Isotopic composition of modern ice wedges and winter precipitation in the Laptev Sea region (Table 2)

The first step for the application of stable isotope analyses of ice wedges for the correct paleoclimatic reconstruction supposes the study of the isotopic composition of modern ice wedges and their relationship with the isotopic composition of modern precipitation. The purpose of this research is to present, to analyze and to discuss new data on isotopic composition (d18O, dD, 3H) of modern ice wedges obtained in the Laptev Sea region in 1998-99. Investigations were carried out at two sites: on Bykovsky Peninsula in 1998 and on Bol'shoy Lyakhovsky Island in 1999 and were based on the combined application of both tritium CH) and stable isotope (d18O, dD) analyses. Tritium analyses of the atmospheric precipitation collected during two field seasons show seasonal variations: high tritium concentration in snow (to a maximum of 207 TU) and low values of tritium concentration (<20 TU) in rain. High tritium concentrations are also observed in the surface water, in suprapermafrost ground waters, and in the upper part of permafrost. High tritium concentrations range between 30-40 TU and 750 TU in the studied modern ice wedges (active ice wedges), which let us believe that they are of modern growth. Such high tritium concentrations in ice wedges can not be associated with old thermonuclear tritium because of the radioactive decay. High tritium concentrations found in the snow cover in 1998/99, in the active layer and in the upper part of permafrost give evidence of modern (probably the last decade) technogenic tritium arrival from the atmosphere on to the Earth surface in the region. The comparison of the isotopic composition (d18O, dD and d-excess) of active ice wedges and modern winter precipitation in both sites shows: 1) the isotopic composition of snow correlates linearly with a slope close to 8.0 and parallel to the GMWL at both sites; 2) the mean isotopic composition of active ice wedges on Bykovsky Peninsula is in good agreement with the mean isotopic composition of modern snow; 3) the isotopic composition of active ice wedges and snow on Bol'shoy Lyakhovsky Island are considerably different. There are low values of d-excess in all studied active ice wedges (mean value is about 4.8 per mil), while in snow, the mean value of d-excess is about 9.5 per mil. Possible reasons for this gap are the following: 1) the modification of the isotopic composition in snow during the spring period; 2) changes in the isotopic composition of ice wedges due to the process of ice sublimation in open frost cracks during the cold period; 3) mixing of snowmelt water with different types of surface water during the spring period; 4) different moisture source regions.

Composition of bioclastic sands, carbonates and pyroclastic rocks of the Great Meteor and Josephine Seamounts, eastern North Atlantic

