Dear Subscribers, I have found a few different methods which explain how soil samples should be prepared for the removal of carbonates, hence getting a handle on the organic C signature. Some say 0.5 M HCl some say 1.0 M HCl, some say leave for 3 days others say until bubbles stop. Some also say separation through density must be completed using different solutions before attempting HCl wash. Is there now some consistent method everybody uses. These are forest soils if this is helpful. Also can soil samples be frozen prior to preparation. Until you have a few free days to tend samples. Any clarification would help on the standard procedure most people refer to now. Thanks. Lisa Wingate Edinburgh University Biosphere Atmosphere Programme Institute of Ecology and Resource Management The King's Buildings Edinburgh Scotland UK EH9 3JU e-mail: [log in to unmask] phone: 0131 650 5425 fax: 0131 662 0478