Phytoremediation macroscopic modeling of Ni-polluted soil based on linear and non-linear reduction function

Remediation of heavy metals polluted soils by physical and chemical methods requires large investments and complicated technologies. Phytoremediation is a relatively new technology that employs plants to decontaminate soils، water، sediments and atmosphere. This technology، compared to other technological approaches، is an environmental-friendly، easy to use and inexpensive method. Modeling Phytoremediation process is needed for further understanding the governing process and also to manage the contaminated soils. The objective of this study was to present a macroscopic phytoremediation model for of Ni-Polluted Soil. For this purpose، a new formulation was derived based on soil and plant responses to Ni pollutants. This approach assumes that relative yield reduction function can resemble the total Ni concentration in the soil. Combining the related functions of soil and plant responses to soil Ni concentrations، the phytoremediated amounts of Ni were predicted. In order to verify the proposed models، large quantities of soil was thoroughly polluted with Ni. After achieving soil and pollutants equilibrium، the contaminated soils were then carefully packed into pots. Upland Cress (Lepidum sativum) seeds were germinated in these pots. The Ni of soil samples and plant materials were extracted by 4M HNO3 oxidation and wet oxidation methods، respectively. Ni concentrations in the soil extracts and plant digestion were measured by Atomic Absorption Spectrometer (Shimadzu، AA 670-G) and Inductively Coupled Plasma Optical Emission Spectrometry (Varian Vista-PRO). The results indicated that relative yield reduction function followed a non-linear reduction trend. The results indicated that the proposed model for quantifying Ni concentration in plant can simulate the experimental data well (R2>0. 93(. The results also indicated that combining the non-linear relative yield reduction function and the proposed power model for Ni concentration in plant، provides a reasonable performance to predict Ni phytoremediation (R2>0. 93).