Journal Articles (PAS)

Effects of Catchment Land Use on Water Quality in Maragua and Mathioya Riverine Wetlands, Murang’a County, Kenya.

Wed, 01 Jan 2025 00:00:00 GMT

Effects of Catchment Land Use on Water Quality in Maragua and Mathioya Riverine Wetlands, Murang’a County, Kenya. Kipkemoi, Evans; Andayi, Andrew W; Mwangi, Benson; Njagi, Eric C.; Kariuki, Margaret W Wetland ecosystems in Murang’a County are diminishing due to increased catchment land use practices. Part of wetlands have been converted into farmlands where various agricultural activities are carried out while some parts have been converted into settlement points. Agricultural practices carried out along wetland ecosystems involve the use of excessive agrochemicals during crop production which later contribute to wetland pollution through nutrients and heavy metals inflows. This study aimed at assessing the effects of catchment land use on water quality parameters in Maragua and Mathioya river basins in Murang’a County. Water samples were collected using the Grab technique, packed in plastic containers, kept in cool boxes, and transported to the research laboratory for analysis. Salinity, turbidity, total dissolved solids (TDS), electrical conductivity (EC) and PH were analyzed across the sampling levels using hand-held portable pH meter. Salinity mean concentration across the three sampling levels was 116.28 ± 14.31 mg/L; 107.08±13.32 mg/L for TDS; 0.16±0.02 mS/cm for electrical conductivity (EC), turbidity:160.38 ± 8.53 NTU and a PH mean of 6.26±0.09. TDS values differed across sampling levels: Down-Stream (mean = 135.43 ± 1.46 mg/L, range: 132.60 to 139.30 mg/L), Mid-Stream (mean = 138.63 ± 6.60 mg/L, range: 122.70 to 150.60 mg/L), and Up-Stream (mean = 47.18 ± 10.43 mg/L, range: 26.70 to 65.40 mg/L). EC showed significant variation across sampling levels: Down-Stream (mean = 0.20 ± 0.00 mS/cm, range: 0.19 to 0.20 mS/cm), Mid-Stream (mean = 0.21 ± 0.01 mS/cm, range: 0.19 to 0.23 mS/cm), and Up-Stream (mean = 0.07 ± 0.02 mS/cm, range: 0.04 to 0.10 mS/cm). The pH levels varied across the different sampling levels: Down-Stream (mean = 6.47 ± 0.03, range: 6.40 to 6.51), Mid-stream (mean = 6.31 ± 0.10, range: 6.01 to 6.45), and Up-Stream (mean = 6.00 ± 0.22, range: 5.50 to 6.48). Salinity levels varied significantly: Down-Stream (mean = 146.05 ± 1.81 mg/L, range: 141.40 to 150.20 mg/L), Mid-Stream (mean = 150.93 ± 6.15 mg/L, range: 135.00 to 161.60 mg/L), and Up Stream (mean = 51.88 ± 11.52 mg/L, range: 28.90 to 71.70 mg/L) and Turbidity levels also varied: Down Stream (mean = 170.50 ± 15.40 NTU, range: 128.30 to 194.60 NTU), Mid-Stream (mean = 173.53 ± 8.13 NTU, range: 158.40 to 190.90 NTU), and Up-Stream (mean = 137.10 ± 15.00 NTU, range: 108.20 to 177.50 NTU). Post-hoc analysis showed a significant difference in pH between Down-Stream and Up-Stream (mean difference = 0.465, p = .043). Significant differences noted in EC between Down-Stream and Up-Stream (mean difference = 0.130, p < .001), and Mid-Stream and Up-Stream (mean difference = 0.139, p < .001). However, no significant difference was observed between Down-Stream and Mid-Stream. For TDS, significant differences were observed between Down-Stream and Up-Stream (mean difference = 88.250, p < .001), and Mid-Stream and Up-Stream (mean difference = 91.450, p < .001). No significant difference was observed between Down-Stream and Mid-stream. Significant differences in salinity were found between Down-Stream and Up-Stream (mean difference = 94.175, p < .001), and Mid-Stream and Up-Stream (mean difference = 99.050, p < .001). No significant difference was found between Down-Stream and Mid-stream. Variation in the analyzed water parameters across the sampling levels showed that the wetlands have been polluted and the potential sources of pollution are agricultural run-offs and anthropogenic activities.

