Examinando por Autor "Alcántara-Carrió, J."

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    Historical and recent shore erosion along the Colombian Caribbean coast
    (COASTAL EDUCATION & RESEARCH FOUNDATION, 2005-12-01) Correa, I.D.; Alcántara-Carrió, J.; González R, D.A.; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
    The analysis of historical charts, aerial photographs, satellite images and fieldwork provides a general picture of the magnitudes, rates and some of the possible causes of the main shoreline changes occurred along the littoral since 1794 until present. Net littoral accretion took place mostly on localized deltaic zones, but cliff and beach retreat has been by far the dominant trend in this coast, particularly along the coastline to the south of Sierra Nevada de Santa Marta. Data concerning the Guajira Peninsula and Sierra Nevada de Santa Marta shores suggest a coastline retreat of 20-30 m in the last century, while for the southern Caribbean, between the Magdalena delta and the Gulf of Urabá, accurate charts of XVIII-XIX centuries evidence littoral retreat up to 12 km and maximum rates of erosion up to 40 myr -1 at some areas. Shore erosion and consequent flooding along the Caribbean coast of Colombia had induced important land losses, both in non-developed and developed areas, and is impacting severely the infrastructure of all the inhabited littoral sectors. Available data for the most critical areas demonstrates that natural instability and/or pre-existing erosive trends are facilitated by soft lithologies and were dramatically accelerated in the last eight decades by intensive human interventions, including the chaotic building up of hard rock coastal defenses, the diversion of low river courses and the intensive beach and river sand extraction.
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    Impact of terrestrial mining and intensive agriculture in pollution of estuarine surface sediments: Spatial distribution of trace metals in the Gulf of Uraba, Colombia
    (Elsevier Inc., 2016-10-15) Vallejo Toro, P.P.; Vásquez Bedoya, L.F.; Correa, I.D.; Bernal Franco, G.R.; Alcántara-Carrió, J.; Palacio Baena, J.A.; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
    The Gulf of Uraba (northwestern Colombia) is a geostrategic region, rich in biodiversity and natural resources. Its economy is mainly based on agribusinesses and mining activities. In this research is determined the impact of these activities in bottom surface sediments of the estuary. Thus, grain size, total organic carbon, total nitrogen, carbonates, Ag, Al, Ca, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb and Zn concentrations from 17 surface sediment samples were obtained and enrichment factors (EF) as well as geo-accumulation indices (Igeo) were calculated to determine the contamination level in the gulf. EF and Igeo values revealed that the estuary is extremely contaminated with Ag and moderately contaminated with Zn. Therefore, the observed enrichment of Ag may be explained as a residue of the extraction of gold and platinum-group metals and the enrichment with Zn associated mainly to pesticides used in banana plantations. (C) 2016 Elsevier Ltd. All rights reserved.