Influence of Anthropogenic Pollution on Soil and Plants of Gosa Dumpsite, Abuja, Nigeria

Despite increased awareness of the causes of environmental pollution, it continues to pose a serious threat to both developed and developing countries worldwide. The Gosa dumpsite in Abuja serves as a receptacle for various waste materials from both high and low-income areas of the metropolis. Surprisingly, peri-urban farmers residing in the vicinity still cultivate edible crops on this polluted land. This study aims to assess the impact of waste dumping at Gosa dumpsite on selected soil properties and the uptake of heavy metals by plants. In order to achieve this objective, soil and plant samples were collected from established 5 x 5 m2 quadrants during the early and late dry as well as rainy seasons of 2019 and 2020. The collected samples underwent analysis using standard methods to determine their physical and chemical properties. Additionally, the study identified the dominant plant species within the dumpsite through standard methods. The findings revealed that the dumpsite soil exhibited characteristics of loamy sand, with the highest pH value of 8.85 ± 0.90 recorded during the dry season of 2020. Other significant soil results included total nitrogen at 1.09 ± 0.64 g kg-1, organic carbon at 9.88 ± 0.10 g kg-1, Cd at 11.93 ± 2.25 mg kg-1, Hg at 2.18 ± 1.08 mg kg-1, and Pb at 54.68 ± 8.68 mg kg-1, all of which were observed during the early rainy season of 2020. During the remaining seasons considered, lower values were obtained. Notably, these values exceeded the permissible levels set by the FAO for soil intended for cultivating edible crops. Furthermore, the plant species Ageratum conyzoides demonstrated the highest uptake of heavy metals, with concentrations of 4.47 ± 1.15 mg kg-1 for Cd, 1.77 ± 1.08 mg kg-1 for Hg, and 19.56 ± 4.83 mg kg-1 for Pb, all recorded during the early dry season of 2020. In conclusion, although the Gosa dumpsite in Abuja may appear fertile enough for cultivation, the study's results highlight that it cannot be deemed suitable for the production of edible crops. The presence of heavy metals and other pollutants in the soil poses a significant risk to crop health and, consequently, to human consumption.