Key Laboratory of Wet Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
Key Laboratory of Wet Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2021 Jul 20;779:146442. doi: 10.1016/j.scitotenv.2021.146442. Epub 2021 Mar 14.
To date, most studies about the aging of metals in soil were based on the controlled laboratory experiments, and few works have attempted to investigate how aging process influences the distribution and bioavailability of metals in soil under the field condition. The purpose of this study was to compare the aging of cadmium (Cd) in soils under the controlled laboratory and the field by monitoring time-dependent soil Cd speciation changes, Cd release kinetics, and Cd bioavailability to plant through the 438-day aging experiments. During the aging process, the proportions of Cd associated with the most weakly bound fraction tended to decrease, with corresponding increases in the more stable binding fractions. After aging, a higher concentration of available Cd was found in the field aging soil (0.74 mg kg) than the laboratory aging soil (0.65 mg kg). The Elovich equation was the best model to describe the soil available Cd aging process. The constant b in the Elovich equation, which was defined as the transformation rate, was in the order of laboratory aging soil > field aging soil. Moreover, higher Cd release amounts were found for the field aging soil (2.74 mg kg) than the laboratory aging soil (2.57 mg kg) at the end of aging. Additionally, higher body Cd concentrations were found for the vegetables grown in the field aging soils (1.49 mg kg, fresh weight) than those grown in the laboratory aging soils (1.32 mg kg, fresh weight). Therefore, this study indicated that the metal distribution process and its bioavailability may be overestimated or underestimated if research data from the laboratory experiments are used to derive soil quality criteria or investigate soil metal bioavailability.
迄今为止，大多数关于土壤中金属老化的研究都是基于控制实验室实验，很少有工作试图研究老化过程如何影响野外条件下土壤中金属的分布和生物利用度。本研究旨在通过监测 438 天老化实验中随时间变化的土壤 Cd 形态变化、Cd 释放动力学以及 Cd 对植物的生物利用度，比较控制实验室和野外条件下土壤中 Cd 的老化过程。在老化过程中，与最弱结合部分结合的 Cd 比例趋于降低，而与更稳定结合部分结合的 Cd 比例相应增加。老化后，田间老化土壤（0.74mgkg）中有效 Cd 浓度高于实验室老化土壤（0.65mgkg）。Elovich 方程是描述土壤有效 Cd 老化过程的最佳模型。Elovich 方程中的常数 b 定义为转化速率，其顺序为实验室老化土壤>田间老化土壤。此外，在老化结束时，田间老化土壤（2.74mgkg）的 Cd 释放量高于实验室老化土壤（2.57mgkg）。此外，在田间老化土壤中生长的蔬菜体内 Cd 浓度（鲜重 1.49mgkg）高于在实验室老化土壤中生长的蔬菜（鲜重 1.32mgkg）。因此，本研究表明，如果将实验室实验获得的数据用于推导土壤质量标准或研究土壤金属生物利用度，可能会高估或低估金属分布过程及其生物利用度。
