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Titolo:
Po-210 and Pb-210 in the South-equatorial Atlantic: distribution and disequilibrium in the upper 500 m
Autore:
Sarin, MM; Kim, G; Church, TM;
Indirizzi:
Univ Delaware, Coll Marine Studies, Newark, DE 19716 USA Univ Delaware Newark DE USA 19716 ll Marine Studies, Newark, DE 19716 USA Phys Res Lab, Ahmedabad 380009, Gujarat, India Phys Res Lab Ahmedabad Gujarat India 380009 edabad 380009, Gujarat, India
Titolo Testata:
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY
fascicolo: 5, volume: 46, anno: 1999,
pagine: 907 - 917
SICI:
0967-0645(1999)46:5<907:PAPITS>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
SERIES NUCLIDES; ARABIAN SEA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Physical, Chemical & Earth Sciences
Citazioni:
14
Recensione:
Indirizzi per estratti:
Indirizzo: Church, TM Univ Delaware, Coll Marine Studies, Newark, DE 19716 USA Univ Delaware Newark DE USA 19716 tudies, Newark, DE 19716 USA
Citazione:
M.M. Sarin et al., "Po-210 and Pb-210 in the South-equatorial Atlantic: distribution and disequilibrium in the upper 500 m", DEEP-SEA II, 46(5), 1999, pp. 907-917

Abstract

The distribution of Po-210 and Pb-210 (grand daughter-parent) in the dissolved and total (dissolved + particulate) phase of sea water samples has been measured in the upper 500 m at four stations along a western transect in the South-equatorial Atlantic. Such a transect allows one to make inferenceabout the particle-associated scavenging processes in the equatorial versus subtropical regions of the South Atlantic. A common feature of the Po-210profiles is that the dissolved activities in the surface waters are about one-third of the equilibrium concentrations, suggesting weeks to a month removal times of Po-210 by adsorption on settling particles. The mean dissolved Po-210/Pb-210 activity ratios in the equatorial and South Atlantic are 0.27 and 0.39, respectively, representing a pronounced disequilibrium in surface waters. The box-model calculation yields a residence time of about 73 and 130 days for dissolved Po-210 in the surface water at the equatorial and southern sites, respectively. The gross deficiency of Po-210 extends throughout the upper 500 m; however, the Po-210 residence time in the intermediate depths is longer than that in surface water. The observed Po-210-Pb-210disequilibrium has been examined with respect to POC concentration, which yields a significant positive correlation (r(2) = 0.61), suggesting that the Po-210 deficiency is mainly associated with biological removal. The Pb-210 distribution shows distinctively higher concentrations in the equatorial surface waters (19-22 dpm/1001), suggesting an enhanced atmospheric flux of Pb-210. Th, residence time of dissolved Pb-210 (400-780 days), with respect to atmospheric input, is longer than dissolved Po-210 and Th-234 residence times, and also shows a latitudinal decrease toward the equatorin the surface ocean. The shorter residence time in the surface equatorialocean (0-20m) seems associated with higher productivity and more rapid particulate scavenging. (C) 1999 Elsevier Science Ltd. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/11/20 alle ore 19:46:27