Phytoremediation Potential of Crop Plants in Countering Nickel Contamination in Carbonation Lime Coming from the Sugar Industry

Abstract

The phytoremediation potential of four crop species cultivated on carbonation lime coming from the sugar industry with water-soluble nickel (Ni) exceeding the Italian legal limit of 10 µg L−1 was assessed. Two autumn–winter species (spinach and canola) were tested with and without the addition of bentonite in a greenhouse experiment in order to overcome prolonged unfavourable weather conditions. Two spring-summer species (sunflower and sorghum) were grown in outdoor boxes. Plant species were selected among crops of interest for phytoremediation and their rotation throughout the year enable to maintain a permanent vegetation cover. Nickel concentration in different plant tissues and the concentrations of soluble and bioavailable Ni in lime were measured. In the greenhouse study, soluble Ni decreased below the legal limit in all the tests, and the combined effect of bentonite and plants reduced Ni in lime mainly in the bioavailable fraction. Spinach and sunflower emerged to be more suitable for phytoextraction than canola and sorghum, because of the higher concentration of the metal in the epigeal portions. The results from the outdoor experiment highlighted that sorghum has a good phytostabilisation potential since its ability to accumulate Ni mainly at the root level and to attract a significant amount of bioavailable Ni in the rhizosphere. This study arose from a real scenario of environmental contamination and investigated the potential of different approaches on the bioremediation of a specific industrial waste product.

Influence of Clay Mineral Amendments Characteristics on Heavy Metals Uptake in Vetiver Grass (Chrysopogon zizanioides L. Roberty) and Indian Mustard (Brassica juncea L. Czern)

“…Attapulgite and bentonite, generally, limited the root absorption of Ni. De Bernadi et al [53] confirmed that bentonite amendment sequesters Ni and, thus, reduces its bioavailability. Kumararaja et al [49] found that pillared bentonite stabilized heavy metals in soil and reduced absorption by plants, particularly, at a dosage of 2.5% (w/w) (one of the dosages considered in this study).…”

A mesocosm study on the use of clay minerals to improve heavy metal phytoremediation capacity of vetiver grass (Chrysopogon zizanioides L. Roberty)

“…40 The addition of bentonite also reduced the bioavailable Ni in lime and wastewater. 20,41 This is typical of clay minerals, which reduce the bioavailable properties of heavy metals as they adsorb these metals onto their surfaces. 13,19 Vetiver is also tolerant to Zn, absorbing up to 10 000 mg/kg within 30 days with a high translocation factor.…”

“…14,16,17 Considering the negative effects of heavy metals on the environment, several technologies have been identified for managing heavy metal polluted sites. Of these technologies, phytoremediation is a cost-effective and environmentally friendly option 18 , and there is growing interest in the application and optimisation of phytoremediation 19,20 . Vetiver grass (Chrysopogon zizanioides) is a terrestrial plant that has been adapted for soil and water remediation purposes because it is easily propagated, with rapid growth and can survive in extreme climatic conditions.…”

Selected Plant-Related Papers from the First Joint Meeting on Soil and Plant System Sciences (SPSS 2019)—“Natural and Human-Induced Impacts on the Critical Zone and Food Production”

“…De Bernardi et al [ 36 ] directed their research toward testing the phytoremediation potential of four crop species for nickel (Ni) in order to sustain the application of green clean-up techniques suitable for the remediation of Ni-contaminated sites. The legal threshold for water-soluble Ni in soil, set by Italian Legislative Decree 186/2006, is 10 µg L −1 [ 37 ].…”