Salinity is,

+ benthic foraminifera 5 O (with deep north Atlantic salinity taken as global mean salinity) • ptanktic foraminifera: Sea water temperature derived from Transfer Functions

I u and salinity calculated using the planktie foraminifera S O and temperature estimates

Figure 14,3. Distribution of the different water masses in the North Atlantic and Norwegian Sea during the last Glacial Maximum on a T, S, ax diagram, ot = (d-1)*1000„ where d is the density of the surface water. Benthic foraminifera £IH0 are plotted at the intersection between the corresponding equilibrium isotopic fractionation lines and the estimated mean North Atlantic salinity-Surface water values are independently calculated (see text). The potential areas of deep water formation are associated with the vertical arrows, which simulates the temperature changes during winter cooling (from Labeyrie et al., 1TO).

is relative I v small, between 49 N and 54 N, and 20 W to 40 \V, about midway between North America and Europe, south oflccland (Duplessy et al, 1991), Salinities were too low in the Norwegian Sea to produce a significant amount of deep water, even by sea-ice freezing and brine formation during peak w inter conditions. However, during the course of the glaciation, the location of deep and intermediate sources varied within the North Atlantic Ocean. In particular, during massive iceberg discharges, w hich resulted in a strong salinity decrease of North Atlantic surface w ater in the 4€°N—55°N latitudinal band, brine formation was active and resulted in surface water sinking and reaching equilibrium density at 1 to 2 km depth (Veum et al, 1992; Vidal et al., 1998).

14.2.4 Deep Water Flow Lines

The distribution of 5nC in the ocean is controlled principally by photosynthesis and mineralization of organic carbon, and by mixing between water masses of different i so topic composition (Broecker and Peng, 1982). Photosynthesis in surface water preferentially extracts 32C from seawatcr, causing the enrichment in 1 of surface water total dissolved CO?. When all the nutrients are consumed by phytoplankton, surface waters have lost about 10% of their original ECO? (and are about 10% poorer in SCO; than deep waters). Because the carbon that has been removed hy phytoplankton is strongly impoverished in ,?C (<5'^C ~ — 20%o), the surface reservoir is enriched by

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