Chemical composition of bottom sediments and rocks from DSDP Holes 3-14 through 64-477

Data on analyses of chemical composition of DSDP samples of bottom sediments and rocks carried out in P.P. Shirshov Institute of Oceanology are reported. Basal sediments and sedimentary rocks prevail in the sample set.

Sediments in arctic sea ice - entrainment, characterization and quantification

Sediments in Arctic sea ice are important for erosion and redistribution and consequently a factor for the sediment budget of the Arctic Ocean. The processes leading to the incorporation of sediments into the ice are not understood in detail yet. In the present study, experiments on the incorporation of sediments were therefore conducted in ice tanks of The Hamburg Ship Model Basin (HSVA) in winter 1996/1997, These experiments showed that on average 75 % of the artificial sea-ice sediments were located in the brine-channel system. The sediments were scavenged from the water column by frazil ice. Sediments functioning as a nucleus for the formation of frazil ice were less important for the incorporation. Filtration in grease ice during relatively calm hydrodynamic conditions was probably an effective process to enrich sediments in the ice. Wave fields did not play an important role for the incorporation of sediments into the artificial sea ice. During the expedition TRANSDRIFT III (TDIII, October 1995), different types of natural, newly-formed sea ice (grease ice, nilas and young ice) were sampled in the inner Laptev Sea at the time of freeze-up. The incorporation of sediments took place during calm meteorological conditions then. The characteristics of the clay mineral assemblages of these sedirnents served as references for sea-ice sediments which were sampled from first-year drift ice in the outer Laptev Sea and the adjacent Arctic Ocean during the POLARSTERN expedition ARK-XI/1 (July-September 1995). Based on the clay mineral assemblages, probable incorporation areas for the sedirnents in first-year drift ice could be statistically reconstructed in the inner Laptev Sea (eastern, central, and Western Laptev Sea) as well as in adjacent regions. Comparing the amounts of particulate organic carbon (POC) in sea-ice sediments and in surface sediments from the shelves of potential incorporation areas often reveals higher values in sea-ice sediments (TDIII: 3.6 %DM; ARK-XI/1: 2.3 %DM). This enrichment of POC is probably due to the incorporation process into the sea ice, as could be deducted from maceral analysis and Rock-Eval pyrolysis. Both methods were applied in the present study to particulate organic material (POM) from sea-ice sediments for the first time. It was shown that the POM of the sea-ice sediments from the Laptev Sea and the adjacent Arctic Ocean was dominated by reworked, strongly fragmented, allochthonous (terrigenous) material. This terrigenous component accounted for more than 75 % of all counted macerals. The autochthonous (marine) component was also strongly fragmented, and higher in the sediments from newly-formed sea ice (24 % of all counted macerals) as compared to first-year drift ice (17 % of all counted macerals). Average hydroge indices confirmed this pattern and were in the transition zone between kerogen types II and III (TDIII: 275 mg KW/g POC; ARK-XI/1: 200 mg KW/g POC). The sediment loads quantified in natural sea ice (TDIII: 33.6 mg/l, ARK-XI/1: 49.0 mg/l) indicated that sea-ice sediments are an important factor for the sediment budget in the Laptev Sea. In particular during the incorporation phase in autumn and early winter, about 12 % of the sediment load imported annually by rivers into the Laptev Sea can be incorporated into sea ice and redistributed during calm meteorological conditions. Single entrainment events can incorporate about 35 % of the river input into the sea ice (ca. 9 x 10**6 t) and export it via the Transpolar Drift from the Eurasian shelf to the Fram Strait.

