Phytostabilization alternatives for an abandoned mine tailing deposit in northwestern Mexico.

Purpose: Past mining activities in northwestern Mexico have left a large number of abandoned mine tailings deposits, such as in San Felipe de Jesus, Sonora, that is known to be transferring metal(oid)s to nearby agricultural fields. Given the risk and the need to implement mitigation measures, in this paper, we describe the results of two experiments evaluating the phytostabilization potential of five plant species collected in the area. Methods: We evaluated the assisted phytostabilization approach using compost and nutrients and the soil capping approach using combinations of soil, gravel, clay, and tailings layers. Results: The assisted experiment revealed that seedlings were unable to establish under unamended treatments and only Ricinus communis showed potential under this approach. Compost and nutrients reduced the accumulation of As, Pb, Mn, and Zn in leaves of R. communis, but some were above the maximum tolerable levels for domestic animals. Under the capping approach, R. communis also showed better performance under some combinations of soil, gravel, and tailings layers than the other species. The accumulation of As, Pb, and Mn in leaves was below the maximum tolerable levels for domestic animals, indicating that soil capping has greater potential in this abandoned tailing deposit. Conclusion: The capping approach has more phytostabilization potential than the use of amendments, reducing the risk of incorporating metal(oid)s in the trophic web. [ABSTRACT FROM AUTHOR]