Determinación de la edad del agua en el acuifero pampeano en la cuenca del río Quequén Grande (Buenos Aires)

MARTINEZ, DANIEL E.; SOLOMON, KIP; DAPEÑA, CRISTINA; QUIROZ LONDOÑO, MAURICIO; MASSONE, HECTOR

Revista Latino-Americana de Hidrología Subterránea

ALHSUD - Asociación Latinoamericana de Hidrología Subterránea

Lugar: Montevideo, Uruguay; Año: 2010 vol. 7 p. 79 - 82

1676-0999

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Water age in an aquifer system can be defined as the elapsed time since the sample was isolated from the atmosphere. Mean residence time is defined as the ratio between the total water volume and the groundwater outflow. Mean residence time of groundwater within an aquifer can potentially be estimated if water samples that represent a complete distribution of flow paths can be collected. Then, taking samples from gaining rivers and springs can result in a good approximation to the problem. A sampling campaign for CFCs and 3H/3He was carried out during May 2007, including even groundwater and surface water. Different types of samplers were used as copper tubes and diffusion passive samplers. Noble gases and CFCs measurements were made at the laboratories of the University of Utah, and 3H were made at the INGEIS laboratories. The obtained results by CFCs measurements indicate as recharge years between 1948 and 1953 for groundwater samples, and between 1976 and 1989 for streamwater. Apparent air equilibration has occurred for noble gases, giving too young apparent ages. Integrated analysis of CFCs and noble gases information leads to conclude that apparent water ages ca. 50 years can be assigned to groundwater and baseflow. According these results, a shallow groundwater zone of about 75 m is discharging directly on streams, while a deeper groundwater zone is discharging directly to the ocean