Revegetation of arsenic (As)-rich mine spoils is often impeded by the lack of plant species tolerant of high As concentrations and low nutrient availability. Basin wildrye [Leymus cinereus (Scribner & Merr.) A. Löve] has been observed to establish naturally in soils with elevated As content and thus may be useful for the stabilization of As-contaminated soils. An experiment was conducted to evaluate how variable phosphorus (P) concentrations and inoculation with site-specific arbuscular mycorrhizal fungi influence As tolerance of basin wildrye. Basin wildrye was grown in sterile sand in the greenhouse for 16 weeks. Pots of sterile sand were amended to create one of four rates of As (0, 3, 15, or 50 mg As kg(-1)), two rates of P (3 or 15 mg P kg(-1)), and +/-mycorrhizal inoculation in a 2 x 4 x 2 factorial arrangement. After 16 weeks of growth, plants were harvested, shoots and roots thoroughly washed, and the tissue analyzed for total shoot biomass, total root and shoot As and P concentrations, and degree of mycorrhizal infection. Basin wildrye was found to be tolerant of high As concentrations allowing for vigorous plant growth at application levels of 3 or 15 mg As kg(-1). Arsenic was sequestered in the roots, with 30 to 50 times more As in the roots than shoots under low P conditions. Mycorrhizal infection did not confer As tolerance in basin wildrye nor did mycorrhizal fungi influence biomass production. Phosphorus concentrations of 15 mg kg(-1) effectively inhibited As accumulation in basin wildrye. Basin wildrye has the potential to be used for stabilization of As-rich soils while minimizing exposure to grazing animals following reclamation.

Abstract. Lack of salvaged topsoil for the reclamation of historical waste rock piles is a common problem in the arid Great Basin region. Utilization of amended waste rock as a growth media could reduce further disturbance resulting from topsoil harvest, minimize hauling costs, and potentially allow for the use of a higher quality material for plant growth. Getchell Gold Corporation initiated a study in 1995 to determine the suitability of waste rock substrates to support plant growth following application of nutrient and biological amendments. Three nutrient amendments and a biological seed treatment were evaluated for use in establishing vegetative cover on three distinct waste rock substrates. Completely randomized blocks were placed on the three substrates. Treatments included organic fertilizers (Biosol and Gro-Power), a mineral fertilizer (16-20-0), and Azospirillum bacterial inoculant, plus controls. The seed mix consisted of Agropyron riparium, Agropyron spicatum, Elymus cinereus, Poa secunda, and Si/anion hystrix. Canopy and ground cover were monitored for three growing seasons. Conclusions from the study are: 1) two of the three substates supported plant growth following amendment with organic fertilizers; 2) organic fertilizers increased cover substantially over the mineral fertilizer; and 3) Azospirillum had no effect on canopy cover. Additional

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Ammoniacal-nitrogen (N) is a common constituent of mine waste residues, industrial wastewater, and agricultural runoff. The purpose of this study was to evaluate the phytotoxic potential of ammoniacal-N contaminated groundwater encountered at a Department of Energy (DOE) wetland mitigation site near Rifle, Colorado. A series of experiments were conducted using site water modified to represent ammoniacal-N levels ranging from pure site water to dilutions containing 50%, 25%, 10%, and 0% site water. In addition, pH was modified to represent potential site conditions. Studies conducted included: I) a germination study to evaluate seed response to elevated ammoniacal-ON levels; 2) a growth chamber study to evaluate initial seedling growth in response to elevated ammoniacal-N levels; and 3) a greenhouse study to evaluate mature seedlings (> 16 weeks old) growth in response to elevated ammoniacal-N levels. Seed germination and initial seedling growth were affected by levels of 100 ppm ammonium-N or less with resulting reductions in germination percentage, reductions in root and shoot growth, and browning ofroots. Mature seedlings were affected by high ammoniacal-N levels in three of five wetland species as evidenced by low shoot biomass levels, chlorotic leaves, leaf loss, and drought-like symptoms. Typha latifolia and Scirpus acutus were tolerant of levels up to 400 ppm ammonium.Popu/us fremontii and Carex nebraskensis demonstrated tolerance of ground water levels up to 200 ppm anunonium. Salix exigua was impacted by ammonium levels as low as 100 ppm. Overall, this study demonstrated the need for the consideration of the potential phytotoxic effects of ammoniacal-N as part of restoration planning efforts.Additional Key Words: ammonium, ammonia, phytotoxicity, Salix exigua, Typha latifolia, Scirpus acutus, Carex nebraskensis, Populus fremontii, Puccinellia airoides, Deschampsia caespitosa Distichlis spicata. IntroductionAmmoniacal-nitrogen (N) is a common constituent of mine waste residues, industrial wastewater, and agricultural runoff. The goal of this project was to assess the potential impact of elevated nitrogen levels on revegetation efforts planned for a Department of Energy (DOE) wetland mitigation site in Rifle, Colorado. Prior to wetland construction, elevated levels William J. Waugh, Ph.D., Environmental Sciences Laboratory--MACTEC-ERS, U.S. Department of Energy, Grand Junction, CO 81503 of both nitrate-N and ammoniacal-N were discovered in ground water at the project site. While high levels of nitrate-N are generally innocuous, excessive ammoniacal-N has been demonstrated to produce toxic effects in plants (Wong et al. 1983)(Vines and Wedding 1960) (Tiquia et al. 1996)(Lu 1998. Little information is available on wetland species response to high ammoniacal-N level, however (Surrency 1993). · The purpose of this study was to evaluate plant response to elevated levels of ammoniacal-N in order to assist in the revegetation planning effort. Site DescriptionThe Rifle Wetland Mitigation Project is located at the ...

The production of quality native plants materials is essential to largescale reclamation efforts being undertaken at mine sites throughout the United States. Some studies have shown that nursery inoculation with arbuscular mycorrhizal (AM) fungi improved survival, growth, and drought tolerance of installed tree and shrub seedlings. The production of AM-colonized plant material, however, has proven problematic due to a lack of integration between the biotechnical firms that produce inoculum and cultural procedures at commercial nurseries. The objective of our research has been to integrate mycorrhizal inoculum successfully into a nursery program, thereby, producing plant materials with improved outplanting performance. Multiple studies were conducted to investigate the efficacy of various inoculum products, the influence of growth media types, and the influence of standard fertilization techniques on the ability of AM fungi to colonize plant materials under nursery conditions. Our research has resulted in a growth media which promotes colonization of plant materials by AM inoculum in a nursery environment. Plants produced by this tecnhique have significantly higher colonization rates than controls. This study reviews the results of greenhouse trials to increase AM-colonization rates in plant materials and outplanting field trials established in Oregon, Montana, and Utah to compare traditionally grown seedlings with those grown in the AM-promoting growth media formulation.