The diffusion kinetics of CO2 in cordierite: an HT-FTIR microspectroscopy study     

Francesco Radica  Giancarlo Della Ventura  Fabio Bellatreccia  Gianfelice Cinque  Augusto Marcelli  Mariangela Cestelli Guidi 《Contributions to Mineralogy and Petrology》2016,171(2):12

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Probabilistic landslide risk assessment in water supply basins: La Liboriana River Basin (Salgar-Colombia)     

Hidalgo  Cesar Augusto  Vega  Johnny Alexander 《Natural Hazards》2021,109(1):273-301

Landslides are natural hazards that represent a huge economic burden and cause the loss of human life around the world. In countries such as Colombia, the mass movement events that cause the highest number of deaths and economic losses are often related to river or stream flooding caused by landslides in basins. Therefore, it is necessary to develop tools that estimate and assess landslide risk in such areas. This study presents a methodology to assess the risk associated with landslides in streams or river basins. The hazard posed by landslides is evaluated considering probabilistic methods that include the effects of rainfall and earthquakes. In addition, this study assesses the probability of a sliding mass reaching riverbeds and the probability of riverbed obstruction. Vulnerability is then estimated using impact curves based on the obstruction height. Finally, risk is estimated as the probability that economic losses occur along the riverbed. This methodology is based on probability methods, such as the first-order second-moment (FOSM) method, and the punctual estimates method (PEM). The methodology was applied in the La Liboriana River basin, in the municipality of Salgar in the northwestern Colombian Andes. On May 18, 2015, this mountainous and tropical area suffered a flash flood caused by landslides in the basin, which killed more than 100 inhabitants and caused infrastructure damage and significant economic losses. The results suggest that the proposed method coherently assesses the hazard posed by landslides and that the expected losses are comparable with the records from previous events.

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Characterization of a landslide-triggered debris flow at a rainforest-covered mountain region in Brazil     

Cabral  Victor Carvalho  Reis  Fábio Augusto Gomes Vieira  D’Affonseca  Fernando Mazo  Lucía  Ana  dos Santos Corrêa  Claudia Vanessa  Veloso  Vinicius  Gramani  Marcelo Fischer  Ogura  Agostinho Tadashi  Lazaretti  Andrea Fregolente  Vemado  Felipe  Pereira Filho  Augusto José  dos Santos  Claudia Cristina  Lopes  Eymar Silva Sampaio  Rabaco  Lis Maria Reoni  do Carmo Giordano  Lucilia  Zarfl  Christiane 《Natural Hazards》2021,108(3):3021-3043

Natural Hazards - Debris flows represent great hazard to humans due to their high destructive power. Understanding their hydrogeomorphic dynamics is fundamental in hazard assessment studies,...  相似文献   

The South American ancestry of the North Patagonian Massif: geochronological evidence for an autochthonous origin?     

Augusto E. Rapalini  Mónica López de Luchi  Eric Tohver  Peter A. Cawood 《地学学报》2013,25(4):337-342

New U‐Pb and ⁴⁰Ar/³⁹Ar age data from deformed and undeformed granitoids of the North Patagonian Massif establish the presence of Early Cambrian and widespread Ordovician magmatism in northern Patagonia. These data suggest that the Pampean (Cambrian) and Famatinian (Ordovician) magmatic belts of the Sierras Pampeanas are continuous into Patagonia. SHRIMP U‐Pb age spectra from detrital zircons of Cambro‐Ordovician metasedimentary rocks show patterns very similar to those from equivalent units of the Pampia block, over 500 km farther north. These results suggest that the North Patagonian Massif was likely part of the South American margin of Gondwana in the early Palaeozoic and strongly argue in favour of an authochtonous or para‐autochthonous origin for this block.  相似文献   

Holocene and Pleistocene pluvial periods in Yemen,southern Arabia     

Dominik Fleitmann  Stephen J. Burns  Marek Pekala  Augusto Mangini  Abdulkarim Al-Subbary  Mohammad Al-Aowah  Jan Kramers  Albert Matter 《Quaternary Science Reviews》2011,30(7-8):783-787