Effects of Catchment Land Use on Nutrients and Heavy Metals Inflows into Maragua and Mathioya Wetlands in Murang’a County, Kenya

Wed, 01 Jan 2025 00:00:00 GMT

Effects of Catchment Land Use on Nutrients and Heavy Metals Inflows into Maragua and Mathioya Wetlands in Murang’a County, Kenya Kipkemoi, Evans; Andayi, Andrew W; Mwangi, Benson; Njagi, Eric C.; Kariuki, Margaret W Wetland ecosystems in Murang’a County are diminishing due to increased catchment land use practices. Part of wetlands have been converted into farmlands where various agricultural activities are carried out while some parts have been converted into settlement points. Agricultural practices carried out along wetland ecosystems involve the use of excessive agrochemicals during crop production which later contribute to wetland pollution through nutrients and heavy metals inflows. This study aimed at assessing the effects of catchment land use on nutrient and heavy metals inflows into Maragua and Mathioya river basins in Murang’a County. Water samples were collected using the Grab technique, packed in plastic containers, kept in cool boxes, and transported to the research laboratory for analysis. Phosphate and nitrate concentrations were analyzed across different seasons, sampling stations, and sampling levels. During dry season, the mean phosphate concentration was 0.0259 ± 0.0051 mg/L with a standard deviation of 0.0124 mg/L. In wet conditions, the mean phosphate concentration increased to 0.1631 ± 0.1509 mg/L with a standard deviation of 0.3697 mg/L. For nitrate, the mean concentration during dry conditions was 9223.37 ± 2672.33 mg/L with a standard deviation of 6545.84 mg/L, and during wet conditions, it remained the same at 9223.37 ± 2008.17 mg/L with a standard deviation of 4919.00 mg/L. Elemental analysis was performed using Microwave Plasma-Atomic Emission Spectroscopy (MP-AES) instrument. Mean concentrations of lead during dry seasons were 0.005 ± 0.002 mg/L and during wet season, they increased to 0.012 ± 0.004 mg/L. Zinc concentrations were 0.01 ± 0.003 mg/L during dry season and increased to 0.015 ± 0.004 mg/L during the wet season. The mean concentrations of zinc in the water samples were significantly lower than the maximum residue concentrations set for drinking water by the World Health Organization (WHO). However, lead (Pb) concentrations were above the WHO recommended maximum residue level. ANOVA analysis indicated no significant seasonal differences in phosphate (F=0.825, p=0.385) and nitrate (F=3.090, p=0.109) levels. Similarly, no significant differences were found between different sampling stations for phosphate (F=1.081, p=0.323) and nitrate (F=0.478, p=0.505). Analysis by sampling levels showed no significant differences noted for phosphate (F=0.979, p=0.412) and nitrate (F=1.949, p=0.198). For heavy metals, no significant differences were found for lead (F=1.234, p=0.271), cadmium (F=0.893, p=0.348), and zinc (F=1.567, p=0.223) across different seasons and sampling stations. These findings suggest that nutrient and heavy metal inflows into the wetlands are relatively stable and uniform across different spatial and temporal scales. The study highlights the importance of consistent land use practices and the effective buffering capacity of wetlands in maintaining ecological balance.

