Behaviour of boron and strontium isotopes in groundwater–aquifer interactions in the Cornia Plain (Tuscany,Italy) |
| |
| Institution: | 1. Institute for Applied Geosciences, Technische Universität Darmstadt, Schnittspahnstraße 9, 64287 Darmstadt, Germany;2. Geology Department, College of Science, University of Baghdad, Jadreya, Baghdad, Iraq;1. Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA;2. Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile;3. Department of Geology, Juniata College, Huntingdon, PA, USA;1. Earth and Environmental Science Area, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, United States;2. College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, United States;1. Marine Geoscience and Soil Science Laboratory (URAC-45), Earth Sciences Department, University of Chouaïb Doukkali, Faculty of Sciences, El Jadida, Morocco;2. I2M UMR 5295 Laboratory, Environmental Civil Engineering Department, Bordeaux University, Bordeaux, France |
| |
| Abstract: | The Cornia Plain alluvial aquifer, in Tuscany, is exploited intensely to meet the demand for domestic, irrigation and industrial water supplies. The B concentration of groundwater, however, is often above the European limit of 1 mg L?1, with the result that exploitation of these water resources requires careful management. Boron and Sr isotopes have been used as part of a study on the origin and distribution of B dissolved in groundwater, and indirectly as a contribution to the development of appropriate water management strategies.The geochemistry of the Cornia Plain groundwater changes from a HCO3 facies in the inland areas to a Cl facies along the coastal belt, where seawater intrusion takes place. The B concentration of groundwater increases towards the coastal areas, while the 11B/10B ratio decreases. This indicates that there is an increasing interaction between dissolved B and the sediments forming the aquifer matrix, whose B content is in the order of 100 mg kg?1. Adsorption–desorption exchanges take place between water and the sediment fine fraction rich in clay minerals, with a net release of B from the matrix into the groundwater, and a consequent δ11B shift from positive to negative values. The aquifer matrix sediments therefore seem to be the major source of B dissolved in the groundwater.The groundwater–matrix interactions triggered by the ionic strength increase caused by seawater intrusion can also be detected in the Ca–Na ion exchanges. Dissolved Sr follows a trend similar to that of Ca, while the 87Sr/86Sr ratio is equal to that of the exchangeable Sr of the aquifer matrix and therefore does not change significantly.These results have helped to define a new strategy for groundwater exploitation, with the final objective of reducing B concentration in the water extracted from the aquifer. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
