(Table 2) Geochemical composition of suspended matter samples from the northern Dvina River

The results of the analysis of samples of the Northern Dvina River's suspended particulate matter obtained by the sedimentation method from large water volumes in the periods of the spring high water and summer low water are presented. By the method of sequential leaching using different reagents, four fractions have been separated: the F1 is the sorbed complex and carbonates, the F2 is the amorphous hydroxides of Fe and Mn, the F3 is the form connected with the organic matter, and the F4 is the residual or silicate-detrital (inert) form. The data have shown that all ten elements determined were grouped with respect to the ratio of the distinguished forms: F4 is the predominant form for Al and Fe (73-88% of all the forms; however, the summer sample contains only 38% of this form of iron, and F2 is the predominant form for this period with 46.6%). As to Mn, the F1, F2, and F4 are nearly equally distributed in the spring high water samples, and only the F3 form is less important (5.4%). In the summer sample, the manganese sorbed complex is predominant (53.5%); for Cu, Ni, Cr, and Co, the inert F4 form is predominant (60-70%) in the sample of the spring suspended matter. The summer low water suspended matter has a lower F4 contribution (25-45%); for Zn, Pb, and Cd, the equal distribution of the forms in the spring samples is typical, while the summer suspended matter differs by the F2 form's predominance (53-61% for Zn and Pb). The main conclusion from the acquired data is that the geochemical mobility of all the studied elements, except for cadmium, in the summer low water suspended matter is higher than in the spring suspended matter. The more intensive biogeochemical processes in August, the high level of organic matter, and the higher contribution of phytoplankton lead to the intensification of the metals' geochemical activity in the Northern Dvina suspended matter in the end of the summer compared to the spring high water period when the physical processes are predominant over the biogeochemical ones due to the high speeds of the freshened waters flow.

(Table 3) Chemical analyses from DSDP Holes 22-214, 22-215 and 22-216 in the Indian Ocean

The basalts and oceanic andesites from the aseismic Ninetyeast Ridge display trachytic, vesicular and amygdaloidal textures suggesting a subaerial volcanic environment. The normative composition of the Ninetyeast Ridge ranges from olivine picriteto nepheline-normative alkaline basalt, suggesting a wide range of differentiation. This is further supported by the fractionation-differentiation trends displayed by transition metal trace elements (Ni, Cr, V and Cu). The Ninetyeast Ridge rocks are enriched in rare earth (RE) and large ion lithophile (LIL) elements and Sr isotopes (0.7043-0.7049), similar to alkali basalts and tholeiites from seamounts and islands, but different from LIL-element-depleted tholeiitic volcanic rocks of the recent seismic mid-Indian oceanic ridge. The constancy of 87Sr/86Sr ratios for basalts and andesites is compatible with a model involving fractional crystallization of mafic magma. The variation of 87Sr/86Sr ratios between 0.97 and 2.79 may possibly be explained in terms of a primordial hot mantle and/or chemically contrasting heterogeneous mantle source layers relatively undepleted in LIL elements at different periods in the geologic past. In general, the Sr isotopic data for rocks from different tectonic environments are consistent with a "zoning-depletion model" with systematically arranged alternate alkali-poor and alkali-rich layers in the mantle beneath the Indian Ocean.

Major and trace element analyses from DSDP Hole 26-253 at the Ninetyeast Ridge in the Indian Ocean

A basaltic sequence of Eocene submarine-erupted pyroclastic sediments totals at least 388 m at DSDP Site 253 on the Ninetyeast Ridge. These fossiliferous hyaloclastic sediments have been erupted and fragmented by explosive volcanism (hydroexplosions) in shallow water. The occurrence of interbedded basaltic ash-fall tuffs within the younger horizons of the hyaloclastic sequence marks the emergence of some Ninetyeast Ridge volcanic vents above sea level. Considerable textural variation allows subdivision of the sequence into six informal lithostratigraphic units. Hydrothermal and diagenetic alteration has caused the complete replacement of all original glass by smectites, and the introduction of abundant zeolite and calcite cements. The major and trace element contents of the hyaloclastites vary due to the alteration, and the admixture of biogenous calcite. On a calcium carbonate-free basis systematic variations are recognisable. Mg, Ni, Cr and Cu are enriched, and Li and Zn depleted in the three older units relative to the younger three. The chemical variability is reflected by the development of saponite in the older part of the sequence and montmorillonite in the younger; and by the presence of a quartz-normative basalt flow occurring in Unit II, in contrast to the Mg-rich highly olivine-normative basalt at the base of the sequence. The younger and older parts of the sequence therefore appear to have been derived from magmas of different chemistry. The sequence, like other basaltic rocks recovered from the Ninetyeast Ridge, is enriched in the light relative to the heavy rare earth elements (REE) although the REE contents vary unsystematically with depth, probably because of the high-temperature subaqueous alteration and the presence of biogenous calcite. This REE data indicates that the Ninetyeast Ridge volcanism was different from that which produces mid-ocean ridge basalts.

