145 Dynamics of Natural and Built Environments (Posters)

Our communities, economies and infrastructure depend on interactions between the natural and built environments. Engineered systems (e.g. earthworks, structures, utilities) must be resilient to evolving natural forcings, and similarly engineered systems must also minimize negative effects on the natural environment.

Monday, 20 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Assessing the Role of Deep Tilling in the Phytoremediation of Lead and Copper Contamination in Kabwe, Zambia

Paper number: 145-8
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Phytoremediation, the use of plants to clean contaminants from soil, has emerged as a promising strategy for mitigating heavy metal (HM) contamination. However, the effectiveness of phytoremediation can be limited by soil physical and chemical properties. The objectives of this study were to: (1) assess the effectiveness of Tithonia diversifolia and Cymbopogon citratus in phytoremediating HM-contaminated soils, (2) evaluate the effects of deep tilling remediation on phytoremediation efficiency, and (3) investigate the impact of contaminant depths and concentrations microbial communities. The research explores how deep tilling affects the phytoremediation efficiency of these hyperaccumulator plant species in HM-contaminated soils and its effects on soil microbial community composition.

Hyperaccumulator species were planted in a HM-contaminated area of Kabwe at Mines Primary school under deep tilled conditions (11 inches deep) and untilled conditions. Soil and plant samples were collected in January of 2024 and again in May of 2025 to assess HM uptake via calculation of Bioconcentration Factors. Microbial community differences between treatments were investigated by plating samples on nutrient agar and high throughput sequencing.

Following sample collection and analysis, key differences were found across treatments regarding both microbial activity and HM dynamics. Results of this study show that soil microbial activity, including both bacteria and fungi, was the highest in the untilled Cymbopogon citratus soils and lowest in tilled Tithonia diversifolia soils. Soil lead concentrations increased across all treatments over time with the greatest increase observed in tilled Tithonia diversifolia (1071.83 ppm) and the smallest observed in untilled Tithonia diversifolia (606.63 ppm). This same trend occurred with concentrations of copper as the concentration of this HM increased over time in the soil. The largest difference in copper concentrations occurred with untilled Cymbopogon citratus soils (82.6 ppm) and the smallest occurred with both treatments Tithonia diversifolia (35.0 ppm). As for plant tissue lead concentrations, Tithonia diversifolia had the largest concentration whereas both Cymbopogon citratus tilled and untilled had similarly low concentrations of lead. Copper concentrations in plants followed a similar pattern.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412924

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