Arabia is an important potential pathway for the dispersal of Homo sapiens (“out of Africa”). Yet, because of its arid to hyper-arid climate humans could only migrate across southern Arabia during pluvial periods when environmental conditions were favorable. However, knowledge on the timing of Arabian pluvial periods prior to the Holocene is mainly based on a single and possibly incomplete speleothem record from Hoti Cave in Northern Oman. Additional terrestrial records from the Arabian Peninsula are needed to confirm the Hoti Cave record. Here we present a new speleothem record from Mukalla Cave in southern Yemen. The Mukalla Cave and Hoti Cave records clearly reveal that speleothems growth occurred solely during peak interglacial periods, corresponding to Marine Isotope Stages (MIS) 1 (early to mid-Holocene), 5.1, 5.3, 5.5 (Eemian), 7.1, 7.5 and 9. Of these humid periods, highest precipitation occurred during MIS 5.5 and lowest during early to middle Holocene.  相似文献   

Formulation of a tropical town energy budget (t-TEB) scheme     

Hugo Abi Karam  Augusto José Pereira Filho  Valery Masson  Joël Noilhan  Edson Pereira Marques Filho 《Theoretical and Applied Climatology》2010,101(1-2):109-120

This work describes the tropical town energy budget (t-TEB) scheme addressed to simulate the diurnal occurrence of the urban heat island (UHI) as observed in the Metropolitan Area of Rio de Janeiro (MARJ; ?22° S; ?44° W) in Brazil. Reasoning about the tropical urban climate have guided the scheme implementation, starting from the original equations from Masson (Bound-Lay Meteorol 94:357–397, 2000). The modifications include (a) local scaling approaches for obtaining flux–gradient relationships in the roughness sub-layer, (b) the Monin-Obukhov similarity framework in the inertial sub-layer, (c) increasing aerodynamic conductance toward more unstable conditions, and (d) a modified urban subsurface drainage system to transfer the intercepted rainwater by roofs to the roads. Simulations along 2007 for the MARJ are obtained and compared with the climatology. The t-TEB simulation is consistent with the observations, suggesting that the timing and dynamics of the UHI in tropical cities could vary significantly from the familiar patterns observed in mid-latitude cities—with the peak heat island intensity occurring in the morning than at night. The simulations are suggesting that the thermal phase shift of this tropical diurnal UHI is a response of the surface energy budget to the large amount of solar radiation, intense evapotranspiration, and thermal response of the vegetated surfaces over a very humid soil layer.  相似文献   

Picoplankton: Contribution to Phytoplankton Production in the Strait of Messina*     

Giuseppe Magazz  Vivia Bruni  Augusto Piccione  Trevor Platt  Brian Irwin  D. V. Subba Rao 《Marine Ecology》1987,8(1):21-31

Abstract. Biomass and primary production rates derived from photosynthesis-light curves on picoplankton (< 1 um fraction) and total phytoplankton were compared for the Strait of Messina. Picoplankton biomass ranged between 0.063 and 0.094 mg Chi a m^-5 and accounted for 56–63 % of the total. Total primary production rates were between 0.22 and 1.56 mg C-m^-2-h^-1 of which the picoplankton contribution ranged from 24 to 43%. In this turbulent nearshore environment, the contribution of picoplankton to total phytoplankton production is considerably less than in calmer open-ocean waters. Carbon assimilation numbers (Pm^b), the initial slope (a), adaptation parameter (I_k), optimal irradiance (I_m) and compensation intensity (L_m,) for the picoplankton were lower than for the > 1 μm fraction. Fitted respiration (Rm^B) for the picoplankton was, however, on the average higher (10.3 % of Pm^B) than for the > 1 μrn fraction (6.6 %). Assimilation numbers for the > 1 μm fraction in the southern stations were of higher magnitude (8.5–12.0 mg C mg Chi a^-1 h^-1) than in the northern station, possibly due to the impact of upwelled water flowing southward along the Sicilian coast.  相似文献   

