DTPA-extractable heavy metals and their relationship to plant absorption in Chilean soils treated with biosolids. (5077)
Authors:
M.A. Carrasco* - Universidad de Chile I. Ahumada - Universidad de Chile L.G. Alvarez - Universidad de Chile O.A. Leon - Universidad de Chile G. Castillo - Universidad de Chile R.C. Pedraza - Universidad de Chile
Abstract:
Biosolids (sewage sludge) disposal on land may have the risks of heavy metals accumulation in the surface soil and their absorption by plants. A loam soil, pH 8.1, identified as MPO, and a sandy loam soil, pH 6.2, identified as LVZ, were incubated with 0 and 30 Mg/ha of biosolids for seven weeks at 28 Celsius degree. Soil pH and DTPA extractable Mn, Fe, Cu and Zn were analysed every week. Metal absorption by rye-grass was measured in a greenhouse experiment using 2-kg pots and biosolids
applications equivalent to 0, 15, 30 and 45 Mg/ha. After incubation pH decreased less than one unit and DTPA-extractable metals remained higher in a quantity similar to that applied with the biosolid in MPO soil, but DTPA-Fe and DTPA-Mn decreased in soil LVZ. Response to biosolids application was
dependant on soil pH and soil type. Metal absorption was higher in the slightly acid soil LVZ. Metal concentration in rye-grass tissue did not correlate with biosolids application, probably due to
DTPA-extractable metals were initially high on both soils, however, a significant relationship was found with metal plant absorption. This corroborates that DTPA measures the bioavailable metal fraction. It is concluded that DTPA-extractable metals would be a good predictor for metal absorption when rye-grass is used as indicator plant. Acknowledgements: This research was supported by
FONDECYT, Project 1020129.
Speaker Information: María Adriana Carrasco, Universidad de Chile, Casilla 1004, Santiago, ; Phone:
56-2-6785834; E-mail: [email protected]
Session Information: Wednesday, November 3, 2004, 4:00 PM-6:00 PM Presentation Start: 4:00 PM (Poster Board Number: 0416)
Keywords: DTPA-extractable heavy metals; heavy metal absorption; Rye grass; soil pH