Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Niño

Two stations representing coastal and shelf environments (bay of Concepción and adjacent shelf, respectively) were sampled in order to assess benthic nitrogen fluxes. During the study period anomalously high oxygen bottom waters conditions were observed, coinciding with the 1997-1998 El Niño event....

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Autores principales:	MUÑOZ,PRAXEDES, SALAMANCA,MARCO A, NEIRA,CARLOS, SELLANES,JAVIER
Lenguaje:	English
Publicado:	Sociedad de Biología de Chile 2004
Materias:	ammonia pore-water nutrients sediment-water exchanges coastal upwelling El Niño event
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2004000200009
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spelling	oai:scielo:S0716-078X20040002000092004-09-20Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El NiñoMUÑOZ,PRAXEDESSALAMANCA,MARCO ANEIRA,CARLOSSELLANES,JAVIER ammonia pore-water nutrients sediment-water exchanges coastal upwelling El Niño event Two stations representing coastal and shelf environments (bay of Concepción and adjacent shelf, respectively) were sampled in order to assess benthic nitrogen fluxes. During the study period anomalously high oxygen bottom waters conditions were observed, coinciding with the 1997-1998 El Niño event. From both sites, intact sediment cores were collected for incubation experiments to directly estimate total ammonium fluxes. Pore-water chemistry was also assessed to estimate diffusive fluxes of nitrogen compounds (NH4+, NO3- and NO2-). The NH4+ flux from incubation experiments ranged from 0.55 to 2.18 mmol m-2 day-1 in the inner bay and from 1.84 to 2.14 mmol m-2 day-1 on the shelf. NO3- diffusive fluxes to the sediments were observed in the bay in March (-17 x 10-2 mmol m-2 day-1)and on the shelf in November (-2.7 x 10-2 mmol m-2 day-1), associated with the lowest NH4+ diffusive fluxes and coincident with a stronger gradient of Eh in the first centimeters of the sediments. Besides, total NH4+ fluxes lower than in normal periods were observed, suggesting the influence of less reducing conditions, consequence in turn of the lower fluxes of particulated organic material and higher dissolved oxygen in the bottom waters. These conditions were probably imposed by the El Niño event. On the other hand, and relative to previous reports, an increase of irrigation coefficients (DI) was estimated. Thus, the flux extension of other nitrogen compounds could have acquired relevance in relation to NH4+ fluxes during the study periodinfo:eu-repo/semantics/openAccessSociedad de Biología de ChileRevista chilena de historia natural v.77 n.2 20042004-06-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2004000200009en10.4067/S0716-078X2004000200009
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	ammonia pore-water nutrients sediment-water exchanges coastal upwelling El Niño event
spellingShingle	ammonia pore-water nutrients sediment-water exchanges coastal upwelling El Niño event MUÑOZ,PRAXEDES SALAMANCA,MARCO A NEIRA,CARLOS SELLANES,JAVIER Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Niño
description	Two stations representing coastal and shelf environments (bay of Concepción and adjacent shelf, respectively) were sampled in order to assess benthic nitrogen fluxes. During the study period anomalously high oxygen bottom waters conditions were observed, coinciding with the 1997-1998 El Niño event. From both sites, intact sediment cores were collected for incubation experiments to directly estimate total ammonium fluxes. Pore-water chemistry was also assessed to estimate diffusive fluxes of nitrogen compounds (NH4+, NO3- and NO2-). The NH4+ flux from incubation experiments ranged from 0.55 to 2.18 mmol m-2 day-1 in the inner bay and from 1.84 to 2.14 mmol m-2 day-1 on the shelf. NO3- diffusive fluxes to the sediments were observed in the bay in March (-17 x 10-2 mmol m-2 day-1)and on the shelf in November (-2.7 x 10-2 mmol m-2 day-1), associated with the lowest NH4+ diffusive fluxes and coincident with a stronger gradient of Eh in the first centimeters of the sediments. Besides, total NH4+ fluxes lower than in normal periods were observed, suggesting the influence of less reducing conditions, consequence in turn of the lower fluxes of particulated organic material and higher dissolved oxygen in the bottom waters. These conditions were probably imposed by the El Niño event. On the other hand, and relative to previous reports, an increase of irrigation coefficients (DI) was estimated. Thus, the flux extension of other nitrogen compounds could have acquired relevance in relation to NH4+ fluxes during the study period
author	MUÑOZ,PRAXEDES SALAMANCA,MARCO A NEIRA,CARLOS SELLANES,JAVIER
author_facet	MUÑOZ,PRAXEDES SALAMANCA,MARCO A NEIRA,CARLOS SELLANES,JAVIER
author_sort	MUÑOZ,PRAXEDES
title	Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Niño
title_short	Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Niño
title_full	Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Niño
title_fullStr	Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Niño
title_full_unstemmed	Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Niño
title_sort	nitrogen sediment fluxes in an upwelling system off central chile (concepción bay and adjacent shelf) during the 1997-1998 el niño
publisher	Sociedad de Biología de Chile
publishDate	2004
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2004000200009
work_keys_str_mv	AT munozpraxedes nitrogensedimentfluxesinanupwellingsystemoffcentralchileconcepcionbayandadjacentshelfduringthe19971998elnino AT salamancamarcoa nitrogensedimentfluxesinanupwellingsystemoffcentralchileconcepcionbayandadjacentshelfduringthe19971998elnino AT neiracarlos nitrogensedimentfluxesinanupwellingsystemoffcentralchileconcepcionbayandadjacentshelfduringthe19971998elnino AT sellanesjavier nitrogensedimentfluxesinanupwellingsystemoffcentralchileconcepcionbayandadjacentshelfduringthe19971998elnino
_version_	1718439559605256192

Nitrogen sediment fluxes in an upwelling system off central Chile (Concepción Bay and adjacent shelf) during the 1997-1998 El Niño

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