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Phosphogypsum capping depth affects revegetation and hydrology in Western Canada
Mallory E Jackson1, M Anne Naeth, David S Chanasyk
1Department of Renewable Resources, University of Alberta, Edmonton, Canada.
Journal of Environmental Quality
|June 30, 2011
Summary
Soil caps on phosphogypsum (PG) stacks support vegetation establishment and do not negatively impact water quality. Even shallow caps are effective for early revegetation and plant growth, regardless of depth.
Area of Science:
- Environmental Science
- Soil Science
- Agronomy
Background:
- Phosphogypsum (PG) is a byproduct of phosphate fertilizer production.
- Managing PG stacks involves capping with soil for decommissioning.
- Effective capping strategies are crucial for environmental remediation.
Purpose of the Study:
- To evaluate vegetation establishment and hydrologic properties of soil caps on PG stacks.
- To determine the influence of different soil cap depths on plant growth and water movement.
- To assess the impact of soil caps on leachate water quality.
Main Methods:
- Studied shallow (0-30 cm) and thick (46-91 cm) sandy loam caps on a PG stack.
- Monitored vegetation establishment for four grass species and a grass-alfalfa mix over two growing seasons.
- Measured soil water content using time-domain reflectometry and leachate quantity/quality with lysimeters.
Main Results:
- All soil cap depths supported vegetation establishment compared to bare PG, with slender wheatgrass showing the best performance.
- Soil water content fluctuated more in shallow caps but remained between field capacity and wilting point.
- Leachate water quality was unaffected by cap depths up to 30 cm, and leachate volume was independent of cap depth and precipitation.
Conclusions:
- Soil caps less than 1 meter thick are sufficient for early revegetation of PG stacks.
- Shallow soil caps can effectively support plant growth and do not compromise water quality.
- The findings support the use of soil capping as a viable remediation strategy for phosphogypsum stacks.
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