Two Oregon reservoirs contaminated by different mercury
sources were compared for mercury distribution in sediment and
bioaccumulation by fish. The average mercury concentration in
the sediment of Cottage Grove reservoir (0.67 �� 0.05 ��g/g dry
wt) was higher than for Dorena Reservoir (0.12 �� 0.01 ��g/g dry
wt). Sediment mercury in the main tributary of Cottage Grove
Reservoir, which drains the tailing of past mercury mining
activities, was ten fold higher than mercury in sediment from
other reservoir tributaries with no evidence of mining.
However, there were no significant differences between
sediment mercury concentrations in the tributaries of the
Dorena Reservoir, which has no mercury mining history within
its watershed. Three fish species (largemouth bass, bluegill,
crappie) from Cottage Grove Reservoir had significantly higher
levels of mercury than the same species from Dorena Reservoir.
These results indicated that a point source, Black Butte Mine,
contributed amounts of mercury in excess of natural deposits
based on differences in bioaccumulation among fish populations
from these two systems.
Cottage Grove Reservoir was examined for environmental
evidence of point source mercury pollution. High mercury
concentrations were found at various points around the
suspected source, the Black Butte Mine area. The highest
concentration occurred close to the kiln. The mercury
concentration in the sediments of a creek below the mine dump
was up to ten times higher than that of the sediments of a
creek from a watershed adjacent to the watershed of the mine
area. Two sediment cores from the deep area were collected to
assess for pollution history profiles. These showed mercury
loading in Cottage Grove Reservoir was consistent with the
past mercury production in Black Butte Mine. Therefore most of
mercury in Cottage Grove Reservoir was believed to be of Black
Butte Mine origin. Mercury contents in pore water and food web
indicated that continuing mercury transportation from the
point source create a management problem in Cottage Grove
Reservoir. / Graduation date: 1996
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34612 |
| Date | 07 March 1996 |
| Creators | Park, Jeong-Gue |
| Contributors | Curtis, Lawrence R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0021 seconds