Publications by authors named "Humphrey O"

Climate change poses an immediate threat to tropical soils with changes in rainfall patterns resulting in accelerated land degradation processes. To ensure the future sustainability of arable land, it is essential to improve our understanding of the factors that influence soil erosion processes. This work aimed to evaluate patterns of soil erosion using the activity of plutonium isotopes (Pu) at sites with different land use and clearance scale in the Winam Gulf catchment of Lake Victoria in Kenya.

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Pest infestation in crop production have increased farmers' interest in pesticides use with short and long term consequences. This study investigated the occurrence and seasonal variations of organochlorine pesticide residues in vegetable farms in selected areas of Lagos State. Non carcinogenic and carcinogenic risk assessment was also evaluated.

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Emerging from the shadow of the COVID-19 pandemic, it is time to ground ourselves and retrospectively assess the recent achievements of SEGH over the past years. This editorial serves as a comprehensive report on the progress made in comparison to the aspirations and goals set by the society's board in 2019 (Watts et al., Environ Geochem Health 42:343-347, 2019) (Fig.

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The vasa vasorum of the large pulmonary vessels is involved in the pathology of COVID-19. This specialized microvasculature plays a major role in the biology and pathology of the pulmonary vessel walls. We have evidence that thrombosis of the vasa vasorum of the large and medium-sized pulmonary vessels during severe COVID-19 causes ischemia and subsequent death of the pulmonary vasculature endothelium.

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  • Faecal calprotectin (FC) is a key marker used to assess gut inflammation, particularly in children aged 4-17 with abnormal test results but without established inflammatory bowel disease (IBD).
  • The study involved 310 children, where most had FC levels indicating mild inflammation, and a significant percentage with very high levels (500+ μg/g) were eventually diagnosed with IBD or had infectious diarrhea.
  • The findings suggest that while many children had elevated FC levels, they were mostly below the threshold for mucosal inflammation, highlighting the potential of repeat FC testing for better diagnosis.
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The Kakamega gold belt's natural geological enrichment and artisanal and small-scale gold mining (ASGM) have resulted in food and environmental pollution, human exposure, and subsequent risks to health. This study aimed to characterise exposure pathways and risks among ASGM communities. Human hair, nails, urine, water, and staple food crops were collected and analysed from 144 ASGM miners and 25 people from the ASGM associated communities.

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Lacustrine sediment quality indicates the effects of both natural and anthropogenic activities on the ecosystem and communities. Despite its ecological importance, myriad complexities, and potential contaminant sources, the spatial distribution of surficial sediments in Lake Victoria's Winam Gulf has never been comprehensively documented. The purpose of this study was to assess the spatial distribution, pathways, and ecological risk of metal elements in the lake using a sediment matrix.

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  • - Land degradation from soil erosion is a significant global issue, especially in developing countries where resources are limited, and using fallout radionuclides (FRNs) can help assess soil erosion rates.
  • - This research focused on using plutonium (Pu) as an effective soil erosion tracer in western Kenya, finding it superior to traditional isotopes like lead (Pb) and cesium (Cs) in accuracy and reliability.
  • - The study revealed that Pu can effectively identify soil erosion patterns, with its maximum activity occurring between 3 and 12 cm depths, making it a valuable resource for developing strategies to address land degradation in the region.
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  • * An optimized method using TEVA columns was developed to enhance Pu recovery and reduce interference from uranium (U) during analysis, leading to a 20% improvement in throughput.
  • * Validation of this method showed high accuracy and precision through testing with Certified Reference Material, achieving low detection limits for ultra-trace Pu in African soils.
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The impact of population expansion through economic growth and development has been identified as one of the key drivers of both water and sediment contamination from potentially harmful elements (PHEs). This presents a major hazard not only to aquatic ecosystems but local riparian communities and beyond who rely heavily on this natural resource for drinking water and fish-a valuable source of dietary micronutrients and protein. The present study measured biogeochemical concentration of PHEs in water, sediment and fish from locations pooled into four zones within Winam Gulf and Lake Victoria area of Kenya.

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When the SEGH international board released a short editorial paper back in 2019, we described an aim to increase the membership offering, whilst improving the diversity of input regionally, by scientific discipline and to ensure greater and more regular contact across the regions from 2020 onwards. Wider aspirations described in 2019 (Watts et al. 2019) are discussed within this short communication at the end of 2021 to evaluate progress made.

