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