Phytoremediation of Soils Contaminated with Mercury Using Piper marginatum in Ayapel, Colombia

The main problem associated with mining is the release of heavy metals into the environment, impacting the soil and overall environment. Mercury is one of the most contaminating heavy metals. It is present in soils, sediments, surface water, and groundwater. The objective of this research was to evaluate the phytoremediation carried out by the native plant Piper marginatum, in soils contaminated by mercury in an experimental lot in the municipality of Ayapel, where artisanal and small-scale gold mining is carried out. A soil phytoremediation process was carried out at a field scale using the plant species Piper marginatum in a 2.4 ha plot historically contaminated by gold mining, located in Ayapel, Colombia. A completely randomized experimental design was used with nine experimental plots, which were planted with Piper marginatum, and three controls, without planting. Through an initial soil sampling, the physicochemical characteristics and total mercury content in this matrix were determined. Piper marginatum seedlings were planted in the experimental plots and remained in the field for a period of six months. The plant biomass was collected and a final soil sampling was performed for total mercury analysis to determine the total percentage of mercury removal. The results obtained indicated mercury concentrations in soils ranging from 40.80 to 52,044.4 µg kg⁻¹ in the experimental plots and ranged from 55.9 to 2587.4 µg kg⁻¹ in the controls. In the plots planted with Piper marginatum, a 37.3% decrease in total mercury was achieved, while in the plots without planting there was a 23.5% increase. In plants, the average T Hg concentrations in the roots, stems, and leaves were 109.2 µg kg⁻¹, 80.6 µg kg⁻¹, and 122.6 µg kg⁻¹, respectively. An average BCF < 1 and an average TF > 1 were obtained.