Oceanography The Official Magazine of
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Volume 27 Issue 01

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Volume 27, No. 1
Pages 148 - 159


Interannual and Subdecadal Variability in the Nutrient Geochemistry of the Cariaco Basin

By Mary I. Scranton , Gordon T. Taylor, Robert Thunell , Claudia R. Benitez-Nelson , Frank Muller-Karger, Kent Fanning , Laura Lorenzoni, Enrique Montes, Ramon Varela, and Yrene Astor 
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Article Abstract

The CARIACO Ocean Time Series program has made monthly measurements of oxygen, nutrients, and carbon system parameters (∑CO2, alkalinity, pH) in the Cariaco Basin since 1996. At the same time, sediment traps have collected settling particles at four to five depths ranging from 150 to 1,200 m. The depth of the transition from oxic to anoxic conditions has fluctuated dramatically over the time series due to changes in the occurrence of Caribbean water intrusions into the deep basin. Nutrient concentrations in the deep basin have increased steadily with time in a proportion reflective of the elemental ratios in the settling organic matter, although N:P ratios in the water column (approximately 16:1) differ from ratios in the accumulating nutrients (11:1) and the settling flux (ranging between 5:1 and 12.5:1). This difference is likely due to changes in the source material for remineralization, either because of sizeable ecosystem changes or changes in the relative importance of the terrestrial input of inorganic P or scavenging of P by mineral precipitation near the oxic/anoxic interface. Alternatively, there may have been changes in the degree of preferential remineralization of P.


Scranton, M.I., G.T. Taylor, R. Thunell, C.R. Benitez-Nelson, F. Muller-Karger, K. Fanning, L. Lorenzoni, E. Montes, R. Varela, and Y. Astor. 2014. Interannual and subdecadal variability in the nutrient geochemistry of the Cariaco Basin. Oceanography 27(1):148–159, https://doi.org/10.5670/oceanog.2014.18.


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