| Abstrak/Abstract |
Potential acid sulfate soils are characterized by the presence of pyrite (FeS2) at a depth of 0-50
cm, that is stable in anerobic condition. In aerobic condition the pyrite is oxidised and causing acidity.
Efforts to accelerate the oxidation of pyrite and followed by the leaching of acids is the target of this
experiment. This study was aimed to observe the release of SO4
2-
, Fe2+, H+ and Al3+ and the decrease of pyrite
content. The research was conducted at a soil laboratory from September until December 2013 arranged in
a factorial completely randomized design with three replications. The first factor was the degree of
aeration, namely : (a) control (saturated with 1 cm of water above soil surface); (b) aeration by drying for 2
days at 45ºC; and (c) aeration by drying for 4 days at 45ºC. The second factor was the concentration of
pyrite ; (i) 0,70 %, (ii) 1,96 % and (iii) 4,39 %. Soluble concentration of SO4
2-
, Fe2+, H+ and Al3 were observed
every week for 8 times, while the the levels of pyrite was observed at the end of the study. The results show
that the sources of acidity (H+ and Al3+), SO4
2-
, and Fe2+ increased with the length of drying time and the
initial concentration of pyrite. The highest concentration of SO4
2-
, Fe2+, H+
, and Al3+ released were 49.68
cmol(+).kg-1
, 7.33 cmol(+).kg-1
, 29.97 cmol(+).kg-1 and 40.66 cmol(+).kg-1
, respectively. The decline of initial
pyrite content was 47.45 % under the 4 day drying of 4.39 % pyrite content treatment. Under the low pyrite
contents (0.7 %), the acidity decrease was not sigfinicantly different among treatments with a variation of
0.64-0.67 %. This suggests that aeration by drying speeds up of the pyrite oxidation if followed by leaching
at the high pyrite contents (4.39 %).
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