Five soils derived from different parent materials were sampled from red soilregion of southern China and studied by magnetic methodology to understand to what extent ironreduction would affect soil magnetic propertie...Five soils derived from different parent materials were sampled from red soilregion of southern China and studied by magnetic methodology to understand to what extent ironreduction would affect soil magnetic properties and how iron reduction would affect the magneticminerals in soils. Reduction associated with organic matter decomposition strongly affected soilmagnetic parameters at low pH. The losses of original soil magnetic signals in terms of magneticsusceptibility (X), 'Soft' isothermal remanent magnetization ('Soft' IRM), anhysteretic remanentmagnetization (ARM) and saturation isothermal remanent magnetization (SIRM) at pH 4～6 during thetwo-month saturation treatment, were 66%～94%, 54%～90%, 64%～95% and 33%～83%, respectively. Thesechanges were interpreted as a consequence of substantial dissolution of maghaemite and haematite inthe soils. At pH 10, however, there was no significant magnetic change observed. Moreover, stablesingle domain soil maghaemite grains were also sensitive to reduction, which suggested that bothpedogenic and detrital maghaemite were not stable in acid and reducing environments. Goethite,instead, was the most stable iron form under reducing conditions.展开更多
The changes of clay mineral association after high-gradient magnetic separation (HGMS) treatment, and the effects of chemical and physical technologies on concentrating Fe oxides for main soils in central and southern...The changes of clay mineral association after high-gradient magnetic separation (HGMS) treatment, and the effects of chemical and physical technologies on concentrating Fe oxides for main soils in central and southern China were investigated by means of X-ray diffraction (XRD) and chemical analysis methods. Results indicated that the concentrating times of Fe oxides by HGMS treatment were the largest for 0.2-2 μmsize fractions in the examined soils. For the soils in which 2: 1 phyllosilicates were dominant, concentrating times of iron oxides by HGMS treatment were larger than by 5 mol L-1 NaOH treatment. Phyllosili-cates were decreased after HGMS treatment; however, the decrease was less than that of kaorolinite. The goet bite / (goethite + hematie) values in Fe oxides of the soils kept virtually constant after HGMSt reatment.展开更多
文摘Five soils derived from different parent materials were sampled from red soilregion of southern China and studied by magnetic methodology to understand to what extent ironreduction would affect soil magnetic properties and how iron reduction would affect the magneticminerals in soils. Reduction associated with organic matter decomposition strongly affected soilmagnetic parameters at low pH. The losses of original soil magnetic signals in terms of magneticsusceptibility (X), 'Soft' isothermal remanent magnetization ('Soft' IRM), anhysteretic remanentmagnetization (ARM) and saturation isothermal remanent magnetization (SIRM) at pH 4～6 during thetwo-month saturation treatment, were 66%～94%, 54%～90%, 64%～95% and 33%～83%, respectively. Thesechanges were interpreted as a consequence of substantial dissolution of maghaemite and haematite inthe soils. At pH 10, however, there was no significant magnetic change observed. Moreover, stablesingle domain soil maghaemite grains were also sensitive to reduction, which suggested that bothpedogenic and detrital maghaemite were not stable in acid and reducing environments. Goethite,instead, was the most stable iron form under reducing conditions.
文摘The changes of clay mineral association after high-gradient magnetic separation (HGMS) treatment, and the effects of chemical and physical technologies on concentrating Fe oxides for main soils in central and southern China were investigated by means of X-ray diffraction (XRD) and chemical analysis methods. Results indicated that the concentrating times of Fe oxides by HGMS treatment were the largest for 0.2-2 μmsize fractions in the examined soils. For the soils in which 2: 1 phyllosilicates were dominant, concentrating times of iron oxides by HGMS treatment were larger than by 5 mol L-1 NaOH treatment. Phyllosili-cates were decreased after HGMS treatment; however, the decrease was less than that of kaorolinite. The goet bite / (goethite + hematie) values in Fe oxides of the soils kept virtually constant after HGMSt reatment.
