HR: 1400h
AN: H53A-04    [Abstracts]
TI: Isotopic composition of continental and marine waters in Costa Chica, Guerrero, Mexico
AU: * Gonzalez, T
EM: tglez@geofisica.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Ciudad Universitaria, Col. Coyoacan., Mexico, DF 04510, Mexico
AU: Durazo, J
EM: durazo@geofisica.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Instituto de Geofisica, Ciudad Universitaria, Col. Coyoacan., Mexico, DF 04510, Mexico
AU: Morales, P
EM: mopuente@servidor.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Instituto de Geologia, Ciudad Universitaria, Col. Coyoacan., Mexico, DF 04510, Mexico
AU: Cienfuegos, E
AF: Universidad Nacional Autonoma de Mexico, Instituto de Geologia, Ciudad Universitaria, Col. Coyoacan., Mexico, DF 04510, Mexico
AB: The region interesting to the present hydrologically-oriented study is part of the Costa Chica, between the state line of Guerrero and Oaxaca, in southern Mexico, which includes the warm and subhumid lowlands of the 6136 km2 watershed of the Ometepec river. This perennial, although highly seasonal river, drains the southern flank of Sierra Madre del Sur, an elevated mountain range parallel to the Pacific Ocean shoreline, with peaks up to 3000 m asl, and at 98º 43' W; 16º 30' N, discharges into this ocean around 3 × 109 m3 of pristine water per year. So far, anthropic alterations of the whole environment are not immediately obvious. Its coastal wetlands have become a new international Ramsar Site. Our region of interest is a large scale unperturbed natural laboratory, waiting to be studied. The present study shows a several years ongoing survey of 64 paired measurements, (δ 18O, δ 2H) in permil versus Vienna SMOW, of the oxygen-18 and deuterium concentrations of the continental and marine waters of the study region. Rain water was not sampled. The objective is to show and personally discuss the sole "isotopic picture" in a threefold way: i) To test locally the meteoric line, the fractionation coefficients, and the altitude effect, all of them documented for central Mexico through other studies, and, also, to compare the isotope data available for other locations nearby; ii) To display the regularities we found in surface and ground waters, potentially useful studying its catchment isotope hydrology; and iii) To show marine water features that could be indicative of local continental discharges inside the sea, the ones that should be taken into account in future hydrological and ecological balances [in: Zektser IS, RG Dzhamalov, LG Everett (2007). Submarine Groundwater. CRC Press, Boca Raton. 446 pp.]
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 1800 HYDROLOGY
DE: 1829 Groundwater hydrology
DE: 1894 Instruments and techniques: modeling
SC: Hydrology [H]
MN: 2007 Joint Assembly