Long-term changes in organic matter and mercury transport to lakes in the sporadic
discontinuous permafrost zone related to peat subsidence
Jennifer B. Korosi, Jamylynn McDonald, Kristen A. Coleman Michael J. Palmer, John P. Smol,
Myrna J. Simpson, and Jules M. Blais
Supplemental Information
1. Sediment core chronologies
KAK-1
A steady decline in total 210Pb activity was observed from a subsurface maximum of
793.3 ± 77.2 Bq/kg at 5 cm to 15 cm, when background 210Pb activity was reached (Fig. S1a). A
decline in total 210Pb activity was observed from 0-3 cm, to 410.2 ± 81.3 Bq/kg (Fig. S1a).
Sediment age extrapolation below the horizon of unsupported 210Pb activity was not conducted,
as associated errors are often large and can be influenced by unknown changes in sedimentation.
No clear peak in 137Cs was observed that could be associated with 1963, the year of maximum
137
Cs fallout from atmospheric nuclear weapons testing, although no 137Cs could be detected
below 8 cm.
TAH-7
A decline in total 210Pb activity was observed from a subsurface maximum of 829.2 ±
171.3 Bq/kg at 1.5 cm to 14.5 cm, when background 210Pb activity was reached (Fig. S1b). A
decline in total 210Pb activity was observed at 0.5 cm, to 455.4 ± 68.7 Bq/kg (Fig. S1b). Similar
to KAK-1, sediment age extrapolation below the horizon of unsupported 210Pb activity was not
conducted. No clear peak in 137Cs was observed that could be associated with 1963.
2. Geochemical and Biomarker Proxies
TAH-7
Several geochemical and biomarker proxies displayed notable anomalies at 38 cm (or the
35-40 cm interval for the biomarkers), corresponding to a peak in macroscopic charcoal reported
in Coleman et al. (2015) for the same sediment core used in this study, indicative of a local forest
fire at this time. In particular, increases in %N, decreases in C/N, δ15N, and V were observed
(Fig. S2)
Figure Captions
Figure S.1 – Sediment core depth versus total 210Pb, 214Pb, and 137Cs radioisotopic activity with
errors (left panel), and sediment core depth versus date based on the constant rate of supply
model (right panel) for a) KAK-1, and b) TAH-7. Error bars for radioisotopic activity (left panel)
represent counting variability in standard deviation units, and error bars for depth versus date
(right panel) estimate dating uncertainty in years (Binford 1990).
Figure S.2 – Stratigraphies showing temporal changes in vanillyl concentrations (V), percent
nitrogen (%N), organic carbon: nitrogen (C/N), and δ15N in lake TAH-7. The timing of an
inferred local forest fire (Coleman et al. 2015) is shown as a dashed line.
References
Binford, M. W. 1990. Calculation and uncertainty analysis of 210Pb dates for PIRLA project
lake sediment cores. J. Paleolimnol. 3: 253-267.
Coleman, K. A., M. Palmer, J. B. Korosi, et al. 2015. Tracking the impacts of recent warming
and peat subsidence on aquatic ecosystems: a multi-proxy approach using remote sensing and
lake sediments. Boreal Environment Research 20: ISSN (online)
1797-2469.