Sediments and tephra layers from the southern Tyrrhenian abyssal plain near Marsili Seamount

From the south-eastern Tyrrhenian deep-sea floor, four sediment cores of "Meteor" cruise 22 (1971) are described. These cores were taken in the basin between the Aeolian Islands and the Marsili Seamount, an elevation of more tha 3000 m above the sea floor. The sedimentation of the deep-sea basin is distinguished by a sequence of turbidites with a high sedimentation rate. The composition of the clastic material and the position of the cores in the mouth area of the morphologically very pronounced Stromboli Canyon suggest an interpretation of the turbidite sequence as fan of this canyon onto the deep-sea floor. A white rhyolitic pumice-tephra at the base of the 4 m thick sequence of turbidites in core M22-102 has been correlated with the Pelato eruption of the island of Liparo in the 6th century A.D. At the foot of the Marsili Seamount - apparently in morphologically elevated positions - the influence of the turbidite sedimentation increases, the rate of sedimentation is lower and stratigraphic omissions are probable. Here, rather compacted globigerina marls have been found in only 15 -25 cm depth. In addition, volcanic material in the form of lapilli layers, palagonitized ashes and detrital volcanic sands of the Marsili Seamount have been encountered in this area. An up to 3 cm thick layer of completely palagonitized basaltic ash intercalates with the marls at the base of two cores. Layers of very fresh olivine basaltic lapilli in core 103 and palagonitized lapilli of latitic composition in core 104 testify to an explosive submarine volcanism of the Marsili Seamount. According to the stratigraphy of core 103, the latest manifestations of this basaltic volcanism belong to the late Pleistocene (Emiliana huxleyi-zone of Nannoplankton stratigraphy) The basaltic lapilli are glassy to perhyaline with phenocrysts or microphenocrysts predominantely of olivine. The petrological character of the basaltic volcanites with high MgO, Ni, Cr and high MgO/FeO- and Ni/Co-ratios exhibits primitive basaltic features. These basalts clearly differ from basalts of the ocean floors, mid-ocean ridges and marginal basins. Prominent features are a missing iron-enrichment trend and low TiO2. Al2O3 tends to be high, as well as K2O and related trace elements (Ba, Sr). In spite of silica undrsaturation and high color index, the Marsili basalt exhibit some analogies with the calcalkaline basalts of the Aeolian arc, as well as the undersaturated basalts of some other circumoceanic areas.

(Appendix) Chemical composition of bottom sediments at DSDP Leg 72 Holes

The distributions of calcium carbonate, of amorphous silica, and of 21 chemical compounds and elements in sediments of Holes 515A, 515B, 516, 516F, 517, and 518 are highly nonuniform; they change depending on the sediment types, grain size, and mineral composition. The main source of the lithogenous elements (K, Li, Rb, Fe, Ti, Zr, Ni, Cr, Sn) is terrigenous matter of South America. These elements correlate well or at least satisfactorily with each other and with the sum of clay minerals. CaCO3, amorphous SiO2 and organic C form a second group, the main source of which is biota of the ocean. Zn, Cu, Ba, Mo, (V, Na) are a third group, which is supplied by both terrigenous and biogenic matter. Judging by the distribution of chemical elements and components in sediments of Site 515, this area of the Brazil Basin is characterized by the rather constant conditions of pelagic terrigenous sedimentation from upper Eocene till Holocene. Small changes in chemical composition of sediments throughout the section are linked mainly to the evolution of subaerial source provinces, changes in hydrodynamic regime, and fluctuations of the ocean level. The chemical composition of sediments from the Rio Grande Rise sites suggests the existence of three main stages of sedimentation in this area. The first stage is the initial period of sediment accumulation on basalts at the beginning of the Late Cretaceous. Then followed sedimentary conditions notable for their sharp changes in chemical composition and type. Beginning in the middle Eocene and persisting into the Holocene, stable conditions of sedimentation characterize a third stage, represented by the formation of approximately 700 m of nannofossil oozes of rather monotonous chemical composition.

