482
G.E. Glass et al.
Water
Or-------------------------------------------,
100
200
..c~
Q. 300
cu
Q
cu
to
U
- c 400
cu
e
:a cu
rr.J
500
600
Sediment
_===---.
~ ------1,900 years b.p.
___ ------ 5,000 years b.p.
__ -
8,000 years b.p.
60
80
Sediment Mercury Concentration, nglg
IO()
Fig. 7. Mercury concentration (ng/g) as a function of depth into the sediment for a Lake Superior
sediment core, collected in 1980 (latitude 47° II' 04" N; longitude 89° 21' 06" W; water depth of 180 m,
Fig. I). Most surface sediments were not represented, but show significantly higher mercury
concentrations (Thomas 1974) which decrease rapidly with sediment depth (in the first 30 em).
Paleomagnetic (Johnson and Fields 1984) and carbon-13 (Huber 1993) dating indicated sediments
were about 1900 to 8000 years B. P., as indicated
Thomson, the largest reservoir of the six studied, has a dozen small islands and
an additional inlet, the Midway River. The complexity of the flow patterns
coupled with the size, depth, and reservoir operational aspects make the
interpretation of depositional patterns difficult. A number of additional
parameters (including particle size, organic carbon, and total weight loss on
G.E. Glass et al.
Water
Or-------------------------------------------,
100
200
..c~
Q. 300
cu
Q
cu
to
U
- c 400
cu
e
:a cu
rr.J
500
600
Sediment
_===---.
~ ------1,900 years b.p.
___ ------ 5,000 years b.p.
__ -
8,000 years b.p.
60
80
Sediment Mercury Concentration, nglg
IO()
Fig. 7. Mercury concentration (ng/g) as a function of depth into the sediment for a Lake Superior
sediment core, collected in 1980 (latitude 47° II' 04" N; longitude 89° 21' 06" W; water depth of 180 m,
Fig. I). Most surface sediments were not represented, but show significantly higher mercury
concentrations (Thomas 1974) which decrease rapidly with sediment depth (in the first 30 em).
Paleomagnetic (Johnson and Fields 1984) and carbon-13 (Huber 1993) dating indicated sediments
were about 1900 to 8000 years B. P., as indicated
Thomson, the largest reservoir of the six studied, has a dozen small islands and
an additional inlet, the Midway River. The complexity of the flow patterns
coupled with the size, depth, and reservoir operational aspects make the
interpretation of depositional patterns difficult. A number of additional
parameters (including particle size, organic carbon, and total weight loss on