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

Abstract

Phytoremediation is limited when heavy metals reduce soil quality and, subsequently, inhibit plant growth. In this study, we evaluated the use of attapulgite and bentonite as amendments in soil contaminated with multiple metals, to improve the phytoremediation capacity of Vetiver grass and Indian mustard. A 21-day greenhouse study was undertaken, to investigate plant tolerance in heavy-metal-contaminated soil, as well as heavy-metal absorption in plant roots and shoots. The results showed a generally higher root-uptake rate for Cr, Cu, Co, Ni, and Zn in Vetiver grass. Overall, the highest absorption for Ni, Cr, Co, Cu, and Zn was 1.37, 2.79, 1.39, 2.48 and 3.51 mg/kg, respectively, in the roots of Vetiver grass. Clay minerals inhibited the translocation of some heavy metals. The addition of attapulgite improved the phytoremediation capacity of Vetiver for Ni, Cr, and Co, while bentonite improved Vetiver’s absorption of Cu and Zn. The translocation factor for Ni in one of the attapulgite treatments was 2, indicating that attapulgite improved the phytoextraction of Ni by Vetiver grass. Our results confirm that attapulgite at 2.5% (w/w) can successfully improve the phytostabilization of heavy metals by Vetiver grass. Indian mustard showed no significant metal uptake that could be detected by inductively coupled plasma optical emission spectrometry (ICP-OES), despite the addition of attapulgite and bentonite. This research contributes to the knowledge repository of suitable amendments that improve the phytoremediation properties of Vetiver grass.

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

“…In this study, we aimed to examine the efficiency of an optimised hybrid application of vetiver grass and clay minerals for remediation of soil and water contaminated with heavy metals (Al and Mn in water; and Co, Cr, Cu, Ni and Zn in soil) in a mesocosm setting as informed by success in previous greenhouse studies. 16,17 There is little documentation of mesocosm studies concerning assisted phytoremediation of soil and water [27][28][29] ; therefore, this study contributes to the repository of available studies of phytoremediation in mesocosms, further encouraging its application.…”

“…Major examples of clay minerals include attapulgite, bentonite, montmorillonite, zeolite and kaolinite. 13 Previous studies by Otunola et al 16,17 showed that attapulgite administered at 2.5% (w/w) was most effective to improve the phytoremediation capacity of vetiver grass in metals polluted soil, while bentonite administered at 2.5% (w/v) was best for water remediation.…”

“…14,15 In particular, heavy metals including Co, Cr, Cu, Ni, and Zn have been detected in the soil, while Al and Mn have been detected in water bodies surrounding a former coal mining environment located in Sasolburg in the Free State Province of South Africa. 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 zizanoides L.): A Hyper-Accumulator Crop for Bioremediation of Unconventional Water

“…First, it was developed in 1985 by the World Bank to protect India's soil and water [21]. The system contributes to the procedures of agricultural land management [33], environmental protection [63], soil and water conservation [64], infrastructure balancing [65], contamination management [23], as well as water and wastewater treatment [66][67][68]. The origin of the Chryspogon zizanioides species is in South India [69].…”

Remediation of Pb-, Zn-, Cu-, and Cd-Contaminated Soil in a Lead–Zinc Mining Area by Co-Cropping Ilex cornuta and Epipremnum aureum with Illite Application

“…as stabilizing materials of repair technologies can absorb interlayer toxic cations and can fix ions in the crystal structure. The clay minerals as passivate contaminants can change the existing forms of pollutants in the soil and can reduce their mobility and bioavailability in the environment, which can deactivate pollutants [13,14]. The research conducted by Liu et al revealed that the application of phosphate rock and zeolite separately to soil led to a significant reduction in the bioavailability of Cd in the soil and changed the soluble, exchangeable, and specifically sorbed fractions to oxide-bound and organic-bound fractions, effectively remediating Cd-contaminated soil [15].…”