Protein and organic phosphorus in particulate matter and mesoplankton fraction in waters of the East Pacific

Vertical distribution of organic phosphorus and phosphatase activity was studied in the Southeast Pacific Ocean. The average rate of mineralization of organic phosphorus in the 0-200 m layer was shown to differ by a factor of 5-10 in oligotrophic and eutrophic areas, while residence time of phosphorus in production-destruction cycles differed by a factor of only 2-5, apparently because of both concentration of organic phosphorus and phosphorolysis rate increased simultaneously in the areas.

Chemical composition and accumulation rates of chemical elements in metalliferous sediments from axial zones of the East Pacific Rise and the Mid-Atlantic Ridge

In the monograph metalliferous sediments of the East Pacific Rise near 21°S are under consideration. Distribution trends of chemical, mineral and grain size compositions of metalliferous sediments accumulated near the axis of this ultrafast spreading segment of the EPR are shown. On the basis of lithological and geochemical investigations spatial and temporal variations of hydrothermal activity are estimated. Migration rates of hydrothermal fields along the spreading axis are calculated. The model of cyclic hydrothermal process is suggested as a result of tectono-magmatic development of the spreding centre.

Concentration of organic compounds in aerosols and surface waters of the East Atlantic and Antarctic

The data on content and composition of lipids and aliphatic hydrocarbons (HC) in aerosols and surface waters obtained during the spring-summer periods of 2001 and 2003 along the vessel route from the North Sea to the Antarctic and backwards are presented. It was shown that the distribution of organic compounds is caused by influence of zonal supply of eolian matter from land, anthropogenic, and marine autochtonous sources. Concentrations of organic compounds in the aerosols varied from 0.22 to 13.04 ng/m**3 for lipids and from 0.04 to 7.03 ng/m**3 for aliphatic HC; in surface waters, it from 9 to 84 and from 1 to 53 µg/l, respectively. There is correlation between fluxes of lithogenic fraction of the aerosols, HC, and lipids. Growth of productivity in the aquatic area increases levels of the HC in the surface waters but to a lower degree than HC supply with oil contamination.

Onset of south summer snowmelt on Antarctic sea ice between 1988 and 2007

The annual onset of snowmelt on sea ice is essential for climate monitoring since it triggers a decrease in surface albedo that feeds back into a stronger absorption of shortwave radiation - a process known as the snowmelt-albedo feedback - and thus strongly modifies the surface energy balance during summer. Algorithms designed for the detection of snowmelt on Arctic sea ice and based on longterm passive-microwave data revealed the melt season in the Arctic from 1979 to 1998 to be significantly elongated and the onset of melt to be shifted toward earlier dates.

Palynology of the Middle to Late Miocene from ODP Hole 175-1085A off the west coast of South Africa

Aim To test whether the radiation of the extremely rich Cape flora is correlated with marine-driven climate change. Location Middle to Late Miocene in the south-east Atlantic and the Benguela Upwelling System (BUS) off the west coast of South Africa. Methods We studied the palynology of the thoroughly dated Middle to Late Miocene sediments of Ocean Drilling Program (ODP) Site 1085 retrieved from the Atlantic off the mouth of the Orange River. Both marine upwelling and terrestrial input are recorded at this site, which allows a direct correlation between changes in the terrestrial flora and the marine BUS in the south-east Atlantic. Results Pollen types from plants of tropical affinity disappeared, and those from the Cape flora gradually increased, between 10 and 6 Ma. Our data corroborate the inferred dating of the diversification in Aizoaceae c. 8 Ma. Main conclusions Inferred vegetation changes for the Late Miocene south-western African coast are the disappearance of Podocarpus-dominated Afromontane forests, and a change in the vegetation of the coastal plain from tropical grassland and thicket to semi-arid succulent vegetation. These changes are indicative of an increased summer drought, and are in step with the development of the southern BUS. They pre-date the Pliocene uplift of the East African escarpment, suggesting that this did not play a role in stimulating vegetation change. Some Fynbos elements were present throughout the recorded period (from 11 Ma), suggesting that at least some elements of this vegetation were already in place during the onset of the BUS. This is consistent with a marine-driven climate change in south-western Africa triggering substantial radiation in the terrestrial flora, especially in the Aizoaceae.

Uranium and thorium isotopes and sedimentation rates in metalliferous sediments from the western flank of the East Pacific Rise at 21°-22°S

Isotopic compositions of uranium (234U and 238U) and thorium (230Th and 232Th) were measured in metalliferous sediments from the western flank of the East Pacific Rise at 21°-22°S, in the area of hydrothermal activity and massive sulfide accumulation at the axis of the EPR. Concentration of 232Th (on the carbonate-free base) is consistent with composition of mafic extrusive rocks; isotope ratios 232Th/238U and 234U/238U indicate that about 70% of uranium passes into sediments from sea water with hydrothermal iron hydroxide. Mean sedimentation rates are calculated for seven cores by the nonequilibrium 230Th method with use of the constant concentration model. Flux of 230Th to bottom sediments is calculated and its mean value is used to determine sedimentation rate in four other cores. The constant flux model is used to calculate change of sedimentation rate with depth for seven cores over time interval of 100-300 ky. Sedimentation rates varied not much (0.3-0.6 cm/ky). The greatest changes occurred in two cores: one located near massive sulfide structures, and another near the spreading axis. Determinations of mean rates by the radiocarbon method and the nonequilibrium thorium method are in good agreement.