Trends of tropical deforestation in Southeast Mexico     

José Reyes Díaz‐Gallegos  Jean‐François Mas  Alejandro Velázquez 《Singapore journal of tropical geography》2010,31(2):180-196

We assessed deforestation in Southeast Mexico (a surface area of 29 000 km² in seven states) through the comparison of land use/land cover maps at a scale of 1:250 000. This facilitated mapping of the land use/land cover change (LULCC) processes and calculation of the rates of change and the change matrix for the period 1978–2000. An original method was used to assess the accuracy of the LULCC map. The verification sites were selected through a stratified random sampling and were corroborated with aerial photographs for 1978 and 2000. Error matrices were elaborated using both hard and fuzzy set approaches in order to take into account the errors related to generalization of the map in fragmented landscapes. The results showed an average annual deforestation rate of 1.1 per cent which represents an average annual loss of 190 000 ha of forest, or an estimated total reduction of 4.2 million ha over 22 years. Furthermore, deforestation processes are concentrated in some areas such as Yucatan and Chiapas states, which registered major forest conversions to grassland and slash‐burning. The overall accuracy of the LULCC map, assessed with hard and fuzzy set approaches, was 72 per cent and 88 per cent respectively.  相似文献   

Using the damage from 2010 Haiti earthquake for calibrating vulnerability models of typical structures in Port-au-Prince (Haiti)     

S. Molina  Y. Torres  B. Benito  M. Navarro  D. Belizaire 《Bulletin of Earthquake Engineering》2014,12(4):1459-1478

After the 2010 Haiti earthquake, that hits the city of Port-au-Prince, capital city of Haiti, a multidisciplinary working group of specialists (seismologist, geologists, engineers and architects) from different Spanish Universities and also from Haiti, joined effort under the SISMO-HAITI project (financed by the Universidad Politecnica de Madrid), with an objective: Evaluation of seismic hazard and risk in Haiti and its application to the seismic design, urban planning, emergency and resource management. In this paper, as a first step for a structural damage estimation of future earthquakes in the country, a calibration of damage functions has been carried out by means of a two-stage procedure. After compiling a database with observed damage in the city after the earthquake, the exposure model (building stock) has been classified and through an iteratively two-step calibration process, a specific set of damage functions for the country has been proposed. Additionally, Next Generation Attenuation Models (NGA) and \(\hbox {Vs}^{30}\) models have been analysed to choose the most appropriate for the seismic risk estimation in the city. Finally in a next paper, these functions will be used to estimate a seismic risk scenario for a future earthquake.  相似文献   

Geophysical Exploration of Fractured-Media Aquifers at the Mexican Mesa Central: Satellite City,San Luis Potosí, Mexico     

Héctor López Loera  José Alfredo Ramos Leal  Pablo Dávila Harris  David Ernesto Torres Gaytan  Victor Julian Martinez Ruiz  Avto Gogichaishvili 《Surveys in Geophysics》2015,36(1):167-184

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Weather at Sierra Negra: 7.3-yr statistics and a new method to estimate the temporal fraction of cloud cover     

E. Carrasco  A. Carramiñana  R. Avila  C. Gutiérrez  J. L. Avilés  J. Reyes  J. Meza  O. Yam 《Monthly notices of the Royal Astronomical Society》2009,398(1):407-421

Sierra Negra, one of the highest peaks in central Mexico, is the site of the Large Millimeter Telescope. We describe the first results of a comprehensive analysis of the weather data measured in situ from 2000 October to 2008 February to be used as a reference for future activity in the site. We compare the data from two different stations at the summit considering the accuracy of both instruments. We analysed the diurnal, seasonal and annual cycles for all the parameters. The thermal stability is remarkably good, crucial for a good performance of the telescopes. From the solar radiation data, we developed a new method to estimate the fraction of time when the sky is clear of clouds. We show that our measurements are consistent with a warm standard atmosphere model. The conditions at the site are benign and stable given its altitude, showing that Sierra Negra is an extremely good site for millimeter and high-energy observations.  相似文献   

