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Water quality evaluation of the Akumal aquatic ecosystem (SE Mexico)

IWRA World Water Congress 2008 Montpellier France
1. Water availability, use and management
Author(s): Laura Hernández-Terrones
Paul Sánchez-Navarro R
Mélina Soto
Adrien Le Cossec
Edith Sosa Bravo
Emiliano Monroy Ríos

(1) Centro de Investigación Científica de Yucatán, Unidad Quintana Roo / Centro para el Estudio del Agua, Calle 8, No. 39, L1, Mz29, SM64, 77500 Cancún, Quintana Roo, Mexico; Tel./Fax: +52 998 211 3008; email: laurah@cicy.mx (2) Centro Ecológico Akum

Keyword(s): Water quality, coastal, lagoon, estuary, nutrient, coliforms, pollution
Article: Poster:

AbstractIntroduction The dramatic increase in population growth is affecting the natural ecosystems in the area including the Mesoamerican coral reef. The coral reef in Akumal, part of the Mesoamerican coral reef barrier (the second largest after the Great Barrier Reef), makes this region very attractive for the tourism industry. Tourism activities have immediate and vast consequences for ecological systems, which are particularly vulnerable in this region. In addition, fractures and groundwater streams, characteristic of karst aquifers like those of Akumal mean that contaminants can be transported long distances with little dilution. Karst environments are highly vulnerable to a variety of degradation and pollution problems. Geology (fractured carbonate rocks), morphology (presence of a network of cavities produced by karst processes), and hydrogeology (rapid concentrated flow through fractures and conduits) of karst carbonates strongly promotes the movement of contaminants towards the water table. As a consequence, water quality can deteriorate severely, which implies very high economic and social costs in order to clean the polluted sites and restore the original situation. The purpose of the present study is to forecast the water quality condition of the aquatic ecosystem of Akumal Quintana Roo, Mexico (20°23’46’’N/ 87° 18’50’’W). Methods Waters entering the Yal Kú estuary and Lagartos coastal lagoon were sampled and analyzed for physicochemical and bacteriological parameters. The Yal Kú estuary is the outlet for the main groundwater flows in the whole Akumal area. The physicochemical measurements were performed by a data sonde, (Hydrolab®). Samples were immediately filtered in field using a manual filtration system through a 0,22 µm filtration membrane and stored in High Density Polyethylene bottles previously washed with HNO3 and rinsed with MilliQ® deionized water. Samples for bacteriological analysis (E. coli) were taken in sterilized bottles. The Escherichia coli densities were determined in laboratory with IDEXX® method. The water samples for nutrients were analyzed by a Skalar San++®. Results The results in some points show higher concentrations for coliforms, higher than the Mexican standard values (<200 NMP/100 ml) for both systems. The pH for Lagartos lagoon and Yal Kú estuary is between 7 and 8. Two sampling points in Yal Ku, present dissolved oxygen values lower than 6 mg/l. Regarding nitrates, the values are below 5.9 mg/l NO3 for both systems. Sea water enters Yal Kú from the east. The distribution of chlorides in Lagartos shows a general increase of the concentration down gradient, to the north towards the coastal line. Conclusions Variations in water quality along Yal Kú indicate that the waters from the south are more polluted and polluted by effluents from homes and/or small condos. Different types of pollution characterize the different waters in Akumal. We tracked the impacts of toxic pollution on ecosystem health and hence on human health. The rising groundwater contamination will increase the stress on available water resources and valuable ecosystems, especially the adjacent coral reef. The results of this monitoring will provide baseline data to propose and/or improve protection, conservation measures as well as suggest further research on human health in the area.
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