The clay minerals of more than 200 soil samples collected from various sites of Fujian Province were studied by the X-ray diffraction method and transmission electron microscopy to study their distribution and evoluti...The clay minerals of more than 200 soil samples collected from various sites of Fujian Province were studied by the X-ray diffraction method and transmission electron microscopy to study their distribution and evolution. Montmorillonite was found in coastal solonchak, paddy soils derived from marine deposit, lacustrine deposit and river deposit, and some latentic red soil, red soil and yellow soil with a low weathering degree. Chlorite existed mainly in coastal solonchak and paddy soil developed from marine deposit. 1.4 nm intergradient mineral appeared frequently in yellow soil, red soil and latentic red soil. The content of l.4 nm intergradient mineral increased with the decrease of weathering degree from latentic red soil to red soil to yellow soil. Hydrous micas were more in coastal solonchak, paddy soils derived from marine deposit, lacustrine deposit and river deposit, and purple soil from purple shale than in other soils. Kaolinite was the most important clay mineral in the soils in this province. The higher the soil weathering degree, the more the kaolinite existed. From yellow soil to red soil to latentic red soil, kaolinite increased gradually. Kaolinite was the predominant clay mineral accompanied by few other minerals in typical latentic red soil. Tubular halloysite was a widespread clay mineral in soils of Fujian Province with varying quantities. The soil derived from the parent rocks rich in feldspar contained more tubular halloysite. Spheroidal halloysite was found in a red soil and a paddy soil developed from olivine basalt. Gibbsite in the soils in this district was largely 'primary gibbsite' which formed in the early weathering stage. Gibbsite decreased with the increase of weathering degree from yellow soil to red soil to latentic red soil. Goethite also decreased in the same sequence while hematite increased.展开更多
The effect of three organic materials (rice straw, Chinese milk vetch and pig manure) on the fractionationof cadmium added into two soils (a red soil and a fiuvo-aquic soil) was studied using submerged incubationexper...The effect of three organic materials (rice straw, Chinese milk vetch and pig manure) on the fractionationof cadmium added into two soils (a red soil and a fiuvo-aquic soil) was studied using submerged incubationexperiment. The organic materials increased soil solid organic carbon (SOC), pH value, the concentration ofactive Si in all the treatments and active Fe and Mn in some treatments. Accumulated SOC caused directlythe increase of Cd bound to solid organic matter and consequently the decrease of exchangeable Cd. Higheractive Si and pH, as well as lower Eh, were also responsible for the reduction of exchangeable Cd. Cd boundto Mn oxide was positively correlated with pH values and rose significatly after one-month incubation, butdecreased after three-month incubstion. Cd bound to amorphous Fe oxide increased with the incubationtime, but was not effected significantly by adding organic materials.展开更多
文摘The clay minerals of more than 200 soil samples collected from various sites of Fujian Province were studied by the X-ray diffraction method and transmission electron microscopy to study their distribution and evolution. Montmorillonite was found in coastal solonchak, paddy soils derived from marine deposit, lacustrine deposit and river deposit, and some latentic red soil, red soil and yellow soil with a low weathering degree. Chlorite existed mainly in coastal solonchak and paddy soil developed from marine deposit. 1.4 nm intergradient mineral appeared frequently in yellow soil, red soil and latentic red soil. The content of l.4 nm intergradient mineral increased with the decrease of weathering degree from latentic red soil to red soil to yellow soil. Hydrous micas were more in coastal solonchak, paddy soils derived from marine deposit, lacustrine deposit and river deposit, and purple soil from purple shale than in other soils. Kaolinite was the most important clay mineral in the soils in this province. The higher the soil weathering degree, the more the kaolinite existed. From yellow soil to red soil to latentic red soil, kaolinite increased gradually. Kaolinite was the predominant clay mineral accompanied by few other minerals in typical latentic red soil. Tubular halloysite was a widespread clay mineral in soils of Fujian Province with varying quantities. The soil derived from the parent rocks rich in feldspar contained more tubular halloysite. Spheroidal halloysite was found in a red soil and a paddy soil developed from olivine basalt. Gibbsite in the soils in this district was largely 'primary gibbsite' which formed in the early weathering stage. Gibbsite decreased with the increase of weathering degree from yellow soil to red soil to latentic red soil. Goethite also decreased in the same sequence while hematite increased.
文摘The effect of three organic materials (rice straw, Chinese milk vetch and pig manure) on the fractionationof cadmium added into two soils (a red soil and a fiuvo-aquic soil) was studied using submerged incubationexperiment. The organic materials increased soil solid organic carbon (SOC), pH value, the concentration ofactive Si in all the treatments and active Fe and Mn in some treatments. Accumulated SOC caused directlythe increase of Cd bound to solid organic matter and consequently the decrease of exchangeable Cd. Higheractive Si and pH, as well as lower Eh, were also responsible for the reduction of exchangeable Cd. Cd boundto Mn oxide was positively correlated with pH values and rose significatly after one-month incubation, butdecreased after three-month incubstion. Cd bound to amorphous Fe oxide increased with the incubationtime, but was not effected significantly by adding organic materials.
