Biochemical and physiological insights into Lemna minor as a remediator of multi metal–microplastic contaminated waters

Abstract

Aquatic ecosystems face escalating threats from heavy metals (HMs) and microplastics (MPs), which bioaccumulate and disrupt plant physiology, necessitating effective phytoremediation strategies. This study evaluated the impacts of synthetic wastewater (WW at 25%, 50%, 100%) containing Cd, Cr, Cu, Pb, and polyethylene MPs (0.5 g/L, 1 g/L) on Lemna minor in a 42-day hydroponic experiment. Morphological traits declined significantly, with fresh weight reduced by 92.33% and dry weight by 88.04% at 100% WW + 1 g MPs compared to controls. Photosynthetic pigments decreased up to 91.27% in total chlorophyll, while antioxidant enzymes surged (e.g., CAT by 533.18%, SOD by 423.81%). Markers of reactive oxygen species (ROS), such as H₂O₂ and MDA, increased by 108.06% and 154.52%, respectively, alongside HM accumulation exceeding the highest concentration for Cu. These findings elucidate synergistic stress mechanisms, highlighting L. minor potential for hyperaccumulating HM-MP, which informs sustainable wastewater treatment and ecosystem restoration practices.