Water vapor in the atmosphere over the northern Tien Shan

Refined data of systematic measurements of total water vapor in the atmosphere from May 1980 to April 2005 are presented. The data were obtained at the Issyk Kul atmospheric-monitoring station by the method of solar molecular-absorption spectroscopy. Over 25 years, the annual mean water-vapor content in the atmosphere increased by 4.5% at a mean rate of increase of 0.18% per year. However, the water-vapor content decreased in the last five years. The results of statistical processing of experimental data (general statistical characteristics, correlation coefficients, composite oscillations) are described. A refined model is proposed for forecasts of temporal variations in the monthly mean and annual mean water-vapor contents for the coming years. The model includes a linear trend and the sum of oscillations with periods close to the periods of a number of well-known geophysical phenomena. Regression equations are proposed to relate the water-vapor content in the atmospheric column to the surface temperature and absolute humidity.     

Chlorinated hydrocarbons in seawater: Analytical method and levels in the northeastern Pacific

A method is described for analyzing nanogram quantities of chlorinated hydrocarbons from 1-1 samples of seawater. Seawater samples are pumped through a copper column containing a mixture by weight of 5% activated carbon powder, 10% MgO and 85% refined diatomaceous earth. The chlorinated hydrocarbons in the seawater are adsorbed or trapped on the column and subsequently eluted with 30% benzene in acetone (v/v) for analysis by gas-liquid chromatography.This procedure was used to analyze chlorinated hydrocarbon levels in samples collected off the southern California coast. We suggest that anthropogenic chlorinated hydrocarbons can be used for the investigation of large-scale ocean currents and mixing processes.     

Comparative tolerance of two estuarine annelids to fluoranthene under normoxic and moderately hypoxic conditions

The tolerance of the oligochaete Monopylephorus rubroniveus and the polychaete Streblospio benedicti to sediment-associated fluoranthene was characterized under normoxic (>80% dissolved oxygen saturation) and moderately hypoxic ( approximately 50% dissolved oxygen saturation) conditions. Under both conditions, M. rubroniveus was highly tolerant of fluoranthene. Streblospio benedicti was considerably less tolerant of fluoranthene compared with M. rubroniveus. In addition, S. benedicti was less tolerant to fluoranthene under moderately hypoxic conditions, although no differences in sensitivity between the two oxygen conditions were observed based upon median lethal tissue residues. Bioaccumulation factors were higher for S. benedicti exposed to moderate hypoxia, suggesting that behavioral adaptations to compensate for the lower dissolved oxygen increased its bioaccumulation of fluoranthene. The results of the present laboratory study demonstrate that (1). changes in annelid tolerance to fluoranthene under varying oxygen conditions is a species-dependent phenomenon and (2). the differential tolerance of these two annelids to these combined stressors is consistent with their relative abundances in the field.     

Physical and anthropogenic effects on observed long-term nutrient changes in the Irish Sea

The trend in Irish Sea nutrient concentrations over the last four decades has been considered to reflect changes in anthropogenic loading. Comparison of a long-term database for the Menai Strait, North Wales, with an established historic data set for the Cypris station, Isle of Man, indicates that climate also has a significant influence on observations of nutrient concentrations. Data are presented detailing long-term shifts in nitrate, phosphate and silicate measurements since the 1960s at these two fixed sampling sites in the Irish Sea. Broad systematic changes observed in all three nutrients over the decades show a rise from the 1960s through to the 1980s, followed generally by an overall decline in the 1990s. Decadal-scale salinity changes occur in the opposite sense to nutrient changes. Anthropogenic inputs from freshwater cannot fully account for observed nutrient trends, neither is there evidence for shifts in nutrient concentrations in oceanic waters over the past four decades. Climatically forced movement in the geographical position of the freshwater/seawater mixing zone over a decadal time scale could, however, give rise to the observed shifts in nutrient concentration and salinity. This cannot alter nutrient concentration and salinity per se, but causes the measurements taken at fixed sampling sites to fluctuate inversely over this time scale. It is concluded that there is complex interplay between anthropogenic loading and climate affecting the distribution of nutrients in the Irish Sea.     

Modern sediment supply to the lower delta plain of the Ganges-Brahmaputra River in Bangladesh

Vibracores and auger samples collected from the lower (tidal) delta plain of the Ganges-Brahmaputra River in Bangladesh were examined to determine whether the area is a significant sink for riverine sediments. Measurements of ¹³⁷Cs activity and radiocarbon in the sediments indicate sediment accumulation is taking place on decadal and millennial time scales at rates reaching 1.1 cm/year. The sediment of the lower delta plain is primarily derived from an offshore source after having originally been supplied by the Ganges-Brahmaputra river system, carried westward by prevailing currents and advected inland by monsoonal coastal setup and cyclonic events.     

Stratigraphy of the sediment infill in Bosphorus Strait: water exchange between the Black and Mediterranean Seas during the last glacial Holocene

The sediment infill over the Paleozoic bedrock in the Bosphorus Strait consists of four sedimentary units which were deposited in the last 26,000 ¹⁴C years B.P. The stratigraphy of these units suggests that this part of the Bosphorus was a freshwater lake between 26,000 and 5,300 ¹⁴C years B.P., depositing sands with a freshwater mollusc fauna of Black Sea neo-euxinian affinity (Dreissena rostriformis, Dreissena polymorpha, and Monodacna pontica). The first appearance of euryhaline Mediterranean molluscs (e.g., Ostrea edulis, Mytilus edulis) was observed at 5,300 ¹⁴C years B.P. in this part of the Bosphorus. Deposition of coarse Mytilus-bank and Ostrea-bank units suggests that the establishment of the present dual-flow regime in the Bosphorus took place at about 4,400 ¹⁴C years B.P.     

Volcanogenic complexes of the Sea of Okhotsk and the Sea of Japan (Comparative analysis)

Several coeval volcanogenic complexes indicating synchronous volcanic events in the Sea of Japan and the Sea of Okhotsk are defined. Volcanics from different-age complexes of the Sea of Okhotsk show many features in common and are attributed to the Pacific type of calc-alkaline series. They were formed in geodynamic settings of the active continental margin and point to its origination on the continental crust of the fragmented Asian continent margin. The volcanic rocks developed in the Sea of Japan reflect different rifting stages. The initial stage was marked by an eruption of calc-alkaline lavas (Paleocene-Eocene complex). At the stage of the marginal-sea spreading, erupted volcanics of the middle Miocene-Pliocene complex were melted from the depleted mantle and magmatism terminated by an eruption of postspreading Pliocene-Holocene volcanics melted from the enriched mantle EM I. Along with the differences, the magmatism in the Sea of Japan and Sea of Okhotsk has some features in common. In both cases, the sialic component of the lithosphere substantially influenced the magma generation.