http://41.89.205.12/handle/123456789/171 Sat, 18 Apr 2026 13:51:14 GMT 2026-04-18T13:51:14Z http://41.89.205.12/handle/123456789/2845 Evaluation of Selected Heavy Metals in Indoor Dust and Interior Painted Walls of Nursery Schools in Nairobi County, Kenya Ondoo, Kevin Omondi; Ogilo, Joel Klement; Onditi, Anam Ouma; Salim, Ali Mohammed; Magero, Denis; Pembere, Antony School playgrounds found in painted environments have become death chambers for millions of innocent children who unknowingly ingest toxic metals. The objective of this study is to determine the levels of the heavy metals in paint chips from painted interior walls and indoor dust samples from 14 selected nursery schools in Nairobi County. The paint chips and indoor dust samples collected were digested using the Environmental Protection Agency method SW846 3050B then analyzed using Flame Atomic Absorption Spectrometry. Iron (Fe) had the highest concentrations in both the paint chip from interior walls and the indoor dust while Cadmium (Cd) had the lowest concentration followed by Chromium (Cr), Lead (Pb) and Zinc (Zn) respectively. 50% of the nursery schools had Lead (Pb) concentrations that exceeded the 90 µg/g limit set by KEBS. For Cadmium (Cd) and Chromium (Cr), the concentration in the nursery schools and the indoor dust was below the 200 µg/g used in Germany. Generally, the correlation between the various metal pairs for the samples analyzed showed a non-significant correlation with exception of Lead - Iron (Pb-Fe) and Chromium - Cadmium (Cr-Cd) for the indoor dust samples from pre-schools. The t-tests carried out show that levels of the heavy metals in the paint chip did not differ significantly with the levels in the indoor dust for nursery schools at 95% confidence level. School playgrounds found in painted environments have become death chambers for millions of innocent children who unknowingly ingest toxic metals. The objective of this study is to determine the levels of the heavy metals in paint chips from painted interior walls and indoor dust samples from 14 selected nursery schools in Nairobi County. The paint chips and indoor dust samples collected were digested using the Environmental Protection Agency method SW846 3050B then analyzed using Flame Atomic Absorption Spectrometry. Iron (Fe) had the highest concentrations in both the paint chip from interior walls and the indoor dust while Cadmium (Cd) had the lowest concentration followed by Chromium (Cr), Lead (Pb) and Zinc (Zn) respectively. 50% of the nursery schools had Lead (Pb) concentrations that exceeded the 90 µg/g limit set by KEBS. For Cadmium (Cd) and Chromium (Cr), the concentration in the nursery schools and the indoor dust was below the 200 µg/g used in Germany. Generally, the correlation between the various metal pairs for the samples analyzed showed a non-significant correlation with exception of Lead - Iron (Pb-Fe) and Chromium - Cadmium (Cr-Cd) for the indoor dust samples from pre-schools. The t-tests carried out show that levels of the heavy metals in the paint chip did not differ significantly with the levels in the indoor dust for nursery schools at 95% confidence level. Sun, 01 Jan 2023 00:00:00 GMT http://41.89.205.12/handle/123456789/2845 2023-01-01T00:00:00Z http://41.89.205.12/handle/123456789/2844 Assessment of Water Quality and Heavy Metal Pollution in River Ndambuk, Busia County, Kenya Magero, Denis; Meng’wa, Victor; Ondoo, Kevin Omondi; Pembere, Antony M. S.; Wanakai, Sammy This study's objective is to determine how polluted the Ndambuk River in Busia County, Kenya, is with heavy metals and other physico-chemical parameters throughout both the dry and wet seasons. In every test point during the dry and wet seasons, turbidity was greater than the WHOrecommended threshold of 5 NTU. At sampling points 5, 6, and 7 during both seasons, pH was over the WHO-recommended limit of 6.5 to 8.5; this can be attributed to mining activities along the Kenya-Uganda border. All the sampling stations during the dry and wet seasons had levels of Lead, Cadmium, Cobalt, Nickel, and Iron that were higher than the WHO-recommended limits. At sampling points 1, 2, and 4 during the dry season and at sampling point 2 during the wet season, Chromium concentrations were, however, below the WHO standards. The significant correlation between the heavy metals suggests that metal-metal complexes are present in solution. The strong correlation between the metals, electrical conductivity, total dissolved solids and turbidity suggests that anthropogenic activities have increased, particularly in the downstream