Evaluation of the Effect of an Industrial Wastewater Sample on Heavy Metals Contaminated Soil

Agricultural and specifically industrial activities have led to the substantial release of toxic heavy metals into the environment posing a major hazard to ecosystem and human health. Today, contamination of soil, groundwater, sediments, surface water and air with hazardous and toxic metal is considered as a serious problem worldwide. In assessment of the risk associated with metal contaminated soils, metal absorption by food chain is one of the major problems. Thus, it is highly important to assess and control metal concentration in industrial wastewater before it isreleased to the natural environments. The presence of heavy metals, such as Ni, Cr, Cu, Cd and Pb, that are phenomenally seen in industrial sawage can be toxic to human and other organisms, even at low concentration. Nowadays, soils in many places have been contaminated with heavy metals and these soils have turned into one of the most important problems specially in disposal areas.
Material and

In this study, in order to investigate the effect of an industrial wastewater on the heavy metals contaminated soil, it was sampled in 4 points and 4 depths including 0-25, 25-50, 50-75 and 75-100 cm, along the soil draine. Soil samples went through a physical and chemical analysis and were assessed for the heavy metal concentration. The electrical coductivity of soil saturation extract was determined by ohm-meter; soil texture was investigated by the Hydrometer method; the lime percentage was detrmined by Titrimetric method; total heavy metals concentration was specified by the acid nitric digestion method; and cation exchangable capacity in soil samples was identified by the Acetate method. Finally, the data analysis was done by SASS.

According to the obtained results and based on the standard limits in agricultural and industrial lands, soil samples were found to be toxic only for Ni, refering to low heavy metal concentration in wastewater samples. Statistical analysis results showed that there is a negative correlation between the soil depth and heavy metal concentration, which refers to low mobility rate of heavy metals specially in soils with a high content of lime and pH.