Ability of Alfalfa Plant to Refine Soil Contaminated with Nickel and Lead

In the recent decade, the issue of soil contamination with heavy metals such as nickel and lead is one of the most important environmental problems. According to data from the environmental protection agency, nickel is hazardous at large amounts and a dangerous pollutant and lead is the most important pollutant in the environment. This study was conducted to investigate the soil pollution status of Gachsaran refinery using environmental indicators of pollution coefficient, pollution degree index and modified pollution degree index and to investigate the potential of alfalfa refining plant which is native to Gachsaran region.

From the soil of Gachsaran refinery in 2017 as the center of pollution, were selected four ranges of 0-500 meters, 1000-500 meters, 1500-1000 meters and 2000-1500 meters. In each range, 5 soil samples were taken from a depth of 0 to 30 cm. The ICP-OES device was used to determine heavy metals. Statistical analysis was performed using SPSS software.

The analysis of the environmental indicators of the studied area showed a significant degree of contamination for nickel and a high contamination rate for lead. Comparison of mean concentrations of nickel and lead in cultivated soil samples with alfalfa cultivars showed significant difference with mean nickel and lead concentrations in the studied area.

In general, Alfalfa as a native plant of the region in inappropriate pollution conditions can absorb and extraction nickel and lead from the soil. The final results of this study indicate that ability of alfalfa plant for phytoremediation of nickel in the soil contaminated with petroleum products is higher than that of lead in the Gachsaran refinery.