 2004. Temporal variability of Δ14C, δ13C, and C/N in sinking particulate organic matter at a deep time series station in the northeast Pacific Ocean. Global Biogeochemical Cycles 18:GB4015, doi: 10.1029/2004GB002221. Google Scholar
Laws, EA, Bienfang, PK, Ziemann, DA, Conquest, LD. 1988. Phytoplankton population-dynamics and the fate of production during the spring bloom in Auke Bay, Alaska. Limnology and Oceanography 33:5765.Google Scholar
Longhurst, AR, Harrison, WG. 1989. The biological pump: profiles of plankton production and consumption in the upper ocean. Progress in Oceanography 22(1):47123.Google Scholar
Lynn, RJ, Simpson, JJ. 1987. The California Current System: the seasonal variability of its physical characteristics. Journal of Geophysical Research 92(C12):12,94766.Google Scholar
Mahadevan, A. 2001. An analysis of bomb radiocarbon trends in the Pacific. Marine Chemistry 73(3–4):273–90.Google Scholar
Masiello, CA, Druffel, ERM, Bauer, JE. 1998. Physical controls on dissolved inorganic radiocarbon variability in the California Current. Deep-Sea Research II 45(4–5):617–42.Google Scholar
Pearcy, WG, Stuiver, M. 1983. Vertical transport of carbon-14 into deep-sea food webs. Deep-Sea Research A 30(4):427–40.Google Scholar
Roland, LA, McCarthy, MD, Guilderson, T. 2008. Sources of molecularly uncharacterized organic carbon in sinking particles from three ocean basins: a coupled Δ14C and δ13C approach. Marine Chemistry 111:199213.Google Scholar
Southon, J, Santos, G, Druffel-Rodriguez, K, Druffel, E, Trumbore, S, Xu, XM, Griffin, S, Ali, S, Mazon, M. 2004. The Keck Carbon Cycle AMS laboratory, University of California, Irvine: initial operation and a background surprise. Radiocarbon 46(1):41–9.CrossRefGoogle Scholar
Vogel, JS, Southon, JR, Nelson, DE. 1987. Catalyst and binder effects in the use of filamentous graphite for AMS. Nuclear Instruments and Methods in Physics Research B 29(1–2):50–6.Google Scholar
Williams, PM, Linick, T. 1975. Cycling organic carbon in the ocean: use of naturally occurring radiocarbon as a long and short-term tracer. IAEA Report SM-191-26, Vienna: IAEA. p 53165.Google Scholar
Williams, PM, Druffel, ERM, Smith, KL Jr. 1987. Dietary carbon sources for deep-sea organisms as inferred from their organic radiocarbon activities. Deep-Sea Research A 34(2):253–66.Google Scholar