837 resultados para East Gloucester
Resumo:
Data on the concentration and mineral composition of aerosols collected by nets in Cruise 18 of R/V Akadernik Fedorov on a submeridional section in the East Atlantic are presented. An empirical curve for calculating efficiency factor of a net is given for different concentrations of mineral part of aerosols. Fluxes of lithogenic part of aerosols to the sea surface are calculated. A comparison of lithogenic fluxes from the atmosphere and in the water column of the ocean showed that values of fluxes practically coincide in areas with dominating supply of dry atmospheric material. These fluxes strongly differ in the intratropical convergence zone, where deposition of aerosols depends on atmospheric precipitation, or in regions, where sedimentary material is supplied to the ocean mainly by river run-off. Residence time of aerosol lithogenic matter in the euphotic layer is calculated.
Resumo:
Mineral and chemical compositions of highly ferruginous layered silicates (HLS) of glauconite sands occurred on the East Korean Rise outside volcanic structures and on an unnamed volcano and the Chentsov Volcano have been studied. The use of cluster and discriminant analyses has resulted to more objectively distinguished groups among HLS, and the use of factor analysis - to illustrate correlations between chemical elements in different groups. It has been found that green mineral assemblages of the East Korean Rise are heterogeneous in terms of morphology, composition and origin, and their formation is a complex multistage process including both neoformation and degradation.
Resumo:
We investigated the multivariate relationships between adipose tissue residue levels of 48 individual organohalogen contaminants (OHCs) and circulating thyroid hormone (TH) levels in polar bears (Ursus maritimus) from East Greenland (1999-2001, n = 62), using projection to latent structure (PLS) regression for four groupings of polar bears; subadults (SubA), adult females with cubs (AdF_N), adult females without cubs (AdF_S) and adult males (AdM). In the resulting significant PLS models for SubA, AdF_N and AdF_S, some OHCs were especially important in explaining variations in circulating TH levels: polybrominated diphenylether (PBDE)-99, PBDE-100, PBDE-153, polychlorinated biphenyl (PCB)-52, PCB-118, cis-nonachlor, trans-nonachlor, trichlorobenzene (TCB) and pentachlorobenzene (QCB), and both negative and positive relationships with THs were found. In addition, the models revealed that DDTs had a positive influence on total 3,5,3'-triiodothyronine (TT3) in AdF_S, and that a group of 17 higher chlorinated ortho-PCBs had a positive influence on total 3,5,3',5'-tetraiodothyronine (thyroxine, TT4) in AdF_N. TH levels in AdM seemed less influenced by OHCs because of non-significant PLS models. TH levels were also influenced by biological factors such as age, sex, body size, lipid content of adipose tissue and sampling date. When controlling for biological variables, the major relationships from the PLS models for SubA, AdF_N and AdF_S were found significant in partial correlations. The most important OHCs that influenced TH levels in the significant PLS models may potentially act through similar mechanisms on the hypothalamic-pituitary-thyroid (HPT) axis, suggesting that both combined effects by dose and response addition and perhaps synergistic potentiation may be a possibility in these polar bears. Statistical associations are not evidence per se of biological cause-effect relationships. Still, the results of the present study indicate that OHCs may affect circulating TH levels in East Greenland polar bears, adding to the "weight of evidence" suggesting that OHCs might interfere with thyroid homeostasis in polar bears.
Resumo:
Hair sampled from 96 East Greenland polar bears (Ursus maritimus) over the periods 1892-1927 and 1988-2009 was analyzed for cortisol as a proxy to investigate temporal patterns of environmental stress. Cortisol concentration was independent of sex and age, and was found at significantly higher (p<0.001) concentrations in historical hair samples (1892-1927; n = 8) relative to recent ones (1988-2009; n = 88). In addition, there was a linear time trend in cortisol concentration of the recent samples (p< 0.01), with an annual decrease of 2.7%. The recent hair samples were also analyzed for major bioaccumulative, persistent organic pollutants (POPs). There were no obvious POP related time trends or correlations between hair cortisol and hair POP concentrations. Thus, polar bear hair appears to be a relatively poor indicator of the animal's general POP load in adipose tissue. However, further investigations are warranted to explore the reasons for the temporal decrease found in the bears' hair cortisol levels.
