dD values of long-chain n-alkanes (dDwax) reflect dD of water used by terrestrial vegetation after modification by biosynthetic processes (Sachse et al., 2012 and references therein). Soil moisture provides the source water for terrestrial plants, while lake water is the source for aquatic macrophytes and algae. dD of water in soils can be modified to some extent from dD of annual precipitation by evaporation. However, it has been shown that dDwax is unaltered by plants following leaf formation and therefore reflects dDwater used during leaf flush (Kahmen et al., 2011; Sachse et al., 2010; Tipple et al., 2013). In the Arctic, the majority of leaf formation takes place in late spring/early summer following the return of appreciable sunlight. Because snowmelt is the predominant water source available to plants at the time of leaf formation, the dDwax is potentially biased toward wintertime dDp (i.e. snowfall months). In Tasiilaq, the difference between precipitation-weighted annual average dDp (?92?) and precipitation- weighted average dDp during months with below zero average temperatures (October-April; ?96?) is negligible (Bowen, 2008; Cappelen et al., 2011), and thus, any changes in the timing of leaf formation during the Holocene, or in the seasonality of precipita- tion, are unlikely to have had much impact on dDwaxd

?D values of long-chain n-alkanes (?Dwax) reflect ?D of water used by terrestrial vegetation after modification by biosynthetic processes (Sachse et al., 2012 and references therein). Soil mois- ture provides the source water for terrestrial plants, while lake water is the source for aquatic macrophytes and algae. ?D of water in soils can be modified to some extent from ?D of annual precipitation by evaporation. However, it has been shown that ?Dwax is unaltered by plants following leaf formation and there- fore reflects ?Dwater used during leaf flush (Kahmen et al., 2011; Sachse et al., 2010; Tipple et al., 2013). In the Arctic, the majority of leaf formation takes place in late spring/early summer follow- ing the return of appreciable sunlight. Because snowmelt is the predominant water source available to plants at the time of leaf formation, the ?Dwax is potentially biased toward wintertime ?Dp (i.e. snowfall months). In Tasiilaq, the difference between precip- itation-weighted annual average ?Dp (?92?) and precipitation- weighted average ?Dp during months with below zero average temperatures (October?April; ?96?) is negligible (Bowen, 2008; Cappelen et al., 2011), and thus, any changes in the timing of leaf formation during the Holocene, or in the seasonality of precipita- tion, are unlikely to have had much impact on ?Dwax.