Effects of a ladle furnace slag added to soil on morpho-physiological and biochemical parameters of Amaranthus paniculatus L. plants

Abstract

Industrial slag from steelwork activities is considered a by-product by the EU legislation and it can be used for civil construction. In this work, an experiment in a greenhouse was conducted over a 6-week period to investigate the effect of soil enrichment with ladle furnace slag on morpho-physiological parameters of Amaranthus paniculatus L. plants. Results showed that the addition of 5% (w/w) slag to soil did not alter the plant growth, highlighting a high tolerance to this slag concentration. Contrarily, plants cultivated in a soil with 10% (w/w) slag showed a marked reduction both in growth and biometric parameters. Moreover, plants grown on a slag-rich soil (20% w/w) highlighted a very low survival rate. This behaviour was confirmed by the biochemical and physiological investigations on chlorophyll a and b content, gas exchange and chlorophyll fluorescence analyses. Metal(loid)s determination showed the accumulation of Ni, Se, Sn, As, Sb and Cd in 10% slag-treated plants, while revealed an increase in Ni, Cd, As and Pb in 5% slag-treated plants. Results are discussed highlighting the profitability of the cultivation of Amaranthus plants on slag enriched soil, as this plant species is largely used both as feedstock for energy production and for environmental restoration.

Keywords: Environmental restoration; Heavy metals; Industrial by-products; Photosynthesis; Phytoremediation.