Suitability of Mentha arvensis L. for Phyto-stabilization and Remediation of Heavy Metals/Metalloid Rich Fly-ash Contaminated Soil

Abstract

Agricultural fields nearby thermal power plant receives air blown fly ash in huge amount. The fly ash contains heavy metals/metalloids along with essential elements for plant growth and productivity. The conventional crops growing in the fly ash contaminated agrifields accumulate toxic metals in different tissues. Thus, there is need to explore the crop plant of economic importance for phyto-stabilization of fly ash contaminated agrifields and slowdown the rate of metals/metalloid entering in food chain. In the present study, Mentha arvensis (var. Kosi) was used to evaluate the physiological and biochemical responses in six concentrations (w/w) of fly ash (0, 15, 30, 45, 60 and 100%). The morphometric traits, growth and photosynthetic pigments were analysed in M. arvensis and found maximum shoot & root length, biomass, no. of leaves and primary branches at 15% fly ash mixed soil. Chlorophyll a, b, total chlorophyll and carotenoids were elevated with 15% fly ash exposure while reduced at 100% fly ash. Oxidative stress markers (malondialdehyde & hydrogen peroxide) were also significantly (Tukey-HSD post-hoc, p < 0.05) upregulated with rising level of fly ash. Further, the level of Cellular antioxidants (cysteine, TPC, NP-SH) was increased up to 60% fly ash. The study also documented the differential accumulation of Iron, Copper, Manganese, Chromium and Mercury in leaves and stems of M. arvensis at different fly ash concentrations while reduced level of Potassium was observed with increasing fly ash levels. The antioxidative responses and potential of test plant to accumulate metal/metalloids make it suitable for eco-stabilization in fly ash contaminated agrifields.