Intensive management of tropical pastures has shown potential for greenhouse gas (GHG) mitigation due to high forage production and C accumulation in the soil. This study aimed to evaluate different pasture management options in relation to their effect on soil C stocks and soil organic matter (SOM) humification. Pastures in four beef cattle production systems were assessed: intensive and irrigated pasture with high stocking rate (IHS); dryland pasture with high stocking rate (DHS); dryland pasture with moderate stocking rate (DMS); degraded pasture (DP). The soil under the native forest was also evaluated and soil carbon stocks from the 0-100 and 0-30 cm layers were assessed. Carbon stocks (0-100 cm) ranged from 99.88 to 142.33 Mg ha-1 in DP and DMS, respectively and were, respectively, 14 % and 24 % higher compared to the soil under the forest and indicate the capacity of adequately managed tropical pastures to mitigate GHG emissions from livestock production. Humification indexes indicated the presence of more labile C in pastures with greater C accumulation (DHS and DMS), mainly in the upper soil layers, indicating recent C accumulation resulting from correct management. However, more labile C can be easily lost to the atmosphere as CO 2 , depending on pasture management. Low C stocks associated with high humification indexes are characteristics of DP in which significant amounts of SOM are lost. It is necessary to develop technologies to improve C sequestration in IHS and results indicate the importance of quantifying C stocks in association with C stability.
Advanced field methods of carbon (C) analysis should now be capable of providing repetitive, sequential measurements for the evaluation of spatial and temporal variation at a scale that was previously unfeasible. Some spectroscopy techniques, such as laser-induced breakdown spectroscopy (LIBS), have portable features that may potentially lead to clean and rapid alternative approaches for this purpose. The goal of this study was to quantify the C content of soils with different textures and with high iron and aluminum concentrations using LIBS. LIBS emission spectra from soil pellets were captured, and the C content was estimated (emission line of C (I) at 193.03 nm) after spectral offset and aluminum spectral interference correction. This technique is highly portable and could be ideal for providing the soil C content in a heterogeneous experiment. Dry combustion was used as a reference method, and for calibration a conventional linear model was evaluated based on soil textural classes. The correlation between reference and LIBS values showed r = 0.86 for medium-textured soils and r = 0.93 for fine-textured soils. The data showed that better correlation and lower error (14%) values were found for the fine-textured LIBS model. The limit of detection (LOD) was found to be 0.32% for medium-textured soils and 0.13% for finetextured soils. The results indicated that LIBS quantification can be affected by the texture and chemical composition of soil. Signal treatment was shown to be very important for mitigation of these interferences and to improve quantification.
Primeiramente a Deus ... por mais uma encarnação, por iluminar meu caminho e me dar forças para seguir em frente, permitindo a superação dos obstáculos para a conclusão desta etapa da minha vida profissional. Aos meus familiares, especialmente minha irmã Mainara, minhas avós Lourdes (in memorian) e Lázara. ... pela compreensão, força, incentivo, carinho e educação. À minha namorada Samara ... pela paciência, amor, conselhos, apoio tanto nos momentos bons quanto nos momentos ruins e por todo companheirismo. À Dra. Débora Marcondes Bastos Pereira Milori da Embrapa Instrumentação ... pela confiança, orientação, oportunidade, incentivo, amizade e todo o ensinamento fornecido. Às Dras. Aline Segnini e Edilene Ferreira ... pelas instruções e auxílio que contribuíram para o meu crescimento acadêmico e pela grande amizade.
Of 166 surgical patients for whom the diagnosis of primary hyperparathyroidism was established over a 20-year period, about one-third were over 60 years of age. For an additional 9 patients, or operation was advised, usually because of other life-endangering disease and the presence of only a mild degree of hypercalcemia without complications. In recent years, nearly 50 per cent of the patients did not have renal calculi or osteitis fibrosa cystica; this was unrelated to age. Most of the patients with management problems were seen since 1965. Age alone was not a dominant factor in relation to serious complications from hypercalcemia, the presence of other critical disease increasing the risk of operation, or the development of major postoperative complications. The only death from primary hyperparathyroidism occurred in a 74-year old patient who refused re-operation and died from an acute hypercalcemic crisis. A liberal, but selective, policy of surgical treatment is justified for primary hyperparathyroidism in the elderly. Patients for whom the diagnosis of primary hyperparathyroidism is established may be separated into three groups: those for whom early operation is indicated, those for whom operation should be delayed to permit recovery from other life-endangering acute disease, and those for whom operation is unjustified because of minimal uncomplicated hypercalcemia and other serious disease greatly limiting life expectancy. These categories encompass all age groups and are not restricted to the elderly. All patients require periodic re-evaluation.
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