title: Changes in pH and organic acids in mucilage of Eriophorum angustifolium roots after exposure to elevated concentrations of toxic elements.
abstract: The presence of Eriophorum angustifolium in mine tailings of pyrite maintains a neutral pH, despite weathering, thus lowering the release of toxic elements into acid mine drainage water. We investigated if the presence of slightly elevated levels of free toxic elements triggers the plant rhizosphere to change the pH towards neutral by increasing organic acid contents. Plants were treated with a combination of As, Pb, Cu, Cd, and Zn at different concentrations in nutrient medium and in soil in a rhizobox-like system for 48-120 h. The pH and organic acids were detected in the mucilage dissolved from root surface, reflecting the rhizospheric solution. Also the pH of root-cell apoplasm was investigated. Both apoplasmic and mucilage pH increased and the concentrations of organic acids enhanced in the mucilage with slightly elevated levels of toxic elements. When organic acids concentration was high, also the pH was high. Thus, efflux of organic acids from the roots of E. angustifolium may induce rhizosphere basification.
authors.affiliation: Department of Botany, Stockholm University, 106 91, Stockholm, Sweden. tariq.javed@botan.su.se
authors.forename: M Tariq
authors.initials: MT
authors.lastname: Javed
authors.forename: Eva
authors.initials: E
authors.lastname: Stoltz
authors.forename: Sylvia
authors.initials: S
authors.lastname: Lindberg
authors.forename: Maria
authors.initials: M
authors.lastname: Greger
mesh_terms: D019342:Acetic Acid / Q000032:analysis; D000143:Acids / Q000032:analysis; D019343:Citric Acid / Q000032:analysis; D029785:Cyperaceae / Q000737:chemistry / Q000187:drug effects*; D005561:Formates / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008293:Malates / Q000032:analysis; D019216:Metals, Heavy / Q000494:pharmacology; D009930:Organic Chemicals / Q000032:analysis*; D019815:Oxalic Acid / Q000032:analysis; D062087:Plant Mucilage / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry / Q000187:drug effects*; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000494:pharmacology*; D019802:Succinic Acid / Q000032:analysis
chemical_list: D000143:Acids; D005561:Formates; D008293:Malates; D019216:Metals, Heavy; D009930:Organic Chemicals; D062087:Plant Mucilage; D012987:Soil; D012989:Soil Pollutants; C030544:formic acid; D019343:Citric Acid; C030298:malic acid; D019815:Oxalic Acid; D019802:Succinic Acid; D019342:Acetic Acid