Comparative Analysis of Heavy Metals Concentration in Soil and Vegetable (Capsicum annum) Collected from Two Sampling Sites (Farmland and Dumpsite) and the Effect on Plant DNA

Abstract

The levels of heavy metals and their effect on the DNA of Capsicum annuum collected from dumpsite (in Ojota) and farmland (in Badagry) in Lagos, Nigeria, were examined using standard procedures. The results of concentration of heavy metals in the soil for the farmland and dumpsite respectively are: Zn (882.0 ±0.006mg/kg, 14316.8±1.009mg/kg), Cr (2.006 ±0.002mg/kg,3.888± 0.002mg/kg), Cd (0.098 ± 0.001mg/kg, 0.644 ± 0.002mg/kg), Cu (0.206± 0.001mg/kg, 0.997 ± 0.001mg/kg) and Pb (0.005 ± 0.003mg/kg, 0.843± 0.002mg/kg) respectively. The values of N (3153.6± 0.008mg/kg, 4191.2± 0.006mg/kg), P (7598.3 ± 0.009mg/kg, 8794.5 ± 0.003mg/kg) and K (113.56 ± 0.004mg/kg, 532.12 ± 0.004mg/kg) were recorded in the soil from farmland and dumpsite respectively. While the values of N, P, and K in soil from dumpsite were higher (p<0.05) than that from farmland, the only value of Zn in the soil of dumpsite was significantly higher than in soil from farmland. Similarly, the values of all metals except Zn recorded in the leaf, stem, and root of C. annuum showed no significant difference between the sample collected from dumpsites and farmland. The values of Zn in leaf, stem, and root of C. annuum from farmland were significantly higher (p<0.05) than that of the dumpsite.  The DNA bands of the Capsicum annuum from the control site have a clearer band spectrum than that from the dumpsite site, however, there was no DNA mutation. In conclusion, C. annuum collected from both farmland (in Badagry) and dumpsite (in Ojota) contained minerals and heavy metals whose concentrations were still within standard permissible limits. Thus, C. annuum from both sites is safe for human consumption.