02171naa a2200325 a 450000100080000000500110000800800410001910000200006024500980008026000090017852012860018765000170147365000210149065000200151165000130153165000180154465000170156265000090157965300170158865300130160565300160161865300200163465300140165465300130166865300190168170000150170070000210171570000240173677300850176010159532014-03-25       2007    bl uuuu     u00u1 u    #d1 aPIRES, A. M. M.  aOrganic acids in the rhizosphere and phytoavailability of sewage sludge-borne trace elements.  c2007  aThe aim of this work was to quantify low molecular weight organic acids in the rhizosphere of plants grown in a sewage sludge-treated media, and to assess the correlation between the release of the acids and the concentrations of trace-elements in the shoots of the plants. The species utilized in the experiment were cultivated in sand and sewage sludge-treated sand. The acetic, citric, lactic, and oxalic acids, were identified and quantified by high performance liquid chromatography in samples collected from a hydroponics system. Averages obtained from each treatment, concentration of trace elements in shoots and concentration of organic acids in the rhizosphere, were compared by Tukey test, at 5% of probability. Linear correlation analysis was applied to verify an association between the concentrations of organic acids and of trace elements. The average composition of organic acids for all plants was: 43.2, 31.1, 20.4 and 5.3% for acetic, citric, lactic, and oxalic acids, respectively. All organic acids evaluated, except for the citric acid, showed a close statistical agreement with the concentrations of Cd, Cu, Ni, and Zn found in the shoots. There is a positive relationship between organic acids present in the rhizosphere and trace element phytoavailability.  aheavy metals  aÁcido Orgânico  aAdubo de Esgoto  aExsudato  aLodo Residual  aMetal Pesado  aSolo  aavailability  abiosolid  abiossólido  adisponibilidade  aexsudatos  aexudates  ametais pesados1 aMARCHI, G.1 aMATTIAZZO, M. E.1 aGUILHERME, L. R. G.  tPesquisa Agropecuária Brasileira, Brasília, DFgv. 42, n. 7, p. 917-924, 2007.