Phytoremediation potential of Leersia hexandra Swartz of copper contaminated soil and its enhancement by using agronomic management practices

doi:10.1016/j.ecoleng.2018.03.009

Ecological Engineering

Volume 127, February 2019, Pages 561-566

https://doi.org/10.1016/j.ecoleng.2018.03.009 Get rights and content

Abstract

The objective of this study was to discuss the phytoremediation potential of Leersia hexandra Swartz in Cu contaminated soil and its enhancement by agronomic management practices. The results showed that L. hexandra had a high extraction capacity for copper (Cu), and Cu concentration was found maximum in shoots (755.4 mg/kg), which is very close to the Cu-hyperaccumulators. Three successive harvests did not reduce the biomass and Cu level in shoots of L. hexandra (p > 0.05), indicating that sequential harvest was feasible for the increase of total biomass and Cu extraction amount. Fertilization could obviously increase the tissue dry weight, resulting in the total amount of extracted-Cu up to 52.3%. 3-Indole acetic acid (IAA) also significantly increased biomass, causing the efficiency of Cu phytoextraction up to 204.6%. These suggested that fertilization and IAA were effective for enhancing Cu phytoextraction by L. hexandra.

Introduction

For plants, copper (Cu) is an important micronutrients. However, excessive Cu has a high degree of phytotoxicity for its growth (Adrees et al., 2015). In addition, Cu can enter into the human or animal body through the food chain, and cause great harm (Stern, 2010). The sources of Cu contamination is extensive, such as metal extraction and processing, plating, paints, dyes, use of sludge, fertilizers, pesticides and fungicides (Kabata-Pendias, 2010). China is a major Cu producing country where Cu was mined 600,000 tons per year from 1607 mines, causing numerous soils were contaminated(Jin et al., 2012). Thus, it is urgent to restore Cu contaminated soils for agricultural sustainable development and human health.

Conventional physiochemical methods for removal of contaminants from the soils are quite expensive and labour intensive which lead to soil alterations (Bhargava et al., 2012). In comparison, phytoextraction is an environmentally friendly, cost effectiveness effective alternative technology that was being accepted by scientists, remediation engineers, and environmental professionals in government and industries in recent years (Ali et al., 2013). For Cu, there are about 40 species of hyperaccumulators(defined as capable of accumulating more than 1000 mg Cu kg⁻¹ shoot dry weight (Baker and Brooks, 1989). However, merely Elsholtzia splendens and Commelina communis have been reported in China (Ent et al., 2013). Therefore, it is necessary to look for the other useful accumulators of Cu that supply new genetic resources for the successful phytoremediation of Cu-contaminated soils.

It is sure that L. hexandra has a good phytoremediation for chromium (Zhang, et al., 2007), while it is also able to accumulate Cu (Lin et al., 2016). Due to the powerful regeneration capacity, L. hexandra could be harvested many times in one year. These suggest that it could be an ideal candidate for remediation of Cu-contaminated sites (Lin et al., 2016). Moreover, several studies have demonstrated that the application of fertilizer can improve the growth of plants, resulting in the increase of contaminant uptake (Wei et al., 2010, Titah et al., 2013). Simultaneously, sequential harvests is able to promote the efficiency of heavy metal remediation (Liu et al., 2011). In recent years, auxins, such as exogenous 3-indole acetic acid (IAA), have been proved to be conducive for phytoextraction, owing to the higher biomass production and more efficient systems of antioxidation (Bulak et al., 2014).

For the exploration of the Cu enrichment of L. hexandra, a batch of pot experiments were carried out in the greenhouse. The effect of parameters (sequential harvest, fertilizer and IAA) on the growth of L. hexandra was discussed. The effect of above measures on Cu uptake and accumulation in L. hexandra was assessed. The purposes of this study were to evaluate the potentiality of L. hexandra for phytoextraction of Cu from contaminated soil and to explore the possible approaches to enhance the Cu phytoextraction with this species.

Section snippets

Plant, soil and fertilizer

L. hexandra seedlings were obtained from paddy fields in Guilin, China. (The Cu concentrations in its shoots were ranged from 9.82 mg/kg to 20.1 mg/kg). The seedlings were washed with redistilled water three times and cultured in a plastic box filled with half-strength Hoagland’s nutrient solution which was consisted of 5 mmol/L Ca(NO₃)₂, 5 mmol/L KNO₃, 2 mmol/L MgSO₄, 1 mmol/L KH₂PO₄, 0.1 mmol/L EDTA-Fe, 46 mmol/L H₃BO₃, 9.1 mmol/L MnCl₂, 0.32 mmol/L CuSO₄, 0.76 mmol/L ZnSO₄, and 0.5 mmol/L H₂

Cu phytoremediation potential of L. hexandra

Generally, the plants could be successfully applied in phytoextraction should have the following characteristics: rapid growth, high biomass, developed roots, strong heavy metals tolerance and absorption capacity, good metal translocation efficiency from roots to shoots, strong adaptability to the environment, easy agricultural management (Ghosh and Singh, 2005, Seth, 2012, Kuppens et al., 2014). However, there is no plant till now which fully meet the above conditions (Bhargava et al., 2012).

Conclusion

In this study, L. hexandra potential for phytoextraction of copper contaminated soil as well as the ability of agronomic management practices to increase this potential was demonstrated. Three sequential harvests did not affect the above-ground Cu accumulation and biomass production, indicating that more harvests might enhance Cu phytoextraction of L. hexandra. The application of fertilization and IAA could improve biomass yield, increase Cu uptake by above-ground biomass thus increase the

Acknowledgments

This work was supported by the National Natural Science Foundations of China (NO. 51638006, NO. 51608143, NO. 41361085), Guangxi Graduate Education Innovation Project, Guangxi Scientific Experiment Center of Mining, Metallurgy and Environment (KH2012ZD004) and the Guangxi Talent Highland for Hazardous Waste Disposal Industrialization.

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Phytoremediation potential of Leersia hexandra Swartz of copper contaminated soil and its enhancement by using agronomic management practices

Abstract

Introduction

Section snippets

Plant, soil and fertilizer

Cu phytoremediation potential of L. hexandra

Conclusion

Acknowledgments

Chemosphere

J. Environ. Manage.

Biotechnol. Adv.

J. Hazard. Mater.

Plant Sci.

J. Hazard. Mater.

J. Geochem. Explor.

Pedosphere

Ecol. Eng.

Environ. Exp. Botany

J. Hazard. Mater.

Chemosphere

The effect of excess copper on growth and physiology of important food crops: a review

Environ. Sci. Pollut. Res.

Routine Methods for Soil and Agrochemical Analyses

Terrestrial higher plants which hyperaccumulate metal elements: are view of their distribution, ecology, and phytochemistry

Biorecovery

Plant growth regulators-assisted phytoextraction

Biologia Plantarum.

Evaluation of plant growth regulators to increase nickel phytoextraction by alyssum species

Int. J. Phytorem.

Phytoremediation of inorganics: realism and synergies

Int. J. Phytorem.

How phytohormone iaa and chelator edta affect lead uptake by Zn/Cd hyperaccumulator picris divaricata

Int. J. Phytorem.