Boron and helium isotopes in geothermal fluids from Larderello

Elemental and isotopic composition of boron and helium in selected wells of the Larderello geothermal field have been determined. The main results indicate that boron is sensitive to reinjection, while R/Ra ratio is little or not affected by waste water reinjection. The higher R/Ra measured values correspond to higher boron content. The delta B-11 values exclude that the dominant boron source be magmatic and indicate a contribution from fluids related to the evaporitic and carbonatic sediments of the Tuscan Nappe.