Phyto-remedial detoxification of arsenic by Pistia stratiotes and assessment of its anti-oxidative enzymatic changes

Abstract

Arsenic (As), a major groundwater contaminant has gained attention as a surface water pollutant, due to its deposition on agricultural fields and nearby waterbodies as a result of over usage of groundwater. Several plants have the unique ability to phyto-remediate and accumulate As but differ in their potential. The present study focuses on removal of arsenic by Pistia stratiotes exposed to 10, 50, 100, and 200 ppb of As (As₂O₃), and simultaneous anti-oxidative changes in plants facilitating arsenic tolerance in these aquatic macrophytes. The removal percentage rate of As was found to decrease with the increase in initial As levels in the hydroponic solution over an experimental period of 28 days. The maximum removal percentage was obtained at the 10 ppb As level (61.42%). Changes in concentration of anti-oxidative enzymes, i.e., catalase, ascorbate peroxidase and guaiacol peroxidase, were measured over intervals of 7 days. Significant changes were observed in activities of catalase, guaiacol peroxidase, and ascorbate peroxidase with highest catalase activity on 28th day at 200 ppb As concentration. Ascorbate peroxidase activity varied over 28-day period with increased activity from seventh day. Activity of guaiacol peroxidase showed the same trend as ascorbate peroxidase. The present research work highlights the assessment of anti-oxidative enzymatic changes in Pistia stratiotes due to As exposure and uptake.

Keywords:

• Arsenic
• oxidative stress
• phyto-remediation
• pistiastratiotes
• reactive oxygen species

Acknowledgement

Authors acknowledge the help of School of Environmental Studies (SOES), Jadavpur University. Financial supports from SOES, Jadavpur University and Inter University research project are highly acknowledged.