Anthropogenic lead isotopes in Antarctica

We report the first measurements of Pb isotopes in Antarctic snow, which show that even recent snow containing 2.3 pg/g is highly polluted with anthropogenic Pb. This follows from a comparison of isotope abundances of Pb in surface snow and terrestrial dust extracted from ancient Antarctic ice (Dome C, depth 308 m, approximate age 7,500 a BP), the latter being distinctly more radiogenic. This result is independent of geochemical arguments based on measurements of Al, Na and SO_4. South America is suggested as a likely source of this anthropogenic Pb. The presence of significantly less radiogenic Pb in the snow adjacent to two Antarctic base stations indicates that there is contamination from station emissions, although emission from Australia is an alternative explanation for a site 33 km from Dumont d'Urville

O corpo feminino como gerador de lucro : pressão estética e o mercado brasileiro de cirurgias plásticas

O Brasil é o primeiro colocado no ranking de países que mais realizam cirurgias plásticas. Dada essa informação, o principal objetivo desse trabalho é identificar elementos do mercado da cirurgia plástica que sofrem influência da insatisfação das mulheres em relação à adaptação do seu corpo ao padrão de beleza vigente. O trabalho se estrutura por três principais tópicos: beleza, subordinação pelo padrão de beleza e feminismo; o mercado de cirurgia plástica estética no Brasil; e análise dos resultados do questionário. Além disso, conta com a metodologia de abordagem quali-quantitativa, primeiramente com um levantamento teórico, seguido de análise de índices referente ao mercado de cirurgia estética, mundial e brasileiro, além de um questionário de elaboração própria. Ao relacionar os resultados obtidos pela pesquisa de campo às bibliografias teóricas, foi possível confirmar que o principal elemento da população feminina brasileira que permite identificar a relação entre o padrão de beleza imposto às mulheres e o crescimento do setor das modificações corporais, a partir da realização de cirurgias plásticas, é a insatisfação com a aparência corporal. Ademais, expõe-se a influência que a divulgação de produtos e serviços de beleza exercem sobre as mulheres e como o sistema econômico capitalista se beneficia com a busca incessante pela beleza padronizada.Brazil is ranked first in the ranking of countries that most perform plastic surgery. Given this information, the main objective of this work is to identify elements of the plastic surgery market that are influenced by women's dissatisfaction with the adaptation of their body to the current beauty standard. The work is structured around three main topics: beauty, subordination by the standard of beauty and feminism; the aesthetic plastic surgery market in Brazil; and analysis of the results of the questionnaire. In addition, it relies on a qualitative and quantitative approach methodology, first with a theoretical survey, followed by analysis of indices for the cosmetic surgery market, worldwide and Brazilian, in addition to a questionnaire of its own elaboration. By relating the results obtained by the field research to the theoretical bibliographies, it was possible to confirm that the main element of the Brazilian female population that allows identifying the relationship between the standard of beauty imposed on women and the growth of the sector of body modifications, from the realization plastic surgery, is dissatisfaction with body appearance. Furthermore, it exposes the influence that the dissemination of beauty products and services have on women and how the capitalist economic system benefits from the incessant search for standardized beauty

Histoire de la pollution en métaux lourds de l'atmosphère de l'hémisphère nord au cours des deux derniers siècles retracée dans les neiges du Groenland central : thèse soutenue sur un ensemble de travaux

Cette these presente l'evolution temporelle des concentrations en metaux lourds (pb, cd, zn et cu) mesurees dans les neiges de Summit (Groenland central) deposées entre 1773 et 1992. Les resultats obtenus mettent en evidence que les activites industrielles ont largement pollue la troposphere de l'hemisphere nord a l'echelle globale. Pour le plomb, nous confirmons et completons pour la premiere fois l'augmentation d'un facteur 200 depuis les niveaux naturels (il y a 8000 ans) observé pour les neiges du milieu des années 1960, mise en evidence par c. Patterson et ses collègues en 1969. L'augmentation observee pour les autres metaux (8 fois pour cd, 5 et 4 fois pour zn et cu) montre pour la première fois l'émergence de la source anthropique sur la période 1773-1970. Malgrè la décroissance très nette des concentrations en plomb (6.3 fois), en cadmium (2,3 fois) et en zinc (1.7 fois) observée sur la periode 1970-1992, les teneurs actuelles en métaux lourds des neiges du Groenland central sont encore supérieures aux concentrations observées pour les glaces de l'Holocène, ce qui prouve que les cycles atmosphériques biogéochimiques sont toujours largement dominés par les émissions d'origine humaine.pas de résum

Effect of trace metal availability on coccolithophorid calcification

The deposition of atmospheric dust into the ocean has varied considerably over geological time. Because some of the trace metals contained in dust are essential plant nutrients which can limit phytoplankton growth in parts of the ocean, it has been suggested that variations in dust supply to the surface ocean might influence primary production. Whereas the role of trace metal availability in photosynthetic carbon fixation has received considerable attention, its effect on biogenic calcification is virtually unknown. The production of both particulate organic carbon and calcium carbonate (CaCO3) drives the ocean\u27s biological carbon pump. The ratio of particulate organic carbon to CaCO3 export, the so-called rain ratio, is one of the factors determining CO2 sequestration in the deep ocean. Here we investigate the influence of the essential trace metals iron and zinc on the prominent CaCO3-producing microalga Emiliania huxleyi. We show that whereas at low iron concentrations growth and calcification are equally reduced, low zinc concentrations result in a de-coupling of the two processes. Despite the reduced growth rate of zinc-limited cells, CaCO3 production rates per cell remain unaffected, thus leading to highly calcified cells. These results suggest that changes in dust deposition can affect biogenic calcification in oceanic regions characterized by trace metal limitation, with possible consequences for CO2 partitioning between the atmosphere and the ocean

Recent advances in measurement of Pb isotopes in polar ice and snow at sub-picogram per gram concentrations using thermal ionisation mass spectrometry

Techniques for Pb measurements have reached the stage where Antarctic ice with sub-picogram per gram concentrations can be reliably analysed for isotopic composition. Here, particular attention has been given to measuring the quantity of Pb added during the decontamination and sample storage stages of the sample preparation process because of their impact on accuracy at low concentrations. These stages, including the use of a stainless steel chisel for the decontamination, contributed 5.2 pg to the total sample analysed, amounting to a concentration increase of 13 fg g−1, which is significantly less than expected. Consequently, the corrections to the isotopic ratios and concentration were also smaller. Other contributions to the blank, such as Pb fallout onto critical working areas in the HEPA-filtered air laboratories, were also relatively small as was the amount of Pb leached from preconditioned perfluoroalkoxy (PFA) beakers during sample processing. The ion source contributed typically 89±19 fg to the blank. Although this was relatively large, its influence depended upon the amount of Pb available for analysis and it had the greatest impact when small volumes of samples with a very low concentration were analysed. A 15 months investigation of the leaching characteristics of Pb from a low-density polyethylene (LDPE) sample storage bottle showed 11 fg cm−2 per day was released immediately following the initial 2 months cleaning process, but this decreased to immeasurable values after a further 3 months of cleaning