Dear all,

 I am currently busy with a research project as a part of my hydrogeology
study which deals with nitrogen isotopes in a limestone aquifer. The
aquifer contains NH4+ and a reaction which is likely to occur is the
exchange of NH4 for Ca ; where Ca dissolves or desorbs and NH4 is sorbed
to the aquifer matrix.
 My question is what is the fractionation factor for this sorption/exchange
reaction, because an isotopic depletion trend can be seen in the 15N-NH4+
isotope data with distance along flow.

 I hope someone can provide me more information on this topic and i am
willing to explain the situation more elaborately for those who are

with regards,

Kyrian van Vliet
CSIRO Land and Water         Email:  [log in to unmask]
Private Bag                  Phone:  +61-8-9387 0280
PO Wembley  WA  6014         Fax:    +61-8-9387 8211
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