Hydrology and Biogeochemistry of Three Alpine Proglacial Environments Resulting From Recent Glacier Retreat
BRUCKNER, Monica Z.¹*, Skidmore, Mark L.¹, and Bond, Jeff²
¹Department of Earth Sciences, Montana State University, Bozeman, MT, 59717, ²Yukon Geological Survey, Whitehorse, YT, Canada *monica.bruckner@myportal.montana.edu
2.5
• SSC is not directly related to
discharge in the ELS, LO, or UWL.
LO
ELS
UWL
2.0
1.5
• 1.4°C, σ = 0.6 in the LO,
• 0.3°C, σ = 0.2 in the ELS, and
• 0.4°C, σ = 0.3 in the UWL.
• LO water temperature fluctuates
1.0
Date
9-Aug
30-Jul
0.5
0
• Mean water temperatures were:
the most, possibly due to 2 inputs:
• Meltwater flowing in direct
current from glacier to LO
• Meltwater that has been
warmed in lake prior to
exiting via LO.
Acknowledgements: Research funding provided by Yukon Geological Survey, Montana State University, VP Research, and American Alpine Club. Thanks to Galena Ackerman, Sco� Montross, & Shawn McGlynn from Montana State University and Jeff Bond,
Carrie Labonte, Amber Church, and Erin from the Yukon Geological Survey, for all their help in making this project a success. Thanks also to Dr. Julia Foght, Dr. Martin Sharp, & Joel Barker from University of Alberta for advise, laboratory time, and equipment loan.
Thank you to USGS Boulder Carbon laboratory for laboratory space, time and equipment. Thanks to Al VonFinster, Yukon Fisheries, for the boat loan, and to Karl Birkeland, USFS, for datalogger & temperature sensor loan. Thanks also to Delmar (helicopter pilot) for his
humor and field transportation.
Concentration (μeq L-1)
0
80
8.0E+03
4.0E+03
0.0E+00
Date
Sulfate
60
40
20
0
Date
10-Aug
Bacterial Cell Count
16-Jul
0
1.2E+04
40
5-Aug
1
80
31-Jul
2
120
26-Jul
3
Bicarbonate
21-Jul
Concentration (μeq L-1)
Lake Primary Productivity
11-Jul
Sediment (mg L-1) (UWL)
10-Aug
5-Aug
31-Jul
deposited in the lake before being
exported via the LO stream.
0
Water Temperature
20-Jul
Photo 1: (A) Sept. 1995 aerial photo of the Wheaton Glacier
catchment with drainage areas delineated & streams outlined.
Stream gauging stations (dots) for the (B) East Lobe Stream
(ELS), (C) Upper West Lobe (UWL), & (D) Lake Outlet (LO) are
shown. The air temperature monitoring station (E) was set up
~10 m N of the LO gauging station. Rebar pole height is ~1.5 m
(B, C, D, E).
• Some suspended sediment is
WATER TEMPERATURE
Whitehorse
Study Site
E
Date
26-Jul
21-Jul
16-Jul
1-Jul
0
11-Jul
20
10-Jul
LO
D
5000
30-Jun
C
40
20-Jun
B
UWL
Stream Confluence
230 m N
15000
10000
Temperature (°C)
ELS
x
60
Suspended Sediment
Photo 3: The west lobe
terminates into a proglacial
lake, which is drained via
the LO stream.
Lake
Camp
80
6-Jul
LO Drainage
Area
0.6 km2
(0.4 km2
glacier ice)
Sediment (mg L-1) (Lake, LO, and ELS)
Photo 2: The east lobe
terminates directly into
the ELS proglacial stream.
20000
• [Suspended sediment] (SSC) in UWL
is an order of magnitude
higher than the LO and ELS.
4
0
160
Concentration (μeq L-1)
SUSPENDED SEDIMENT CONCENTRATION
UWL Drainage Area
1.3 km2
(0.8 km2 glacier ice)
100
9-Aug
Photo 4: Snow (a) to ice (b)
transition on lower lake
lobe results in a decrease
in albedo on the ice surface.
A
L1
L2
L3
LO
ELS
UWL
40
30-Jul
b) Lake lobe, 29 July
Calcium
200
20-Jul
• UWL discharge is more flashy than ELS and LO
discharge.
100
Particulate Organic Carbon
60
0
lag may be affected by albedo.