(Appendix B) Carbonate fraction geochemistry at DSDP Hole 72-516F

This paper presents data on trace elements (Sr, Mg, Na, K, Mn, Fe, Ni, Cr) and isotopes (13C, 18O) on the carbonate fraction of bulk sediments from the Coniacian to Paleocene samples of Hole 516F. Relationships of trace elements to mineralogy and stratigraphic position are discussed at length, with special emphasis on 1) the differences between Hole 516F and other oceanic sites, and 2) the transitions observed at the Cretaceous/Tertiary boundary. Isotope data are compared to those obtained in other localities of the same age. The sections show the same major 13C variations at the Cretaceous/Tertiary boundary, indicating that this event is a planetary phenomenon.

Composition of Upper Quaternary bottom sediments from the Syrian area of the Mediterranean Sea

Results of a lithological study of bottom sediments in the Syrian region of the Mediterranean Sea during Cruise 27 of R/V Vityaz (1993) are reported. Suspended sediment discharge of the Nile River are of the greatest importance for terrigenous sedimentation in the SE part of the Mediterranean Sea, especially in deep-sea areas. Suspended load entering from the Syrian catchment area plays an important role in formation of recent shelf and slope deposits. Supply of aerosols from Syrian and Arabian deserts was distinguished by the patchiness of surface distribution of quartz. During Late Quaternary accumulation of terrigenous material supplied from both the Syrian and the Nile drainage areas was irregular. Sedimentation was remarkably enhanced during sapropel formation 7000-9000 years BP.

Metals in suspended matter and bottom sediments from of North Dvina estuary

In 1995-1997 three oceanographic cruises to the White Sea were undertaken in the framework of the INTAS project 94-391, and a multi-disciplinary geochemical study of the major North Dvina estuary has been carried out. Distribution of temperature, salinity and concentration of suspended matter in water columm, as well as contents of Al, Fe, Mn, Co, Cu, Ni, Cr, Pb, Zn, and organic carbon contents in suspended matter and sediments of the North Dvina estuary were determined. Most of the metals and organic matter studied appear to be of terrestrial origin, since the main source of investigated elements in the estuary is river run-off. It was found that metals incorporated in minerals are absolutely prevailing forms in estuarine sediments, they comprise up to 60-99% of total metal contents. Two zones of metal accumulation in the sediments were found in the North Dvina estuary. These zones are considered as local geochemical barriers within a major river-sea barrier. Distribution of most elements studied in the sediments of the North Dvina estuary is controlled by grain size variability in the sediments. Analysis of data on heavy metal contents in the sediments and bivalves of the North Dvina estuary did not reveal any anthropogenic heavy metal pollution in the region.

Speciation of metals in bottom sediments from the south Kara Sea and Ob and Yenisei estuarine zones

Speciation of Fe, Mn, Zn, Cu, Co, Ni, Cr, Pb, and Cd was studied in 52 samples of bottom sediments collected during Cruise 49 of the R/V "Dmitry Mendeleev" to the estuaries of the Ob and Yenisei rivers and to the southwest Kara Sea. Immediately after sampling the samples were subjected to on-board consecutive extraction to separate metal species according to their modes of occurrence in the sediments: (1) adsorbed, (2) amorphous Fe-Mn hydroxides and related metals, (3) organic + sulfide, and (4) residual, or lithogenic. Atomic absorption spectroscopy of the extracts was carried out at a stationary laboratory. Distribution of Fe, Zn, Cu, Co, Ni, Cr, Pb, and Cd species is characterized by predominance of lithogenic or geochemically inert modes (70-95% of bulk contents), in which the metals are bound in terrigenous and clastic mineral particles and organic detritus. About half of total Mn amount and 15-30% of Zn and Cu are contained in geochemically mobile modes. Spatiotemporal variations in proportions of the metal species in the surface layer of sediments along sub-meridional sections and through vertical sections of bottom sediment cores testify that Mn and, to a lesser extent, Cu are the most sensitive to changes in sedimentation environment. The role of their geochemically mobile species notably increases under reducing conditions.

