PREPARATION OF ALUNDUM/CERAMIC PLATE TENSION LYSIMETERS FOR SOIL WATER COLLECTION

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Abstract
Distilled water leaching of new alundum/ceramic plate lysimeters removed considerable amounts of Ca, Mg, Na, K, SO4, Cl and Zn. After washing with 3 L of distilled water, levels were still of sufficient magnitude to interfere with the analysis of solutions with low solute concentration. Washing the plates with 2 L of 1 N HCl extracted considerable amounts of Ca, Mg, Na and K, and higher amounts of Fe, Zn, Al and Mn, but further distilled water washing resulted in rapid equilibration with a spike solution. Rinsing new lysimeters with progressively more acidic solutions indicated residual zinc contamination when the solution pH was below 6.0. There was virtually no iron or manganese contamination from the lysimeters at a solution pH between 3.0 and 5.0. Aluminum was leached from the plates at solution pH of between 3.5 and 4.0; however, the high Al concentration in the soil solution at these pHs may mask this interference. Although Al poses a considerable contamination problem at solution pHs of 3.0, soil solutions at this pH level are unlikely except in unusual situations (e.g. soils developed on acid mine tailings). The pumping of 2 L of 1 N HCl followed by large volumes of distilled water through the lysimeters is recommended for most field studies. Prior testing of the plates is required if low solute concentrations are expected or if elements other than those mentioned here are of interest. Key words: Lysimeters, ceramic samplers, soil water collection, alundum lysimeters, soil solution

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