TOXICOLOGICAL ASSESSMENT OF CARBON NANOMATERIALS ON LEMNA MINOR L.: INSIGHTS INTO PHYSIOLOGICAL AND BIOCHEMICAL ALTERATIONS

Synthetic carbon-based nanomaterials, such as multi-walled carbon nanotubes (MWCNTs), carboxyl-functionalized nanotubes (MWCNTs-COOH), and fullerene soot, are increasingly being utilised in practical industrial and agricultural applications. This reality raises concerns about their potential unfavourable ecotoxicological impact on aquatic ecosystems where they may accidentally end up. In this context, the present research aimed to evaluate several physiological and biochemical responses of plants belonging to the species Lemna minor L. when interacting with these types of nanomaterials, experimentally added at two concentrations (50 and 200 mg/L) to their culture medium over a 14-day cultivation period. The results obtained demonstrated the appearance in the test plants of functional effects dependent on the dose and nature of the tested nanomaterial, reflected by significant changes in photosynthetic performance (decreases in the content of photo-assimilatory pigments and the efficiency of photosystem II), as well as by the activation of biochemical markers of oxidative stress (increases in the content of flavonoids and polyphenols, changes in POD and SOD activities). The functionalized nanotubes (MWCNTs-COOH) induced the most pronounced biochemical responses, while fullerene soot had more moderate effects, possibly due to its reduced bioavailability in the cultivation media. The results highlight the sensitivity of Lemna minor to chemical stress generated by synthetic carbon-based nanomaterials present in the cultivation medium, thus confirming its usefulness as a model organism in ecotoxicological studies and emphasising the need for rigorous assessments regarding the potential impact of these nanomaterials on aquatic plants in natural ecosystems, to lay the groundwork for responsible ecological management strategies.