The estimation of an anthropogenic depth boundary using the magnetic susceptibility method in Kogi State, North-Central Nigeria

Magnetic susceptibility measurements remain one of the most reliable methods used to investigate the pollution of both surface and subsurface soil from metallic anthropogenic sources. Most of the geological rocks within the study area increase the susceptibility of the soil; however, knowing the natural background susceptibility of the parent rocks will give an idea of the anthropogenic influence on the susceptibility of the soil. This study was carried out in Kogi State, North Central Nigeria, with the aim of determining the depth of the boundary between the anthropogenic influences on soil magnetic susceptibility from those of a lithogenic origin. Magnetic susceptibility measurements were carried out on 1,760 soil samples, collected from 220 soil profiles at a depth of 80.0 cm and at intervals of 10.0 cm. From the spatial distribution of magnetic susceptibility maps at different depths, the boundary between the basement complex and the sedimentary basin was clearly demarcated. The result further shows the highest magnetic susceptibility values of 350–650 × 10−5 SI, which dominates the surface soil to a depth of 40.0 cm. At the depth of 40–50 cm, the result indicates the combination of a natural anthropogenic influence on soil magnetic susceptibility with an average of 250 × 10−5 SI. Furthermore, no evidence of layering along the depth sections was observed, suggesting that the soil profiles indicate areas mainly covered by anthropogenically influenced susceptibility, which were localized and restricted to commercial places within the state. This study reveals that the average depth of soil affected by anthropogenic pollutants is between 40–50 cm in commercial places and 20–30 cm in other places with less commercial activities

Integrating geoelectrical and borehole data in the characterization of basement-rock aquifers in the Lokoja area, northcentral Nigeria

The study area is composed of mainly basement rocks, with problems of low yield of groundwater in most of the boreholes drilled. Therefore, this study was carried out to evaluate the hydraulic parameters of the basement aquifers using the vertical electrical sounding (VES), constant rate pumping test, and borehole logs. The mean value of aquifer resistivity and thickness are 408.4 Ωm and 20.2 m. The depth ranges from 20.9-88.0 m with a mean value of 55.5 m; showing appreciable groundwater potential mostly within the southern part. The value of transmissivity and hydraulic conductivity from the resistivity data ranges from 2.058-1761.033 m2/day and 0.205-138.664 m/day with a mean value of 152.251 m2/day and 8.841 m/day, respectively, indicating porous and permeable zones within the southern and northwestern part of the study area. The value of longitudinal conductance and transverse unit resistance ranges from 0.0034-4.2333 m-hom and 38.1-146439 Ωm2 with a mean value of 0.3250 m-hom and 9704.1 Ωm2; indicating poor to moderate protective capacity in almost the entire area except for the small portion within the southern part. The mean value of fracture contrast and the reflection coefficient are 0.743 and -0.333, showing that the southern part has more water-filled fractures. Conclusively, this study reveals, that the aquifer depth ranges from 60-90 m, the transmissivity and hydraulic conductivity demonstrate high porosity and permeability within the southern parts of the study area, and serve as a baseline for groundwater resource management policy in Nigeria

Assessment of Groundwater Potential and Aquifer Characteristics using Inverted Resistivity and Pumping Test Data within Lokoja Area, North-central Nigeria

Communication in Physical Sciences, 2023, 9(3):336-349 Authors: Kizito O. Musa*, Jamilu B. Ahmed*, Fabian A. Akpah, Ernest O. Akudo, Ikenna A. Obasi, Solomon S. Jatto, Andrew C. Nanfa, Jacob B. Jimoh Received: 12May 2023/Accepted 08 July 2023 Aquifer potential were evaluated within Lokoja and environs with the aim of estimating their hydraulic parameters from resistivity and pumping test data. Twenty-six (26) vertical electrical sounding (VES) and eight (8) pumping test data were obtained and utilized for this purpose. The results of the analysis indicate that the area is underlain by five (5) geoelectric sections which have been interpreted as the topsoil, lateritic clay, sandy-clay/weathered/ fractured basement complex rocks (aquiferous units), and clay/fresh basement complex rocks for the sedimentary and basement portions respectively. The resistivity and thickness of these lithologic units are; the topsoil (10.8 – 407.7 Ωm; 0.7 –17.5 m), lateritic clay (1.1 – 1488.5 Ωm; 2.2 – 42.0 m), sandy-clay/weathered/ fractured basement (10.4 – 3,595.6 Ωm; 5.2 – 82.6 m), clay/fresh basement (3.2 – 3,844.2 Ωm; 4.5 – 23.4 m). The resistivity of the aquifer zone indicates that the southeastern to the northwestern portion of the study area has higher groundwater potential than the other portions. The aquifer thickness is higher in the southern portion compared to the rest of the study area. Depth to the aquifer is higher in the northern and parts of the southern portions. Transmissivity (7.605 – 721.648 m2/day) and permeability (0.423 – 45.103 m/day) values support the view that the southeastern portion is most prolific for groundwater exploration in the study area. The Longitudinal conductance (0.013 – 1.600 mho-m), and the transverse resistance (119.0 – 29,710.7 Ωm2) values suggest that the area has a poor – good vulnerability index. The fracture contrast (0.040-22.430) and reflection coefficient (-0.902-0.915) indicate that the water-filled fractures occur mostly in the southern part of the study area. The study highlighted the efficacy of the VES data in estimating aquifer hydraulic parameters and hence is recommended in areas with no available pumping test data

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit