Abstract
The Clark Fork River basin in western Montana is an excellent area to study solute metals in contaminated systems. Past flooding events have deposited mine tailings in the river's floodplain. Surface runoff flowing over, and groundwater flowing through, these floodplain deposits provide non-point sources to the dissolved-phase (
The headwaters region produced elevated concentrations of As, Cu, Fe, and Mn in surface waters with relatively high pH values (8.5 to 9.2). Treatment ponds downstream from the river's headwaters precipitate trace metals due to the addition of liming agents to the surface water. Most trace element concentrations decrease through this treatment system, with the exception of As. On a basin-wide scale, the concentration trends for trace elements in the system vary from reactivity to domination by dilution with the surface water discharge of the Clark Fork and its tributaries. Major ions appear to have downstream sources associated with tributaries or groundwater. This contrast in concentration trends illustrates the difficulty in studying geochemical trends on the large scale of a basin.
Tables and Figures referred to in McKinnon’s full paper are linked at the bottom of McKinnon’s abstract page. (Note: Figure 1, map of upper Clark Fork, is not available).
Start Date
14-4-2000 12:00 AM
End Date
14-4-2000 12:00 AM
Document Type
Poster
Table 1: Metal loads in excess of calculated backgrounds
McKinnonposter solute plots.xls (53 kB)
Figure 2: Downstream trends in metal levels, upper Clark Fork
McKinnonexcess loads.xls (57 kB)
Figure 3: Measured vs. modeled metal loads, upper Clark Fork
Basin reactivity: Determination of solute fate on a basin scale
The Clark Fork River basin in western Montana is an excellent area to study solute metals in contaminated systems. Past flooding events have deposited mine tailings in the river's floodplain. Surface runoff flowing over, and groundwater flowing through, these floodplain deposits provide non-point sources to the dissolved-phase (
The headwaters region produced elevated concentrations of As, Cu, Fe, and Mn in surface waters with relatively high pH values (8.5 to 9.2). Treatment ponds downstream from the river's headwaters precipitate trace metals due to the addition of liming agents to the surface water. Most trace element concentrations decrease through this treatment system, with the exception of As. On a basin-wide scale, the concentration trends for trace elements in the system vary from reactivity to domination by dilution with the surface water discharge of the Clark Fork and its tributaries. Major ions appear to have downstream sources associated with tributaries or groundwater. This contrast in concentration trends illustrates the difficulty in studying geochemical trends on the large scale of a basin.
Tables and Figures referred to in McKinnon’s full paper are linked at the bottom of McKinnon’s abstract page. (Note: Figure 1, map of upper Clark Fork, is not available).