Kd Values

["Robert M. Beinstein" <r.beinstein@snet.net>]

Radsafers,

An update on my earlier question on determining site-specific Kd values for
use in DandD.  I received several responses, most of them asking me to share
whatever I learned with the group.  So here goes (I'll not repeat info
already posted to the list):

There are apparently two ASTM methods for use in lab trials to determine Kd
values.  They are: ASTM D 4319-83; "Distribution Ratios by the Short-Term
Batch Method" and ASTM D 4646-87; "24-h Batch-Type Measurement of
Contaminant Sorption by Soils and Sediments".  I believe there are also
continuous flow, column-type methods available, but I have yet to track them
down.  From several sources came the caveat that many factors can affect Kd,
including contaminants' chemical form, water chemistry, soil chemistry,
water pH, etc..  Several folks suggested that little is to be gained from
attempting to determine Kds specific to a site in the lab, and that
published values or empirically derived values work just as well as
experimental ones.

It was also brought to my attention (off-line) that I probably shouldn't
have requested responses via private mail on such a topical issue.  Sorry,
it was my (newbie) attempt to save Melissa's bandwidth.

I'll keep watching for more on the subject.

Thanks,

Bob Beinstein
Cabrera Services, Inc.
r.beinstein@snet.net

860-533-1334 (office)
860-533-7151 (fax)

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