Oxygen isotopic and species composition of planktonic foraminiferas in sediment cores from the North Atlantic

Paleotemperature curves were drawn from oxygen-isotope ratios in CaCO3 of planktonic foraminiferal tests and by the micropaleontological method using quantitative relationships of their species. Two series of curves yield similar results. These data confirm that isotope composition of oxygen reflects primarily temperature, and not isotope composition in ocean water. Temperature of the upper layer of ocean water increased from north to south both during the last two glaciations and in the interglacials. All three sediment cores collected from different latitudes show approximately the same amplitudes of fluctuation of mean annual temperature during times of their accumulation, as determined independently by different methods; these amplitudes are estimated as 5-7°C.

Silicate in marine sediments from the Emerland Basin, North Atlantic

A method was developed to measure porosity and dissolved interstitial silicate at millimeter intervals or less in a sediment core. In cores from Emerald Basin (Scotian Shelf), interstitial concentrations near the sediment surface did not drop rapidly to bottom-water concentrations as measured in bottle casts (28 µM) but remained as high as 166 µM in the upper 0.5 mm of sediment High rates of benthic silicate release were measured which could not be accounted for by interstitial concentration gradients or by ventilation of macro-invertebrate burrows. The silicate discontinuity observed between the sediments and water column suggests that a diffusive sublayer exists in a zone of viscous flow above the sediment surface. This is possible only if a surface reaction is primarily responsible for silicate release. By assuming a linear concentration gradient across this diffusive sublayer, the silicate release rates were used to estimate the thickness of the sublayer to be about 2 mm.

Total length, and lipid and toxaphene content in blubber of minke whales (B. acutorostrata) from the North Atlantic

Toxaphene contamination of minke whales (Balaenoptera acutorostrata) from North Atlantic waters was examined for the first time. Total toxaphene and SumCHB (sum of 11 chlorobornanes) concentrations in blubber samples ranged from 170 ± 110 and 41 ± 39 ng/g lipid weight (l.w.) for female minke whales from southeastern Greenland to 5800 ± 4100 and 1100 ± 780 ng/g l.w. for males from the North Sea, respectively. Very large variations in toxaphene concentrations among sampling areas were observed suggesting a spatial segregation of minke whales. However, much of the apparent geographical discrimination was explained by the seasonal fluctuation of animal fat mass. Patterns of CHBs in males revealed that recalcitrant CHBs were in higher proportions in animals from the more easterly areas than in animals from the more westerly areas. This trend may be influenced by the predominance of the US, over the European, input of toxaphene to North Atlantic waters.

Early Maastrichtian stable isotopes: changing deep water sources in the North Atlantic?

We propose that the observed short-term stable isotope fluctuations reflect changes in high- and low-latitude intermediate to deep water sources, based on a high-resolution stable isotope record of planktic and benthic foraminifera from the Early Maastrichtian (~71.3 to ~ 69.6 Ma) of Blake Nose (DSDP Site 390A, North Atlantic). Sources of these waters may have been the low-latitude eastern Tethys and high-latitude North Atlantic. Changes in intermediate to deep water sources were probably steered by eccentricity-controlled insolation fluctuations. Lower insolation favored the formation of high-latitude deep waters due to positive feedback mechanisms resulting in high-latitude cooling. This led to a displacement of low-latitude deep waters at Blake Nose. Higher insolation reduced intermediate to deep-water formation in high latitudes, yielding a more northern flow of low-latitude deep waters.