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| Effects of exogenous organic acids on soil pH, enzyme activity, and cadmium migration and transformation |
| Received:September 26, 2019 |
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| KeyWord:organic acid;pH value;soil enzyme activity;Cd form;dry matter quality;rapeseed |
| Author Name | Affiliation | E-mail | | LU Hong-fei | Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China
Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China | | | QIAO Dong-mei | Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China | qiaodongmei78@163.com | | QI Xue-bin | Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China | | | HU Chao | Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China
Agricultural Water Soil Environmental Field Research Station of Xinxiang, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China | | | ZHAO Zhi-juan | Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China
Key Laboratory of High-efficient and Safe Utilization of Agriculture Water resources, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China | | | BAI Fang-fang | Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China | | | ZHAO Yu-long | Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China | | | HAN Yang | Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453002, China | |
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| Abstract: |
| To screen suitable exogenous organic acids for phytoremediation of soil Cd pollution, a pot experiment was conducted in a greenhouse with rapeseed as the test material. Five organic acids(acetic acid, oxalic acid, citric acid, malic acid, and tartaric acid)were added to heavily Cd-contaminated soil(the Cd content of original soil was 0.838 mg·kg-1; by spraying CdCl2 solution, we created a test soil with a Cd content of 4.838 mg·kg-1), with no organic acid treatment as the control. Six organic acid gradients were set at 1, 2, 3, 4, 5 mmol·kg-1, and 6 mmol·kg-1. Soil pH value, enzyme activity, dry matter content, and Cd absorption of rapeseed were determined when the rapeseed was harvested. The relationship between physical and chemical indexes and soil Cd morphology was analyzed. The results showed that:Compared to the CK, 1, 3, 4, 5, 6 mmol·kg-1 acetic acid, 4, 5, 6 mmol·kg-1 citric acid, 3 mmol·kg-1 malic acid, and 3, 6 mmol·kg-1 tartaric acid could significantly increase soil pH, and there was no significant difference between the oxalic acid treatment and that of the CK. However, the effect of organic acid application on soil enzyme activity was not obvious. The application of 1, 4 mmol·kg-1, and 6 mmol·kg-1 acetic acid significantly improved dry matter content of rapeseed shoots, 1 mmol·kg-1 and 6 mmol·kg-1 acetic acid significantly increase the dry matter content of rapeseed roots, 4 mmol·kg-1 and 6 mmol·kg-1 malic acid significantly increased the dry matter content of rapeseed roots by 77.13% and 88.30%, respectively, and there was no significant difference between other treatments with that of the CK. Cd uptake in shoots in the 1 mmol·kg-1 acetic acid treatment was 51.52% higher than that of the CK, Cd uptake in roots of the 2 mmol·kg-1 oxalic acid treatment was 1.58 times higher than that of the CK, and the total uptake in shoots and roots of 1 mmol·kg-1 citric acid treatment was significantly higher than that of the CK. Increasing malic acid application was beneficial in increasing the total uptake of Cd in roots, and applying 1 mmol·kg-1 and 2 mmol·kg-1 tartaric acid was also beneficial in increasing root Cd uptake, but they exhibited no significant difference with that of the CK. Under the acetic acid condition, soil pH was negatively correlated with Fe-Mn oxide Cd and total Cd, whereas under the citric acid condition, soil pH was positively correlated with carbonate Cd and total Cd. When malic acid was applied, there was a significant positive correlation between soil pH and exchangeable Cd, but there was no significant correlation between pH and Cd form under other treatments. When rapeseed was planted on alkaline soil, the application of the five organic acids increased the pH value of the soil at harvest, and the effect of different organic acids on the form of Cd in the soil was different. Among the five organic acids, acetic acid was the most beneficial in improving the quality of dry matter content and Cd accumulation of rape. |
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