Removal of Cadmium from Public Smoking area Soil using indoor Plants and Electrical Grounding

Abstract

Objectives In this study, the absorption of heavy metals in the soil from smoking areas using indoor plants and electrical grounding was investigated to increase the utility of indoor plants for soil decontamination. Methods Soil from plant pots in a smoking area was collected for the experimental plant pot preparations. Some of the prepared pots were connected to electrical ground via an electrode. Kidney beans (Phaseolus vulgaris) were seeded, and their growth were observed. After 30 days of the cultivation, TOC (Total Organic Carbon), and metagenomics profiles in the soil was analyzed. To estimate the behavior of the heavy metals in soil and plants, Cadmium concentrations in the samples were analyzed using ICP-MS (Inductively Coupled Plasma-Mass Spectrometry). Results and Discussion The connection of the electrical ground to the plant pot induced the rapid growth of plant (48.2 ± 2.3% increase in stem growth), compare to the plant in the pot without the electrical ground. TOC analysis showed that the soil from the grounded pots showed the highest value, compared to the control soil (3.08 ± 1.22%), and the soil from the pot without ground connection (2.3 ± 0.1%). The ICP-MS analysis indicated that the plant body in the grounded pot had the highest cadmium concentration at 0.33 ± 0.018 μg/kg. Using the metagenomic analysis, biomineralization related bacterial species (Nocardioides sp., Streptomyces sp., Sphingomonas sp. etc.) were identified from the grounded soil sample. These results suggested that the indoor plant cultivation with the electrical ground connection as an electrical fertilizer enhances the cadmium absorption by plant, exudate secretion from the plant root, and bacterial flora change in the rhizosphere. Conclusion Cadmium in the soil from the smoking area was absorbed by indoor plant with the electrical ground. Therefore, the application of the electrical ground connection (earth) to the electrically insulated outdoor plant pots might enhance the plant growth rate and physiological activity. This application could be a novel soil decontamination method using plants.

Keywords

• soil heavy metal contamination
• electrical grounding
• electrochemical fertilizer
• phytoremediation
• cadmium
• metagenomics