Heavy metals in paddy soils and their uptake in rice plants collected along Ogbese River, Southwest Nigeria: Implications for contamination and health risk

Abstract

This investigation was aimed at ascertaining the amount of metals and their absorption in the rice and paddy soils of the Ogbese River in Ondo State,  Nigeria. Forty samples were gathered for this investigation along the River. Every sample was taken using legal international sampling methods.  Additionally, rice crops were gathered in five separate places. Using atomic absorption spectrometer, the values of Zn, Cd, Cu, Pb, and Fe were  determined for each sample. Assessments of the risk of contamination and health problems were performed using reliable models. According to the  findings, the mean amount of Zn, Cd, Cu, Pb, and Fe in the local soils were 4.84, 0.19, 0.25, 1.31, and 397.44 mg/kg, respectively, whereas the  corresponding concentrations in paddy rice grain were 0.35, 0.02, 0.12, 0.02, and 3.25 mg/kg. The bioaccumulation factor (BAF) and transfer factor (TF) of  elements from soils to crops were both 1, indicating that there was no appreciable absorption of metals by plants. Heavy metals in soils had Pollution  Load Index values greater than one, suggesting that the soils were contaminated. In rice grains, the contamination load index of heavy metals revealed  that Cd had values >1 in 80% of the samples. This demonstrated that Cd was a significant rice contaminant in the area. Children's Zn, Cd, Cu, Pb, and Fe  Targeted Health Quotient (THQ) readings were all less than 1, suggesting that they were not exposed to any noncarcinogenic health problems. THQ for  adults were less than 1 for Zn, Cd, Cu, and Pb, but > 1 for Fe. Adults may get non-carcinogenic health problems if they ingest too much Fe in the grains. To  avoid any health problems brought on by their use, it is advised that heavy metals in the soil and rice grains in this region be routinely examined.