1. Great Meteor Seamount (GMS) is a very large (24,000 km**3) guyot with a flat summit plateau at 330-275 m; it has a volcanic core, capped by 150-600 m of post-Middle-Miocene carbonate and pyroclastic rocks, and is covered by bioclastic sands. The much smaller Josephine Seamount (JS, summit 170- 500 m w. d.) consists mainly of basalt which is only locally covered by limestones and bioclastic sands. 2. The bioclastic sands are almost free of terrigenous components, and are well sorted, unimodal medium sands. (1) "Recent pelagic sands" are typical of water depths > 600 m (JS) or > 1000 m (GMS). (2) "Sands of mixed relict-recent origin" (10-40% relict) and (3) "relict sands" (> 40% relict) are highly reworked, coarse lag deposits from the upper flanks and summit tops in which recent constituents are mixed with Pleistocene or older relict material. 3. From the carbonate rocks of both seamounts, 12 "microfacies" (MF-)types were distinguished. The 4 major types are: (1) Bio(pel)sparites (MF 1) occur on the summit plateaus and consist of magnesian calcite cementing small pellets and either redeposited planktonic bioclasts or mixed benthonic-planktonic skeletal debris ; (2) Porous biomicrites (MF 2) are typical of the marginal parts of the summit plateaus and contain mostly planktonic foraminifera (and pteropods), sometimes with redeposited bioclasts and/or coated grains; (3) Dense, ferruginous coralline-algal biomicrudites with Amphistegina sp. (MF 3.1), or with tuffaceous components (MF 3.2); (4) Dense, pelagic foraminiferal nannomicrite (MF 4) with scattered siderite rhombs. Corresponding to the proportion and mineralogical composition of the bioclasts and of the (Mgcalcitic) peloids, micrite, and cement, magnesian calcite (13-17 mol-% MgCO3) is much more abundant than low-Mg calcite and aragonite in rock types (1) and (2). Type (3) contains an "intermediate" Mg-calcite (7-9 mol-X), possibly due to an original Mg deficiency or to partial exsolution of Mg during diagenesis. The nannomicrite (4) consists of low-Mg calcite only. 4. Three textural types of volcanic and associated gyroclastic rocks were distinguished: (1) holohyaline, rapidly chilled and granulated lava flows and tuffs (palagonite tuff breccia and hyaloclastic top breccia); (2) tachylitic basalts (less rapidly chilled; with opaque glass); and (3) "slowly" crystallized, holocrystalline alkali olivine basalts. The carbonate in most mixed pyroclastic-carbonate sediments at the basalt contact is of "post-eruptive" origin (micritic crusts etc.); "pre-eruptive" limestone is recrystallized or altered at the basalt contact. A deuteric (?hydrothermal) "mineralX", filling vesicles in basalt and cementing pyroclastic breccias is described for the first time. 5. Origin and development of GMS andJS: From its origin, some 85 m. y. ago, the volcano of GMS remained active until about 10 m. y. B. P. with an average lava discharge of 320 km**3/m. y. The volcanic origin of JS is much younger (?Middle Tertiary), but the volcanic activity ended also about 9 m. y. ago. During L a t e Miocene to Pliocene times both volcanoes were eroded (wave-rounded cobbles). The oldest pyroclastics and carbonates (MF 3.1, 3.2) were originally deposited in shallow-water (?algal reef hardground). The Plio (-Pleisto) cene foraminiferal nannomicrites (MF 4) suggest a meso- to bathypelagic environment along the flanks of GMS. During the Quaternary (?Pleistocene) bioclastic sands were deposited in water depths beyond wave base on the summit tops, repeatedly reworked, and lithified into loosely consolidated biopelsparites and biomicrites (MF 1 and 2; Fig. 15). Intermediate steps were a first intragranular filling by micrite, reworking, oncoidal coating, weak consolidation with Mg-calcite cemented "peloids" in intergranular voids and local compaction of the peloids into cryptocrystalline micrite with interlocking Mg-calcite crystals up to 4p. The submarine lithification process was frequently interrupted by long intervals of nondeposition, dissolution, boring, and later infilling. The limestones were probably never subaerially exposed. Presently, the carbonate rocks undergo biogenic incrustation and partial dissolution into bioclastic sands. The irregular distribution pattern of the sands reflects (a) the patchy distribution of living benthonic organisms, (b) the steady rain of planktonic organism onto the seamount top, (c) the composition of disintegrating subrecent limestones, and (d) the intensity of winnowing and reworking bottom current

Sedimentology and Th, Pa, U, and N isotopic composition of core MD84-527

High-resolution records of opal, carbonate, and terrigenous fluxes have been obtained from a high-sedimentation rate core (MD84-527: 43°50'S; 51°19'E; 3269 m) by normalization to 230Th. This method estimates paleofluxes to the seafloor on a point-by-point basis and distinguishes changes in sediment accumulation due to variations in vertical rain rates from those due to changes in syndepositional sediment redistribution by bottom currents. We also measured sediment delta15N to evaluate the changes in nitrate utilization in the overlying surface waters associated with paleoflux variations. Our results show that opal accumulation rates on the seafloor during the Holocene and stage 3, based on 14C dating, were respectively tenfold and fivefold higher than the vertical rain rates, At this particular location, changes in opal accumulation on the seafloor appear to be mainly controlled by sediment redistribution by bottom currents rather than variations in opal fluxes from the overlying water column. Correction for syndepositional sediment redistribution and the improved time resolution that can be achieved by normalization to 230Th disclose important variations in opal rain rates. We found relatively high but variable opal paleoflux during stage 3, with two maxima centered at 36 and 30 kyr B.P., low opal paleoflux during stage 2 and deglaciation and a pronounced maximum during the early Holocene, We interpret this record as reflecting variations in opal production rates associated with climate-induced latitudinal migration of the southern ocean frontal system. Sediments deposited during periods of high opal paleoflux also have high authigenic U concentrations, suggesting more reducing conditions in the sediment, and high Pa-231/Th-230 ratios, suggesting increased scavenging from the water column. Sediment delta15N is circa 1.5 per mil higher during isotopic stage 2 and deglaciation. The low opal rain rates recorded during that period appear to have been associated with increased nitrate depletion. This suggests that opal paleofluxes do not simply reflect latitudinal migration of the frontal system but also changes in the structure of the upper water column. Increased stratification during isotopic stage 2 and deglaciation could have been produced by a meltwater lid, leading to lower nitrate supply rates to surface waters.

