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Exchangeable organic carbon (OC) dynamics and CO2 fluxes in the Antarctic Peninsula region during austral summer are highly variable. By stations, the region is a weak source of CO2 to the atmosphere, however, continuous records of CO2 revealed this area as a weak sink. OC fluxes are also in both directions but generally towards the ocean and much higher than CO2 fluxes, sometimes by a factor of 10. Surface exchangeable dissolved organic carbon (EDOC) measurements had a 43±3 μmolCL-1 overall mean, while the gaseous organic carbon equilibrated in water as given by the Henry's Law constant (H') resulted in (GOC H'-1) concentrations of 46±3 μmolCL-1. EDOC represents around 66% of surface dissolved organic carbon (DOC) in Antarctic waters. There is a tendency towards low partial pressures of CO2 in waters with high Chlorophyll a (Chl a) content and high fCO2 in areas with high krill densities. However, such relationships were not found for EDOC. Depth profiles of EDOC were also quite variable and followed Chl a profiles, but only in some instances, while diel cycles of EDOC revealed two distinct peaks around midday and middle of the short austral dark period concurrent with solar radiation maxima and krill night migration patterns. However, there was no evident diel pattern for GOC H'-1. The pool of exchangeable OC reveals itself as an important compartment of the carbon budget in the Antarctic Peninsula and adds to previous studies highlighting its importance in the redistribution of carbon in marine environments. [ABSTRACT FROM AUTHOR]

Achilles tendon disorders are among the most common conditions seen by sports medicine physicians. The request for radiological assessment and for radiologically assisted therapy is on the steady increase. Thus understanding the anatomy and biomechanics of the Achilles tendon is crucial to the effective radiological diagnosis and thus the management of such conditions. [ABSTRACT FROM AUTHOR]

The evaluation performed with the intention of education is a priority and essentially an ethical issue, not technical. Acquire the technical sense precisely when they are guided by ethical principles. Therefore the objective of this paper is to propose alternatives that contribute to an educational evaluation using "webquest" labyrinths of action and concept maps. Evaluation is not and can not be teaching the appendix is part of teaching and learning. To the extent that an individual learns, simultaneously evaluates, discriminates, appreciates, decides, judges, chooses what it believes has a value in itself and what it lacks. The final evaluation of the General Chemistry Laboratory of Radiochemistry was that the students identify the essential elements for designing a webquest about some of the environmental problems. Concept maps can be used to evaluate various topics of General Chemistry, and the labyrinth of action in the laboratories of Analytical Chemistry Basic. As a result of the work were developed different means of learning and a methodology for educational evaluation. [ABSTRACT FROM AUTHOR]

Air-sea CO2 exchange depends on the air-sea CO2 gradient and the gas transfer velocity (k), computed as a function of wind speed. Large discrepancies among relationships predicting k from wind suggest that other processes also contribute significantly to modulate CO2 exchange. Here we report, on the basis of the relationship between the measured gas transfer velocity and the organic carbon concentration at the ocean surface, a significant role of surface organic matter in suppressing air-sea gas exchange, at low and intermediate winds, in the open ocean, confirming previous observations. The potential role of total surface organic matter concentration (TOC) on gas transfer velocity (k) was evaluated by direct measurements of air-sea CO2 fluxes at different wind speeds and locations in the open ocean. According to the results obtained, high surface organic matter contents may lead to lower air-sea CO2 fluxes, for a given air-sea CO2 partial pressure gradient and wind speed below 5 m s-1, compared to that observed at low organic matter contents. We found the bias in calculated gas fluxes resulting from neglecting TOC to co-vary geographically and seasonally with marine productivity. These results support previous evidences that consideration of the role of organic matter in modulating air-sea CO2 exchange may improve flux estimates and help avoid possible bias associated to variability in surface organic concentration across the ocean. [ABSTRACT FROM AUTHOR]

Air-sea CO2 exchange depends on the air-sea CO2 gradient and the gas transfer velocity (k), computed as a simple function of wind speed. Large discrepancies among relationships predicting k from wind suggest that other processes may also contribute significantly to modulate CO2 exchange. Here we report, on the basis of the relationship between the measured gas transfer velocity and the ocean surface organic carbon concentration at the ocean surface, a significant role of surface organic matter in suppressing air-sea gas exchange, at low and intermediate winds, in the open ocean. The potential role of total surface organic matter concentration (TOC) on gas transfer velocity (k) was evaluated by direct measurements of air-sea CO2 fluxes at different wind speeds and locations in the open ocean. According to the results obtained, high surface organic matter contents may lead to lower air-sea CO2 fluxes, for a given air-sea CO2 partial pressure gradient and wind speed below 5ms-1, compared to that observed at low organic matter contents. We found the bias in calculated gas fluxes resulting from neglecting TOC to co-vary geographically and seasonally with marine productivity. These findings suggest that consideration of the role of organic matter in modulating air-sea CO2 exchange can improve flux estimates and help avoid possible bias associated to variability in surface organic concentration across the ocean. [ABSTRACT FROM AUTHOR]

A series of dust pollen samples was collected along N-S transects in east China (18°N to 53°N latitudes). Sample sites extend from the cold-temperate zone in the north to the tropical region in the south. Pollen taxa characterize each region and reflect the natural and devastated vegetation as well as corresponding climatic zones. The quantitative pollen data can be used to estimate the spatial distribution of planted and introduced species. Valuable information of human disturbance of the natural forest is evaluated by quantitative comparison between dust pollen and in-situ pollen of protected forest. In addition, percentages of grass pollen vary regularly from north to south that is consistent with spatial distribution of net primary productivity in east China. Among all grasses, Artemisia and the Gramineae carry the clearest signal: their ratio increases northwards and therefore represent a suitable and convenient tool for palaeoclimate reconstructions. [ABSTRACT FROM AUTHOR]