Effects of aluminate ion toxicity on plant growth and mineral nutrition in bauxite residue reclamation (alabama, distichlis)
Durham, NC, Duke Univ., Diss., 1983
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Tag hinzufügen | Zusammenfassung: | Durham, NC, Duke Univ., Diss., 1983 Extraction of aluminum from bauxite ore with caustic sodium hydroxide produces an alkaline waste termed bauxite residue. Methods of vegetating bauxite residue impoundments were investigated utilizing alkaline tolerant species with readily available organic amendments. Bauxite residue from a Mobile, Alabama impoundment ranged from a sandy texture near the outer dike to a fine clayey texture at the center; and exhibited high pH (9.2-12.5) and alkalinity (16-244 meq/1); high concentrations of soluble aluminate (5-1,000 mg/1 Al(OH)(,4)('-)-Al) and sodium (17-238 meq/1); and low concentrations of Mg, NO(,3)('-), PO(,4)('3-) and Mn('2+). Additions of sewage sludge reduced pH, decreased A1(OH)(,4)('-) concentration, and increased concentrations of Ca, Mg, NO(,3)('-) and PO(,4)('3-). Species screening experiments identified Distichlis spicata var. stricta, an alkaline tolerant grass, as a potential species for bauxite residue reclamation. Additions of sewage sludge to bauxite residue increased growth over 10-fold. Low yields were associated with high shoot tissue concentrations of Fe and Al, and low concentrations of Mg, K, P, Ca and N. Distichlis exhibited optimal growth in hydroponic culture up to pH levels as high as 10.5. One mM Al(OH)(,4)('-), however, reduced shoot yield by over 90% and reduced shoot concentrations of anions (N and P) and cations (Mg, Ca, and K). At pH 9.5 and Al-P compound appeared to precipitate in the root. Additions of sewage sludge to Al containing solutions increased growth a small amount by causing slight reductions in pH and Al solubility. Theories on physiological mechanisms of aluminum toxicity, which is the dominant factor affecting plant growth in bauxite residue, are advanced on the basis of plant nutritional evidence. In field experiments at a bauxite residue impoundment in Mobile, Alabama, organic amendments (paper pulp waste, coastal bermuda grass mulch and sewage sludge) were tested as ameliorants to increase growth of Distichlis. In coarse textured bauxite residue amended with sewage sludge, a dense cover of Distichlis formed within 1.5 years. After 2.5 years, substantial declines in Distichlis cover occurred. The appearance of necrotic lesions on leaf surfaces, and low levels of shoot Mm('2+) indicated that Mn('2+) deficiency may have been responsible. Additions of large quantities (6 cm) of sewage sludge to the surface of fine textured bauxite residue fostered growth of numerous local species. Most successful were Panicum dichotomiflorum and Cynodon dactylon. This research indicates the use of alkaline tolerant species with organic ameliorants has potential for bauxite residue reclamation. Problems with aluminum toxicity and Mn('2+) deficiency must be overcome through additional research. The use of local, perhaps Al tolerant, species is also indicated if methods of effectively isolating roots from bauxite residue alkalinity are successful. |
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| Beschreibung: | 213 S. |