Mineralogy micromorphology, and geochemistry at DSDP Site 89-585

At Site 585 of Deep Sea Drilling Project Leg 89 more than 500 m of volcaniclastic to argillaceous middle-Late Cretaceous sediments were recovered. Analyses by X-ray diffraction (bulk sediment and clay fraction), transmission electron microscopy, molecular and atomic absorption, and electron microprobe were done on Site 585 samples. We identify four successive stages and interpret them as the expression of environments evolving under successive influences: Stage 1, late Aptian to early Albian - subaerial and proximal volcanism, chiefly expressed by the presence of augite, analcite, olivine, celadonite, small and well-shaped transparent trioctahedral saponite, Al hydroxides, Na, Fe, Mg, and various trace elements (Mn, Ni, Cr, Co, Pb, V, Zn, Ti). Stage 2, early to middle Albian - submarine and less proximal volcanic influence, characterized by dioctahedral and hairy Mg-beidellites, a paucity of analcite and pyroxenes, the presence of Mg and K, and local alteration of Mg-smectites to Mg-chlorites. Stage 3, middle Albian to middle Campanian - early marine diagenesis, marked by the development of recrystallization from fleecy smectites to lathed ones (all of alkaline Si-rich Fe-beidellite types), by the development of opal CT and clinoptilolite, and by proximal to distal volcanic influences (Na parallel to Ti, K). Local events consist of the supply of reworked palygorskite during the Albian-Cenomanian, and the recurrence of proximal volcanic activity during the early Campanian. Stage 4, late Campanian to Maestrichtian - development of terrigenous supply resulting from the submersion of topographic barriers; this terrigenous supply is associated with minor diagenetic effects and is marked by a clay diversification (beidellite, illite, kaolinite, palygorskite), the rareness of clay recrystallizations, and the disappearance of volcanic markers.

Geochemistry of basalts at DSDP Hole 83-504B

The major element geochemistry of basalts recovered from Leg 83, Hole 504B, shows the typical features of midocean ridge basalts (MORB). The range of variation in their composition, together with the behavior of compatible trace elements (Co, Ni, Cr), indicate the well-known relative abundance of minerals that crystallize from these basaltic liquids: plagioclase, olivine, pyroxene, and spinel in decreasing abundance. The hygromagmaphile (or LILE or incompatible) elements are extremely depleted in light rare earths. Nevertheless, some units show flat and enriched REE patterns. These patterns, together with the values of the La/Ta ratio, are interpreted in terms of local mantle heterogeneity.

Trace metals in shells of mussels and clams from deep-sea hydrothermal vent fields of the Mid-Atlantic Ridge and East Pacific Rise

Bioaccumulation of trace metals in carbonate shells of mussels and clams was investigated at seven hydrothermal vent fields of the Mid-Atlantic Ridge (Menez Gwen, Snake Pit, Rainbow, and Broken Spur) and the Eastern Pacific (9°N and 21°N at the East Pacific Rise and the southern trough of Guaymas Basin, Gulf of California). Mineralogical analysis showed that carbonate skeletons of mytilid mussel Bathymodiolus sp. and vesicomyid clam Calyptogena m. are composed mainly of calcite and aragonite, respectively. The first data were obtained for contents of a variety of chemical elements in bivalve carbonate shells from various hydrothermal vent sites. Analyses of chemical compositions (including Fe, Mn, Zn, Cu, Cd, Pb, Ag, Ni, Cr, Co, As, Se, Sb, and Hg) of 35 shell samples and 14 water samples from mollusk biotopes revealed influences of environmental conditions and some biological parameters on bioaccumulation of metals. Bivalve shells from hydrothermal fields with black smokers are enriched in Fe and Mn by factor of 20-30 relative to the same species from the Menez Gwen low-temperature vent site. It was shown that essential elements (Fe, Mn, Ni, and Cu) more actively accumulated during early ontogeny of the shells. High enrichment factors of most metals (n x 100 - n x 10000) indicate efficient accumulation function of bivalve carbonate shells. Passive metal accumulation owing to adsorption on shell surfaces was estimated to be no higher than 50% of total amount and varied from 14% for Fe to 46% for Mn.

(Table 2) Contents of trace elements in plankton from the White Sea

With a view to more complete understanding of the role of phyto- and zooplankton in biogeochemical cycles, spatial distributions of Fe, Mn, Co, Ni, Cr, Cu, Cd, Pb, Zn, As, Hg, and Corg in the White Sea seston (21 samples) collected in August 2004 during Cruise 64 of R/V ''Professor Shtokman'' were studied. It was shown that the elements in study are accumulated in plankton with enrichment factors from 10**2 for Hg to 10**5 for Fe, as compared to seawater. Spatial distribution of trace elements is determined by sources of their supply and correlates with distribution of primary production and biomass of zooplankton. Increased values of trace element contents (excluding As) are characteristic of the Dvina Bay, whereas the highest As concentrations were found in the Kandalaksha Bay.