Age and emplacement of the Permian–Jurassic Menghai batholith,Western Yunnan,China     

Elizabeth J. Catlos  Enrique Reyes  Michael Brookfield  Daniel F. Stockli 《International Geology Review》2017,59(8):919-945

The Menghai batholith (Yunnan Province, China) is the southern extension of the ~370 km long Lincang granite body that syntectonically intruded the collisional zone between Gondwana (Baoshan block) and Laurasia (Simao block) terranes during closure of the Palaeo-Tethyan Ocean. Eight Menghai granodiorites were analysed across an ~45 km E–W transect from the pluton’s central region to eastern perimeter. Each rock was imaged in cathodoluminescence and geochemically analysed for major and trace elements. A minimum 30 zircons per sample were dated using laser ablation inductively coupled plasma–mass spectrometry. Samples are peraluminous to strongly peraluminous, magnesian, calcic or calc-alkalic granodiorites. Trace element suggest a high pressure (12–15 kbar) low clay source with >20–30% volume interaction with basalt. Crustal anatexis was likely related to post-collisional lithosphere delamination and upwelling of hot asthenosphere, forming large-volume melts. Zircon ages (²⁰⁷Pb–²⁰⁶Pb and ²³⁸U–²⁰⁶Pb) range from 3234 ± 42 to 171.7 ± 5.4 Ma (±2σ). Inherited zircon ages include the Palaeoarchaean–Neoarchaean (average 2938 ± 27 Ma, n = 8 ages), Lüliang (2254 ± 38 Ma, n = 7), Changcheng–Jixianian (1274 ± 47 Ma, n = 33), Qinbaikou (963 ± 29 Ma, n = 7), Nanhua (787 ± 24 Ma, n = 7), Sinian (595.4 ± 12.2 Ma, n = 14), Qilian (452.2 ± 8.7 Ma, n = 24) and Tienshan (358.9 ± 12.4 Ma, n = 5). The presence of these ages decrease from the batholith’s central portion (>50% ages) to eastern perimeter (2–16% ages), as the rocks appear progressively metamorphosed. The distribution of U/Th ratio suggests inherited zircons are Carboniferous (317.6 ± 5.7 Ma) and older and crystallization ages span the Permian to Early Jurassic. The average and youngest zircon age per sample decreases from the centre of the batholith to its eastern perimeter, from 226.8 ± 8.8 and 210.7 ± 3.3 to 211.8 ± 5.7 and 171.0 ± 5.4 Ma, respectively. If recorded by syntectonic zircon crystallization, collision and closure of a branch of the Palaeo-Tethyan Ocean occurred here over an ~100 million years time period from the Permian (281.0 ± 13.0 Ma) to Jurassic (171.5 ± 5.4 Ma).  相似文献   

Helioseismology program for the PICARD satellite     

T. Corbard  P. Boumier  T. Appourchaux  S.J. Jimnez‐Reyes  B. Gelly  the PICARD team 《Astronomische Nachrichten》2008,329(5):508-516

The PICARD mission is a CNES micro‐satellite to be launched in 2009. Its goal is to better understand the Sun and the potential impact of its activity on earth climate by measuring simultaneously the solar total and spectral irradiance, diameter, shape and oscillations. We present the scientific objectives, instrumental requirements and data products of the helioseismology program of PICARD which aims to observe the low to medium l p‐mode oscillations in intensity and search for g‐mode oscillation signatures at the limb. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Pollution by polychlorinated biphenyls in an estuary of the Gulf of California. Their toxicity and bioaccumulation in shrimp Litopenaeus vannamei     

Reyes GG  Verdugo JM  Cassin D  Carvajal R 《Marine pollution bulletin》2003,46(8):959-963

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Subsoil contaminated by hydrocarbons in an out-of-service oil distribution and storage station in Zacatecas,Mexico     

