Department of Environmental Engineering and Management, Chaoyang University of Technology, 168, Jifeng E. Rd., Wufeng District, Taichung, 41349, Taiwan,
Environ Monit Assess. 2014 Jan;186(1):375-82. doi: 10.1007/s10661-013-3382-1. Epub 2013 Aug 13.
Air-drying and oven-drying are pretreatment processes often used before testing and analyzing various soil characteristics in the laboratory. This study selected three kinds of soil, including red soil, entisol, and alluvial soil, and examined the variation of the Cr(VI) content and Cr bond forms in these soils during air-drying and oven-drying. The results show that when the soil is air-dried in natural environment, the Cr(VI) content decreases with air-drying time. On day 10 of air-drying, the Cr(VI) content in these soils is 22.8∼47.9 % of the initial value. When the soil is oven-dried, the Cr(VI) concentration decays faster; on day 8, the Cr(VI) is no longer detected in these soil samples. When the Cr(VI)-contaminated soil is treated by air-drying and oven-drying, the Cr bond form converts into a more stable form. After oven-drying, the Cr mainly exists in Fe-Mn oxide form, organic bond form, and residual form. The air-drying and oven-drying pretreatment processes of soil reduce the Cr(VI) content and stabilize the Cr bond form. If the laboratory analytic results are applied to risk analysis or remediation strategy planning for chromium-contaminated soil, the toxicity, bioavailability, and mobility of Cr in soil may be underrated.
风干和烘干是实验室测试和分析各种土壤特性前常用的预处理过程。本研究选择了红土、灰土和冲积土三种土壤，考察了风干和烘干过程中土壤中六价铬（Cr(VI)）含量和 Cr 键合形态的变化。结果表明，土壤在自然环境中风干时，Cr(VI)含量随风干时间的延长而降低。风干第 10 天时，这些土壤中 Cr(VI)的含量为初始值的 22.8%~47.9%。当土壤烘干时，Cr(VI)浓度衰减更快；在第 8 天，这些土壤样品中已检测不到 Cr(VI)。当用风干和烘干处理受 Cr(VI)污染的土壤时，Cr 键合形态转变成更稳定的形态。烘干后，Cr 主要以铁锰氧化物结合态、有机结合态和残渣态存在。风干和烘干预处理过程降低了土壤中 Cr(VI)的含量并稳定了 Cr 的键合形态。如果将实验室分析结果应用于铬污染土壤的风险分析或修复策略规划，可能会低估土壤中 Cr 的毒性、生物可利用性和迁移性。
