Enhancement of sulfide auto-oxidation by metal ion in artificial seawater and a seawater which is a possible source of aoshio

Citation
K. Nanba et al., Enhancement of sulfide auto-oxidation by metal ion in artificial seawater and a seawater which is a possible source of aoshio, FISHERIES S, 67(1), 2001, pp. 14-20
Citations number
11
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Aquatic Sciences
Journal title
FISHERIES SCIENCE
ISSN journal
0919-9268 → ACNP
Volume
67
Issue
1
Year of publication
2001
Pages
14 - 20
Database
ISI
SICI code
0919-9268(200102)67:1<14:EOSABM>2.0.ZU;2-Q
Abstract
Aoshio is hypoxic milky blue-green seawater observed in some eutrophic bays . Previous studies have shown that colloidal sulfur causes the coloration a nd that the source of aoshio water is attributed to coastal anoxic bottom w ater. Occurrences of aoshio have been reported in limited areas of coastal seawater, although hypoxic transparent water seems rather universal. Promot ion in auto-oxidation of sulfide by metal ions in seawater was investigated to explain the occurrences of aoshio. Artificial seawater containing 10 mu M metal ion was assayed for the sulfide oxidation rate. The velocity consta nt which represents the oxidation rate within the initial 30 min and the am ount of reacted sulfide in 2h were determined by oxygen monitoring and sulf ide quantification, respectively. Fe2+ and Cu2+ enhanced the initial 30 min reaction. Fe2+, Fe3+ and Ni2+ increased the amount of reacted sulfide in 2 h, forming whitish turbid water. Seawater from a suspected source of aoshio water was also assayed for the auto-oxidation rate of sulfide. The oxidati on rate in water from 12 m depth was 13-19 times higher than the artificial seawater without an addition of heavy metal ions. More than 15% of the oxi dation rate in 12 m deep seawater was explained by dissolved iron in the se awater.