EARLY DIAGENESIS OF SEDIMENT FROM KELLY...
Transcript of EARLY DIAGENESIS OF SEDIMENT FROM KELLY...
EARLY DIAGENESIS OF SEDIMENT FROM KELLY LAKE, SUDBURY, ONTARIO – A LAKE
CONTAMINATED BY SEWAGE EFFLUENT AND HIGH LEVELS OF COPPER AND NICKEL FROM
MINING AND SMELTING
Alan Lock
Outline
ØIntroduction and Background to Kelly LakeØSediment GeochemistryØ Sequential leach 1. easily exchangeable
2. carbonate bound3. Fe/Mn oxide bound4. organic bound5. residual recalcitrants6. residual fraction.
Ø137Cs age datingØPorewater ØSaturation Index SI = log(IAP/ksp)IAP=ion activity product, ksp=solubility product constant(Activity coefficient assumed to be 1)
ØSummary
12Dep
th (m
)
16
0
84
A Western Shelf
A
Kelley Lake exit
0
Eastern Basin
Delta
B
Scale in Metres
1000500
Robinson Lake
st.38X
6
24
108
BDelta
Creek
Junction
NBathymetric map and cross section of Kelly Lake showing the position of monitoring station 38.
Kelly Lake in the upper Junction Creek watershed showing urban and industrial areas.
INCO’s smelter stacks north of Kelly Lake
1.5 m
Sediment core from eastern basin (station 38).
Section of core showing coupled organic dominated (dark) and inorganic dominated (light) layers.
Objectives
The general goal of this investigation was to provide fundamental information required for future development of a Kelly Lake remediation plan.
Specific objective:
To assess the importance of factors potentially relevant to explaining Kelly Lake’s storage or release of Ni and Cu including the chemical stability of Ni, Cu complexes in Kelly Lake sediment.
Kelly Lake
Junction Creek
SSTP
Results
NICKEL0
20
40
60
80
100
120
140
1600 2 4 6 8 10 12
Concentration (mg/g)
Dep
th (
cm)
Exchangeable Carbonate Bound Fe Mn Oxide Bound"Organic Bound" Residual Recalcitrant Residual
super stack 1972
1980
COPPER0
20
40
60
80
100
120
140
1600 2 4 6 8 10 12 14
Concentration (mg/g)
Dep
th (
cm)
Exchangeable Carbonate Bound Fe Mn Oxide Bound
"Organic Bound" Residual Recalcitrant Residual
1960
1980
1960
Nickel and Copper Event Record
1986
1962
Nickel
NICKEL0
20
40
60
80
100
120
140
1600 2 4 6 8 10 12
Concentration (mg/g)
Dep
th (
cm)
Exchangeable Carbonate Bound Fe Mn Oxide Bound"Organic Bound" Residual Recalcitrant Residual
super stack 1972
1980
MANGANESE0
20
40
60
80
100
120
140
1600 2 4 6 8 10
Concentration (mg/g)
Dep
th (
cm)
Exchangeable Carbonate Bound Fe Mn Oxide Bound
"Organic Bound" Residual Recalcitrant
Comparison of Ni and Mn sequential extraction results.
R2 = 0.879
0
2
4
6
8
10
0 2 4 6 8 10Ni [mg/g]
Mn
[m
g/g
]Correlation between the Fe/Mn oxide bound portions of Ni and Mn from the average of three sediment profiles
from station 38.
Change in significance of Fe/Mn oxide bound and organic bound fractions of nickel with depth.
020406080
100120
0 20 40 60 80 100
Percent
Dep
th (
cm)
Organic Bound Fe/Mn Oxide Bound
Dissolved Ni and Mn concentrations in porewater from a sediment profile near station 38.
Profile of the saturation index of a Ni mineral in the sediment near station 38.
0102030405060708090
100110120130
-10 -5 0 5 10
Log (IAP/Ksp)
Dep
th (c
m)
Millerite
Copper
COPPER0
20
40
60
80
100
120
140
1600 2 4 6 8 10 12 14
Concentration (mg/g)
Dep
th (c
m)
Exchangeable Carbonate Bound Fe Mn Oxide Bound
"Organic Bound" Residual Recalcitrant Residual
1960
1980
Sequential extraction of an average of three sediment profiles for Cu from station 38.
Dissolved Cu and DOC concentrations from a sediment profile near station 38.
R2 = 0.5207
0
20
40
60
80
0 0.005 0.01 0.015
Cu [mg/l]
DO
C [
mg
/l]Correlation between DOC and Cu from a sediment
profiles near station 38.
Profile of the saturation index of Cu minerals near station 38.
0102030405060708090
100110120130
-15 -10 -5 0 5 10 15
Log (IAP/Ksp)
Dep
th (c
m)
Covellite Chalcopyrite
Covellite smelter particle with chalcopyrite growth
Sediment Geochemistry
Ø Distinct events recorded in the sediment for Cu and Ni may be primarily controlled by soil stability and not directly related to smelter emissions.
Ø Ni was primarily bound to Mn oxides in the sediment.
Ø Cu was bound to the operationally defined organic fraction and Cu sulphides were forming at depth.
Ø The diagenetic activity in the sediment appeared to increase the stability of metals discussed in this study.
Summary
Acknowledgments
Supervisor - Dr. David Pearson
Committee members - Dr. Nelson Belzile, Dr. Graeme Spiers, Dr.Robert Whitehead and Dr. Robert Morris
Funding and support - Inco Ltd. and Glen Watson; the City of Greater Sudbury through Paul Graham; Dr. Bob Bowins and the Ontario Geoscience Laboratories; and MIRARCO and the Earth Sciences Department at Laurentian University