INVESTIGADORES
LARA Ruben Jose
artículos
Título:
Non-Redfield carbon and nitrogen cycling in the Arctic: Effects of ecosystem structure and dynamics
Autor/es:
DALY, K.L.; WALLACE, D.W.R.; SMITH, W.O.JR.; SKOOG, ANNELIE; LARA, RUBÉN JOSÉ; GOSSELIN, M.; FALCK, E.; YAGER, P.L.
Revista:
JOURNAL OF GEOPHYSICAL RESEARCH
Editorial:
American Geophysical Union
Referencias:
Lugar: Washington; Año: 1999 p. 3185 - 3199
ISSN:
0148-0227
Resumen:
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The C:N ratio is a critical
parameter used in both global ocean carbon models and field studies to
understand carbon and nutrient cycling as well as to estimate exported carbon
from the euphotic zone. The so-called Redfield ratio (C:N = 6.6 by atoms) [Redfield et al., 1963] is widely used for such calculations. Here
we present data from the NE Greenland continental shelf that show that most of the
C:N ratios for particulate (autotrophic and heterotrophic) and dissolved pools
and rates of transformation among them exceed Redfield proportions from June to
August, owing to species composition, size, and biological interactions. The
ecosystem components that likely comprised sinking particles and had relatively
high C:N ratios (geometric means) included (1) the particulate organic matter
(C:N = 8.9) dominated by nutrient-deficient diatoms, resulting from low initial
nitrate concentrations (approximately 4 μM) in Arctic surface
waters; (2) the dominant zooplankton, herbivorous copepods (C:N = 9.6), having
lipid storage typical of Arctic copepods; and (3) copepod fecal pellets (C:N =
33.2). Relatively high dissolved organic carbon concentrations (median 105 μM) were approximately 25 to 45 μM higher than
reported for other systems and may be broadly characteristic of Arctic waters.
A carbon-rich dissolved organic carbon pool also was generated during summer.
Since the magnitude of carbon and nitrogen uncoupling in the surface mixed
layer appeared to be greater than in other regions and occurred throughout the
productive season, the C:N ratio of particulate organic matter may be a better
conversion factor than the Redfield ratio to estimate carbon export for broad
application in northern high-latitude systems.