Arsenic range finding phytotoxicity test against ludwigia octovalvis as first step in phytoremediation

Studies were conducted to determine the range of arsenic concentration through a phytotoxicity test on the plant species of Ludwigia octovalvis. Pots contained 3 kg of sand spiked with As salt of sodium arsenate dibasic heptahydrate. Arsenate [As(V)] concentrations were set as 0 mg kg^-1 as control 1 without plant, 0 mg kg^-1 as control 2 with plant, 4, 20, 40, 60 and 80 mg kg^-1. The experiment was carried out for 28 days. The parameters such as pH and temperature in spiked sand were also monitored. The As bioavailability in spiked sand was extracted using Na₂-EDTA method and were determined using Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) Optima 7300DV. Based on the range finding test results, L. octovalvis can survive up to As(V) concentration of 40mgkg^-1, whereas the plant were wilted and dried at 60 and 80 mg kg^-1. The EC₅₀ value for single As(V) phytotoxicity to L. octovalvis was predicted between 40 and 60 mg As kg^-1. Reductions of As(V) bioavailability in spiked sands were calculated as between 13.0±3.3 and 70.4±0.1%. Hence, the next step experiment on a prolonged phytotoxicity test will be based on the value of this As(V) concentration effect.