Atmospheric deposition and movement of mercury in small stream watersheds in Maine
- Univ. of Maine, Orono, ME (United States)
The authors studied two small paired stream watershed in eastern Maine. Discharge, stream chemistry, and precipitation chemistry and amount were determined weekly or more frequently. Beginning in 1990, one watershed was acidified by aerial application of dry (NH{sub 4}){sub 2}SO{sub 4} to increase SO{sub 4} deposition to 120 kg/ha/yr. Hg was determined in precipitation, soil water, stream water, soils, and fish (brook trout Salvelinus fontinalis). The streams were chemically similar in 1990, but diverged as a result of the manipulation such that the manipulated stream has lower pH, acid neutralizing capacity (ANC), and dissolved organic carbon (DOC), and higher concentrations of all major cations and anions. Hg averaged 8.9 ng/L in precipitation, and 1.62 ng/L in the reference and 0.49 ng/L in the manipulated stream in 1990, for a ratio of concentration in reference: manipulated of 3.31. The reference stream also had higher average DOC, which likely accounts at least in part for the higher Hg concentration. In 1992, total Hg was 0.58 ng/L in the reference and 0.19 ng/L in the manipulated stream, and DOC also declined. In 1990, fish Hg was not different between streams, but in 1992 fish Hg was significantly higher in the reference stream. As stream water and fish Hg declined in the manipulated stream, Hg increased in watershed soils. More than 90% of the Hg in precipitation was retained in the watersheds.
- OSTI ID:
- 33550
- Report Number(s):
- CONF-9410273--
- Country of Publication:
- United States
- Language:
- English
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