Session: Government Agency Student Posters

Paper Number: 172890

Influence of Soil Texture on Heavy Metal Uptake by Vetiver Grass (Chrysopogon Zizanioides) From Leachate-Impacted Soils 

The uncontrolled infiltration of landfill leachate into terrestrial environments remains a persistent environmental concern, especially in areas lacking engineered containment systems. Landfill leachate often contains high concentrations of toxic heavy metals such as chromium (Cr) and nickel (Ni), which pose significant risks to soil health, groundwater quality, and ecological balance. This study investigates the phytoremediation potential of Vetiver grass (Chrysopogon zizanioides) to remove Cr and Ni from landfill leachate-contaminated soils, with a specific focus on how soil texture—sandy versus clayey—influences contaminant mobility, plant uptake, and retention mechanisms. The research aims to advance the scientific understanding of substrate-dependent phytoremediation by combining experimental, chemical, and microstructural analyses.

Vetiver plants were first propagated hydroponically to establish uniform root systems and then transplanted into cylindrical planters filled with either sandy or clayey soils, which were characterized through particle size distribution and Atterberg limit tests. After a one-month acclimation period, each planter received 2 liters of municipal landfill leachate, which had a pH of 8.12. Soil pH measurements taken before and after contamination showed an increase from 6.07 to 7.43 in sandy soil and from 7.29 to 7.68 in clayey soil, indicating the buffering influence of leachate and its potential effect on heavy metal solubility. Soil samples were collected at three phases: one month before contamination (baseline), immediately after leachate application, and one month after contamination to assess remediation. Heavy metal concentrations in soil and plant tissues were quantified using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), while Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM/EDX) was used to investigate root microstructure and localized metal accumulation.

Leachate analysis revealed that nickel (0.42 mg/L) and chromium (0.09 mg/L) were present in the highest concentrations among the tested heavy metals, warranting focused remediation efforts. In sandy soil, Cr and Ni concentrations increased from 11.5 to 24.7 mg/kg and 4.6 to 7.3 mg/kg, respectively, post-contamination, and then decreased to 14.1 mg/kg and 4.4 mg/kg after one month of Vetiver growth. In clayey soil, Cr and Ni increased from 49.5 to 81.2 mg/kg and 21.4 to 36.5 mg/kg, respectively, then declined to 46.7 mg/kg and 23.8 mg/kg, indicating more substantial retention and uptake. Vetiver root analysis showed that plants grown in clay accumulated more heavy metals in their roots compared to sandy soil: chromium uptake reached up to 23.2 mg/kg in clay (Clay 3) versus 9.68 mg/kg in sand (Sand 3), and nickel uptake peaked at 52.44 mg/kg in clay versus 31.76 mg/kg in sand. In contrast, shoot analysis revealed higher translocation of metals in sandy soils, where mean Cr and Ni concentrations were approximately 27.6 mg/kg and 33.1 mg/kg, respectively, compared to 17.2 mg/kg and 20.5 mg/kg in clayey soil shoots. This contrast suggests that sandy soils promote greater metal mobility and translocation to aerial parts, whereas clayey soils enhance retention near the root zone, favoring stabilization.

SEM micrographs confirmed significant anatomical differences in Vetiver roots grown under different soil textures. Roots in sandy soil appeared more porous and had thinner cortical layers, potentially allowing faster water and metal movement. In contrast, roots in clayey soil displayed thicker epidermal layers and denser vascular bundles, which may act as a barrier to metal translocation and facilitate retention within the root zone. EDX mapping further confirmed that Cr and Ni were predominantly localized in the outer cortex of roots, especially in clayey samples. Additionally, the pH increase following leachate application likely influenced the speciation and availability of metals, with the higher cation exchange capacity of clay maintaining greater metal bioavailability compared to sand.

Altogether, these findings demonstrate that Vetiver grass is a viable and effective phytoremediation candidate for landfill leachate-contaminated environments. The performance of the plant is strongly influenced by soil texture, with sandy soils favoring phytoextraction via shoot translocation, and clayey soils enhancing phytostabilization by retaining metals in root tissues. The observed root structural adaptations suggest a physiological response that improves metal handling under different substrate conditions. This work contributes to the advancement of phytoremediation science by elucidating the influence of soil-plant interactions on heavy metal dynamics and highlights the potential of Vetiver grass as a scalable, cost-effective remediation tool. Future studies should explore longer-term uptake cycles, field-scale applications, and the integration of microbial-assisted processes to further enhance remediation outcomes.

Presenting Author: Anika Mahzabin Jackso State University

Presenting Author Biography: Anika Mahzabin <anika.mahzabin@students.jsums.edu>
Attachments
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to Audrika

Ms. Mahzabin has completed her Bachelors in Water Resources Engineering from BUET(Year 2021).Then she started working in the field of water resources, groundwater modeling & hydrological modeling since April,2021 at a renowned research organization in Bangladesh named CEGIS (Centre of Environmental and Geographic Information Services).She has received training on Groundwater resources management,monitoring & modeling, Introduction & Application of Remote sensing during her professional life in CEGIS.Later in 2023 she joined in a UK based software company named Indetechs Software Ltd. She worked for 8 months in the company on domain of different environmental solutions softwares. From 2024 Spring semester she joined Civil Engineering Department of Jackson State University in the United States of America. She is a Masters student at JSU and also a Graduate Research Assisstant at CREATE Lab. She is currently working with Phytoremediation and solute transport modelling.

Authors:

Anika Mahzabin Jackso State University
Sadik Khan Jackson State University
Subrata Chandra Roy Jackson State University
Kiyan Sorgog Jackson State University
Saiful M. Islam Jackson State University