Seasonal freeze-thaw cycle (FTC) is one of the key processes that affect heavy metal behaviors in soil. However, previous studies are mainly focused on extreme FTC treatments which may exaggerate the real FTC effects in the field. This study aimed to compare the effects of different FTC conditions on the adsorption and desorption behaviors of Cd in the surface black soil. Different minimum freezing temperatures (- 2, - 5, and - 15 °C), FTC rates (1 and 20 °C h-1), freezing lengths (2 and 24 h), and FTC frequencies (1, 3, and 9) were investigated. The thawing temperature was set at 5 °C. The amplitude for the FTC rate, length, and frequency experiments ranged from 5 to - 2 °C. Our results indicated that the adsorption amounts of Cd presented an order of - 2 °C > - 15 °C > - 5 °C and 24 h > 2 h for different FTC amplitude- and freezing length-treated soils, and the adsorption amounts decreased with increasing FTC rate and frequency. Soil maximum adsorption amount of Cd increased with the increases of FTC frequency, freezing length, and FTC rate, while it decreased with the decreases of freezing temperature. Soil Cd desorption ratio decreased with the increases of FTC frequency, freezing length, and TFC rate, and it increased with the increasing freezing temperature. Our results suggested that FTC conditions can significantly influence the adsorption and desorption behaviors of heavy metal in soil.

中文翻译：

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不同冻融处理对黑土中镉吸附和解吸行为的影响。

季节性冻融循环（FTC）是影响土壤中重金属行为的关键过程之一。但是，先前的研究主要集中在极端的FTC治疗上，这可能会夸大该领域的实际FTC效应。本研究旨在比较不同FTC条件对黑土表层Cd吸附和解吸行为的影响。不同的最低冻结温度（-2，-5和-15°C），FTC速率（1和20°C h-1），冻结长度（2和24 h）和FTC频率（1、3和9 ）进行了调查。解冻温度设定为5℃。FTC速率，长度和频率实验的幅度范围为5到-2°C。我们的结果表明，Cd的吸附量顺序为-2°C>-15°C>-5°C和24 h> 对于不同的FTC振幅和冰冻长度处理的土壤2 h，吸附量随FTC速率和频率的增加而降低。土壤最大镉吸附量随FTC频率，冷冻时间和FTC速率的增加而增加，随冷冻温度的降低而降低。随着FTC频率，冷冻时间和TFC速率的增加，土壤Cd的解吸率降低，而随着冷冻温度的升高，土壤Cd的解吸率增加。我们的结果表明，FTC条件可以显着影响土壤中重金属的吸附和解吸行为。而随着冷冻温度的降低而降低。随着FTC频率，冷冻时间和TFC速率的增加，土壤Cd的解吸率降低，而随着冷冻温度的升高，土壤Cd的解吸率增加。我们的结果表明，FTC条件可以显着影响土壤中重金属的吸附和解吸行为。而随着冷冻温度的降低而降低。随着FTC频率，冷冻时间和TFC速率的增加，土壤Cd的解吸率降低，而随着冷冻温度的升高，土壤Cd的解吸率增加。我们的结果表明，FTC条件可以显着影响土壤中重金属的吸附和解吸行为。