Table S2.

Stable carbon (δ13C) end-members for different BC sources

BC sourceLiquid fossilCoalGas flaringDomestic*BiomassR fossil
Δ14C, ‰1,000 ± 01,000 ± 01,000 ± 0265 ± 1.2+225 ± 601,000 ± 0
δ13C, ‰31.4 ± 123.4 ± 1.338 ± 325.5 ± 3626.7 ± 1.825.5 ± 1.3
  • The end-members are site-/region-specific. Applied end-members are according to Andersson et al. (28) for coal and R fossil, Mašalaitė et al. (40) for liquid fossil, and Widory (44) for gas flaring. For biomass, the δ13C end-member is used according to Andersson et al. (28) and Winiger et al. (13), reflecting the photosynthesis pathway of trees. Although we applied a ∆14C end-member of 225 ± 25‰ for the European Arctic (13, 31), an end-member with higher variability was used for the Russian Arctic, to account for possible differences in biota or lumbering behavior (e.g., trees older than 60 y).

  • * Estimated as 60% biomass, 39% coal, and 1% liquid fossil (24).

  • Biomass (open fires) were used interchangeably with GFED, even though GFED captures also other events.

  • Liquid fossil fuels of regular origin, i.e., consumed in, e.g., Western Europe or China.