Distribution of²²⁸Ra in the world ocean

Abstract

Surface and subsurface samples of seawater collected in the Atlantic, Arctic, Indian, Pacific, and Antarctic oceans have been analyzed for 228Ra. The results agree with those obtained by Moore (1969) and show that near‐shore surface waters normally contain much higher 228Ra concentrations than surface waters collected in the open sea, that surface waters normally contain much higher 228Ra concentrations than intermediate and deep waters, but that nearbottom waters are somewhat enriched in 228Ra. Surface waters of the North Atlantic and Indian oceans contain significantly higher concentrations of 228Ra than those of the Pacific and Antarctic oceans. Vertical profiles of 228Ra activities have been used to calculate values of the constant for vertical eddy diffusion Kz of about 0.3 cm2/sec in the Arctic Ocean in the zone between the cold water mass that originates in the Bering Sea and the underlying warmer but more saline water mass that originates in the Atlantic. Values of Kz of about 0.5 to about 7 cm2/sec have been calculated for the upper 200 meters of the Atlantic and Pacific and of about 5–100 cm2/sec for the bottom water masses of the Atlantic and Pacific. The. meridional gradient of 228Ra in the surface waters south of Australia and New Zealand has been used to calculate a value of the constant for horizontal eddy diffusion perpendicular to the wind‐driven circulation KY of about 107–108 cm2/sec.

228Ra/226Ra and 226Ra/Ba ratios in the Western Mediterranean Sea: Barite formation and transport in the water column

“…2). Dissolved 228 Ra activities are highest in the upper water column and decrease rapidly through the permanent pycnocline (Moore, 1972;Kaufman et al, 1973;Li et al, 1980;Moore, 1987). The high 228 Ra activities in the upper water column reflect lateral transport of 228 Ra that diffused from shelf sediments.…”

Radium isotopes as tracers of iron sources fueling a Southern Ocean phytoplankton bloom

“…The offshore transect consisted a series of six stations between the surf zone within the (Kaufman et al, 1973).…”

“…Kaufman et al, 1973;Sarmiento et al, 1976;Sarmiento et al, 1982) and across the thermocline (e.g. Moore, 1972;Trier et al, 1972, Kaufman et al, 1973. Kaufman et al (1973) were the first to use 228 Ra to calculate horizontal mixing rates away from the coastline.…”

“…Moore, 1972;Trier et al, 1972, Kaufman et al, 1973. Kaufman et al (1973) were the first to use 228 Ra to calculate horizontal mixing rates away from the coastline.…”

“…The first widespread application was the use of 228 Ra during the GEOSECS (Geochemical Ocean Sections) expeditions as a tracer of vertical mixing in the deep ocean (e.g. Kaufman et al, 1973;Sarmiento et al, 1976;Sarmiento et al, 1982) and across the thermocline (e.g. Moore, 1972;Trier et al, 1972, Kaufman et al, 1973.…”