agricultural and mining areas. This study suggests further research into the relationship between land use and heavy metal pollution, regulation of mining activities along the Kenya-Uganda border and correct agricultural practices to prevent soil erosion. This study's objective is to determine how polluted the Ndambuk River in Busia County, Kenya, is with heavy metals and other physico-chemical parameters throughout both the dry and wet seasons. In every test point during the dry and wet seasons, turbidity was greater than the WHOrecommended threshold of 5 NTU. At sampling points 5, 6, and 7 during both seasons, pH was over the WHO-recommended limit of 6.5 to 8.5; this can be attributed to mining activities along the Kenya-Uganda border. All the sampling stations during the dry and wet seasons had levels of Lead, Cadmium, Cobalt, Nickel, and Iron that were higher than the WHO-recommended limits. At sampling points 1, 2, and 4 during the dry season and at sampling point 2 during the wet season, Chromium concentrations were, however, below the WHO standards. The significant correlation between the heavy metals suggests that metal-metal complexes are present in solution. The strong correlation between the metals, electrical conductivity, total dissolved solids and turbidity suggests that anthropogenic activities have increased, particularly in the downstream agricultural and mining areas. This study suggests further research into the relationship between land use and heavy metal pollution, regulation of mining activities along the Kenya-Uganda border and correct agricultural practices to prevent soil erosion. Sun, 01 Jan 2023 00:00:00 GMT http://41.89.205.12/handle/123456789/2844 2023-01-01T00:00:00Z http://41.89.205.12/handle/123456789/2842 Test of the Orbital-Based LI3 Index as a Predictor of the Height of the 3MLCT →3MC Transition-State Barrier for [Ru(N∧N)3]2+ Polypyridine Complexes in CH3CN Ala, Aldin M. H. M. Darghouth; Magero, Denis; Casida, Mark E. Ruthenium(II) polypyridine compounds often have a relatively long-lived triplet metal–ligand charge transfer (3MLCT) state, making these complexes useful as chromophores for photoactivated electron transfer in photomolecular devices (PMDs). As different PMDs typically require different ligands and as the luminescence lifetime of the 3MLCT is sensitive to the structure of the ligand, it is important to understand this state and what types of photoprocesses can lead to its quenching. Recent work has increasingly emphasized that there are likely multiple competing pathways involved, which should be explored in order to fully comprehend the 3MLCT state. However, the lowest barrier that needs to be crossed to pass over to the nonluminescent triplet metal-centered (3MC) state has been repeatedly found to be a trans dissociation of the complex, at least in the simpler cases studied. This is the fourth in a series of articles investigating the possibility of an orbital-based luminescence index (LI3, because it was the most successful of three) for predicting luminescence lifetimes. In an earlier study of bidentate (N∧N) ligands, we showed that the gas-phase 3MLCT → 3MC mechanism proceeded via an initial charge transfer to a single N∧N ligand, which moves symmetrically away from the central ruthenium atom, followed by a bifurcation pathway to one of two 3MC enantiomers. The actual transition state barrier was quite small and independent, to within the limits of our calculations, of the choice of ligand studied. Here, we investigate the same reaction in acetonitrile, CH3CN, solution and find that the mechanism differs from that in the gas phase in that the reaction passes directly via a trans mechanism. This has implications for the interpretation of LI3 via the Bell-Evans–Polanyi principle. Ruthenium(II) polypyridine compounds often have a relatively long-lived triplet metal–ligand charge transfer (3MLCT) state, making these complexes useful as chromophores for photoactivated electron transfer in photomolecular devices (PMDs). As different PMDs typically require different ligands and as the luminescence lifetime of the 3MLCT is sensitive to the structure of the ligand, it is important to understand this state and what types of photoprocesses can lead to its quenching. Recent work has increasingly emphasized that there are likely multiple competing pathways involved, which should be explored in order to fully comprehend the 3MLCT state. However, the lowest barrier that needs to be crossed to pass over to the nonluminescent triplet metal-centered (3MC) state has been repeatedly found to be a trans