Distribution of heavy metals Pb, Cu and Ni in irrigated fields by wastewater of Tehran city, Iran, using Sentinel2 image

Heavy metals pollution is one of the main drawbacks of using wastewater for irrigation. Exploring the pollution of heavy metals in a big area needs frequent experimental measurements, which is mostly time and money consuming. In such a condition, using satellite images and making a relationship between images and heavy metal’s concentration can be a solution for estimating the polluted area. In this study, the image of Sentinell2 satellite was used to evaluate the heavy metals pollution of wastewater irrigated area in south of Tehran. For this aim, 30 soil-surface samples were collected in the area that is irrigated by raw wastewater. After preparing the samples, the concentration of Pb, Cu and Ni was determined using atomic absorption spectroscopy. Then the relation between the heavy metals concentration and reflectance in the bands or the ration of the bands at the corresponded sampling points was determined by applying the stepwise regression method. The developed models were applied on the satellite image for zoning the heavy metals concentrations in the study area. Finally, the accuracy of the developed models was examined by Root-Mean-Square Error (RMSE) and Pearson correlation coefficients. The results showed that the amounts of RMSE for the equations of Pb, Cu and Ni were 1.90, 2.54 and 1.59 respectively while the amounts of R were 0.81, 0.75 and 0.73 for these metals that showed a promising match between predicted and measured results of the models.