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3 resultados encontrados para: AUTOR: Curtis, Jason H
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1.
Artículo
Aquatic ecosystems of the Yucatán Peninsula (Mexico), Belize, and Guatemala
Pérez, Liseth ; Bugja, Rita (coaut.) ; Lorenschat, Julia (coaut.) ; Brenner, Mark (coaut.) ; Curtis, Jason H. (coaut.) ; Hoelzmann, Philipp (coaut.) ; Islebe, Gerald A. (coaut.) ; Scharf, Burkhard (coaut.) ; Schwalb, Antje (coaut.) ;
Contenido en: Hydrobiologia Vol. 661, no. 1 (February 2011), p. 407-433 ISSN: 0018-8158
Resumen en: Inglés |
Resumen en inglés

This study presents limnological and morphological characteristics, physical and chemical properties of waters, and geochemistry of surface sediments for 63 aquatic ecosystems located on the karst Yucatán Peninsula and surrounding areas of Belize and the Guatemalan highlands and eastern lowlands. Our principal goal was to classify the aquatic systems based on their water variables. A principal component analysis (PCA) of the surface water chemistry data showed that a large fraction of the variance (29%) in water chemistry is explained by conductivity and major ion concentrations. The broad conductivity range, from 168 to 55,300 μS cm−1 reflects saline water intrusion affecting coastal aquatic environments, and the steep NW–S precipitation gradient, from ~450 to >3,200 mm year−1. Coastal waterbodies Celestún and Laguna Rosada displayed the highest conductivities. Minimum surface water temperatures of 21.6°C were measured in highland lakes, and warmest temperatures, up to 31.7°C, were recorded in the lowland waterbodies. Most lakes showed thermal stratification during the sampling period, with the exception of some shallow (<10 m) systems. Lakes Chichancanab, Milagros, and Bacalar displayed sulfate-rich waters. Waters of sinkholes had relatively high conductivities (<3,670 μS cm−1) and a broad range of δ18O values (−4.1 to +3.8‰).

Ca, HCO3, and SO4 dominated the waters of the lowland lakes, whereas Na was the dominant cation in highland lakes. Coastal aquatic ecosystems were dominated by Na and Cl. Cluster analysis based on surface water variables classified aquatic environments of the lowlands and highlands into three groups: (1) lowland lakes, ponds, wetlands, and coastal waterbodies (2) highland lakes, and (3) sinkholes and rivers. A broad trophic state gradient was recorded, ranging from the eutrophic Lake Amatitlán and the Timul sinkhole to oligotrophic Laguna Ayarza, with the highest water transparency (11.4 m). We used major and trace elements in surface sediments to assess pollution of waterbodies. Lakes Amatitlán, Atescatempa, El Rosario, Cayucón, Chacan-Lara, La Misteriosa, rivers Subín and Río Dulce, the wetland Jamolún, and the sinkhole Petén de Monos showed evidence of pollution and urban development. Their surface sediments displayed high concentrations of As, Cu, Fe, Ni, Pb, Se, Zn, and Zr, which suggest moderate to strong pollution.


2.
Artículo
Resumen en: Inglés |
Resumen en inglés

Palynological studies document forest disappearance during the late Holocene in the tropical Maya lowlands of northern Guatemala. The question remains as to whether this vegetation change was driven exclusively by anthropogenic deforestation, as previously suggested, or whether it was partly attributable to climate changes. We report multiple palaeoclimate and palaeoenvironment proxies (pollen, geochemical, sedimentological) from sediment cores collected in Lake Petén Itzá, northern Guatemala. Our data indicate that the earliest phase of late Holocene tropical forest reduction in this area started at not, vert, similar 4500 cal yr BP, simultaneous with the onset of a circum-Caribbean drying trend that lasted for not, vert, similar 1500 yr. This forest decline preceded the appearance of anthropogenically associated Zea mays pollen. We conclude that vegetation changes in Petén during the period from not, vert, similar 4500 to not, vert, similar 3000 cal yr BP were largely a consequence of dry climate conditions. Furthermore, palaeoclimate data from low latitudes in North Africa point to teleconnective linkages of this drying trend on both sides of the Atlantic Ocean.


3.
Artículo
*En proceso técnico. Solicítelo con el bibliotecario de SIBE-Chetumal
A multi-proxy study of Holocene environmental change in the Maya Lowlands of Peten, Guatemala
Curtis, Jason H. (autor) ; Brenner, Mark (autor) ; Hodell, David A. (autor) ; Balser, Richard A. (autor) ; Islebe, Gerald A. (autor) ; Hooghiemstra, Henry (autor) ;
Contenido en: Journal of Paleolimnology Vol. 19, no. 2 (1998), p. 139-159 ISSN: 0921-2728
Bibliotecas: Chetumal
Cerrar
SIBE Chetumal
44481-10 (Disponible)
Disponibles para prestamo: 1
Nota: En proceso técnico. Solicítelo con el bibliotecario de SIBE-Chetumal