Phytoremediation Potential, Photosynthetic and Antioxidant Response to Arsenic-Induced Stress of Dactylis glomerata L. Sown on Fly Ash Deposits

Arsenic (As) from coal fly ash can be released into soil/groundwater, presenting a global threat to the environment and human health. To overcome this environmental problem, phytoremediation represents an urgent need, providing 'green' cleanup of contaminated lands. The present study focused on As concentrations in fly ash and plants, evaluation of phytoremediation potential of Dactylis glomerata sown on fly ash deposits together with its photosynthetic activity, and oxidative and antioxidative response to As stress. Field research was carried out on fly ash deposits at the thermal power plant "Nikola Tesla", Obrenovac (TENT-A, Serbia) and the control site. Fly ash is characterized by alkaline pH reactions, small amounts of organic matter, a large amount of available phosphate, and total and available As concentrations. Results in this study indicate that phosphate application can ameliorate As toxicity, uptake and root-shoot transport. Furthermore, D. glomerata can be considered as good As phytostabilizator, because it retains more As in roots than in leaves. Excess As in leaves decreases photosynthetic efficiency (Fv/Fm) and concentrations of chlorophylls, carotenoids, and anthocyanins, whereas high content of malondialdehyde (MDA) can be a signal for biosynthesis phenolics and ascorbic acid, providing cellular redox homeostasis and recovery of photosystem II (PSII) photochemistry. In the roots, low oxidative stress under high concentrations of As is related to intense antioxidant biosynthesis. Taken together, the results in this study indicate a high adaptive potential of D. glomerata to As stress. These findings may suggest that physiological and metabolic tools can be used as a way forward in the 'real field' scenario, phytomanagement of fly ash and ecosystem services providing sustainable phytoremediation of As-contaminated sites around the globe.

Keywords: Arsenic; Dactylis glomerata; adaptation; fly ash; metabolites; oxidative stress; photosynthesis; phytoremediation.