2
0
300
20
• Air temperature affects discharge with 0-3 hr. lag time;
4
6-Jul
Date
SITE DESCRIPTION
ELS Drainage Area
1.9 km2
(1.1 km2 glacier ice)
a) Lake lobe, 19 July
6
1-Jul
0
0.4
20-Jun
-2
III
II
Nitrate
Concentration (μeq L-1)
0.2
Beginning of
discharge data
0.6
0
80
POC (mg L-1)
0
I
0.2
0.4
ELS
8
Dissolved Organic Carbon
10-Jul
LO
2
DOC (ppm)
Discharge (m3s-1km-2)
Beginning of
discharge data
(UWL)
0.8
Primary Production (μg C L-1d-1)
•
The three proglacial environments have similar bedrock geology, weather, and source
waters for the contributing areas, which provides an ideal environment for the
comparison of hydrology, biology, and carbon and nutrient dynamics for these
distinct headwater systems.
4
Air temperature (ºC)
ELS discharge (m3 s-1)
LO discharge (m3 s-1)
UWL stream discharge (m3 s-1)
Snow-ice transition
Major precipitation event
Overcast day(s)
Clear day(s)
CARBON AND ION DYNAMICS AND BIOTA
Number of Cells (ml-1)
and unique outlet streams draining a small glacier in a remote, high alpine catchment
in south-central Yukon Territories, Canada. One stream flows directly from the glacier,
a second stream has a longer flow path from its source with high degree of contact with
the medial moraine, and a third stream drains a proglacial lake.
0.6
9-Aug
• This study compares the hydrology, biology, and hydrochemistry for three adjacent
0.8
6
30-Jul
climate change, as they are sensitive environments and few anthropogenic factors
directly affect them.
1.0
8
20-Jul
• High alpine environments, especially those in remote areas, are excellent indicators for
10
10-Jul
deglaciation as they are the first in a chain of variables that affect downstream
chemistry and hydrology.
Strong
Winds
30-Jun
• Headwater catchments are crucial to examining the effects of climate change and
12
20-Jun
retreat in high alpine headwater catchments with regard to the formation of different
proglacial environments?
Air Temperature vs. Area-Normalized Discharge
Air Temperature (ºC)
• Climate-induced deglaciation is occurring worldwide - what is the consequence of this
HYDROLOGY AND WEATHER
30-Jun
OVERVIEW AND SIGNIFICANCE
GC41A-0099
L1: Lake surface ; L2: 1.5 m Lake depth ; L3: 5.0 m Lake depth ; LO: Lake Outlet ; ELS: East Lobe Stream ; UWL: Upper West Lobe Stream
• Three periods in the DOC record:
I: DOC utilized until depletion
II: DOC depleted
III: Rebound in DOC
•
• Decline in lake productivity 24 June-10 July at
0.5-1.5 m depth possibly due to photoinhibition
from high solar irradiance1.
2+
Ca
and bicarbonate are the dominant ions
•
in the catchment.
• Bacterial cells increase in LO & decrease in ELS,
potentially indicating a viable and growing
population of biota in the lake.
•
[NO3-] higher in ELS than LO and UWL for
most of season, possibly due to microbial
utilization in the lake (LO) and within
snowpack (UWL).
[SO42-], [Ca2+], & [bicarbonate] increase in
UWL on 1 Aug. & 10 Aug., possibly due to
increased supply of reactive sediments from
medial moraine.
SUMMARY
• The presence of a lake in the catchment results in water storage which increases meltwater
temperatures by 0.5-1°C, which may promote biotic growth within lake and LO; increasing bacterial
biomass in LO and lower [NO3-] than the ELS potentially indicate a viable microbial community
forming in the lake as the field season progresses.
• The UWL has greater access to & thus transports medial morainal sediments leading to high [SSC]
and greater sediment export, whereas a portion of SSC & POC are deposited in the lake before being
exported via the LO.
• Primary productivity rates in the young Wheaton proglacial lake are consistent with those in an older
oligotrophic high Arctic lake in Svalbard2 and 15 sub-Arctic lakes in northern Sweden3.
References Cited: 1Vinebrooke, R.D., Leavi�, P.R. (1996) Effects of ultraviolet radiation on periphyton in an alpine lake. Limnology and Oceanography: v. 41, pp. 1035-1040.
2
Laybourn-Parry, J. and Marshall, W.A. (2003) Photosynthesis, mixotrophy, and microbial plankton dynamics in two high Arctic lakes during summer. Polar Biology: v. 26,
pp. 517-524. 3Karlsson, J., Honsson, A., and Jansson, M. (2005) Productivity of high-latitude lakes: climate effect inferred from altitude gradient. Global Change Biology:
v. 11, pp. 710-715.