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| Effect of Sheep Manure Biochar Application Under Flooding Condition on the Availability of Pb and Zn in Heavy Metal Contaminated Soil |
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| DOI：10.16768/j.issn.1004-874X.2024.07.013 |
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| Abstract: |
| 【Objective】The study was conducted to explore the effect of sheep manure biochar on the availability of
Pb and Zn in soil polluted by compound heavy metals under flooding conditions, and provides the basis for controlling heavy
metal pollution of farmland soil.【Method】Using the polluted farmland soil near a lead-zinc mining area in Yunnan as the
research object, static culture experiments were conducted to study the effects of different addition rates of sheep manure
biochar (0%, 2.5%, 5.0% and 7.5%) on the pH and availability of Pb and Zn in polluted soil under flooding condition. And the ecological and environmental risks were evaluated by the toxicity characteristics leaching procedure (TCLP).【Result】
Compared with the control, the soil pH value of sheep manure biochar treatment increased by 0.04-0.11 units, and the mass
fractions of soil available Pb and Zn were significantly reduced by 32.01%-58.09% and 6.44%-9.15%, respectively. The soil
pH and mass fractions of soil available Pb and Zn showed extremely significant negative correlation and significant negative
correlation, respectively. From the perspective of heavy metal occurrence forms, sheep manure biochar significantly promoted
the passivation of Pb and Zn. Among them, 5.0% sheep manure biochar treatment had the best passivation effect, promoting
the transformation of heavy metal Pb into more stable forms in soil, resulting in the highest mass fractions of oxidizable and
residual forms, which were 64.05% and 27.50%, respectively. In the soil, Zn mainly transformed into an oxidizable state, but
residual Zn showed a decreasing trend with a relatively small decrease. The mass fractions of Pb and Zn extracted by TCLP
significantly decreased with the increase of biochar addition rate, effectively reducing the ecological risk of polluted farmland
soil. 【Conclusion】For heavy metal contaminated farmland soil near lead-zinc mining areas, the method of flooding combined
with applying sheep manure biochar can reduce the availability and ecological risks of Pb and Zn in soil. The addition amount of
5.0% sheep manure biochar has the best passivation effect on soil heavy metals Pb and Zn. |
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