Pedosphere 10(3): 221--228, 2000
ISSN 1002-0160/CN 32-1315/P
©2000 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Acid release from an acid sulfate soil sample under successive extractions with different extractants
C. LIN1,2, M. M. ISLAM2, R. T. BUSH1, L. A. SULLIVAN1 and M. D. MELVILLE2
1 Centre for Acid Sulfate Soil Research, Southern Cross University, Lismore, NSW 2480 (Australia)
2 School of Geoqraphy, The University of New South Wales, Sydney, NSW 2052 (Australia)
ABSTRACT
      An acid sulfate soil sample was successively extracted with deionized water, 1 mol L-1 KCl and 0.0005 mol L-1 Ca(OH)2 solutions. The results showed that only very small amounts of acidity were extracted by deionized water, possibly through slow jarosite hydrolysis. Acid release through jarosite hydrolysis was greatly enhanced by Ca(OH)2 extraction at the expense of the added OH- being neutralized by the acid released. Successive extraction of the sample with KCl removed the largest amounts of acidity from the sample. However, it is likely that the major form of acidity released by KCl extraction was exchangeable acidity. The results also show the occurrence of low or non charged Al and Fe species in water and Ca(OH)2 extracts after first a few extractions. It appears that such a phenomenon was related to a decreasing EC value with increasing number of extractions.
Key Words:  acid release, acid sulfate soil, successive extraction
Citation: Lin, C., Islam, M. M., Bush, R. T., Sullivan, L. A. and Melville, M. D. 2000. Acid release from an acid sulfate soil sample under successive extractions with different extractants. Pedosphere. 10(3): 221-228.
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