Resumo:
Physical properties of basalts from Ocean Drilling Program Sites 800 and 801 in the Pigafetta Basin and Site 802 in the East Mariana Basin, including porosity, wet-bulk density, grain density, compressional wave velocity, and thermal conductivity, were measured aboard JOIDES Resolution during Leg 129. The ranges for the properties are large, as typified by the velocity, which varies from 3.46 to 6.59 km/s. Extensively altered basalts immediately above and below a silicified hydrothermal deposit (60-69 m sub-basement depth) at Site 801 display the highest porosity, and lowest bulk density, velocity, and thermal conductivity, whereas the slightly altered rocks from Site 802 and the lowermost part of Site 801 represent the other extreme in physical properties variations. In order to better establish the relationship between physical properties and alteration of the rocks, the compressional wave velocities were compared with results from major and trace elemental analyses and petrographic examination of select samples. For the Leg 129 basalts, velocity displays a generally consistent decrease with increasing K2O, H2O+, loss on ignition, and Rb contents and the value of Fe3+/FeT and decreasing concentrations of SiO2, FeOT, CaO, MgO, and MnO. These trends are consistent with trends documented for the progressive alteration of oceanic crust and indicate that on a laboratory sample scale, basalt alteration is largely responsible for the variation of the physical properties of basalts sampled at Sites 800, 801, and 802.
Resumo:
The members of the two International Glaciological Greenland Expeditions (EGIG) in 1959 and 1968 determined the altitudes in the West-East-profile by levelling. The comparison of these two measurements gives evidence of the change of altitudes and of the surface-waves. The ways of measurement and of analysis are described here. The graphic representation of the result is discussed here in connexion with the possible causes.
Resumo:
Persistent organochlorine (OC) contaminants (PCBs, DDTs, chlordanes (CHLs), dieldrin, hexachlorocyclohexanes (HCHs), chlorobenzenes (CBzs)) were determined in adipose tissue of 92 polar bears (Ursus maritimus) sampled between 1999 and 2001 in central East Greenland (69°00'N to 74°00'N). OC data were presented from subadults (S: females: <5 years and males: <6 years), adult females (F: >=5 years) and adult males (M: >=6 years). Summed chlorobiphenyl (SumCBs) concentrations (41 congeners including co-eluters), SumCHLs and SumDDTs were the dominant classes of OCs. SumCBs concentrations were found to be 6470, 8240 and 9100 ng/g lipid weight (lw) i subadults, adult females and adult males, respectively. The corresponding figures were: 2010 (S), 2220 (F) and 1710 (M) ng/ g lw for SumCHLs and 462 (S), 462 (F) and 559 (M) ng/g lw for SumDDTs. The dominant CB congeners were CB153 (32.3%), CB180 (21.4%), CB170 (12.2%) and CB138 (11.0%). The metabolite p,p'-DDE (88.2%) dominated the SumDDTs, while oxychlordane was the dominant (57.1%) CHL-related compound. Concentrations of SumCBs, SumCBzs, SumDDTs, mirex and dieldrin were highest in adult males, whereas concentrations of SumHCHs were lower than in adult females but not than those in subadults. Adult females had the lowest concentrations of SumCBzs, mirex and dieldrin. Concentrations of SumCHLs were lowest in adult males, intermediate in subadults and highest in adult females. SumCB, SumHCH and SumCHL concentrations showed high seasonal variability in adult females but remained relatively constant in adult males and subadults. In general, the OC levels in females appeared to be highest in March and lowest in January or September. Concentrations of SumCBzs and dieldrin showed seasonal variability in all three groups, with a maximum in March in adult females. SumCBz concentrations in adult males and subadults of both sexes peaked in April-July, and dieldrin concentrations peaked in April-July in subadults, but not until August in adult males. SumDDT concentrations increased from January to a maximum in April-July for subadults and in August for adults. Temporal trends within the last decade were examined by comparing the present data to the concentrations reported in samples from 1990 from the same region. SumCB, p,p'-DDE and SumHCH concentrations in 1999-2001 were 22.1%, 66.3% and 39.3% lower than the 1990 concentrations, respectively. in contrast, SumCHL and dieldrin concentrations showed differences amongst sex and age groups in the temporal trends, where present concentrations are between 24.4% to 69.3% and 27.0% to 69.0% lower, respectively, relative to the 1990 levels. However, power analysis suggested that firm conclusions could not be drawn regarding the general time trend based on these two sampling periods. The range of half-lives of the various OC classes were estimated to lie between 4.5 and 20.6 years depending on the age and sex groups considered.