Potential phytoremediation system using macrophyte Limnobium laevigatum to remove in situ Cr from contaminated bottom sediments

The contamination of aquatic environments with heavy metals is an important issue, and in turn, it is crucial to study remediation techniques that can be applied in situ. In this work, the use of a containment system with macrophytes Limnobium laevigatum is explored in the laboratory to evaluate the remotion of Cr in contaminated sediments. The roots of the plants were placed in contact with the bottom sediment through a containment system. The concentration of Cr in macrophyte and sediment samples exposed to different exposure times (1, 4 and 7 days) was determined by laser-induced breakdown spectroscopy technique. The initial concentration of Cr in the sediment was 112 +/- 5 mg/kg and decreased by 65% to the control (p < 0.05) after 24 h of exposure. The removal continued throughout the study time until reaching values of 23 +/- 1 mg/kg. In macrophytes, the Cr concentration increased from 20 +/- 5 mg/kg to 2066 +/- 216 mg/kg after seven days of exposure. The correlation coefficient between Cr concentrations in both matrices was -0.96. Finally, the bioaccumulation factor of Cr in L. laevigatum was 95.22 +/- 8.51. Therefore, the system studied could be a potential tool to remedy the bottom sediments of streams and lakes contaminated with heavy metals in situ.

Automated summary

Contamination of aquatic environments with heavy metals is a significant concern. This study investigated the use of the macrophyte Limnobium laevigatum to remove Cr from contaminated sediments. Results showed high removal efficiency of Cr in the sediment using a containment system with the macrophyte, and significant increase of Cr concentration in the plant. This system has the potential to be an effective tool for remediation of heavy metal-contaminated sediments in situ.