Js. Bhatti et al., SULFATE SORPTION IN RELATION TO PROPERTIES OF PODZOLIC AND BRUNISOLICSOILS IN NORTHEASTERN ONTARIO, Canadian Journal of Soil Science, 77(3), 1997, pp. 397-404
An insight into sulphate (SO42-) retention by podzolic and brunisolic
soils was obtained by examining SO42- sorption by B horizons from fore
st soils in northeastern Ontario. The amount of water soluble and adso
rbed SO42- present in the soils and the ability to adsorb additional S
O42- was evaluated. Relationships between soil pH, organic carbon and
different iron (Fe) and aluminum (Al) fractions with water soluble and
adsorbed SO42- were examined. Using a surface complexation approach,
modelling was carried out to predict the soil SO42- sorption capacity
at any given pH. The potential SO42- adsorption capacity was also meas
ured by applying adsorption equations. Both the Freundlich and Langmui
r sorption isotherms gave comparative fits to the SO42- adsorption dat
a. The soils contained small amounts of water extractable SO42- (0.1 t
o 0.8 mmole kg(-1)). There was a significant positive correlation betw
een water extractable SO42- and organic carbon in the podzolic soils b
ut not for the brunisolic soils. Approximately 90 % of the sulphate ex
tracted was contained in the insoluble SO42- fraction. Sulphate sorpti
on by both soil types was most closely related to amorphous inorganic
Al. In brunisolic soils, total adsorbed SO42- also had a strong positi
ve correlation with the oxalate extractable silica fraction and a nega
tive correlation with pH. Sulphate adsorption simulations were close t
o the measured values.