Evaluation of the phytoremediation uptake model for predicting heavy metals (Pb, Cd, and Zn) from the soil using Nerium oleander L.

Abstract

The experiment was carried out during two seasons (spring and autumn) of the year 2015, in El-Max (industrial zone) and Antoniadis park (control zone), Alexandria, Egypt. Nerium oleander L. plants has been used in this experiment because of its capability to remediate heavy metals (HMs) from the soil. This study aimed to evaluate the performance of the Phytoremediation Uptake Model (UPM) in predicting the uptake of HMs (lead (Pb), cadmium (Cd), and zinc (Zn)) from the soil. UPM was used to estimate the contribution of various pathways in the remediation of these HMs through different parts, leaves, stem, and root. Besides, it includes soil-root-leaf and soil-leaf pathways and its deposition. The performance of the UPM has been examined using many statistical calculations tools (Person correlation coefficient (R2), root mean square error (RSME %), mean bias error (MB %), and Willmott index of agreement degree (d)). The results showed a high harmony between the UPM predictions and the experiment. Moreover, most R2 values are ranged mostly between 0.97 and 0.99 during the spring and the autumn in the study areas. Therefore, the correlation is very strong between the measured and the predicted HMs concentrations. In addition, the less value of RMSE% (0.13) was obtained in the lower parts of the plant, while the greatest value was observed in leaf model (42.53). Also, the values of MB% were acceptable and within the range between 3.01 and 10.41. In addition, the values of the Willmott index of the agreement were within the acceptable range (0.80 to 0.97). Thus, one may conclude that the UPM has proved a high performance in estimating the uptake and removal of different concentrations of HMs from soil under different spatial and temporal conditions.