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Abstract: The increasing population has subjected rivers and streams to high levels of both industrial and domestic pollution. Significant environmental challenges have been brought about by their effects, particularly with regard to biota, ecosystem processes, soil quality, and groundwater pollution. This study examined the effects of human activity by applying pollution index models to evaluate the input of toxic elements in river sediments. Prior to sediment quality analysis, the total amount of arsenic (As), lead (Pb), cadmium (Cd), mercury (Hg), thorium (Th), and uranium (U) was determined in the concentration range of 1.09–10.0 mg/kg, 8.53–475 mg/kg, 0.12–0.16 mg/kg, 4.85–77.5 mg/kg, 3.14–5.9 mg/kg and 0.93–2.86 mg/kg, respectively. The enrichment factor, contamination factor, pollution load index, and geo-accumulation index revealed alarmingly high levels of Pb and Hg contamination at some sampling points, which are related to possible human input, ranging from severe enrichment to considerable contamination. The low ranges of pollution indices of some toxic elements suggest enrichment through the natural weathering process and atmospheric deposition. The Pearson correlation coefficient revealed a significant correlation between Pb-Fe and As-Fe, suggesting the possibility of acid mine contamination. Continual monitoring of river sediment is essential to minimize the impact of toxic elements to sustain sediment health and quality. [ABSTRACT FROM AUTHOR]

Nickel hydroxide (Ni(OH)2) is a valuable compound derived from nickel, widely utilized across various fields because of its versatile properties. This study aimed to characterize as-prepared β-Ni(OH)2 via chemical precipitation using various analytical techniques. X-ray diffraction (XRD) analysis confirmed the formation of a β-Ni(OH)2 hexagonal crystalline structure, validating the successful precipitation. Fourier-transform infrared spectroscopy (FTIR) spectra exhibited main characteristic peaks of (υOH) and υ(NiO), corresponding to the formation of nickel hydroxide (Ni(OH)2). Subsequently, X-ray photoelectron spectroscopy (XPS) revealed a prominent peak for Ni2+ oxidation, confirming the successful precipitation of nickel hydroxide at pH 6.5, which identifies the existence of impurities, such as chlorine and calcium, from the waste matrix. Scanning electron microscopy (SEM) micrographs demonstrated stratified granules with a nearly pure brucite crystalline phase, typical of β-Ni(OH)2. Furthermore, the surface morphology revealed a coarse texture and uneven clustering, suggesting possible elevated oxide levels on the Ni surface. Energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of nickel (Ni) and oxygen (O), with Ca impurities attributed to the chemical precipitation process. Particle size distribution analysis estimated an average particle size of 2.0 µm. Additionally, the precipitation of nickel was investigated using inductively coupled plasma optical emission spectroscopy (ICP-OES). Ni was observed in decreasing order, 62.7 g/L, 0.8 g/L, and 0.501 g/L in the pregnant leach, precursor solution, and solid precipitate (cake), respectively. The separation of Ni(OH)2 through the precipitation process from the waste (acidic chloride media) enabled efficient recycling and re-use of nickel, which provides a cost-effective and environmentally friendly method for the highly efficient utilization of waste (acidic chloride media). [ABSTRACT FROM AUTHOR]

The research focused on risk assessment of some heavy metals in common vegetables and fish sold on open markets in three towns of Zambia. The mean level of heavy metals ranged as follows (mg/kg): 1.9 to 662.7, 3.0 to 3472.3 and 2.0 to 1698.7 of cadmium (lowest) and aluminium (highest) for samples from Kabwe, Kitwe and Lusaka, respectively. Statistical analysis indicated that the concentrations of samples from Kitwe and Lusaka towns were similar, P > 0.05. However, there were noteworthy differences in the mean amounts of heavy metals in samples from Kitwe and Kabwe, and samples from Kabwe and Lusaka towns, P <.0167. The health risk analysis indicates possible non-carcinogenic and carcinogenic risks to the consumer. This is because the hazard index (HI) for all metals in all samples from all towns was greater than 1 and the cancer risk (CR) for cadmium was above 10−4 in all samples from all towns. [ABSTRACT FROM AUTHOR]