RI;ATERUYX r%hD 3lETHODS B
Soil colunzn
The forest soil was taken fiom Mae Moll district, Lampang province which located
bl the northern part of Thailand at the level of 25 centimeter undergrouud. The soil sample
was packed iu the acrylic colu~nuo f 15 cm diameter with 50 cm high for microbiological
change observation and 6.5 cm diameter with 25 cm high for (chemical change study.
Acid rain application
Simulation of acid raiu using sukric acid at various pH were applied to the soil
colurmls with certain quantity and soil samples \ere taken to analyzed at the appropriate
time interval..
Me ta I analysis
Exchange acidity, exchange alumhum, iron and exchange hydrogen ion were
measure with potassium cldoride method. Cation exchange capacity (CEC) was done by
ammonium saturation method. Exchange calcium and exchange magnesium were detected
by atomic absorption spectrophotometer while exchange potassium aud exchauge sodiulll
were measured by flame photometer.
Microbial count
Numerical method of bacterial, fungi, actinolnyces and total couut were done by
plate count techique with soil extract agar as cultivated medium. Nitrogen fig bacteria
in term of Azotobacter was count with azotobacter medium [4]. Ammollify;Ug bacteria
and nitriEyiUg bacteria were uurnerated usbg Most Probable Number method with nut~ieut
broth and nitrite oxidizer medium, respectively, as the media.
RESULT AND DISCUSSION
Soil properties
The soil samples taken fiom the forest it1 the northern p art of Thailaud, where mah
liguite base power plant was located, was classified as the reddish brouv latteritic soil wit11
39 % of sand, 16 % of silt and 45 % of slay. The chemical properties was studied and
fouud that the organic content was 1.33 % wit11 low CaC03 (0.20 %), lli& aluminum
content (7.29%) and ferric content (9.44 %).lie soil pH was sliglitly acid (yH 5.05).
Chenlical change
Shulatqd acid raiu with H' concentration 0.001-100 meq were applied to 100 gm
of soil iu order to study the g adsorption iu the reddish brow11 latteritic soil. It was found
that the g buffering capability of the soil without pH change was limited at 0.1
meq/lOOgm soil. The lligher concentration than the threshold caused gradually decrease iu
the soil pH as show in figure 1. Exchange aluminum ion was increased when the additioll
of H' was higher than 2 meq/100gm soil. Potassium was markedly decreased when 13'was
above 10 meq/100gm soil. The other metal and nutrient were not siguijicmtly influe~lced
by acid raiu. 'i The study on the eirect of simulated acid rain hi the soil colm with the highest
H' application at 1 meq/lOOgm soil indicate a ullchanged iu soil pH when the & addition
was lower than 0.2 meq/lOOgm soil. The decrease of pH was found ollly iu the upper part
of the column. However the leachate collected fiom 40 to 100 days of experiment, while
the stable soil y1-I was observed, slightly change to low pH.