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| Influence of freeze/thawing on Cd adsorption capacity and formation of the adsorbed Cd in a chernozem soil |
| Received:February 13, 2025 Revised:May 15, 2025 |
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| KeyWord:chernozem soil;Cd;freeze/thawing;adsorption capacity;adsorbed formation |
| Author Name | Affiliation | E-mail | | WANG Zhan | College of Land and Environment of Shenyang Agricultural University, Shenyang 110866, China | | | ZHANG Yulong | College of Land and Environment of Shenyang Agricultural University, Shenyang 110866, China | | | ZOU Hongtao | College of Land and Environment of Shenyang Agricultural University, Shenyang 110866, China | zht@syau.edu.cn |
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| Abstract: |
| To determine the effects of soil moisture content and freeze-thaw times on the Cd adsorption capacity and adsorbed formation in chernozem soil, this study investigated the adsorption process of Cd on soil which subjected to different freeze/thawing times under different soil water content conditions, and the chernozem soil was chosen as the tested soil. The adsorption ability of Cd absorbed on soil, the form of adsorbed Cd and their biological activity were measured. The results indicated that the Cd adsorption capacity of chernozem soil enhanced first and then reduced with the freeze/thawing times increase, and it reached the maximum when the soil was subjected to 3 freeze/thawing times. When the soil moisture content was adjusted to 70% of the field capacity, the Cd adsorption capacity of chernozem soil was the most sensitive to freeze-thaw treatments. The lower or higher water content both reduced the influence of freeze/thawing on the Cd adsorption capacity of chernozem soil. The main form of adsorbed Cd on soil subjected with different freeze/thawing treatments was exchange state, the content of which is more than 58%, and the physical sorption was the dominant mechanism in the adsorption progress. The influences of freeze/thawing on different forms of adsorbed Cd were various. With the increase of freeze/thawing times, the content of exchange state Cd was stable, the content of carbonate Cd, Fe-Mn oxide Cd and organic binding state Cd decreased, and that of residual state Cd gradually increased. Soil water content and freeze-thaw times had significant effects on the different forms of adsorbed Cd on soil （except for the freeze/thawing times on exchange Cd, and the soil water content on carbonate bonded Cd）. The bioactivity of adsorbed Cd in chernozem soil is strong, but the effect of freeze/thawing on the bioactivity of it is weak, only the soil water content has a significant effect on the migration ability of adsorbed Cd. The results showed that the less freeze/thawing times could increase the Cd adsorption capacity in chernozem soil, and appropriate soil water content can enhance the response of Cd adsorption capacity of soil to freeze/thawing. The freeze/ thawing affected the form of adsorbed Cd, and then affected its biological activity. |
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