R.?IturbeEmail author  R.?M.?Flores  L.?G.?Torres 《Environmental Geology》2003,44(5):608-620

A currently out-of-service oil distribution and storage station (ODSS) operated in Zacatecas, Mexico, from 1966 to 2000. At present, it is subject to a dismantling process. In 2000, a project, focused mainly on the characterization of the soil contamination in the ODSS, was required, and the convenience of carrying out a health risk assessment (HRA) to determine the required cleaning-up-levels was stated. The study concluded that the ODSS soil was contaminated mainly by gasoline and diesel, showing the presence of methyl-tertbutylether (MTBE), benzene, toluene, ethylbenzene, and xylene (BTEX). Nine of the 16 polycyclic aromatic hydrocarbons (PAHs) identified by the US Environmental Protection Agency (EPA) as priority hydrocarbons were found in the ODSS subsoil. Selected metals were also considered in the evaluation. The geo-accumulation indexes proposed by Muller for Fe, Pb, V, and Zn showed values characteristic of no geo-accumulation. The HRA suggested the reduction of three PAHs, [benzo (a) anthracene, benzo (a) pyrene, and benzo (b) fluoranthene], and vanadium.  相似文献   

Oxidative stress in the mussel Mytella guyanensis from polluted mangroves on Santa Catarina Island,Brazil     

Torres MA  Testa CP  Gáspari C  Masutti MB  Panitz CM  Curi-Pedrosa R  de Almeida EA  Di Mascio P  Filho DW 《Marine pollution bulletin》2002,44(9):923-932

Digestive glands of the mangrove mussel Mytella guyanensis, collected at one non-polluted site (site 1) and two polluted sites (sites 2 and 3), were analysed for different antioxidant defenses, lipid peroxidation and DNA damage. Thiobarbituric acid-reactive substance (TBARS) and 8-oxo-7,8-dihydro-2'-deoxyguanosine levels were enhanced at the polluted sites. With the exception of superoxide dismutase, the activities of catalase and glutathione peroxidase were also higher at the polluted sites. Greater increases were observed in glutathione reductase, glutathione S-transferase and etoxyresorufine-O-deethylase activities at the polluted sites. Conversely, reduced glutathione content was higher at the control site. Trace metal contents in mussels collected at polluted sites were increased compared to the control site, and there were strong positive correlations between TBARS and Cu and Pb contents. M. guyanensis is routinely exposed to an oxidative stress condition at both polluted sites, and considering xenobiotic bioaccumulation in bivalve molluscs, the mangrove mussel represents an excellent bioindicator for environmental monitoring studies.  相似文献   

Ground Motion Zoning of Santiago de Cuba: An Approach by SH Waves Modelling   总被引：3，自引：0，他引：3  

Leonardo Alvarez  Julio García  Franco Vaccari  Giuliano F. Panza  Bertha González  Carmen Reyes  Bárbara Fernández  Ramón Pico  José A. Zapata  Enrique Arango 《Pure and Applied Geophysics》2004,161(5-6):1041-1059

— The expected ground motion in Santiago de Cuba basin from earthquakes which occurred in the Oriente fault zone is studied. Synthetic SH-waves seismograms have been calculated along four profiles in the basin by the hybrid approach (modal summation for the path source-profile and finite differences for the profile) for a maximum frequency of 1 Hz. The response spectra ratio (RSR) has been determined in 49 sites, distributed along all considered profiles with a spacing of 900 m. The corresponding RSR versus frequency curves have been classified using a logical-combinatorial algorithm. The results of the classification, in combination with the uppermost geological setting (geotechnical information and geological geometry of the subsoil) are used for the seismic zoning of the city. Three different main zones are identified, and a small sector characterized by major resonance effects, due to the particular structural conditions. Each zone is characterized in terms of its expected ground motion parameters for the most probable strong earthquake (M_S=7), and for the maximum possible (M_S=8).  相似文献