Physico-chemical Properties and Heavy metal Contamination Levels of Soils from Riruwai Mining Area, North-western Nigeria

This study was aimed to investigate the physico-chemical properties and heavy metals contamination levels of the soils around Riruwai mining area, North-western Nigeria. A total of 60 surface soil samples from four (4) sampling sites which include 18 from active mine sites, 12 from abandoned mine sites, 21 from farmlands and 9 from control site were collected during the dry and rainy seasons. The physico-chemical properties (pH, Electrical conductivity, soil organic matter and cation exchange capacity) were determined using various analytical techniques. The concentrations of heavy metals were analysed using Microwave Plasma Atomic Emission Spectrometer (MP-AES) and the measured concentrations were used to evaluate the pollution load index (PLI). The findings of the study indicated that mining activities had a significant impact on the physicochemical properties of the soils. The levels of arsenic, cadmium, chromium, mercury, manganese, nickel, lead and zinc are in the range of 13.40-35.23, 0.91-13.50, 59.52-116.05, 0.01-1.01,115.19-314.49,11.04-26.04, 43.11-245.00 and 135.09-1653.40, and 7.62-29.12, 0.07-11.61, 38.50-96.24, 0.01- 0.35, 114.5-256.00, 7.34 to 24.43, 39.07-237.00 and 115.30-1394.56 during the dry and rainy seasons respectively. Except for mercury, chromium, manganese and nickel, all the heavy metals were above the recommended maximum limit set by FAO/WHO (2011) in both seasons. The PLI values indicated that the soils in active and abandoned mining sites are strongly polluted by heavy metals, while farmland soils are moderately polluted, and control site soils were unpolluted. The soils in the study area are significantly contaminated by heavy metals, particularly in active and abandoned mining sites and the contamination had slightly spread to farmland, suggesting a significant need for proper containment of heavy metals pollution levels in the area especially arsenic, cadmium, lead and zinc. &nbsp

Speciation of Potentially Toxic Metals from the Mine Impacted soils: A Case Study of Riruwai Mining Area, Kano State, Northern Nigeria

Mining and smelting sectors contribute significantly to global growth on a regional and local scale. However, the operations are causing significant environmental damage, particularly pollution of the soil with potentially toxic metals (PTMs).  In this study, the speciation of PTMs (arsenic, cadmium, chromium, mercury, manganese, nickel, lead and zinc) from the mine impacted soils of Riruwai mining area was investigated using a modified Tessier sequential extraction method. The findings of the study revealed that all the PTMs examined are considerably associated with non-residual fractions in all the sampling locations. This indicates that all the PTMs investigated in the study area may be highly mobile in the soils and hence potentially toxic. The concentrations of PTMs in the soil’s geochemical fractions were found to vary with the sampling locations, with active mining sites significantly (p ≤ 0.05) recording the highest value, followed by farmland, while the lowest value was reported at the control site. Therefore, to protect the environment and the health of the local populace, PTMs in the soils of the study area should be regularly monitored and a treatment program should be put in place

Heavy Metals Contamination Levels in the Vegetables Grown around Riruwai Mining Area, Kano State, Nigeria

Vegetables grown in mining areas can accumulate significant amounts of heavy metals (HMs), which can cause serious developmental disorders and have long-term negative effects on public health. In the present study, the HMs contamination level in vegetables grown around the Riruwai mining area in Kano State, Nigeria, was investigated. Fifteen (15) vegetable samples were collected, including lettuce (Lacuta sativa L.), tomato (Solanum lycopersicum L.), and bean (Phaseolus vulgaris L.), as well as their corresponding soils. The levels of As, Cd, Cr, Hg, Mn, Ni, Pb, and Zn in all the samples were determined using Microwave Plasma Atomic Emission Spectrometry, and the measured concentrations were used to calculate the bioaccumulation factor (BAF). The results of the study revealed that HMs concentrations in the investigated vegetables were found to be significantly high, with the majority of levels exceeding the WHO/FAO (2007) recommended limit, and the concentration of HMs in the soil decreased in the order of Zn > Mn > Cr > Pb > As > Ni > Cd > Hg, with As, Pb, and Zn exceeding the WHO/FAO (2001) recommended limit. Pollution levels were found to significantly differ between HMs and vegetable types. BAF results revealed that cadmium is an accumulator of all the studied vegetables (BAFs > 1), while mercury was found to be an accumulator of L. sativa. Higher concentrations of these metals in vegetables and soil, particularly arsenic, cadmium, lead, and zinc, necessitate immediate scientific attention and further research to determine the optimum concentration required for human health. Planting of vegetables for human and animal consumption should be stopped until this is accomplished