Evaluation of Cynara cardunculus L. and municipal solid waste compost for aided phytoremediation of multi potentially toxic element–contaminated soils

Abstract

The suitability for aided phytoremediation of Cynara cardunculus L. var. altilis and municipal solid waste compost (MSWC) applied at 2% and 4 % rates was evaluated in a multi potentially toxic element (PTE)-contaminated mining soil (Pb ~ 15,383 mg kg−1, Zn ~ 4076 mg kg−1, As ~ 49 mg kg−1, Cd ~ 67 mg kg−1, Cu ~ 181 mg kg−1, and Sb ~ 109 mg kg−1). The growth of C. cardunculus significantly increased with compost amendment and followed the order: MSWC-4% > MSWC-2% > Control. PTE concentrations in the roots of plants grown on amended soils decreased compared with control plants (i.e., less than ~ 82, 94, and 88% for Pb, Zn, and Cd respectively). PTE translocation from roots to shoots depended on both PTE and amendment rate but values were generally low (i.e., < 1). However, PTE mineralomasses were always higher for plants grown on MSWC-amended soils because of their higher biomass production, which favored an overall PTE bioaccumulation in roots and shoots. After plant growth, labile As and Sb increased in amended soils, while labile Pb, Zn, Cu, and Cd significantly decreased. Likewise, dehydrogenase and urease activities increased significantly in planted soils amended with MSWC. Also, the potential metabolic activity and the catabolic versatility of soil microbial communities significantly increased in planted soils amended with MSWC. Overall, our results indicate that C. cardunculus and MSWC can be effective resources for the aided phytoremediation of multi PTE-contaminated soils.

Innovative amendments derived from industrial and municipal wastes enhance plant growth and soil functions in potentially toxic elements-polluted environments

“…By contrast, As accumulation in shoots of P. australis and A. donax grown in MSWC-amended soils was comparable and in some cases significantly lower than that observed in plants grown on control soils (Castaldi et al, 2018). Garau et al (2020) reported a significant decrease in the concentration of different PTE in cardoon tissues grown in soil treated with 2% and 4% (w/w) MSWC. For example, As concentration in roots decreased by 11.7-fold and 8.7-fold, and Sb by 6.7-fold and 6.5-fold, in 2% and 4% (w/w) amended soils respectively, compared to control (unamended) roots.…”

“…Root biomass of C. cardunculus increased by more than 17-fold and 23-fold in polluted soils amended with 2% and 4% (w/w) MSWC respectively, compared to unamended soil, while shoot biomass increased by approx. 5-fold and 10-fold (Garau et al, 2020).…”

“…Plant growth, estimated by root and shoot dry weight, was generally highly influenced by soil, contamination type and amendment addition, supporting the view that the amendment effectiveness needs to be evaluated case by case. Generally, adding MSWC, WTR, RM and BCH to PTEpolluted soils had a positive impact on plant growth even if some important exceptions were also reported (Castaldi et al, 2005(Castaldi et al, , 2018Garau et al, 2017;Garau et al, 2020; unpublished data related to BCH).…”

“…Because of these physico-chemical properties, MSWC could be a strategic resource for the improvement of soil functionality and plant growth in PTE-contaminated soils (Castaldi et al, 2005(Castaldi et al, , 2018Garau et al, 2020). Moreover, humic substances of MSWC can immobilize PTE forming complexes of different strengths and reducing their mobility and bioavailability in soil (Paradelo et al, 2012;Silvetti et al, 2017).…”

“…Kumpiene et al, 2014;Garau et al, 2014;Castaldi et al, 2018). Plant growth in PTEcontaminated environments can reduce soil erosion and spread of contaminants, limit PTE mobility and bioavailability through their immobilization in roots, reduce PTE leaching to groundwater and stimulate microbial activity through the release of root exudates (Castaldi et al, , 2018Garau et al, 2020). Moreover, the cultivation of plant species with phytoremediation capacities, but also able to produce some income, e.g.…”