On-site spectroscopy as a tool for monitoring phytoremediation by ferns of arsenic contaminated water

Arsenic (As) is recognized as one of the main toxicants worldwide. Arsenic in the environment can be due to natural sources such as the weathering of rocks and volcanic material, but its presence is increasing due to anthropogenic activities such as the use of pesticides, industrial waste and smelting. The accumulation of this heavy metal in the biosphere produces serious effects on the environment and health. Nowadays, the removal of As from drinking water to respect the law limit involves high costs filtering systems. Therefore, a low cost and eco-sustainable strategy based on the use of ferns for phytodepuration of As-contaminated groundwater was developed. The aim of this work was to investigate the possibility of monitoring, by spectroscopy working in the Vis–SWIR regions (350 – 2500 nm), the phytoextraction capacity of the hyper-accumulator Pteris vittata fern, hydroponically grown in greenhouse conditions. The proposed approach is non-destructive, being based on the acquisition of spectroscopic data on fern leaves, followed by chemometric analysis. Reflectance spectra were acquired by a portable spectrophotoradiometer (ASD FieldSpec® 4 Standard–Res). Comparative evaluations were then performed analyzing Pteris vittata leaves (fronds) collected from plants grown on both As contaminated and not contaminated water. The achieved results are very promising for the further development of a full on-site scale monitoring of the phytoremediation process.