Figure captions
Figure 1. (a) The study area and (b–f) sampling locations in
Lützow-Holm Bay, Eastern Antarctica. MODIS-Terra satellite images were
obtained on (b) 19 January 2019, (d) 24 April 2015 at site JARE57_EM,
(e) 25 April 2017 at site JARE59_POPs, and (f) 18 March 2018 at sites
JARE60_KU1 and JARE60_KU2. The images in (d−f) show the sea-ice
condition before winter at each coring site; dark areas indicate where
the sea ice was broken, and the cores obtained from these sites were
first-year ice. The background image in (c) is an Advanced Land
Observing Satellite (ALOS)/Panchromatic Remote-sensing Instrument for
Stereo Mapping (PRISM) image obtained on 26 January 2010 by the Japan
Aerospace Exploration Agency (JAXA).
Figure 2. Vertical profiles of (a, c) salinity and (b, d)
δ18O values in snow, first-year ice cores (left), and
multi-year ice cores (right). Horizontal solid lines at 0 cm depth
indicate the snow–ice interface. Dashed lines in (b, d) show the
δ18O value of under-ice water (−0.7‰) sampled during
JARE60. The photo in (a) is a vertical thin section of the top 5 cm of
core JARE60_KU2.
Figure 3. (a) Vertical profiles of salinity and δ18O
values in core JARE57_P31.5 compared to (b) its ice structure. (c–f)
Representative vertical thin section photographs are provided for each
ice structure.
Figure 4. Vertical profiles of (a, e)
NO3−, (b, f)
PO43−, (c, g) Si(OH)4,
and (d, h) chl.a concentrations in first-year ice (top) and multi-year
ice cores (bottom). Horizontal solid lines at a depth of 0 cm indicate
the snow–ice interface. The photo in (c) and (d) is the ice algae
community assemblage for the bottom of core JARE60_KU1.
Figure 5. Plots of (a) PO43−, (b)
Si(OH)4, (c) NO3−, and
(d) NO2− concentrations versus snow
fraction in multi-year ice cores.
Figure 6. Time series of the mean snow fraction in the top 200 cm of
each multi-year ice core from 2015 (core JARE56_NMS) to 2018 (core
JARE59_2).
Figure 7. Plots of (a, b) Si(OH)4, (c, d)
PO43−, (e, f)
NO3−, and (g, h)
NO2− concentrations versus salinity in
first-year (left) and multi-year ice cores (right). Dilution lines are
based on the nutrient concentrations and salinity of under-ice water.
Figure 8. Dissolved inorganic nitrogen (DIN =
NO3− +
NO2−) versus
PO43− concentrations in multi-year ice
cores. The red solid line indicates the Redfield ratio (DIN:P = 16:1)
and the black dashed line indicates the ratio for uptake by diatoms
(DIN:P = 12:1) (Takeda, 1998).
Figure 9. Vertical profiles of N* (Equation 3) and chl.a concentrations
in multi-year ice cores (a) JARE56_NMS and (b) JARE57_P31.5.
Figure 10. Conceptual illustration of the evolution of nutrient
concentrations produced by photosynthesis and remineralization during
the desalination process from new ice to first-year ice to multi-year
ice.