We have recently had a site with this type of contamination. The bulk samples were soaked in Decon 90 for at least two weeks prior to processing. The samples did smell awful but the charred plants remains were not affected at all.
Decon 90 is a surface active cleaning agent, and/or radioactive decontaminant, for laboratory, medical and specialised industrial applications. We actually use it routinely in our clay samples as a substitute for the traditional Calgon or hydrogen peroxide. It is extremely effective at breaking down the clay prior to tank processing.
Details for Decon:
It is quite expensive, about £30 for 5 litres but you only need about 20ml for a 10 litre sample.
Archaeological Field Unit,
Cambridgeshire County Council,
Fulbourn Community Centre, Haggis Gap, Fulbourn, Cambridge CB1 5HD
Direct Dial: 01223-714119
From: The archaeobotany mailing list
[mailto:[log in to unmask]]On Behalf Of Allan Hall
Sent: 07 April 2006 09:25
To: [log in to unmask]
Subject: Sieving samples contaminated with hydrocarbons
An archaeological colleague is faced with a site where the ground has been
contaminated with hydrocarbons (specifically diesel). I wonder if list
members have experience of processing samples for charred remains under
these circumstances? Apart from the smell and the problem of being unable to
use material for dating, what problems were there in sieving - was charred
material easier to collect because the hydrocarbons made it float better, or
was flotation more difficult for some reason? I'd be interested to hear of
members' experiences, as mine have been restricted to diesel-contaminated
samples which were being investigated for waterlogged plant and insect
remains and where the issue of flotation (at least for charred plant
material!) was not important.
Dr Allan Hall, English Heritage Senior Research Fellow, Department of
Archaeology, University of York, The King's Manor, York YO1 7EP, UK
+44 1904 434950 (fax 433902)
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