title: Phytostabilization potential of quailbush for mine tailings: growth, metal accumulation, and microbial community changes.
abstract: Abandoned mine tailings sites in semiarid regions remain unvegetated for extended periods of time and are subject to eolian dispersion and water erosion. This study examines the potential phytostabilization of a lead-zinc mine tailings site using a native, drought-tolerant halophyte, quailbush [Atriplex lentiformis (Torr.) S. Wats.]. In a greenhouse study germination, growth, and metal uptake was evaluated in two compost-amended mine tailings samples, K4 (pH 3) and K6 (pH 6) at 75, 85, 90, 95, and 100% mine tailings, and two controls, off-site and compost. Microbial community changes were monitored by performing MPN analysis of iron- and sulfur-oxidizing bacteria as well as heterotrophic plate counts. Results demonstrate that germination is not a good indicator for phytostabilization since it was only inhibited in the unamended K4 treatment. Plant growth was significantly reduced in 95 and 100% mine tailings, while growth in 75, 85, and 90% treatments was similar to the off-site control. Quailbush accumulated elevated levels of the nutrient metals Na, K, Mn, and Zn in the shoot tissues; however, metal accumulation was generally below the domestic animal toxicity limit. Initially, autotrophic population estimates were four to six logs higher than heterotrophic counts, indicating extremely stressed conditions. However, post-harvest, heterotrophic bacterial counts increased to normal levels (approximately 10(6) CFU g-1 dry tailings) and dominated the rhizosphere. Therefore, with compost amendment, quailbush has good potential as a native species candidate for phytostabilization of mine tailings in semiarid environments.
authors.affiliation: Dep. of Soil, Water, and Environmental Science, Univ. of Arizona, 429 Shantz Building #38, Tucson, AZ 85721-0038, USA.
authors.forename: Monica O
authors.initials: MO
authors.lastname: Mendez
authors.forename: Edward P
authors.initials: EP
authors.lastname: Glenn
authors.forename: Raina M
authors.initials: RM
authors.lastname: Maier
mesh_terms: D027466:Atriplex / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D018525:Germination; D008670:Metals / Q000378:metabolism*; D008906:Mining; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D008670:Metals; D014874:Water Pollutants, Chemical