Phosphate, Lime and Bentonite Affect Heavy Metals and Phosphorus Availability in Acidic and Calcareous Soils

ABSTRACT

This work investigated the effect of soil amendments on the mobility of heavy metals and P in acidic and calcareous heavy metal polluted soils after incubated for one year. Compared to phosphate alone, the phosphate+bentonite amendment had lower available P concentrations (13.1 and 16.3% in the acidic and calcareous soils, respectively) and similar heavy metal immobilization capacity. The lime amendment increased soil P availability possibly by increasing the negative charges of soil particles in both soils. Lime amendment greatly reduced the DTPA-extractable concentrations of Cd, Cu, Mn, Ni, Pb and Zn in both soils; greater reductions were observed with higher rate compared to the lower rate and in the acidic soil compared to the calcareous soil, especially for Cd, Mn, Ni and Zn (23.9–95.3% lower than the control). The bentonite in the phosphate+bentonite treatment may have reduced soil P availability by adsorption of soluble P. Based on the results, phosphate+bentonite instead of phosphate alone may be used to reduce heavy metal and P availability in heavy metal contaminated soil. When only lime is used, caution should be taken with respect to potential soil P losses and subsequent off-site degradation in water and environmental quality.

KEYWORDS:

• Bentonite
• heavy metals
• lime
• Ph
• phosphate

Acknowledgements

This work was sponsored by The National Key Research and Development Programs of China (2018YFD0800304 & 2016YFE0106400) and National Natural Science Foundation of China (41471253). The authors would like to thank Mr Linlin Zhao for his help in sample analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was supported by the Ministry of Science and Technology of the People’s Republic of China [2016YFE0106400]; National Natural Science Foundation of China [41471253]