Hydrochemical Atlas of the Arctic Ocean

Introduction: Chemical composition of water determines its physical properties and character of processes proceeding in it: freezing temperature, volume of evaporation, density, color, transparency, filtration capacity, etc. Presence of chemical elements in water solution confers waters special physical properties exerting significant influence on their circulation, creates necessary conditions for development and inhabitance of flora and fauna, and imparts to the ocean waters some chemical features that radically differ them from the land waters (Alekin & Liakhin, 1984). Hydrochemical information helps to determine elements of water circulation, convection depth, makes it easier to distinguish water masses and gives additional knowledge of climatic variability of ocean conditions. Hydrochemical information is a necessary part of biological research. Water chemical composition can be the governing characteristics determining possibility and limits of use of marine objects, both stationary and moving in sea water. Subject of investigation of hydrochemistry is study of dynamics of chemical composition, i.e. processes of its formation and hydrochemical conditions of water bodies (Alekin & Liakhin 1984). The hydrochemical processes in the Arctic Ocean are the least known. Some information on these processes can be obtained in odd publications. A generalizing study of hydrochemical conditions in the Arctic Ocean based on expeditions conducted in the years 1948-1975 has been carried out by Rusanov et al. (1979). The "Atlas of the World Ocean: the Arctic Ocean" contains a special section "Hydrochemistry" (Gorshkov, 1980). Typical vertical profiles, transects and maps for different depths - 0, 100, 300, 500, 1000, 2000, 3000 m are given in this section for the following parameters: dissolved oxygen, phosphate, silicate, pH and alkaline-chlorine coefficient. The maps were constructed using the data of expeditions conducted in the years 1948-1975. The illustrations reflect main features of distribution of the hydrochemical elements for multi-year period and represent a static image of hydrochemical conditions. Distribution of the hydrochemical elements on the ocean surface is given for two seasons - winter and summer, for the other depths are given mean annual fields. Aim of the present Atlas is description of hydrochemical conditions in the Arctic Ocean on the basis of a greater body of hydrochemical information for the years 1948-2000 and using the up-to-date methods of analysis and electronic forms of presentation of hydrochemical information. The most wide-spread characteristics determined in water samples were used as hydrochemical indices. They are: dissolved oxygen, phosphate, silicate, pH, total alkalinity, nitrite and nitrate. An important characteristics of water salt composition - "salinity" has been considered in the Oceanographic Atlas of the Arctic Ocean (1997, 1998). Presentation of the hydrochemical characteristics in this Hydrochemical Atlas is wider if compared with that of the former Atlas (Gorshkov, 1980). Maps of climatic distribution of the hydrochemical elements were constructed for all the standard depths, and seasonal variability of the hydrochemical parameters is given not only for the surface, but also for the underlying standard depths up to 400 m and including. Statistical characteristics of the hydrochemical elements are given for the first time. Detailed accuracy estimates of initial data and map construction are also given in the Atlas. Calculated values of mean-root deviations, maximum and minimum values of the parameters demonstrate limits of their variability for the analyzed period of observations. Therefore, not only investigations of chemical statics are summarized in the Atlas, but also some elements of chemical dynamics are demonstrated. Digital arrays of the hydrochemical elements obtained in nodes of a regular grid are the new form of characteristics presentation in the Atlas. It should be mentioned that the same grid and the same boxes were used in the Atlas, as those that had been used by creation of the US-Russian climatic Oceanographic Atlas. It allows to combine hydrochemical and oceanographic information of these Atlases. The first block of the digital arrays contains climatic characteristics calculated using direct observational data. These climatic characteristics were not calculated in the regions without observations, and the information arrays for these regions have gaps. The other block of climatic information in a gridded form was obtained with the help of objective analysis of observational data. Procedure of the objective analysis allowed us to obtain climatic estimates of the hydrochemical characteristics for the whole water area of the Arctic Ocean including the regions not covered by observations. Data of the objective analysis can be widely used, in particular, in hydrobiological investigations and in modeling of hydrochemical conditions of the Arctic Ocean. Array of initial measurements is a separate block. It includes all the available materials of hydrochemical observations in the form, as they were presented in different sources. While keeping in mind that this array contains some amount of perverted information, the authors of the Atlas assumed it necessary to store this information in its primary form. Methods of data quality control can be developed in future in the process of hydrochemical information accumulation. It can be supposed that attitude can vary in future to the data that were rejected according to the procedure accepted in the Atlas. The hydrochemical Atlas of the Arctic Ocean is the first specialized and electronic generalization of hydrochemical observations in the Arctic Ocean and finishes the program of joint efforts of Russian and US specialists in preparation of a number of atlases for the Arctic. The published Oceanographic Atlas (1997, 1998), Atlas of Arctic Meteorology and Climate (2000), Ice Atlas of the Arctic Ocean prepared for publication and Hydrochemical Atlas of the Arctic Ocean represent a united series of fundamental generalizations of empirical knowledge of Arctic Ocean nature at climatic level. The Hydrochemical Atlas of the Arctic Ocean was elaborated in the result of joint efforts of the SRC of the RF AARI and IARC. Dr. Ye. Nikiforov was scientific supervisor of the Atlas, Dr. R. Colony was manager on behalf of the USA and Dr. L. Timokhov - on behalf of Russia.