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Copyright of Revista Facultad de Ciencias Basicas is the property of Revista Facultad de Ciencias Basicas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Se determinó en el sedimento superficial del Lago de Maracaibo los metales: Cu, Cd, Cr, Pb, V y Ni. El estudio abarcó 13 estaciones distribuidas en la Bahía El Tablazo, Estrecho de Maracaibo y Lago de Maracaibo propiamente dicho. Se realizaron un total de cuatro (4) muestreos desde 1999 a 2001, en los meses de octubre 1999 (lluvia), marzo 2000 (sequía), noviembre 2000 (lluvia) y mayo 2001 (final lluvia). Los niveles promedio (mínimo-máximo) de metales fluctuaron de la siguiente manera: Cu: 27,07 (2,31-75,46), Cd: 3,37 (0,46-7,9), Cr: 39,50 (3,98-98,28), Pb: 60,59 (17,8-143,9), V: 50,44 (1,29-121,2) y Ni: 65,31 (16,76-177,62) mg.Kg-1. El orden de los metales según sus promedios generales fue: Ni > Pb > V > Cr > Cu > Cd. Las concentraciones de metales en sedimento del Sistema Lago de Maracaibo reportadas en este estudio son similares a las reportadas en sistemas acuáticos con alta actividad petrolera. A excepción del muestreo de octubre de 1999, con fuertes precipitaciones atípicas, el resto de los muestreos presentó una tendencia clara a valores altos en la zona oriental del lago y con valores bajos en la zona occidental.Ni, V, Cr, Cd, Cu and Pb were determined in superficial sediment samples from System Maracaibo Lake. Thirteen sampling points were sampled in Tablazo bay, Maracaibo Strait and Maracaibo Lake, four times during 2 years as follows: October 1999 (rainy season), March 2000 (dry season), November 2000 (rainy season) and May 2001 (low rainy period). Mean values (minimum-maximum) of heavy metals were: Cu: 27,07 (2,31-75,46), Cd: 3,37 (0,46-7,9), Cr: 39,50 (3,98-98,28), Pb: 60,59 (17,8-143,9), V: 50,44 (1,29-121,2) y Ni: 65,31 (16,76-177,62) mg.Kg-1. The metal concentrations present in sediments were in the following order: Ni>Pb>V>Cr>Cu>Cd. Metal concentration in sediments of Maracaibo Lake system, are similar to the aquatic systems with a high oil activity. Samples showed a clear tendency to higher values in the eastern area of Maracaibo Lake and lower value in the western zone.

Los acuíferos subterráneos son una fuente primordial del agua que se utiliza en actividades domésticas y agrícolas en algunas regiones de la cuenca del Lago de Maracaibo, Venezuela. En el presente estudio, se analizó el contenido de cadmio (Cd), cobre (Cu), hierro (Fe), níquel (Ni), plomo (Pb), vanadio (V) y zinc (Zn) en 46 muestras de aguas subterráneas obtenidas de pozos someros ubicados en tres localidades de la región occidental del Lago de Maracaibo: una urbana (Sierra Maestra) y dos áreas rurales (Pompey y Viateca). Las muestras se colectaron en varios meses durante un año de monitoreo. Los metales fueron cuantificados mediante Espectrometría de Absorción Atómica. Se encontraron diferencias significativas en el contenido de Cd, V y Zn en aguas subterráneas de las tres localidades. Las concentraciones de elementos tóxicos como el Cd y V fueron mayores en aguas subterráneas de Sierra Maestra, detectándose en la totalidad de la muestras de esta localidad valores que sobrepasaron los límites permisibles para agua potable, según normativas nacionales e internacionales. Se discuten otras implicaciones sobre la calidad del agua en los acuíferos del área en estudio y los procesos que pueden llegar a modificarla, tales como la contaminación por actividades humanas.Underground aquifers are a fundamental source of water for both domestic and agricultural activities in some regions of the Lake Maracaibo Basin, Venezuela. In this study the contents of cadmium (Cd), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), vanadium (V) and zinc (Zn) were determined in 46 samples of water from shallow wells in three locations of the Western region of the Lake: an urban area (Sierra Maestra) and two rural area (Pompey and Viateca). The samples were collected for several months during a monitoring year. The elements were quantified by Atomic Absorption Spectrometry both FAAS and GFAAS. Significant differences were found in the levels of metals for all locations. Toxic metals such as cadmium and vanadium were detected at higher concentrations in water from Sierra Maestra being their values above the allowed limits, both national and international, for drinking water. Other implications such as the influence of human activities and its contribution to our results are discussed.

