Phytoremediation of Contaminated Sites to Produce Feedstock for Sustainable Biofuels

YOUNG, B; HRUBY, S; HEREDIA, B; RIZZO, P; PACHECO, P; VILLAVICENCIO, S; ESCUDERO, E; ROQUEIRO, G

Congreso; SETAC North America 44th Annual Meeting; 2023

Adverse effects on human and wildlife health by exposure to mining waste havegenerated public and scientific concern. Abandoned mines cause environmentalpollution due to changes in the landscape and the persistence of metals. The goal of thisstudy was to assess the degree of soil pollution caused by mining waste and to evaluatedifferent strategies to (phyto)remediate it to achieve long-term ecosystem restorationworking together with the community of La Planta town. Since 2013, our research teamhas evaluated the occurrence of metal(loids) and the physicochemical properties in soil,vegetal diversity and cover, ecotoxicological effects using aquatic and terrestrialorganisms, and the perception level of the peasant community that inhabits thesurroundings of the site. A contamination plume was detected up to 2.1 km away andcorrelated with the concentration of several metal(loids), pH, conductivity, toxicity,vegetal diversity and soil cover. The most contaminated site was located in the dischargepoint of the abandoned treatment plant which was characterized by acidic pH (2.7), highconductivity (42.9 mS/cm), and high concentration of Pb (450), Cu (826), Cd (19), Zn(2227), Mn (707) and As (2383 mg/kg). A sensitivity distribution profile showed that52% of the endpoints had values of EC50 less than 1%. Using a combination transects infield and satellite images, a decrease of 50% in plant richness (13 spp.) and 70% invegetation cover (bare soil=42%) were found (Shannon index=0.02). As an outcome,four native trees and shrubs were identified as potential bioaccumulator plants. A seriesof surveys and workshops carried out with the peasant community allowed a successfulexchange of knowledge in social, economic and environmental aspects. Afterremediation trials, a combination of soil with 5% compost and 18% dolomite allowed toincrease the pH, organic matter and nutrients, and reduce the metal availability andtoxicity. Chronic exposure of the four native plants to amended soil demonstrated theirsuccessful ability to grow and phytoextract metal(loids). Two ongoing experimental 500m2-plots were installed and are being monitored together with the community. Plantsare growing faster in the less contaminated plot (1-y). Therefore, this socio-environmental study shows the ability to long-term articulate between interdisciplinaryand inter-institutional research groups together with a peasant community throughouta restoration process of the ecosystem.