Benthic oxygen flixes on the Washington shelf and slope

Benthic oxygen fluxes calculated from in situ microelectrode profiles arc compared with benthic flux chamber O2 uptake measurements on a transect of eight stations across the continental shelf and three stations on the slope of Washington State. Station depths ranged from 40 to 630 m and bottom-water oxygen concentrations were 127-38 µM. The fluxes measured by the two methods were similar on the slope, but on the shelf, the chamber flux exceeded the microelectrode flux by as much as a factor of 3-4. We attribute this difference to pore-water irrigation, a process which apparently accounts for the oxidation of a significant amount of organic C in the continental shelf sediments. Combining our diffusive flux data with other data demonstrates clearly that the bottomwater oxygen concentration must play some significant role in determining the sedimentary oxygen consumption rate. Numerical simulation of the microelectrode 0, profiles suggests that roughly half the diffusive 0, flux must be consumed within - 1 mm of the sediment surface. If this conclusion is correct, then the magnitude of the diffusive flux depends both on the bottom-water oxygen concentration and on the supply rate of labile C to the sediment surf'ace.

Etchenique, Jorge, Pampa libre. Anarquistas en la pampa argentina, Santa Rosa (La Pampa), Universidad Nacional de Quilmes / Ediciones Amerindia, 2000

Fil: Gutiérrez, Talía Violeta. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Técnicas corporales de resistencia y creación cultural

Las artes escénicas constituyen una forma de manifestación cultural interrelacionada con el momento histórico de una sociedad. Para algunos antropólogos suponen: transgredir lo instituido, realizar y alimentar símbolos o restituir conflictos dormidos en la sociedad. Se propone indagar sobre los procesos y repercusiones que genera una obra de "danza integradora" ya que resulta especialmente significativa para aprender más sobre nuestra cultura y las concepciones de cuerpo incorporadas socialmente. El grupo de danza elegido reúne personas con y sin discapacidad, plasmando en sus composiciones un proceso de creación artístico que, "busca romper con la seriedad y la dureza de la sociedad uruguaya". Se procura analizar las expresiones de las bailarinas respecto de lo corporal, junto con las técnicas de creación observadas en sus ensayos, para dar cuenta de los significados que construyen en torno al cuerpo y reflexionar qué suponen socialmente. Ellas irrumpen en el escenario desmontando para el público la concepción capacitado /discapacitado, sin minimizar las diferencias físicas entre ellas, sino resaltándolas para construir otro sentido estético. Parecen hacer de sus cuerpos un medio de resistencia y creatividad, frente a la propuesta hegemónica en la modernidad que propone cuerpos homogéneos y adaptados a las necesidades productivas.

Geochemistry of continental slope and deep sea basin sediments off Uruguay

Pore water and solid phase from surface sediments of the continental slope off Uruguay and from the Argentine Basin (southwestern Atlantic) were investigated geochemically to ascribe characteristic early diagenetic reactions of iron and manganese. Solid-phase iron speciation was determined by extractions as well as by Mössbauer spectroscopy. Both methods showed good agreement (<6% deviation) for total-Fe speciation. The proportion of easy reducible iron oxyhydroxide relative to total-Fe oxides decreased from the continental slope to the deep sea which is attributed to an increase in crystallinity during transport as well as to a general decrease of iron mobilization. The product of iron reoxidation is Fe oxyhydroxide which made up less than 5% of total Fe. In addition to this fraction, a proportion of smectite bound iron was found to be redox reactive. This fraction made up to 10% of total Fe in sediments of the Argentine Basin and was quantitatively extracted by 1 N HCl. The redox reactive Fe(+II) fraction of smectite was almost completely reoxidized within 24 h under air atmosphere and may therefore considerably contribute to iron redox cycling if bioturbation occurs. In the case of the slope sediments we found concurrent iron and manganese release to pore water. It is not clear whether this is caused by dissimilatory iron and manganese reduction at the same depth or dissimilatory iron reduction alone inducing Mn(+IV) reduction by (abiotic) reaction with released Fe2+. The Argentine Basin sediment showed a significant manganese solid-phase enrichment above the denitrification depth despite the absence of a distinct pore-water gradient of Mn. This implies a recent termination of manganese mobilization and thus a non-steady-state situation with respect to sedimentation or to organic carbon burial rate.

Age and chemical composition of magmatic rocks from the Belkovsky Island, New Siberian Islands

The study was inspired by information on Paleozoic andesites, dacites, and diabases on the Belkovsky Island in the 1974 geological survey reports used to reconstruct tectonic evolution of the continental block comprising the New Siberian Islands and the bordering shelf. We did not find felsic volcanics or Middle Paleozoic intrusions in the studied area of the island. Igneous rocks are mafic subvolcanic intrusions including dikes, randomly shaped bodies, explosion breccias, and peperites. They belong to the tholeiitic series and are similar to Siberian traps in petrography and trace-element compositions, with high LREE and LILE and prominent Nb negative anomalies. The island arc affinity is due to continental crust contamination of mantle magma and its long evolution in chambers at different depths. K-Ar biotite age (252+/-5 Ma) of magmatism indicates that it was coeval to the main stage of trap magmatism in the Siberian craton at the Permian-Triassic boundary. The terrane including the New Siberian Islands occurred on the periphery of the Siberian trap province where magmatism acted in rifting environment. Magma intruded into semiliquid wet sediments at shallow depths shortly after their deposition. Therefore, the exposed Paleozoic section in Belkovsky Island may include Permian or possibly Lower Triassic sediments of younger ages than it was believed earlier.

Técnicas corporales de resistencia y creación cultural

Las artes escénicas constituyen una forma de manifestación cultural interrelacionada con el momento histórico de una sociedad. Para algunos antropólogos suponen: transgredir lo instituido, realizar y alimentar símbolos o restituir conflictos dormidos en la sociedad. Se propone indagar sobre los procesos y repercusiones que genera una obra de "danza integradora" ya que resulta especialmente significativa para aprender más sobre nuestra cultura y las concepciones de cuerpo incorporadas socialmente. El grupo de danza elegido reúne personas con y sin discapacidad, plasmando en sus composiciones un proceso de creación artístico que, "busca romper con la seriedad y la dureza de la sociedad uruguaya". Se procura analizar las expresiones de las bailarinas respecto de lo corporal, junto con las técnicas de creación observadas en sus ensayos, para dar cuenta de los significados que construyen en torno al cuerpo y reflexionar qué suponen socialmente. Ellas irrumpen en el escenario desmontando para el público la concepción capacitado /discapacitado, sin minimizar las diferencias físicas entre ellas, sino resaltándolas para construir otro sentido estético. Parecen hacer de sus cuerpos un medio de resistencia y creatividad, frente a la propuesta hegemónica en la modernidad que propone cuerpos homogéneos y adaptados a las necesidades productivas.

Etchenique, Jorge, Pampa libre. Anarquistas en la pampa argentina, Santa Rosa (La Pampa), Universidad Nacional de Quilmes / Ediciones Amerindia, 2000

Fil: Gutiérrez, Talía Violeta. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.