Bioconcentration of Heavy Metals by Wild Plants Along Holomorphic Soils in Sule-Tankarkar Local Government Area, Jigawa State, Nigeria

Abstract

This study aims at assessing the heavy metals concentration levels in wild plants along the holomorphic soil in Suletankarkar Local Government Area of Jigawa State, Nigeria. Soil and Plant samples were collected from 7 different locations. Two (2) locations each from Danaldi and Danzomo districts while a location each from Dangwanki, Jeke and Suletankarkar districts. A 20cm² quadrant was thrown at random. At each location, soil sample was collected from 0 – 10cm depth and mixed to obtain one composite sample. Samples of all plant species found growing within 1 m radius of each sampling point were collected and preserved in pressed paper. Both Soil and Plant samples were analyzed for heavy metals concentration using Atomic Absorption Spectrophotometer. The results show that; Cd with 3.6 ppm has the highest while Zn with 0.28 ppm has the least concentration in the soil at Danzomo I. The plants have varying concentrations ranging from Pd with 0.04 ppm to Zn with 5.42 ppm in Mitracarpus hirtus; Cr with 0.07 ppm to Zn with 6.42 ppm in Spermacoce radita; Co and Cr both with 0.04 ppm to Mn with 1.47 ppm in Corchonis olitorius. The elemental concentration in the soil at Danzomo II ranges from Co with 0.4 ppm to Cd with 2.75 ppm. In plants, the concentration ranges from Cr with 0.04 ppm to Mn with 1.87 ppm in Cenchrus biflorus; Cr with 0.04 to Mn with 11.8 ppm in Commelina erecta; Cr with 0.04 ppm to Mn with 21.5 ppm in Guiera senegalensis; again Cr with 0.04 ppm to Mn with 3.1 ppm in Cassia singueana. Zn with 0.28 ppm has the least while Mn with 4.0 has the highest elemental concentration value in the soil at Danladi I. The mineral concentration ranges from Cr with 0.04 ppm to Mn with 2.54 ppm in Philliostigma thonningii; Co with 0.04 ppm to Mn with 16.8 ppm in Sida cordifolia; Co and Cr both with 0.04 ppm to Mn with 5.15 ppm in Alysicarpus vaginalis. These results support the conclusion that the heavy metal concentration in all the sampled plants exceeded the WHO standard limit for consumption. Therefore, the authors recommended that the heavy metal concentrations in plants, soils, water and air should be frequently monitored by the appropriate authority in the State.

Keywords: Heavy metals, Concentration, Plants, Soils