Organic compounds in snow, ice, and sub-ice waters from the mouth of the Severnaya Dvina River and the Kandalaksha Gulf (White Sea)

The paper reports data on concentrations of organic compounds (organic carbon, lipids; aliphatic hydrocarbons, and polycyclic aromatic hydrocarbons) in snow, ice, and sub-ice waters from the mouth of the Severnaya Dvina River in March 2005-2007 and the Kandalaksha Gulf (Chupa Bay) in March 2004. It was established that organic compounds are accumulated in snow and the upper ice layer near Archangelsk city. Distribution of molecular markers indicates that pollutions were mainly caused by local fallouts. In the Chupa Bay organic compounds are concentrated in the lower ice layer; it is typical for Arctic snow-ice cover. High contents of organic compounds in the snow-ice cover of the White Sea are caused by pollution of air and water during the winter season.

Quaternary radiolarians and plamktonic foraminifera from the mouth of the Gulf of California

I recovered well-preserved radiolarian assemblages from the Quaternary sediments drilled at all four sites at the mouth of the Gulf of California during Leg 65. The sites, with positions and water depths averaged for all hole locations per site, are Site 482 - 22°47.4'N, 107°59.6'W; water depth, 3022 meters. Site 483 - 22°53.0'N, 108°44.8' W; water depth, 3070 meters. Site 484 - 23°11.2'N, 108°23.6'W; water depth, 2887 meters. Site 485 - 22°44.9'N, 107°54.2'W; water depth, 2981 meters. The nearly 200 taxa I identified are listed alphabetically in the systematic reference list. The only reliable radiolarian biostratigraphic datum determined for the Quaternary sedimentary section is the highest occurrence of Axoprunum angelinum (Hays) at Sites 483, 484, and 485.

Sediment facies of the Indian-Pakistan continental margin, Indian Ocean Expedition

The studies described here base mainly on sedimentary material collected during the "Indian Ocean Expedition" of the German research vessel "Meteor" in the region of the Indian-Pakistan continental margin in February and March 1965. Moreover,samples from the mouth of the Indus-River were available, which were collected by the Pakistan fishing vessel "Machhera" in March 1965. Altogether, the following quantities of sedimentary material were collected: 59.73 m piston cores. 54.52 m gravity cores. 33 box grab samples. 68 bottom grab samples Component analyses of the coarse fraction were made of these samples and the sedimentary fabric was examined. Moreover, the CaCO3 and Corg contents were discussed. From these investigations the following history of sedimentation can be derived: Recent sedimentation on the shelf is mainly characterized by hydrodynamic processes and terrigenous supply of material. In the shallow water wave action and currents running parallel to the coast, imply a repeated reworking which induces a sorting of the grains and layering of the sediments as well as a lack of bioturbation. The sedimentation rate is very high here. From the coast-line down to appr. 50 m the sediment becomes progressively finer, the conditions of deposition become less turbulent. On the outer shelf the sediment is again considerably coarser. It contains many relicts of planktonic organisms and it shows traces of burrowing. Indications for redeposition are nearly missing, a considerable part of the fine fraction of the sediments is, however, whirled up and carried away. In wide areas of the outer shelf this stirring has gained such a degree that recent deposits are nearly completely missing. Here, coarse relict sands rich in ooids are exposed, which were formed in very shallow stirred water during the time when the sea reached its lowest level, i.e. at the turn of the Pleistocene to the Holocene. Below the relict sand white, very fine-grained aragonite mud was found at one location (core 228). This aragonite mud was obviously deposited in very calm water of some greater depth, possibly behind a reef barrier. Biochemic carbonate precipitation played an important part in the formation of relict sands and aragonite muds. In postglacial times the relict sands were exposed for long periods to violent wave action and to areal erosion. In the present days they are gradually covered by recent sediments proceeding from the sides. On the continental margin beyond the shelf edge the distribution of the sediments is to a considerable extent determined by the morphology of the sea bottom. The material originating from the continent and/or the shelf, is less transported by action of the water than by the force of gravity. Within the range of the uppermost part of the continental slope recent sedimentation reaches its maximum. Here the fine material is deposited which has been whirled up in the zone of the relict sands. A laminated fine-grained sediment is formed here due to the very high sedimentation rate as well as to the extremely low O2-content in the bottom water, which prevents life on the bottom of the sea and impedes thus also bioturbation. The lamination probaly reflects annual variation in deposition and can be attributed to the rhythm of the monsoon with its effects on the water and the weather conditions. In the lower part of the upper continental slope sediments are to be found which show in varying intensity, intercalations of fine material (silt) from the shelf, in large sections of the core. These fine intercalations of allochthonous material are closely related to the autochthonous normal sediment, so that a great number of small individual depositional processes can be inferred. In general the intercalations are missing in the uppermost part of the cores; in the lower part they can be met in different quantities, and they reach their maximum frequency in the upper part of the lower core section. The depositions described here were designated as turbid layer sediments, since they get their material from turbid layers, which transport components to the continental slope which have been whirled up from the shelf. Turbidites are missing in this zone. Since the whole upper continental slope shows a low oxygen-content of the bottom water the structure of the turbid layer sediments is more or less preserved. The lenticular-phacoidal fine structure does, however, not reflect annual rhythms, but sporadic individual events, as e.g. tsunamis. At the lower part of the continental slope and on the continental rise the majority of turbidites was deposited, which, during glacial times and particularly at the beginning of the post-glacial period, transported material from the zone of relict sands. The Laccadive Ridge represented a natural obstacle for the transport of suspended sediments into the deep sea. Core SIC-181 from the Arabian Basin shows some intercalations of turbidites; their material, however, does not originate from the Indian Shelf, but from the Laccadive Ridge. Within the range of the Indus Cone it is surprising that distinct turbidites are nearly completely missing; on the other hand, turbid layer sediments are to be found. The bottom of the sea is showing still a slight slope here, so that the turbidites funneled through the Canyon of the Swatch probably rush down to greater water depths. Due to the particularly large supply of suspended material by theIndus River the turbid layer sediments show farther extension than in other regions. In general the terrigenous components are concentrated on the Indus Cone. It is within the range of the lower continental slope that the only discovery of a sliding mass (core 186) has been located. It can be assumed that this was set in motion during the Holocene. During the period of time discussed here the following development of kind and intensity of the deposition of allochthonous material can be observed on the Indian-Pakistan continental margin: At the time of the lowest sea level the shelf was only very narrow, and the zone in which bottom currents were able to stir up material by oscillating motion, was considerably confined. The rivers flowed into the sea near to the edge of the shelf. For this reason the percentage of terrigenous material, quartz and mica is higher in the lower part of many cores (e.g. cores 210 and 219) than in the upper part. The transition from glacial to postglacial times caused a series of environmental changes. Among them the rise of the sea level (in the area of investigation appr. 150 m) had the most important influence on the sedimentation process. In connection with this event many river valleys became canyons, which sucked sedimentary material away from the shelf and transported it in form of turbidites into the deep sea. During the rise of the sea level a situation can be expected with a maximum area of the comparatively plane shelf being exposed to wave action. During this time the process of stirring up of sediments and formation of turbid layers will reach a maximum. Accordingly, the formation of turbidites and turbid layer sediments are most frequent at the same time. This happened in general in the older polstglacial period. The present day high water level results in a reduced supply of sediments into the canyons. The stirring up of sediments from the shelf by wave action is restricted to the finest material. The missing of shelf material in the uppermost core sections can thus be explained. The laminated muds reflect these calm sedimentation conditions as well. In the southwestern part of the area of investigation fine volcanic glass was blown in during the Pleistocene, probably from the southeast. It has thus become possible to correlate the cores 181, 182, 202. Eolian dust from the Indian subcontinent represents probably an important component of the deep sea sediments. The chemism of the bottom as well as of the pore water has a considerable influence on the development of the sediments. Of particular importance in this connection is a layer with a minimum content of oxygen in the sea water (200-1500 m), which today touches the upper part of the continental slope. Above and beyond this oxygen minimum layer somewhat higher O2-values are to be observed at the sea bottom. During the Pleistocene the oxygen minimum layer has obviously been locatedin greater depth as is indicated by the facies of laminated mud occuring in the lower part of core 219. The type of bioturbation is mainly determined by the chemism. Moreover, the chemism is responsible for a considerable selective dissolution, either complete or partial, of the sedimentary components. Within the range of the oxygen minimum layer an alkaline milieu is developed at the bottom. This causes a complete or partial dissolution of the siliceous organisms. Here, bioturbation is in general completely missing; sometimes small pyrite-filled burrowing racks are found. In the areas rich in O2 high pH-values result in a partial dissolution of the calcareous shells. Large, non-pyritized burrowing tracks characterize the type of bioturbation in this environment. A study of the "lebensspuren" in the cores supports the assumption that, particularly within the region of the Laccadive Basin, the oxygen content in the bottom sediments was lower than during the Holocene. This may be attributed to a high sedimentation rate and to a lower O2-content of the bottom water. The composition of the allochthonous sedimentary components, detritus and/or volcanic glass may locally change the chemism to a considerable extent for a certain time; under such special circumstances the type of bioturbation and the state of preservation of the components may be different from those of the normal sediment.