Modelling stalagmite growth and δC as a function of drip interval and temperature     

Christian Mühlinghaus  Denis Scholz  Augusto Mangini 《Geochimica et cosmochimica acta》2007,71(11):2780-2790

Growth and stable isotope composition of stalagmites are affected by climate changes. To understand the underlying mechanisms, we developed a time dependent multi-box model that describes stalagmite growth and stable isotope fractionation of carbon under disequilibrium conditions. The model takes variations of the drip interval, temperature and the amount of mixing between the impinging drops and the solution on top of the stalagmite into account, which allows to quantify the influence of these parameters. To calculate the variations of δ¹³C, the multi-box model was calibrated by comparison with an existing growth model. The results show that drip interval, temperature and the mixing coefficient do have a significant influence on δ¹³C. However, considering the higher natural variability of the drip interval, this parameter might have the largest influence.  相似文献   

Synoptic hydrography of a highly stratified estuary     

Carlos Augusto França Schettini  Klaus Ricklefs  Eliane Cristina Truccolo  Volker Golbig 《Ocean Dynamics》2006,56(3-4):308-319

This study investigates the hydrodynamic characteristics of the lower, middle, and upper sectors of a highly stratified estuary, the Itajaí-Açu river estuary (south of Brazil ∼27° S/48.5° W). The study is based on a 25-h field campaign with three sampling stations positioned at 2, 17, and 38 km inward from the river mouth, during low river discharge condition and spring tide. The experimental data gathered was reduced and analyzed in terms of distribution of variables in time and space tide average vertical profiles and decomposition of the advective transport of salt and suspended particulate matter (SPM). Tidal range was nearly constant along the estuary, presenting time lag of about 2 h between lower and upper estuary. The ebb discharge peaks were about twice the discharge flood peaks and occurred simultaneously. The tide was the main determining agent in the lower estuary, where currents, salt stratification, and SPM distributions presented a repetitive behavior. In the middle estuary, the tide effects were also observed, but the presence of saline waters decreased along the time due to increasing river discharge during the campaign. The distribution of SPM in the mid- and upper estuary presented patched pattern not associated with tides and may be attributed to short-term flood contributions of tributaries. Currents presented ebb dominance in all three sectors; in the middle and upper estuary, they presented also a time asymmetry, with ebb currents longer than flood. The advective transport of salt in the lower estuary was upstream, with dominance of gravitational circulation term. In the mid-estuary, there was practically no transport, with balance between fluvial discharge (downstream) and tidal correlation (upstream). The advective transport of SPM was upstream in the lower estuary and downstream in the mid- and upper estuary, being dominated by gravitational circulation in the former and fluvial discharge in the others.  相似文献   

Estimating the uncertainty of coral isochron U–Th ages     

Denis Scholz  Augusto Mangini   《Quaternary Geochronology》2006,1(4):279-288

Recently, alternative models to estimate the age of diagenetically altered fossil reef corals have been presented based on either redistribution of U or its immediate daughters ²³⁴Th and ²³⁰Th. Here, we present three methods to estimate the uncertainty of ages derived using an amended version of our coral isochron method [Scholz et al., 2004. U-series dating of diagenetically altered fossil reef corals. Earth and Planetary Science Letters 218, 163–178], which is based on addition/loss of U. The obtained uncertainties are substantially larger than those previously published and should, in general, be more reliable. The isochron method yields larger uncertainties than alternative models based on Th redistribution due to -recoil processes. However, comparison of model open-system ages based on such redistribution of U-series daughters for different sub-samples from an individual coral specimen shows that the smaller errors derived with these models cannot account for the observed variability. We recognise that none of the available models is applicable to all corals, probably reflecting different diagenetic processes even in different sub-samples from one coral specimen. To better understand the diagenetic processes and precisely constrain the uncertainties of the ages derived from diagenetically altered corals, the application of all available models is recommended.  相似文献