Some chemical characteristics of the brines in Bannock and Tyro basins: salinity, sulphur compounds, Ca(II), fluoride ions, pH, At, phosphate, SiO2, NH3

• Published in: Marine chemistry 1990-01, Vol.31 (1/3), p.35-62
• Main Authors: Bregant, D, Catalono, G, Civitarese adn, G., Luchetta, A
• Format: Article
• Language: English
• ISSN: 0304-4203

Chemical parameters were measured in samples collected from 2 deep-water eastern Mediterranean basins during 4 cruises (1986-88). Brines in both basins were hypersaline (about 10 times the salinity of normal seawater) and anoxic. The transition from normal seawater to anoxic brine was sharp, occurring within a few metres, at a depth greater than 3327 dbar (pressure/depth conversion not applicable). At this interface, concentrations of most species analysed increased, but dissolved oxygen and nitrate immediately fell to zero. Hydrogen sulphide and ammonium accumulated in the anoxic brine. The Libeccio sub-basin of the Bannock area was the deepest, and its brine was layered. The upper layer (140 dbar thick) was separated from a lower layer (300 dbar thick) by an interface at which hydrogen sulphide, sulphate and fluoride concentrations increased, and calcium concentration decreased. In this sub-basin, ranges of parameter measured were salinity 39-321 psu; pH 8.2-6.5, total alkalinity 2.7-4.0 mM; dissolved oxygen 0.2-0 mM, hydrogen sulphide, 0-1669 uM; thiol 0-198 uM; sulphate 31-99 mM; calcium 11-21 mM; fluoride 7-100 uM, ammonium 0.2-3080 uM; nitrite 5.8-0 uM; phosphate 0.2-12 uM; and silicate 8-130 uM. There are 54 references.