Assessment of Cadmium Distribution in Some Australian Krasnozems by Sequential Extraction

A sequential extraction procedure was used to investigate the influence of long-term phosphate fertilization on the distribution of cadmium throughout the major components of krasnozemic soils in the potato growing district located to the East of Ballarat, Victoria, Australia. The soil fractions investigated consisted of the water soluble, exchangeable, weakly bound to metal oxides, strongly bound to metal oxides, bound to organic material and residual. Other soil parameters, such as pH_H2O, pH_CaCl2, electrolytical conductivity and total organic material were investigated. The concentrations of Ca, Mg, Fe, Mn and Zn in each soil fraction were also measured. The total concentration of cadmium in the farmed soils had increased from the background level of 100.5 μg/kg to an average of 210 μg/kg. The proportion of cadmium available or potentially available for plant uptake was very low. On average, 89% of the cadmium in the farmed soils had been adsorbed by amorphous metal oxides and organic material, or was associated with silicates, and is therefore unavailable for plant uptake. The metal oxides adsorbed the highest proportion of cadmium.     

微波预处理加速阔叶树材干燥的技术分析

微波用于阔叶树木材预处理,可缩短木材的干燥时间;降低木材干燥降等损失、增加高质量木材出材率,为大截面木材干燥提供了可能性;减少了贮存场地及占用资金,降低了木材运输费用。澳大利亚的应用研究结果表明,微波处理费用只占低质量木材价格的4.1%～4.9%,或高质量木材价格的2.3%～2.8%。