One method for removing heavy metals or other contaminants from soils or water is through the use of green plants, or phytoremediation. This emerging technique offers the benefits of beingin situ, low cost, and environmentally sustainable. Phytoremediation is defined as the use of plants for removal of environmental pollutants or detoxification to make them harmless.
The objective of this project was to determine arsenic concentration in higher plants growing wild in contaminated area of Bijar County. Also, effects of growth period and contamination intensity were surveyed for remediation of contaminated area. For this way, the plant samples which growing wild in contaminated area were sampled in two seasons (outmen and spring) and arsenic concentration of their shoots were determined. Based on previous information about contaminated area in Kurdistan province and by GPS data, 3 sampling sites with different arsenic concentration (A, B and C) were selected. These sites are located in villages Ali Abad (A with highest Arsenic concentration), Ebrahim Abad (B) and Najaf Abad (C) which site C had very low arsenic concentration and selected as control.
Samples of water, soil and higher plants were collected from these 3 sites in there repeat and transferred to laboratory for arsenic analysis. The arsenic analysis of water, soil and plant samples was performed by hydride generation atomic absorption. About 40 percent of all sampled water (36 sample) had arsenic concentration higher than the WHO drinking water standard 10 ?g/L. The season of sampling (time) had significant effects on arsenic concentration in soil samples, which its concentration in autumn collected samples were 3 time higher than same samples collected in spring. The arsenic concentration of all sampled soil was higher than the WHO soil standard 40 mg/kg.
Only 4 (Astraglus bisnlcatus, Descurainia Sophia, Chenopodium Album and Mentha logifolia) of the 17 plant species sampled had higher arsenic in their leaves. Overall, shoot arsenic concentrations dependent on plant species, total soil arsenic concentrations and season (time) of sampling which variable from 0 to 150 mg/kg. The season of sampling (time) had significant effects on arsenic concentration in plant samples (P<0.05). Arsenic concentration in plant speciesJunicus<Astraglus bisnlcatus<Mentha logifolia were 23.06<49.43<83.75 respectively whereMentha logifolia accumulated highest arsenic grew in C (uncontaminated) site.
Juncushad low ability of arsenic concentration which the highest accumulation was 1.2% by this species in site C. Overall, the ability of plant species collected in spring was higher than those of autumn. In conclusion, arsenic concentration in shoots of plants species, soil samples, shoot to soil ratio and plant biomass showed thatAstraglus bisnlcatus and Mentha logifolia are the best case for arsenic uptake and resistance among all collected plants.