dissociation of the complex, at least in the simpler cases studied. This is the fourth in a series of articles investigating the possibility of an orbital-based luminescence index (LI3, because it was the most successful of three) for predicting luminescence lifetimes. In an earlier study of bidentate (N∧N) ligands, we showed that the gas-phase 3MLCT → 3MC mechanism proceeded via an initial charge transfer to a single N∧N ligand, which moves symmetrically away from the central ruthenium atom, followed by a bifurcation pathway to one of two 3MC enantiomers. The actual transition state barrier was quite small and independent, to within the limits of our calculations, of the choice of ligand studied. Here, we investigate the same reaction in acetonitrile, CH3CN, solution and find that the mechanism differs from that in the gas phase in that the reaction passes directly via a trans mechanism. This has implications for the interpretation of LI3 via the Bell-Evans–Polanyi principle. Wed, 01 Jan 2025 00:00:00 GMT http://41.89.205.12/handle/123456789/2842 2025-01-01T00:00:00Z http://41.89.205.12/handle/123456789/2840 Assessment of Selected Physico-Chemical Parameters of Waste Water from a Gold Mine in Alupe Sub-County, Busia County, Kenya Magero, Denis; Ondoo, Kevin Omondi; Meng’wa, Victor; Wanakai, Sammy The rise in cost of living and unemployment in the Sub – Saharan Africa has witnessed the rise of both small scale and large-scale mining activities; putting more economic pressure on families to increase their daily income. This economic hardship has led to the search for precious metals like gold and gemstones, resulting in environment degradation as mining involves digging deep into the Earth’s crust in search of these minerals. This study sought to investigate the physico-chemical characteristics of wastewater from the Alupe gold mine in Busia County, Kenya. The five physical parameters investigated include: temperature, electrical conductivity, pH, turbidity and total dissolved solids. The heavy metals under investigation were: Cr, Cd, Pb, Cu, Fe, Co, Zn and Ni. Among the physical parameters, only pH and turbidity recorded values beyond the WHO permissible levels, while all heavy metals recorded values that were beyond the WHO permissible levels. Strong correlation was registered by EC – temperature, TDS – temperature, TDS – EC and TDS – turbidity. Vast majority of metal pairs recorded strong correlation (r ˃ 0.7) indicating the presence of alloys and metal pair complexes. The correlational studies were conducted at 95% level of confidence (P ˂ 0.05). The study recommends treatment of industrial wastes before they are released into rivers and lakes, use of improved processing technologies by industries to regulate the ever-high levels of waste generated during manufacturing and policy review that will see the implementation of environmental laws so as to curb illegal mining The rise in cost of living and unemployment in the Sub – Saharan Africa has witnessed the rise of both small scale and large-scale mining activities; putting more economic pressure on families to increase their daily income. This economic hardship has led to the search for precious metals like gold and gemstones, resulting in environment degradation as mining involves digging deep into the Earth’s crust in search of these minerals. This study sought to investigate the physico-chemical characteristics of wastewater from the Alupe gold mine in Busia County, Kenya. The five physical parameters investigated include: temperature, electrical conductivity, pH, turbidity and total dissolved solids. The heavy metals under investigation were: Cr, Cd, Pb, Cu, Fe, Co, Zn and Ni. Among the physical parameters, only pH and turbidity recorded values beyond the WHO permissible levels, while all heavy metals recorded values that were beyond the WHO permissible levels. Strong correlation was registered by EC – temperature, TDS – temperature, TDS – EC and TDS – turbidity. Vast majority of metal pairs recorded strong correlation (r ˃ 0.7) indicating the presence of alloys and metal pair complexes. The correlational studies were conducted at 95% level of confidence (P ˂ 0.05). The study recommends treatment of industrial wastes before they are released into rivers and lakes, use of improved processing technologies by industries to regulate the ever-high levels of waste generated during manufacturing and policy review that will see the implementation of environmental laws so as to curb illegal mining Wed, 01 Jan 2025 00:00:00 GMT http://41.89.205.12/handle/123456789/2840 2025-01-01T00:00:00Z