Iron oxides from 33 samples of 25 soils derived from various parent materials in the southern China were studied using NaOH selective dissolution technique and X-ray diffraction (XRD). Goethite and hematite were the o...Iron oxides from 33 samples of 25 soils derived from various parent materials in the southern China were studied using NaOH selective dissolution technique and X-ray diffraction (XRD). Goethite and hematite were the only two crystalline Fe oxides occurring in a significant quantity. The goethite / (goethite + hematie )ratios ranged from 0 to 1, being the highest in yellow soil, some yellow-red soils and saprolite samples and the lowest in soils derived from purple sandstone where only hematite was present. Al substitution in goethite ranged from 6.6 to 29.9 mol % with a mean value of 16.7 mol %, while substitution of Al in hematite ranged from 0 to 12.1 mol %. The values of Al substitution of hematite in coexisting goethite and hematite were closely related with corresponding values of goethite (r=0.7292, P<0.01, n=27). The redness rating of soils increased linearly with increasing amount of hematite (r=0.8109, P<0.01). It was suggested that redness rating could be used to crudely estimate hematite contents of soils.展开更多
The economic development in China and the rising of the living standard need to speed up the urbanisation. The development of small towns is an important way to Chinese urbanisation. Land use plays a very important ro...The economic development in China and the rising of the living standard need to speed up the urbanisation. The development of small towns is an important way to Chinese urbanisation. Land use plays a very important role in the development of small towns. However there are many problems in the development of small towns, esp. in land use. The paper first discusses the land problems in the development of small towns. Such as much cultivated land lies idle, under utilization and waste of land, increasing illegal use of land, unstable contractual relationship for land use. The relationship between the development of small towns and land use is also studied. Then the guidelines for the land system innovations of small towns are put forward. Namely the sustainability of social and economic development, the balance between land reservation and land utilization, the provision of service to village, agriculture and farmer, the management of land resource and land assets, the parsimonious and legal use of land. The basic framework of land system innovations of small towns is put forward finally. It include the land replacement policy for small towns and the permanent tenancy of farmland, the overall plan for land uses and other plans in harmony, the establishment of a flexible system of land supplies, using land with payments, the transfer of agricultural land and refining the land law related to the construction of small towns.展开更多
文摘Iron oxides from 33 samples of 25 soils derived from various parent materials in the southern China were studied using NaOH selective dissolution technique and X-ray diffraction (XRD). Goethite and hematite were the only two crystalline Fe oxides occurring in a significant quantity. The goethite / (goethite + hematie )ratios ranged from 0 to 1, being the highest in yellow soil, some yellow-red soils and saprolite samples and the lowest in soils derived from purple sandstone where only hematite was present. Al substitution in goethite ranged from 6.6 to 29.9 mol % with a mean value of 16.7 mol %, while substitution of Al in hematite ranged from 0 to 12.1 mol %. The values of Al substitution of hematite in coexisting goethite and hematite were closely related with corresponding values of goethite (r=0.7292, P<0.01, n=27). The redness rating of soils increased linearly with increasing amount of hematite (r=0.8109, P<0.01). It was suggested that redness rating could be used to crudely estimate hematite contents of soils.
文摘The economic development in China and the rising of the living standard need to speed up the urbanisation. The development of small towns is an important way to Chinese urbanisation. Land use plays a very important role in the development of small towns. However there are many problems in the development of small towns, esp. in land use. The paper first discusses the land problems in the development of small towns. Such as much cultivated land lies idle, under utilization and waste of land, increasing illegal use of land, unstable contractual relationship for land use. The relationship between the development of small towns and land use is also studied. Then the guidelines for the land system innovations of small towns are put forward. Namely the sustainability of social and economic development, the balance between land reservation and land utilization, the provision of service to village, agriculture and farmer, the management of land resource and land assets, the parsimonious and legal use of land. The basic framework of land system innovations of small towns is put forward finally. It include the land replacement policy for small towns and the permanent tenancy of farmland, the overall plan for land uses and other plans in harmony, the establishment of a flexible system of land supplies, using land with payments, the transfer of agricultural land and refining the land law related to the construction of small towns.
