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Boletín de la Sociedad Geológica Mexicana Volumen 69, núm. 2, 2017, p. 433 ‒ 445 |
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Índices de sorción de metales pesados en suelos urbanos: el caso de Morelia, Michoacán
Francisco Bautista, Elsy Campuzano, Carmen Delgado, Avto Goguitchaichvili
Francisco Bautista
Elsy Campuzano
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Laboratorio Universitario de Geofísica Ambiental, Centro de Investigaciones en Geografía Ambiental, Universidad Nacional Autónoma de México. Antigua Carretera a Pátzcuaro No. 8701, Col. Ex-Hacienda de San José de la Huerta. C.P. 58190. Morelia, Michoacán, México.
Elsy Campuzano
Universidad Politécnica del Estado de Guerrero. Carretera Federal Iguala-Taxco, Km 105. C.P. 40321. Taxco de Alarcón, Guerrero, México.
Carmen Delgado
Universidad Michoacana de San Nicolás de Hidalgo, Instituto de Investigaciones en Ciencias de la Tierra (INICIT-UMSNH). Avenida universidad No. 1471, Ciudad Universitaria. C.P. 58066. Morelia, Michoacán, México.
Avto Goguitchaichvili
Laboratorio Universitario de Geofísica Ambiental, Instituto de Geofísica, Unidad Michoacán. Universidad Nacional Autónoma de México. Antigua Carretera a Pátzcuaro No. 8701, Col. Ex-Hacienda de San José de la Huerta. C.P. 58190. Morelia, Michoacán, México.
Abstract
Due to rapid urban growth and significant increase of human activities such as industrialization, use of motor vehicles and the generation of urban solid waste a large amounts of heavy metals are systematically released into the environment contributing to the pollution of urban soils. However, the ability of soil to adsorb heavy metals is still poorly studied. The aim of this investigation was the evaluation and / or development of three heavy metal sorption indices and their mathematical validation using decision trees for classification purposes. The sampling was carried out within the urban area of the city of Morelia, State of Michoacan, Mexico. In total 100 samples of topsoil were collected and the content of organic matter, pH, cation exchange capacity, percentage of clay, structure, stoniness and bulk density were analyzed. The Lehmann index was evaluated and two new indices were developed, the modified Lehmann index and the Bautista-Campuzano index. The mathematical validation and development of decision trees were performed using the WEKA software. The Lehmann index took into account mainly the percentage of clays, aggregates and stoniness. The modified Lehmann index used the cation exchange capacity, organic matter, stoniness and pH. Finally the Bautista-Campuzano index considered the pH, organic matter, clays, stoniness and bulk density. The three indices showed congruence between soil properties and sorption classes of heavy metals with a Kappa coefficient greater than 0.7. However, the Bautista-Campuzano index showed greater theoretical consistency according to the decision tree for classification purpose. This study reveals the importance of the mathematical and theoretical evaluation of the indices using decision trees for classification. For this reason, we consider that the Bautista-Campuzano index is the most efficient methodology for generating information and decision-making related to the improvement of soils in urban areas to increase the sorption of heavy metals.
Keywords: Pollution, Cities, Top soils, Decision trees for classification.
