Microstructure characteristics of aggregates and Cd immobilization performance under a 3–year sepiolite amendment: A field study

Sepiolite is an efficient mineral for the immobilization of Cd in contaminated soils. Here, we conducted a 3–year field experiment to investigate the effect of sepiolite on soil aggregation and porosity, Cd availability, and organic carbon content in the bulk and aggregate soils and Cd accumulation...

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Bibliographic Details
Published in:The Science of the total environment 2021-12, Vol.798, p.149269-149269, Article 149269
Main Authors: Runlong, Wang, Shunan, Zheng, Tong, Sun, Yingming, Xu, Tao, Sun, Yuebing, Sun
Format: Article
Language:English
Subjects:
Immobilization remediation
Pore characteristic
Sepiolite
Soil aggregate
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Summary:Sepiolite is an efficient mineral for the immobilization of Cd in contaminated soils. Here, we conducted a 3–year field experiment to investigate the effect of sepiolite on soil aggregation and porosity, Cd availability, and organic carbon content in the bulk and aggregate soils and Cd accumulation by leafy vegetables. The sepiolite–treated soils showed a 15.4%–53.4% and 5.5%–63.0% reduction in available Cd content in the bulk soil and different particle–size aggregates, respectively. Moreover, the Cd concentrations in the edible parts of Brassica campestris, Lactuca sativa L., and Lactuca sativa var. ramosa Hort. decreased by 5.9%–26.2%, 22.8%–30.1%, and 14.4%–19.1%, respectively, compared with those of the control groups. Treatments with 0.5%–1.5% sepiolite resulted in a significant increase (P < 0.05) in the proportion of 0.25–5.0 mm aggregates, and the increase in the mean weight diameter and geometric mean weight of the soil aggregates indicated that sepiolite treatments enhanced soil aggregate stability. Furthermore, three–dimensional X–ray computed tomography imaging showed that sepiolite treatments resulted in an increase in the total area, average size, and pore perimeter of aggregates, with the maximum values being 1.63–, 1.41–, and 1.401–fold higher than those of the corresponding control groups, respectively. The highest values of soil organic carbon and particulate organic carbon were obtained in 1.5% sepiolite–treated soils and were 2.07– and 1.91–fold higher than those of the control groups, respectively. Additionally, the level of organic carbon functional groups in the bulk soil and different particle–size aggregates generally increased with increasing sepiolite application. Overall, sepiolite, as a soil amendment, not only reduced toxic element bioavailability and uptake by plants but also enhanced soil structure and function. [Display omitted] •Sepiolite treatment increased on soil aggregation and porosity.•Available content of Cd in size of soil aggregates was reduced.•Cd uptake in vegetables was inhibited after applying sepiolite.•Sepiolite-treated soils contained more functional C groups.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2021.149269