| 1. |
- Fattibene, P, et al.
(author)
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The 4th international comparison on EPR dosimetry with tooth enamel Part 1: Report on the results
- 2011
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In: Radiation Measurements. - : Elsevier. - 1350-4487 .- 1879-0925. ; 46:9, s. 765-771
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Journal article (peer-reviewed)abstract
- This paper presents the results of the 4th International Comparison of in vitro electron paramagnetic resonance dosimetry with tooth enamel, where the performance parameters of tooth enamel dosimetry methods were compared among sixteen laboratories from all over the world. The participating laboratories were asked to determine a calibration curve with a set of tooth enamel powder samples provided by the organizers. Nine molar teeth extracted following medical indication from German donors and collected between 1997 and 2007 were prepared and irradiated at the Helmholtz Zentrum Munchen. Five out of six samples were irradiated at 0.1, 0.2, 0.5, 1.0 and 1.5 Gy air kerma; and one unirradiated sample was kept as control. The doses delivered to the individual samples were unknown to the participants, who were asked to measure each sample nine times, and to report the EPR signal response, the mass of aliquots measured, and the parameters of EPR signal acquisition and signal evaluation. Critical dose and detection limit were calculated by the organizers on the basis of the calibration-curve parameters obtained at every laboratory. For calibration curves obtained by measuring every calibration sample three times, the mean value of the detection limit was 205 mGy, ranging from 56 to 649 mGy. The participants were also invited to provide the signal response and the nominal dose of their current dose calibration curve (wherever available), the critical dose and detection limit of which were also calculated by the organizers.
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| 2. |
- Sparovek, Gerd, 1962, et al.
(author)
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Sustainable bioproducts in Brazil: disputes and agreements on a common ground agenda for agriculture and nature protection
- 2016
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In: Biofuels, Bioproducts and Biorefining. - : Wiley. - 1932-1031 .- 1932-104X. ; 10:3, s. 204-221
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Journal article (peer-reviewed)abstract
- A key question for food, biofuels, and bioproducts production is how agriculture affects the environment, and social and economic development. In Brazil, a large agricultural producer and among the biologically wealthiest of nations, this question is challenging and opinions often clash. The Brazilian parliament and several stakeholders have recently debated the revision of the Forest Act, the most important legal framework for conservation of natural vegetation on Brazilian private agricultural lands. Past decades have shown improvements in the agricultural sector with respect to productivity and efficiency, along with great reductions in deforestation and growth of environmentally certified production. However, the opposing sides in the debate have ignored this progress and instead continue to entrench their respective combative positions. A structured exchange involving nine experts associated with major producer interests (livestock, crops, planted forest, and charcoal) and environmental NGOs was moderated based on a framework that sorted viewpoints into four categories: (i) common ground - compatible interests considered to be high priority for Brazilian sustainable agricultural development; (ii) serving exclusive nature conservation interest; (iii) serving exclusive agricultural production interest; and (iv) mainly serving the purpose of sustaining dispute. We conclude that the majority of actions and expected future trends reflect achievements and ambitions to balance production and conservation, but much public opinion - and in turn decisions in the parliament and government for agriculture and conservation - is shaped by a perceived conflict between these objectives and a debate that has become, at least to some extent, an end in itself.
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| 3. |
- Almeida, Rafael M., et al.
(author)
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High Primary Production Contrasts with Intense Carbon Emission in a Eutrophic Tropical Reservoir
- 2016
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In: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 7
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Journal article (peer-reviewed)abstract
- Recent studies from temperate lakes indicate that eutrophic systems tend to emit less carbon dioxide (Co-2) and bury more organic carbon (OC) than oligotrophic ones, rendering them CO2 sinks in some cases. However, the scarcity of data from tropical systems is critical for a complete understanding of the interplay between eutrophication and aquatic carbon (C) fluxes in warm waters. We test the hypothesis that a warm eutrophic system is a source of both CO2 and CH4 to the atmosphere, and that atmospheric emissions are larger than the burial of OC in sediments. This hypothesis was based on the following assumptions: (i) OC mineralization rates are high in warm water systems, so that water column CO2 production overrides the high C uptake by primary producers, and (ii) increasing trophic status creates favorable conditions for CH4 production. We measured water-air and sediment-water CO2 fluxes, CH4 diffusion, ebullition and oxidation, net ecosystem production (NEP) and sediment OC burial during the dry season in a eutrophic reservoir in the semiarid northeastern Brazil. The reservoir was stratified during daytime and mixed during nighttime. In spite of the high rates of primary production (4858 +/- 934 mg C m(-2) d(-1)), net heterotrophy was prevalent due to high ecosystem respiration (5209 +/- 992 mg C m(-2) d(-1)). Consequently, the reservoir was a source of atmospheric CO2 (518 +/- 182 mg C m(-2) d(-1)). In addition, the reservoir was a source of ebullitive (17 +/- 10 mg C m(-2) d(-1)) and diffusive CH4 (11 +/- 6 mg C m(-2) d(-1)). OC sedimentation was high (1162 mg C m(-2) d(-1)), but our results suggest that the majority of it is mineralized to CO2 (722 +/- 182 mg C m(-2) d(-1)) rather than buried as OC (440 mg C m(-2) d(-1)). Although temporally resolved data would render our findings more conclusive, our results suggest that despite being a primary production and OC burial hotspot, the tropical eutrophic system studied here was a stronger CO2 and CH4 source than a C sink, mainly because of high rates of OC mineralization in the water column and sediments.
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