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| Murillo de la Rosa, Arnulfo. |
| Los suelos de la sabana de Huimanguillo, se localizan en lomeríos con pendientes ligeras, son de baja fertilidad, presentan alta acidez con pH que oscilan entre 4.0 a 5.5 y contenidos de materia orgánica de 1 a 4 %, a veces hasta de 20 %. La materia orgánica desempeña un papel importante en el suelo ya que aporta una gran variedad de elementos nutritivos para las plantas, y modifica la estructura del mismo, el conocimiento sobre su aporte de nutrientes es escaso, por lo que, las estimaciones del suministro al suelo se basan más bien en el rendimiento. El presente trabajo tuvo como objetivo estimar la densidad aparente (Dap), las reservas de carbono orgánico total (COT), nitrógeno total (Nt), la relación carbono nitrógeno (C/N), el carbono orgánico soluble... |
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Palavras-chave: Acrisol; Agroecosistemas; Densidad aparente; Carbono orgánico total; Nitrógeno total; Carbono orgánico soluble; Indice óptico y relación C/N; Agroecosystems; Bulk density; Total organic carbon; Total nitrogen; Soluble organic carbon; Optical index and C/N; Maestría; Producción Agroalimentaria en el Trópico. |
| Ano: 2010 |
URL: http://hdl.handle.net/10521/254 |
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| Chang, Yp; Wu, Sm; Wei, Ky; Murayama, M; Kawahata, H; Chen, Mt. |
| Biogenic carbonate and organic carbon content of two deep sea cores (MD012404 and ODP site 1202) are measured to reconstruct surface ocean productivity variations in areas of the Okinawa Trough in the Western Pacific where the modern climate is highly sensitive to the East Asian monsoon and precipitation/river runoff. Based on foraminiferal isotope stratigraphy and AMS C-14 dating, the age models of the cores indicate that core MD012404 shows relatively low sedimentation rates with 50 cm ky(-1) on average, and that the sedimentation rates in core ODP 1202 are extremely high with an average of 500 cm ky(-1). Total organic carbon (TOC) and carbonate contents in core ODP 1202 are 0.56% and 6.80% on average, respectively, and are 0.62% and 15.86%,... |
| Tipo: Text |
Palavras-chave: IMAGES; ODP; Total organic carbon; Calcium carbonate; Okinawa Trough; Paleoceanography; Climate change; East Asian monsoon. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00229/34064/32627.pdf |
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| Zheng, Li-wei; Hsiao, Silver Sung-yun; Ding, Xiao-dong; Li, Dawei; Chang, Yuan-pin; Kao, Shuh-ji. |
| Total organic carbon to total nitrogen ratios (C/N) and their isotopic compositions (δ13CTOC and δ15NTN) are oft-applied proxies to discern terrigenous from marine-sourced organics and to unravel ancient environmental information. In high depositional Asian marginal seas, the inclusion of N-bearing minerals in the bulk sediment dilutes or masks signals sought after in δ15N and δ13C analyses, thus leading to incorrect and even contradictory interpretations. We used KOH-KOBr to separate operationally defined total organic matter into oxidizable (labile) and residual fractions for content and isotope measurements. In a sediment core in the Okinawa Trough, significant amounts of carbon and nitrogen existed in the residual phase, in which the C/N ratio was ~9,... |
| Tipo: Text |
Palavras-chave: Carbon; Nitrogen; Isotope; Okinawa Trough; Sediment; Total organic carbon. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00295/40584/39503.pdf |
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| Shiau, Liang-jian; Yu, Pai-sen; Wei, Kuo-yen; Yamamoto, Masanobu; Lee, Teh-quei; Yu, Ein-fen; Fang, Tien-hsi; Chen, Min-te. |
| Variations in sea surface temperature (SST), productivity, and biogenic components such as total organic carbon (TOC), carbonate, and opal contents measured from IMAGES (International Marine Global Changes Study) core MD972142 provide information about long-term paleoceanographic changes during the past similar to 870000 years in the southeastern South China Sea (SCS). MD972142 U-37(k)-SSTs varied from 25 to 29 degrees C, paralleling the glacial to interglacial changes. MD972142 biogenic components show relatively high carbonate and opal, and low TOC contents in interglacial stages, and low carbonate and opal and high TOC contents in glacial stages, and these variations appear to be sensitive to regional terrestrial sediment input and productivity. Our... |
| Tipo: Text |
Palavras-chave: Total organic carbon; Carbonate; Opal; Productivity; Sea surface temperature; South China Sea; Monsoon; IMAGES. |
| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00237/34817/33682.pdf |
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| Portella,Cibele Mascioli Rebello; Guimarães,Maria de Fátima; Feller,Christian; Fonseca,Inês Cristina de Batista; Tavares Filho,João. |
| Considering that the soil aggregation reflects the interaction of chemical, physical and biological soil factors, the aim of this study was evaluate alterations in aggregation, in an Oxisol under no-tillage (NT) and conventional tillage (CT), since over 20 years, using as reference a native forest soil in natural state. After analysis of the soil profile (cultural profile) in areas under forest management, samples were collected from the layers 0-5, 5-10, 10-20 and 20-40 cm, with six repetitions. These samples were analyzed for the aggregate stability index (ASI), mean weighted diameter (MWD), mean geometric diameter (MGD) in the classes > 8, 8-4, 4-2, 2-1, 1-0.5, 0.5-0.25, and < 0.25 mm, and for physical properties (soil texture, water... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Aggregation indices; Aggregate size classes; Total organic carbon. |
| Ano: 2012 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832012000600021 |
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