Thank you Dwight for clarifying that.  This has been our position all
along. Ecologists here are attempting to calculate mass-balances after
addition of 99atom% tracer to a system and there is some disagreement
about how to proceed, or even if the resulting figures will actually
mean anything......

                                                Thanks again,


Darren and Andy.


Darren Sleep
Stable Isotope Facility
ITE Merlewood
Grange-Over-Sands
Cumbria LA11 6JU
UK