The determination of the D/H ratio of non-exchangeable hydrogen in cellulose extracted from aquatic and land plants

A method has been developed for the analysis of D/H ratios of non-exchangeable hydrogen in plant cellulose. Plant samples are nitrated at low temperature and pure cellulose nitrate is extracted by acetone dissolution. Tests of this nitrated product have demonstrated that the nitration-extraction procedure eliminates the OH hydrogen and does not alter the D/H ratio of the cellulose carbon-bound hydrogen. Significant differences exist between δD values of plant total hydrogen and δD values of cellulose nitrate hydrogen. This difference is due to the effect of chemical heterogeneity of the δD value of plant material. Plant-extracted cellulose nitrate D/H ratios are systematically related to the D/H ratios of the associated environmental water. The overall relationship is linear with slope of one and intercept of ?22%. Five aquatic plants which grew at 16–17°C are related isotopically to the water by a linear curve with a slope of 1 and intercept of ?36%. Three plants which grew at 28–29°C have an intercept of ?11%. The general dependence of plant cellulose non-exchangeable hydrogen D/H ratios on the D/H ratios of the associated environmental water suggests that variations of the extracted cellulose nitrate δD values of plants can be used as indicators of climatic change.