Spatial and temporal distribution of mercury in Caballo and Elephant Butte Reservoirs, Sierra County, New Mexico
Caballo and Elephant Butte reservoirs are located in south-central New Mexico of the Rio Grande. The reservoirs are managed together for flood control and irrigation. As a result, Caballo Reservoir undergoes seasonal water volume fluctuations creating large littoral or shallow areas. Water and sediment samples were collected monthly for one year (July 1995 to June 1996) in Caballo Reservoir to examine spatial and temporal variability of total mercury (THg) and monomethylmercury (MMHg). Concentrations of THg and MMHg were greatest in water and sediments at the site located in the seasonally flooded area (Palomas) compared to five sites in deep water. In contrast, concentrations of MMHg from the five site were at or below 1.0 ng/g. The percentages of THg in the MMHg form was greatest in sediment collected from the Palomas site from September 1995 to June 1996 (5.4-33.8%) compared to sediment from the five sites in deep water. By October 1995, a site above Caballo Reservoir in the Rio Grande had greater concentrations of dissolved MMHg (0.508 ng/L) than the Palomas site (0.411 ng/L). The presence of a potential source of contamination upriver, in addition to a series of unrelated events (fire and late summer rains), precipitated a second study from July 1996 to June 1997. Thus, the second year was initiated to determine the sources of THg and MMHg entering Caballo Reservoir.
- Research Organization:
- New Mexico Cooperative Fish and Wildlife Research Unit, Las Cruces, NM (United States); New Mexico State Univ., Dept. of Fishery and Wildlife Sciences, Las Cruces, NM (United States)
- Sponsoring Organization:
- Geological Survey, Reston, VA (United States)
- OSTI ID:
- 638471
- Report Number(s):
- PB-98-145824/XAB; TRN: 82022284
- Resource Relation:
- Other Information: PBD: May 1998
- Country of Publication:
- United States
- Language:
- English
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