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  • Soil erosion is worsened by bad farming practices, land degradation, and human activities, affecting nutrient cycling, productivity, and economies.
  • This study uses the Revised Universal Soil Loss Equation (RUSLE) to assess soil erosion risk in the Winam Gulf, Kenya, at a monthly level from January 2017 to June 2020, revealing that erosion rates peak from February to April.
  • The findings emphasize the importance of understanding soil erosion patterns for effective policy-making and conservation efforts, with an average annual soil loss of 10.71 Mt in the catchment area.
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Spot urinary elemental concentrations are presented for 357 adults from Western Kenya collected between 2016 and 2019 as part of a wider environmental geochemical survey. The aim of this study was to establish population level urinary elemental concentrations in Western Kenya for micronutrients and potentially harmful elements for inference of health status against established thresholds. For elements where thresholds inferring health status were not established in the literature using urine as a non-invasive matrix, this study generated reference values with a 95% confidence interval (RVs) to contextualise urinary elemental data for this population group.

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We performed autopsies on two cases of COVID-19. The microcirculations of all organs were the site of the pathological findings. Thrombotic microangiopathy was found in the brain and also the kidneys.

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  • - This study investigated groundwater contamination with faecal coliform and nitrate in rural Mardan district, Pakistan, where 100 samples were taken from 25 villages to ensure compliance with national environmental standards.
  • - While average nitrate levels were within the WHO safe limit, two villages exceeded this limit; non-carcinogenic health risk assessments showed potential risks for children but not for adults.
  • - E. coli contamination was found in 13 villages, signaling health risks due to unsafe drinking water, and the findings serve as essential data for researchers and public health officials.
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Conventional soil solution sampling of species-sensitive inorganic contaminants, such as hexavalent chromium (Cr), may induce interconversions due to disruption of system equilibrium. The temporal resolution that these sampling methods afford may also be insufficient to capture dynamic interactions or require time-consuming and expensive analysis. Microdialysis (MD) is emerging as a minimally invasive passive sampling method in environmental science, permitting the determination of solute fluxes and concentrations at previously unobtainable spatial scales and time frames.

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  • Chromium (Cr) exists in two forms; one is essential for metabolism, while the other is toxic and carcinogenic, prompting research on its transfer from soil to plants.
  • A study used isotopically enriched Cr species to analyze their uptake in Spinacia oleracea (spinach) roots, exploring the impact of sulphate as a competitor.
  • Findings revealed that Cr dominated both root uptake pathways, with evidence of Cr reduction as a detoxification mechanism, suggesting the complexity of uptake processes and the need for further research on sulphate's role in improving plant management strategies.
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Assessing the reactions of iodine (I) in soil is critical to evaluate radioiodine exposure and understand soil-to-crop transfer rates. Our mechanistic understanding has been constrained by method limitations in assessing the dynamic interactions of iodine between soil solution and soil solid phase over short periods (hours). We use microdialysis to passively extract soil solution spiked with radioiodine (I and IO) to monitor short-term (≤40 h) in situ fixation and speciation changes.

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  • - The study analyzed soil, water, and food composition data to assess micronutrient intake and deficiencies across regions in Tanzania and Western Kenya, emphasizing the need for updated and comprehensive food balance information.
  • - About 1500 crop samples were tested for essential micronutrients, revealing that Tanzanian foods generally had better micronutrient supply than those in Western Kenya, with leafy vegetables showing the highest concentrations.
  • - The findings indicated high deficiency rates for calcium, zinc, and iodine, especially in Kenya, while some drinking water in Tanzania could significantly contribute to micronutrient intake, highlighting regional disparities in nutrient availability.
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Spot urinary iodine concentrations (UIC) are presented for 248 individuals from western Kenya with paired drinking water collected between 2016 and 2018. The median UIC was 271 µg L, ranging from 9 to 3146 µg L, unadjusted for hydration status/dilution. From these data, 12% were potentially iodine deficient (< 100 µg L), whilst 44% were considered to have an excess iodine intake (> 300 µg L).

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Element cycling in the terrestrial environment is heavily reliant upon processes that occur in soil solution. Here we present the first application of microdialysis to sample iodine from soil solution. In comparison to conventional soil solution extraction methods such as Rhizon™ samplers, centrifugation, and high-pressure squeezing, microdialysis can passively sample dissolved compounds from soil solution without altering the in-situ speciation of trace elements at realistic soil moisture conditions.

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