The Great Mimicker: Chronic Thromboembolic Pulmonary Hypertension

Wed, 01 Jan 2025 00:00:00 GMT

The Great Mimicker: Chronic Thromboembolic Pulmonary Hypertension Gichuki, Joseph Maina; Malik, A.N; Kanyugo, A.M Chronic thromboembolic pulmonary hypertension (CTEPH) is a sub-category of pulmonary hypertension that is unique from other forms of pulmonary hypertension with regards to its pathogenesis, patient characteristics and management. By definition, CTEPH is precapillary hypertension with a minimum of one segmental perfusion abnormality on scintigraphy or a CT pulmonary angiogram having typical findings of CTEPH. Despite advancement in awareness, diagnosis and treatment of CTEPH, its prevalence has remained a question of concern in the field of medicine majorly contributed by its clinical presentation that mimics common cardiorespiratory diseases. This has largely been contributed by misdiagnosis and under-reporting of the incidence. Available data suggest an incidence of 0.56% for early diagnosis and 3% for late diagnosis/survivors. The commonest risk factors associated with CTEPH include unprovoked pulmonary embolism, recurrent pulmonary embolism and antiphospholipid syndrome. In this case report, we present a 24yr old female who presented to our outpatient clinic with features of heart failure and deep venous thrombosis initially being followed up for heart failure. The only clue towards CTEPH was the chronic leg swelling that was more pronounced on the left side otherwise a systemic inquiry was non-contributory. A Doppler ultrasound of the left lower limb demonstrated chronic deep venous thrombosis involving the femoral system of veins. Consistent with CTEPH was an echocardiogram that showed tricuspid regurgitation and elevated pulmonary pressures whereas a CT Pulmonary angiogram showed a dilated pulmonary artery trunk, dilated right ventricle and atrium, and pulmonary oligaemia.

Efficacy of Plant-based Repellents Against Anopheles Mosquitoes: A Systematic Review

Wed, 01 Jan 2020 00:00:00 GMT

Efficacy of Plant-based Repellents Against Anopheles Mosquitoes: A Systematic Review Wangai, Laura Nyawira; Kamau, Kenny Kimani; Munyekenye, Godwil; Nderu, David; Maina, Eva; Gitau, William; Murigi, Mary; Kamau, Susan; Njuguna, Mercy; Gichuki, Joseph; Otieno, Fredrick Mosquitoes are usually targeted using insecticides, insect growth regulators, and microbial agents. Indoor residual spraying and insecticide-treated bed nets. However, these strategies have negative effects on human health, the environment and induce resistance in a number of species. Eco-friendly tools have been recently implemented against mosquito vectors, including plant-based insecticides. To date few studies have adopted World Health Organization (WHO) Pesticide Evaluation Scheme guidelines for repellent testing against mosquitoes. This review presents a summary of recent information on development, and efficacy of plant-based repellents against Anopheles mosquitoes as well as promising new advances in the field. All eligible studies published up to April 2020 were systematically searched in several databases, namely PubMed/Medline, Scopus and Google scholar. The outcomes of interest were percentage repellency, protection time and additional properties identified in repellent compounds. A total of 27 trials met the inclusion criteria. The highest repellency effect against mosquitoes was conferred by citronella, followed by Ligusticum sinense extract, pine, Dalbergia sissoo, and Rhizophora mucronata oils with 100% protection for 8 to 14 hours. Furthermore, essential oils from plants such as lavender, camphor, catnip, geranium, jasmine, broad-leaved eucalyptus, lemongrass, lemon-scented eucalyptus, amyris, narrow-leaved eucalyptus, carotin, cedarwood, chamomile, cinnamon oil, juniper, cajeput, soya bean, rosemary, niaouli, olive, tagetes, violet, sandalwood, litsea, galbanum, and C. longa also showed >90% repellency within 8 hours against different species of Anopheles. Therefore, the review showed, essential oils and extracts of some plants could be formulated for the development of eco-friendly repellents against Anopheles species. Plant oils may serve as suitable alternatives to synthetic repellents in the future as they are relatively safe, inexpensive, and are readily available in many parts of the world.