Sediment geochemistry of ODP Holes 206-1256B and 206-1256C

We measured the chemical composition of 100 samples from the 250-m sediment sequence retrieved from Ocean Drilling Program Site 1256 in the Guatemala Basin using a newly developed microwave-assisted acid digestion protocol followed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis. We compared these data gathered onshore to the results from the flux fusion prepared samples analyzed by shipboard ICP-AES during the leg and published in the Leg 206 Initial Reports volume, as well as to 35 randomly selected samples that were prepared by flux fusion at Boston University and analyzed by ICP-AES. Comparison of the newly developed acid digestion protocol to shore-based flux fusion demonstrates that the microwave-assisted acid technique yields a complete digestion, and because this procedure includes boric acid, it is safe for use with HF acid as boric acid neutralizes excess HF. The precision for nearly all elements in shore-based acid digestions is better than 3% of the measured values, including for elements such as Ni, Cr, and V, which are typically difficult to measure in biogenic-rich sediments. The shore-based flux fusions, while better than shipboard reported precision values (as expected), has precision better than 3% of their respective measured values for all major elements (Si, Al, Ti, Fe, Mn, Ca, Mg, Na, and K) and several trace elements (Ba and Sr). Results for P, Cr, Ni, V, Sc, and Zr are better than 5% of their measured values. Not only does the newly developed acid digestion provide better analytical results than the typical flux fusion method, the shore-based acid procedure also exhibits downhole lithologic and chemical characteristics similar to the shipboard flux fusion prepared results. These results confirm that the current shipboard methods are adequate for first-order geochemical interpretations and that the microwave-assisted acid digestion holds great potential to be the primary technique of preparing sediments on future Integrated Ocean Drilling Program expeditions.

Geochemistry of Neogene sediments of ODP Hole 115-711A

Pelagic sedimentation in the northwest Indian Ocean has been studied using sediments from Hole 711A (the section from 0 to 70.5 mbsf, 0-22 Ma), a deep site (4428 m) drilled during Ocean Drilling Program Leg 115. The clay fraction of the sediments represents poorly developed pelagic deposits with considerably lower contents of Mn, Ba, Cu, Ni, Cr, and Zn than is typical for well-oxidized pelagic sediments formed far from the continents (e.g., in the central Indian or Pacific oceans). Geochemical provenance models, representing conservative mixing models with terrigenous, exhalative-volcanic, and biogenous matter as the only inputs, explain most of the compositional variations in the sediments. The models show that terrigenous matter accounts for about 96%-100% of all SiO2, Al2O3, TiO2, and Zr; about 73%-85% of all Fe2O3, V, and Ni; and about 40%-60% of the Cu and Zn abundances. Exhalative-volcanic matter delivers a large fra tion of Mn (78%-85%), some Fe (15%-219/o), and possibly some Cu (38%-51%). Biogenous deposition is generally of restricted significance; at most 6%-35% of all Cu and Zn may derive from biogenic matter. The exhalative-volcanic matter is slightly more abundant in the oldest deposits, reflecting a plate tectonic drift away from the volcanic Carlsberg Ridge. The Al/Ti ratio reveals that silicic crustal matter plays a somewhat larger role in the upper and lower part of the section studied, whereas the basaltic input is slightly higher in the intermediate levels (age 5-15 m.y.). The sediment abundances of Ba generally exceed those predicted by the models, an anomalous behavior also observed in equatorial Pacific sediments. This is possibly caused by poor knowledge of the input components. Several changes in accumulation rates seem to correlate with climatic changes (onset of monsoon-driven upwellings and sea-level regressions of about 50-100 m at 10, 15-16, and 20-21 Ma). A number of constituents show higher accumulation rates at or shortly after these regressions, suggesting an accelerated removal of fines from shallow oceanic areas. Furthermore, the SiO2/Al2O3 ratio shows a small increase in sediments younger than 10 Ma, implying an increase in biological productivity, particularly after the onset of monsoon-driven upwelling in the northwest Indian Ocean. This trend is paralleled by a general increase in the accumulation rates of Ba and CaCO3. However, these accumulation rates are generally significantly lower than under the biological high-productivity zone in the equatorial Pacific. The onset of these upwelling systems about 10 Ma is probably related to the closing of the gap between India and the main Asiatic continent, preventing free circulation around the Indian subcontinent.