Resumo

RICAURTE-VILLOTA, Constanza; GONZALEZ-YAJIMOVICH, Oscar  e  SANCHEZ, Alberto. Coupled response of rainfall and denitrification to solar forcing during the Holocene in Alfonso Basin. Cienc. mar [online]. 2013, vol.39, n.2, pp.151-164. ISSN 0185-3880.  https://doi.org/10.7773/cm.v39i2.2224.

The bulk sedimentary δ¹⁵N record of Alfonso Basin displayed changes both from a regional source possibly associated with changes in the isotopic signal of NO₃^- dissolved in Subsurface Subtropical Water and from a climate source governed by solar forcing (total solar irradiance) over the strength of the North American monsoon (i.e., rainfall), causing intermediate water suboxia and promoting denitrification in the basin. High values of bulk sedimentary δ¹⁵N (maximum of 14.596o) agree with increases in land-derived organic matter (from -14.8% to 49.2%) and with a decrease in terrigenous percentage (from 84.8% to 61.6%) during the Middle and Late Holocene, suggesting that increased rainfall and freshwater input promotes increased stratification of the water column, which inhibits vertical mixing and produces a reduction in oxygen content in an already oxygen-poor zone.

Palavras-chave : Gulf of California; North American monsoon; laminated sediment record; nitrogen isotopes; Intertropical Convergence Zone.

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