Hydrogen isotopic compositions of plant leaf lipids are unaffected by a twofold pCO2 change in growth chambers

Hydrogen isotopic compositions of leaf lipids have potential for reconstructing past hydrological changes. However, the effect of pCO2 levels on leaf lipid D/H values (δD values) is unknown. Here, we show that leaf lipid (n-alkanes and n-alkanoic acids) δD values of thirteen plant species grown in chambers are unaffected by a twofold change in ambient pCO2 level. We hypothesize that the effect of enhanced evapotranspiration at lower CO2 is accompanied by an increase in kinetic hydrogen isotopic fractionation due to lower rate of plant growth, and vice versa.