Evaluation of Selenium Loading Associated with Phytoremediation & Mancos Shale Projects in the Uncompahgre Valley
The primary purpose of this research is to gain a better understanding of the loading sources of the selenium & salinity in the soils of the Uncompahgre Valley of western Colorado & the mechanisms that mobilize & transport them. This would improve the Bureau of Reclamations procedures for estimating soil to water loads & would also aid in determining the potential for their reduction from irrigated fields by such means as reducing deep percolation
Need and Benefit
Two multi-agency projects (USGS, BLM, NRCS, F&W, BOR, as well as state agencies) are currently underway that the Bureau has participated in to differing degrees & has also previously provided some funding for. Both projects are addressing aspects of selenium & salinity problems in the Uncompahgre Valley. This study would allow us to continue participation in these projects as the primary soil experts. The Phytoremediation Project is nearing completion & our part of the study would help to assess the viability of phytoremediation in reducing selenium in return flows from irrigation, as well as providing a measure of corresponding salinity reduction. This data could also be used to determine the potential for reduction of selenium & salinity loads from irrigated fields by reducing deep percolation. This project is a small scale, very intensely sampled, 2-field area of well-developed soils that have been irrigated for many years. Most of the soils data has been collected but remains unevaluated.
The Mancos Shale Project is in early stages & is focusing on the processes leading to the concentration, mobility, & dispersal of trace metals, particularly selenium, & salinity during chemical weathering & soil formation. The project is primarily funded by the USGS, who has geologists, geochemists, geomorhphologists, clay mineralogists, & GIS specialists working on it, but our portion would provide soil expertise to the program.
Soils derived from black shale terrenes are common in the west & routinely supply large amounts of selenium & salinity to drainage systems. Reclamation projects in a number of areas in the western U.S., including the Uncompahgre, CVP, Stewart Lake (Jensen Unit) & Kendrick, have all experienced problems from selenium loading. Continued participation in these multi-agency research projects will allow us access to large amounts data, information, & interpretations from the work of other agencies involved that would benefit our knowledge of selenium & salinity interactions in plant / soil / water relationships.