Lignin, phenols, and some chemical elements in aerosols and bottom sediments from the Tropical North Atlantic

A study of composition of biomarkers (lignin and phenols) in aerosols and bottom sediments from the Tropical North Atlantic was carried out. It was shown that organic matter of aerosols was mostly composed of products of terrestrial plants (arboreal fibers, pollen, and spores). Biomarker composition in the aerosols and in the bottom sediments was practically similar, which proved delivery of terrigenous organic matter to the ocean via the atmosphere.

Geochemistry of foraminifera from sediment cores of the central California margin

Under present climate conditions, convection at high latitudes of the North Pacific is restricted to shallower depths than in the North Atlantic. To what extent this asymmetry between the two ocean basins was maintained over the past 20 kyr is poorly known because there are few unambiguous proxy records of ventilation from the North Pacific. We present new data for two sediment cores from the California margin at 800 and 1600 m depth to argue that the depth of ventilation shifted repeatedly in the northeast Pacific over the course of deglaciation. The evidence includes benthic foraminiferal Cd/Ca, 18O/16O, and 13C/12C data as well as radiocarbon age differences between benthic and planktonic foraminifera. A number of features in the shallower of the two cores, including an interval of laminated sediments, are consistent with changes in ventilation over the past 20 kyr suggested by alternations between laminated and bioturbated sediments in the Santa Barbara Basin and the Gulf of California [Keigwin and Jones, 1990 doi:10.1029/PA005i006p01009; Kennett and Ingram, 1995 doi:10.1038/377510a0; Behl and Kennett, 1996 doi:10.1038/379243a0]. Data from the deeper of the two California margin cores suggest that during times of reduced ventilation at 800 m, ventilation was enhanced at 1600 m depth, and vice versa. This pronounced depth dependence of ventilation needs to be taken into account when exploring potential teleconnections between the North Pacific and the North Atlantic.

Concentration and composition of aerosols over the North Atlantic in August 1995

Data on composition of aerosols are considered. Investigations include electron microscopy, grain size, mineralogical and chemical analyses. Samples of aerosols were collected Cruise 37 of R/V Akademik Mstislav Keldysh along a transatlantic section along 40°-50°N. Variability of concentrations and composition of aerosols with distance from continents is shown: concentrations of aerosols decrease by factor of ten and more. Significant portion of mineral components in aerosols collected over the continent is replaced by organic matter due to mechanical differentiation during transportation. Such anthropogenic components as soot, ash, and combustion spheres were detected in all samples. North African dust was found in one sample in the western part of the section.