Potential ecological risk, in-situ phytoextraction potential of Lycopersicon esculentum, and pollution indices of selected toxic metals in Hausawan - Kaba, Kano State, Nigeria

Abstract

Anthropogenic pollution due to inappropriate treatment of agricultural and industrial waste has been posing an ecological threats worldwide. However, an increasing pressure and demand for sustainability in farming, brought about the use of many hazardous chemicals and industrial wastes, such as the use of tannery sludge as an effective organic manure. This study was initiated as a follow up investigation to assess the potential ecological risk; the level of metal pollution in soil and Lycopersicon esculentum (L. esculentum) and its potentiality for in-situ phytoextraction in Hausawan - Kaba, Kano State, Nigeria. The suspected sludge, soil and plants grown in three different farms; farmland-1, farmland-2, and farmland-3 (control) in the study area were collected. The concentration of Chromium (Cr), Cadmium (Cd) and Lead (Pb) were spectrophotometrically detected. In addition, Bioaccumulation Factors (B.F), Pollution Index (P.I), Ecological Risk Index (ERI) and Potential Ecological Risk (PER) index of metals in three different sampling sites were calculated. The results indicated that PER value and concentration of metals in soil from farmland-1 is higher than that of farmland-2 and control site. Cd was observed to be the major contributor of ERI and had the highest average concentration in soil and plant samples. The results also showed that properties of soil such as pH, Cation Exchange Capacity (CEC), and organic matter content influenced the metal concentrations. Bioaccumulation Factor (B.F) > 1 observed for the plants manifested their phytoremediation potential. Therefore, the study concluded that based on the PER analysis, the study area is a potentially “low ecological risk” environment and the L. esculentum has a great potential to uptake large quantity of Cd, Pb and Cr in its root system; translocate to shoots and can be evidently used as hyperaccumulator for in-situ phytoextraction when cultivated in a soil contaminated with either Cr, Cd and/or Pb.