The objective of this investigation was to determine the physical and chemical composition of the water streams and sediments of the Maracaibo Lake in three sampling areas located in Tía Juana, Lagunillas and Ceuta in order to know the level of contamination and assess water quality based on permissible values established by the 883 Decree. The results indicate that the overall hydrocarbon concentrations in the water and sediments are above permissible levels. It is concluded that petroleum prospection is the root cause of the lake contamination. [ABSTRACT FROM AUTHOR]

The Maracaibo Lake water and sediment were tested in six sampling stations distributed in the north and south of the lake. The physicochemical and environmental parameters were determined as well as the relation was established between these parameters and the areas affected by waste discharge, landfills, liquid and solid industrial wastes resulting from oil prospection and agricultural activities and organic material carry-overs in rivers and pluvial drainage. This shows a level of contamination caused by increased content of nutrients (nitrogen and phosphorus) in the areas adjacent to the rivers and residual water discharge. It was observed that a saline wedge was formed due to the penetration of lake waters coming from the Gulf of Venezuela. The concentration of heavy metal was below permissible levels in the water and very heterogeneous in the sediments. [ABSTRACT FROM AUTHOR]

Copyright of Cayapa is the property of Universidad de Los Andes (Venezuela) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

 Ni, V, Cr, Cd, Cu and Pb were determined in superficial sediment samples from System Maracaibo Lake. Thirteen sampling points were sampled in Tablazo bay, Maracaibo Strait and Maracaibo Lake, four times during 2 years as follows: October 1999 (rainy season), March 2000 (dry season), November 2000 (rainy season) and May 2001 (low rainy period). Mean values (minimum-maximum) of heavy metals were: Cu: 27,07 (2,31-75,46), Cd: 3,37 (0,46-7,9), Cr: 39,50 (3,98-98,28), Pb: 60,59 (17,8-143,9), V: 50,44 (1,29-121,2) y Ni: 65,31 (16,76-177,62) mg.Kg”“1. The metal concentrations present in sediments were in the following order: Ni > Pb > V > Cr > Cu > Cd. Metal concentration in sediments of Maracaibo Lake system, are similar to the aquatic systems with a high oil activity. Samples showed a clear tendency to higher values in the eastern area of Maracaibo Lake and lower value in the western zone.

This paper analyzes the influence of El Niño (ENSO) and El Anti Niño (NOENSO-La Niña) over the pluviometric regime on annual, monthly and daily extreme values in the south and west region of the Lake of Maracaibo basin, located at the north part of South America. It was observed moderate influence in the south part of the basin, with positive differences of 15% for the NOENSO years and negative differences of 10% in the ENSO years, this behavior is different from the Perú case, where ENSO increases precipitation. The bimodal sequence of monthly rain is not modified, but the second peak is greater in the NOENSO years. There were no significant differences for daily maximum extreme values.

A new species of aquatic snake in the genus Pseudoeryx is described from the Lake Maracaibo Basin in northwestern Venezuela. The new species differs from P. plicatilis, the only other species in the genus, by having a nuchal band, a distinctive ventral coloration, the relative size of the genial plates and having different maxillary dentition. This discovery further supports paleogeographic reconstructions of the course of a proto-Orinoco/Amazon river. [ABSTRACT FROM AUTHOR]

Caño Paijana is a tidal channel that connected, until recently, the Uruba bay at the mouth of the Limón river, to the Gulf of Venezuela north of Maracaibo, Venezuela. It separated the Island of San Carlos from the mainland. In the last 50 years the channel has been drying out rapidly, to the extent that presently there is no water flow into or from the sea through its mouth opening on the Gulf of Venezuela. This mouth was covered by healthy mangroves (mainly Avicennia germinans) until at least 1952. The two extremes of the Paijana water channel differ radically today. At Uruba bay end the channel is fringed by dense mangrove vegetation dominated by Rhizophora mangle, while at the Gulf of Venezuela mouth the vegetation cover is mostly constituted by scrubby, scattered trees of Avicennia germinans, xerophytic shrubs acting as dune fixers, and halophytic strand vegetation. The process is the result of complex interaction between: a) high frequency of low-rainfall years; b) high dune activity during dry years c) dam construction on tributaries of the Limón river that reduced discharge of fresh water into Uruba bay. [ABSTRACT FROM AUTHOR]