Seasonal Variation of Soil Chemical Characteristics at Akwuke Long Wall Underground Mined Site, Nigeria

The on-going action and plan to revive old coal mines in Nigeria necessitated a study on the soil chemical characteristics at abandoned coal mine in Akwuke, Enugu State, Nigeria. A single factor experiment was conducted in a randomized complete block design (RCBD) with three replications to obtain information on soil status of Akwuke mined site. Soil samples were collected randomly from ten different sampling points at 0-10, 10-20, and 20-30 cm soil depth in four cardinal points at north (N), south (S), east (E), west (W), and at the center (c) of crest, middle slope, and valley of Akwuke mined site. The samples were analyzed for heavy metals, macronutrient, soil pH, and organic matter content. Soil pH (4.29-6.14) in wet season is higher than 4.14-5.58 in dry season at Akwuke mine site. The values of N, P, K, Ca, and Mg in soil at Akwuke mine were higher in dry season than in wet season. The highest soil organic matter content (0.96±0.04%) at Akwuke mine is obtained in dry season at 0-10 cm valley. The concentrations of Ni, Pb, and Cd in soil at mined site ranged from 4.15±0.07 to 19.81±1.29, 6.11±0.13 to 21.10±0.85, and 0.01±0.00 to 3.06±0.08 mg/kg. Mg (89.60±1.41 to 251.9±1.41 cmol/kg). Cd and Ni in soil at the mined site was higher than their allowable limits in Austria, Germany, France, Netherlands, Sweden, and United Kingdom. The high concentrations of these metals (Cd and Ni) in soils could expose both animals and local inhabitants to high levels of Cd and Ni, thus, posing a serious health risks to the local people.