9343

• UCREFRP Catalog Number: 9343
• Author: Greve, A. I., N. E. Spahr, P. C. Van Metre and J. T. Wilson.
• Title: Identification of Water-Quality Trends Using Sediment Cores from Dillon Reservoir, Summit County, Colorado.
• USFW Year: 2001.
• USFW - Doc Type: Denver.
• Copyright Material: NO

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0:
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m 8
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~
I 10
f-
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~ 12
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16

18

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o

2

4

8

10

12

14

16

18

20
o 500 1,000 1,500 2,000
TOTAL PAH, IN
MICROGRAMS PER KILOGRAM

2

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2

4

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RATIO OF 4- AND 5-RINGED COMPOUNDS
TO 2- AND 3-RINGED COMPOUNDS

2

20
o 2 468
RATIO OF PHENANTHRENE TO ANTHRACENE

o

2

4

6

8

10

12

14

16

18

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4

6

8

10

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o 0,5 1.0 1.5
RATIO OF FLUORANTHENE TO PYRENE

20
o 200 400 600
TOTAL COMBUSTION PAH,
IN MICROGRAMS PER KILOGRAM

Figure 3. Five polycyclic aromatic hydrocarbon components plotted against depth in core DLN. (The
ratio of 4- and 5-ringed compounds is commonly reported as 2- and 3-ringed compounds to 4- and
5-ringed compounds. The ratio was reversed in this figure in order to show all three ratios that relate
combustion- and noncombustion-derived compounds to be comparable.)

have decreased over time (table 4). The decrease in
trace-element concentrations over time may be due in
part to the decrease in active mining in the drainage
area and efforts to reclaim old mine sites.
Elements shown to increase over time were
cadmium and mercury. Cadmium can be associated
with mining but is typically found in zinc-ore minerals
(Hem, 1992). Zinc concentrations in the sediment
core did not show a trend, which indicates that
there may be a source of cadmium that is not mining
related. Cadmium is used in paint, plastics, ink, and
batteries. It also can enter the environment through the

combustion of fossil fuels (Hem, 1992). The increase
of cadmium concentrations in reservoir sediment may
be associated with the population increase and urban
development in the Dillon Reservoir watershed.
Mercury is a trace element commonly associ-
ated with coal-fired powerplant emissions and
waste incinerators. It can be regionally transported
and enter a watershed through atmospheric deposition
(U.S. Environmental Protection Agency, 1997). Low
concentrations of mercury were identified in snow-
pack samples collected in the region during 1999
(Don Campbell, U.S. Geological Survey, written

12 Identification of Water-Quality Trends Using Sediment Cores from Dillon Reservoir, Summit County, Colorado