J. Jpn. Soc. Soil Phys. No. 3+, p..3 /1,**, * ** ** E#ects of Drying on Bacterial Activity and Iron Formation in Acid Sulfate Soils Kaoru UENO*, Tadashi ADACHI** and Hajime NARIOKA** * The Graduate School of Natural Science and Technology, Okayama University, - + + Tsushima-naka, Okayama 1** 2/-*, Japan ** Faculty of Environmental Science and Technology, Okayama University, - + + Tsushima-naka, Okayama 1** 2/-*, Japan Abstract In acid sulfate soils, the heavy acidity is caused by the oxidation of sulfate, mainly pyrite (FeS,). In the primal acidify stage chemical and bacterial acidify work together. These bacteria (Thiobacillus ferrooxidans, Thiobacillus thiooxidans) have a huge role as a catalyst. This studies were examined the e#ects of drying on bacterial acidification, mainly on Thiobacillus ferrooxidans, and the formation of iron in the soil by the incubate experimentation. Five water content stages were set (+.-* *.,/ kg/kg) by drying process in the incubator at -* for water adjustment. After the treatment, these samples were contained in the each bottles and started to culture at -* Thiobacillus ferrooxidans propagated rapidly in the water content of Liquid Limit (LL) Plastic Limit (PL). Near the water content of PL, the propagation of the bacteria became slow, and they became decline near by the water content of Shrinkage Limit (SL). Amorphous free iron increased at the primal of acidification and changed for crystallized free iron. Around SL, the water content that the soil ph was stable, the propagation of the bacteria became slow, and the formation of iron became stable. In the range of water content +.** *.1* kg/kg (LL PL), the samples acidified strongly Key words : acid sulfate soils, water content, microorganisms, ph, iron + :FeS,,**+ +320 ; +33* +302 ; +33, pf- +33, * 1** 2/-* - + + ** 1** 2/-* - + + : ph
50 3+,**, Thiobacillus ferrooxidans +321, +2/,+* cm +.*, mm +.-,/ kg kg PL SL -* / +.-*, +.**, *.1*, *./*, *.,/ kg kg : +.-* kg kg +./ cm PL *.2* kg kg + cm -* +.-* +.** kg kg *.1* kg kg / 2 mm Thiobacillus ferrooxidans Fe, Fe - ATP +330 ph MPN : +33, ph-.*,,./m : +33. + Table + + +2/,+* cm Fundamental physical and chemical properties ofsample soils (in subsoils Polder-Nakaumi, Shimane, depth ; +2/,+* cm) Mg m -, kg kg LL kg kg PL kg kg SL kg kg Ip A - ph H,O;+ : / ph H,O, EC + : / ;ms cm wt.. SiC.*,4/2 +4-, +4/3 *4/0 *4-, +*,4.. 14/3 04,/,4*/.4.+.433 +, - A Ip, mm. +30+ : +33. Fed : Feo Feo : +33- ph +./../ +33- Thiobacillus ferrooxidans : : Fe, Fe - Fe OH, Fe OH - : Fe, Fe - : Fe OH, Fe, Fe OH - Fe -
: 51 - - + ph ph + ph +.-* kg kg *.,/ kg kg 0. +.** kg kg *.1* kg kg +.-* kg kg *./* kg kg *./* kg kg *.,/ kg kg ph +.** kg kg *.1* kg kg +/ -* -* -* + cm +.** kg kg *.1* kg kg *./* kg kg *.,/ kg kg *./* kg kg + Fig. + Fe - ph +302 -, -, + ph Changes in water content, ph and the number of bacteria (live) in the period of water adjustment. ph ph, ph *.1* kg kg. 0 0 1 *./* kg kg *.,/ kg kg
52 3+,**, 1 ph -,, - Fed Feo Fed Fed Fed, ph Fig., Changes in ph in the culture period. +.-* *.1* kg kg -, - Feo -. +.-* *.1* kg kg *.1* kg kg..33 + Fe, Fe - S * Fe, Darrell, +32, ph/. Fe, Fe - KFe - SO., OH 0 a FeO Fig. - - Changes in crystallized-free-iron and amorphous-free-iron as drying (in the culture period).
: 53. Fig.. Relation between crystallized-free-iron and amorphous-free-iron. / Fig. / Changes in water-changeable Fe ion in the culture period. OH ph- ph a Fe, O -,**+ -,. / *.1* kg kg +.** kg kg +.-* kg kg +.-* kg kg 2 *.1* kg kg ph ph/.0 0 +.-*, +.** kg kg *.1* kg kg *./* kg kg 2 0 +.-*, +.** kg kg *.1* kg kg,. *.,/ kg kg + *./* kg kg,. Fe - 0 +.**, +.-* kg kg + mg g *./* kg kg * ph. -
54 3+,**, 1 Fig. 1 Changes in the number of bacteria (live) in the culture period. 0 Fig. 0 Changes in ferrous and ferric iron in the culture period. -, / -, / + 1 +.-* *.1* kg kg *./* kg kg +.-* kg kg * +.**, *.1* kg kg * +, *./*kg kg *.,/ kg kg +.-* *.1* kg kg LL PL +.-* *.1* kg kg +.-* +.** kg kg *.1* kg kg PL *./* kg kg SL *.,/ kg kg +.-* *.1* kg kg *./* kg kg +.** *.1* kg kg 1 -, /, ph ph 2 ph ph
: 55 2 ph Fig. 2 Relation between ph and the number of bacteria (live) in the culture period. ph +320 ; +33* ph ph -, / - ph +332 ph Fe, Fe - Fe OH, Fe, Fe OH - Fe - +** 3 3 +.-*, +.** kg kg *.1* kg kg ph +.-*, +.**, *.,/ kg kg *.1*kg kg *./* kg kg *.1* kg kg 3 Fig. 3 Relation between the ratio of iron oxidation of soil and the number of bacteria (live) in the culture period. +* ph Fig. +* Relation between ph and the ratio of iron oxidation of soil in the culture period. +.-* +.** kg kg *.1* kg kg 3
56 3+,**, ++ Fig. ++ Changes in the iron oxidize-index per bacteria (live) in the culture period. ph +* ph ph. ph ph ++ +.-* *./* kg kg *.,/ kg kg,2 *.,/kg kg. -* LL PL PL SL *.1*kg kg PL SL ph Fe, Fe - Fe OH, Fe OH - ph/ ph SL ph +.** *.1*kg kg +33, : +0, : 23 30 +330 : pp. /0 1. Darrell Kirk Nordstrom, et al.,(+32,) : Acid Sulfate Weathering, SSSA Special Publication Number +*, pp.-1 /0, Soil Science Society of America, Wisconsin.
: 57 +33, : pp. -,3 --2 +332 :. pp. ++0 +,0 +320 : /1 -,/,,/0 +30+ : -, 0,10,13 +302 : -3, ++0 +,* +33- :. pp.,, -, +321 :,1 - +/- +0+ +320 : 0+,**+ : pp.,*0,*3 +33* : 0+ +.,.1 +322 :,2, -* -1 +323 : 0*, +/+ +/0 +33- : Thiobacillus ferro-oxidans T. thiooxidans +*3 //- //1 :,**, +. :,**, 1.