Rare earth element contents in deposits and minerals of the ocean floor

Current understanding of rare earth element (REE) geochemistry in the ocean is given in the book. Chemical properties determining REE migration ability in natural processes, sources of REE in the ocean, behavior of REE in river-sea mixing zones, fractionation of dissolved and particulate REE in ocean waters under aerobic and anaerobic conditions, distribution of REE in terrigenous, authigenic, hydrothermal and biogenic sediment components (clay, bone detritus, barite, phillipsite, Fe- and Mn-oxyhydroxides, Fe-Ca hydroxophosphate, diatoms and foraminiferas) are under consideration.

Pollen analysis of sediment cores from the mouth of the river Congo to Walvis Bay and Lüderitz

The distribution of pollen in marine sediments is used to record vegetation changes over the past 30,000 years on the adjacent continent. A transect of marine pollen sequences from the mouth of the river Congo (~5°S) to Walvis Bay and Lüderitz (~25°S) shows vegetation changes in Congo, Angola and Namibia from the last glacial period into the Holocene. The comparison of pollen records from different latitudes provides information about the latitudinal shift of open forest and savannahs (Poaceae pollen), the extension of lowland forest (rain forest pollen) and Afromontane forest (Podocarpus pollen), and the position of the desert fringe (pollen of Caryophyllaceae, Chenopodiaceae and Amaranthaceae). High Cyperaceae pollen percentages in sediments from the last glacial period off the mouth of the river Congo suggest the presence of open swamps rather than savannah vegetation in the Congo Basin. Pollen from Restionaceae in combination with Stoebe-type pollen (probably from Elytropappus) indicates a possible northwards extension of winter rain vegetation during the last glacial period. The record of Rhizophora (mangrove) pollen is linked to erosion of the continental shelf and sea-level rise. Pollen influx is highest off river mouths (10-2000 grains year**-1 cm**-2), close to the coast (300-6000 grains year**-1 cm**-2), but is an order of magnitude lower at sites situated far from the continent (<10 grains year**-1 cm**-2).