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The role of organic acids in the soil solution chemistry of a podzolized soil
Author(s) -
LUNDSTRÖM U. S.
Publication year - 1993
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1993.tb00439.x
Subject(s) - chemistry , lysimeter , aluminium , leaching (pedology) , solubility equilibrium , solubility , weathering , soil horizon , inorganic chemistry , podzol , cation exchange capacity , environmental chemistry , soil science , geology , organic chemistry , soil water , geochemistry
SUMMARY The soil solution chemistry of a podzolized soil in the north of Sweden was monitored for four years using percolation lysimeters. Weak organic acids were a major constituent of the soil solution and are important because of their ability to form complexes with aluminium. Dissolved organics leached from the mor layer enhance the weathering rate in the eluvial horizon by forming complexes with aluminium, especially during the autumn when the leaching of dissolved organics was greatest. The weak organic acids were titrated and their p K a values were evaluated. Aluminium was speciated with an ion‐exchange method and by applying equilibrium calculations. Formation constants for the organic aluminium complexes were calculated to be log K Along =5.42±0.32 m −1 ( n =13) in spring and summer and log K Alorg =4.87±0.14 m −1 ( n =6) in autumn. Equilibria of Al 3+ with solid phases were also examined using solubility constants. Percolation lysimeters below undisturbed and cut‐off mor layers were compared.