Hyperaccumulator Oilcake Manure as an Alternative for Chelate-Induced Phytoremediation of Heavy Metals Contaminated Alluvial Soils

Abstract

The ability of hyperaccumulator oilcake manure as compared to chelates was investigated by growing Calendula officinalis L for phytoremediation of cadmium and lead contaminated alluvial soil. The combinatorial treatment T₆ [2.5 g kg⁻¹oilcake manure + 5 mmol kg⁻¹ EDDS] caused maximum cadmium accumulation in root, shoot and flower up to 5.46, 4.74 and 1.37 mg kg⁻¹and lead accumulation up to 16.11, 13.44 and 3.17 mg kg⁻¹, respectively at Naini dump site, Allahabad (S₃). The treatment showed maximum remediation efficiency for Cd (RR = 0.676%) and Pb (RR = 0.202%) at Mumfordganj contaminated site (S₂). However, the above parameters were also observed at par with the treatment T₅ [2.5 g kg⁻¹oilcake manure +2 g kg⁻¹ humic acid]. Applied EDDS altered chlorophyll–a, chlorophyll–b, and carotene contents of plants while application of oilcake manure enhanced their contents in plant by 3.73–8.65%, 5.81–17.65%, and 7.04–17.19%, respectively. The authors conclude that Calendula officinalis L has potential to be safely grown in moderately Cd and Pb-contaminated soils and application of hyperaccumulator oilcake manure boosts the photosynthetic pigments of the plant, leading to enhanced clean-up of the cadmium and lead-contaminated soils. Hence, the hyperaccumulator oilcake manure should be preferred over chelates for sustainable phytoremediation through soil-plant rhizospheric process.

Keywords:

• Calendula officinalis L
• cadmium
• lead
• photosynthetic pigments
• humic acid
• oilcake manure
• EDDS
• remediation ratio

Acknowledgments

Authors are grateful to Dr. Alok Lehri, Central Instrumentation Facility Division, National Botanical Research Institute, Lucknow and Dr. Bechan Sharma, Department of Biochemistry, University of Allahabad, Allahabad for assisting in the analysis of soil and plant samples for heavy metals by A.A.S. (AAnalyst600, PerkinElmer Inc., MA, USA) and photosynthetic pigments respectively.

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Additional information

Funding

The contribution of University Grant Commission, India is also acknowledged for providing the D.Phil. Scholarship during the research period.