Composition of airborne material from yellow snow fallen in the Russian North

Large amounts of dust responsible for bright colors of atmospheric precipitation in the temperate, subpolar and polar zones of the northern hemisphere have been rarely observed. In the twentieth century and in the beginning of the twenty first century in the Northern European Russia such events were not registered up to March 25-26, 2008. At that time in some parts of the Arkhangel'sk region, Komi Republic, and Nenets Autonomous Area atmospheric precipitation as sleet and rain responsible for sand- and saffron colors of ice crust formation on the snow surface was observed. During detailed mineralogical, geochemical, pollen, diatom and meteorological investigations it was established that semidesert and steppe regions of the Northwest Kazakhstan, Volgograd and Astrakhan' regions, and Kalmykia are the main sources of the yellow dust.

(Table 3) Boron and chlorine in atmospheric moisture and rain water collected on the shore of the Golubaya Bay in 1970

Boron and chlorine were determined in rain water and in atmospheric moisture condensed in a "Saratov" refrigerator. Ocean is the main source of boron on the earth surface. Boron evaporates from the ocean and enriches atmospheric precipitation: B/Cl ratio of ocean water (0.00024) increases by factor of 10-15. Assuming that the average Cl content in global river runoff is 7.8 mg/l and boron content 0.013 mgl, B/Cl ratio in this runoff is 0.0017. The average B/Cl ratio in rain water of the Golubaya (Blue) Bay (Gelendzhik, Black Sea region) is 0.0026 and in condensates of atmospheric moisture during onshore and offshore winds in the same region it averages from 0.0029 to 0.0033. The maximum boron content in the condensates of this region during onshore winds was 0.032 mg/l and the minimum during offshore winds, 0.004 mg/l. /Cl ratio in sea water over the Atlantic Ocean and in the Gelendzhik area of the Black Sea varied within narrow range, mostly from 0.0025 to 0.0035. Similar B/Cl ratio (0.0024) was found for atmospheric precipitation on the slope of the Terskei Ala-Tau near the Issyk-Kul Lake in 1969. Thus, although chemistries of boron and chlorine (in chlorides) are very different, the B/Cl ratio in the atmosphere is fairly constant. This can be taken as a confirmation of an assumption that salt composition of sea water passes into the atmosphere in molecularly dispersed state. Supposing that the ocean-atmosphere system is in equilibrium as regards to the boron budget, it can be assumed that the same amount of boron passes from the ocean into bottom sediments and from lithosphere rocks and soils into the hydrosphere.

Impacts of feeding system and season on milk composition and Cheddar cheese yield in a subtropical environment

Milk obtained from cows on 2 subtropical dairy feeding systems were compared for their suitability for Cheddar cheese manufacture. Cheeses were made in a small-scale cheesemaking plant capable of making 2 blocks ( about 2 kg each) of Cheddar cheese concurrently. Its repeatability was tested over 10 separate cheesemaking days with no significant differences being found between the 2 vats in cheesemaking parameters or cheese characteristics. In the feeding trial, 16 pairs of Holstein - Friesian cows were used in 2 feeding systems (M1, rain-grown tropical grass pastures and oats; and M5, a feedlot, based on maize/barley silage and lucerne hay) over 2 seasons ( spring and autumn corresponding to early and late lactation, respectively). Total dry matter, crude protein (kg/cow. day) and metabolisable energy (MJ/cow.day) intakes were 17, 2.7, and 187 for M1 and 24, 4, 260 for M5, respectively. M5 cows produced higher milk yields and milk with higher protein and casein levels than the M1 cows, but the total solids and fat levels were similar (P > 0.05) for both M1 and M5 cows. The yield and yield efficiency of cheese produced from the 2 feeding systems were also not significantly different. The results suggest that intensive tropical pasture systems can produce milk suitable for Cheddar cheese manufacture when cows are supplemented with a high energy concentrate. Season and stage of lactation had a much greater effect than feeding system on milk and cheesemaking characteristics with autumn ( late lactation) milk having higher protein and fat contents and producing higher cheese yields.

Influence of lactation stages and rain periods on subclinical mastitis in meat producing ewes.

