Investigation of Accumulation of Lead and Cadmium in Mint (Mentha Piperital) and Spinach (Spinacia Oleracea) Under Treated Sewage Sludge

One of the problems caused by the use of stabilized sewage sludge as fertilizer is the uptake of heavy metals by the plant. In the present study, the accumulation of heavy metals of lead and cadmium in the mint and spinach plant species treated with sewage sludge was investigated.

By designing the pilots as control and treated with sludge, plant species of mint and spinach were grown in them. 30 samples were considered from both plants and the concentrations of heavy metals lead and cadmium were measured after harvesting by atomic absorption spectrometry.

The average lead concentration in mint was 0/98 under sludge treatment and 0/043 in control sample, the spinach under sludge treatment was 0/82 and in the spinach control, 0/063. The average concentration of cadmium in mint was 0/58 and in control sample 0/073, in spinach under sludge treatment 2/68 in spinach control sample 0/067 mg /kg.

Comparison of the results with the standards shows that the amount of lead in both plants and in all treatments is lower than the standard value, but the uptake of cadmium in the sludge treatments is higher than the standard. This can be due to the similarity of cadmium to calcium and its greater absorption by the plant. Statistical analysis also showed with 0.99 confidence that there is a significant difference between spinach and mint grown in sludge treatment and control treatment in terms of lead and cadmium concentrations.