Mastitis negatively influences the survival and weight gain of ovines for meat production. The purpose of this study was to investigate, in sheep for meat production, the occurrence of subclinical mastitis in ewes at the end of lactation and beginning of the consecutive lactation and to assess the composition and cellular characteristics of milk as a function of different rainfall indices. Mammary halves (821) of Santa Ines (479) and Morada Nova (342) ewes were examined. Milk samples were collected in two different moments of lactation: at weaning and postpartum of the consecutive lactation. Sample collection periods were called ?dry? or ?rainy? according to the rainfall index in the month immediately before the month of collection. The occurrence of subclinical mastitis at weaning in the Santa Ines and Morada Nova ewes were 16.4 and 12.6% in the dry period, and 17.7 and 23.5% in the rainy period, respectively. In the consecutive lactation period, the occurrences were 26.7 and 27.7% in the dry period and 41.8 and 39.1% in the rainy period, for the Santa Ines and Morada Nova ewes, respectively. Postpartum stage was critical for the occurrence of subclinical mastitis, as compared to that at the end of the previous lactation. Occurrence of the disease negatively influenced the SCC in the milk at the beginning of lactation and changed its composition, mainly in the rainiest periods, probably due to a difficulty in maintaining hygiene in the environment where the animals remained.

Exploratory Study Of The Effect Of Lifestyle Counselling On Bone Mineral Density And Body Composition In Users Of The Contraceptive Depot-medroxyprogesterone Acetate.

To compare variations in bone mineral density (BMD) and body composition (BC) in depot-medroxyprogesterone acetate (DMPA) users and nonusers after providing counselling on healthy lifestyle habits. An exploratory study in which women aged 18 to 40 years participated: 29 new DMPA users and 25 new non-hormonal contraceptive users. All participants were advised on healthy lifestyle habits: sun exposure, walking and calcium intake. BMD and BC were assessed at baseline and 12 months later. Statistical analysis included the Mann-Whitney test or Student's t-test followed by multiple linear regression analysis. Compared to the controls, DMPA users had lower BMD at vertebrae L1 and L4 after 12 months of use. They also had a mean increase of 2 kg in total fat mass and an increase of 2.2% in body fat compared to the non-hormonal contraceptive users. BMD loss at L1 was less pronounced in DMPA users with a calcium intake ≥ 1 g/day compared to DMPA users with a lower calcium intake. DMPA use was apparently associated with lower BMD and an increase in fat mass at 12 months of use. Calcium intake ≥ 1 g/day attenuates BMD loss in DMPA users. Counselling on healthy lifestyle habits failed to achieve its aims.

Growth And Body Composition In Brazilian Female Rhythmic Gymnastics Athletes.

The aim was to analyse the physical growth and body composition of rhythmic gymnastics athletes relative to their level of somatic maturation. This was a cross-sectional study of 136 athletes on 23 teams from Brazil. Mass, standing height and sitting height were measured. Fat-free and fat masses, body fat percentages and ages of the predicted peak height velocity (PHV) were calculated. The z scores for mass were negative during all ages according to both WHO and Brazilian references, and that for standing height were also negative for all ages according to WHO reference but only until 12 years old according to Brazilian reference. The mean age of the predicted PHV was 12.1 years. The mean mass, standing and sitting heights, body fat percentage, fat-free mass and fat mass increased significantly until 4 to 5 years after the age of the PHV. Menarche was reached in only 26% of these athletes and mean age was 13.2 years. The mass was below the national reference standards, and the standing height was below only for the international reference, but they also had late recovery of mass and standing height during puberty. In conclusion, these athletes had a potential to gain mass and standing height several years after PHV, indicating late maturation.

Biochemical, Anthropometric And Body Composition Indicators As Predictors Of Hepatic Steatosis In Obese Adolescents.

To describe the prevalence of hepatic steatosis and to assess the performance of biochemical, anthropometric and body composition indicators for hepatic steatosis in obese teenagers. Cross-sectional study including 79 adolecents aged from ten to 18 years old. Hepatic steatosis was diagnosed by abdominal ultrasound in case of moderate or intense hepatorenal contrast and/or a difference in the histogram ≥7 on the right kidney cortex. The insulin resistance was determined by the Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) index for values >3.16. Anthropometric and body composition indicators consisted of body mass index, body fat percentage, abdominal circumference and subcutaneous fat. Fasting glycemia and insulin, lipid profile and hepatic enzymes, such as aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase and alkaline phosphatase, were also evaluated. In order to assess the performance of these indicators in the diagnosis of hepatic steatosis in teenagers, a ROC curve analysis was applied. Hepatic steatosis was found in 20% of the patients and insulin resistance, in 29%. Gamma-glutamyltransferase and HOMA-IR were good indicators for predicting hepatic steatosis, with a cutoff of 1.06 times above the reference value for gamma-glutamyltransferase and 3.28 times for the HOMA-IR. The anthropometric indicators, the body fat percentage, the lipid profile, the glycemia and the aspartate aminotransferase did not present significant associations. Patients with high gamma-glutamyltransferase level and/or HOMA-IR should be submitted to abdominal ultrasound examination due to the increased chance of having hepatic steatosis.