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2021

Cherotich, S, Abong’o DA, Onyatta JO.  2021.  Assessing the Seasonal Changes on Physicochemical Parameters and Major Nutrient Levels in Water and Sediments from Sulal River, Bureti Sub County, Kericho County, Kenya. Chemical Science International Journal. 30(1):46-58. AbstractChemical Science International Journal

Abstract
Sulal River is a victim of nutrient pollution as it crosses different small-scale tea farms in Bureti Sub County, Kericho County. A study was conducted to evaluate different physicochemical parameters and major chemical fertilizer’s nutrients levels in water and sediments from Sulal River. In order to understand the degree of pollution in the river due to inflow of agricultural chemical fertilizer residue levels from its catchment, the samples were collected in the dry (February 2019) and wet seasons (November 2019). The ten chosen sampling sites stretched a length of 12 Km. Samples were analyzed for pH, dissolved oxygen (DO), total dissolved solids (TDS), electrical conductivity (EC), sediment and water content (WC), nitrate-nitrogen (NO3-N), phosphorous (PO3-P) and potassium (K) using standard methods. Results were analyzed using IBM SPSS 20. The average results during dry and wet seasons in water samples for pH were 6.72±0.05 and 6.38±0.21, DO 6.78±0.59 and 9.58±0.64 mg/L, EC 174±5.02 and 205±20.14 µS /cm, TDS 92±4.59 and 120.70±19.57 mg/L, NO3-N 0.58±0.21 and 1.19±0.22 mg/L, PO3-P 0.00±0.00 and 0.13±0.84 mg/L and K 0.26±0.08 and 0.84±0.19 mg/L respectively. The average results during dry and wet seasons in sediment samples for pH were 6.62±0.20 and 6.75±0.17, EC, 67±6.66 and 52±10.19 µS /cm, WC 16.96±3.95 and 129.84±5.00%, NO3-N 0.70±0.35 and 0.42±0.23 mg/kg, PO3-P 0.49±0.25 and 1.14±0.40 mg/kg and K 1.53±0.45 and 2.86±0.31 mg/kg respectively. The levels of P in water during wet season and in sediments samples in both seasons were however, above the WHO (0.025 mg/L) and KEBS (0.030 mg/L) recommended limit for drinking and domestic use and WASREB (0.005 mg/L) level for the likelihood of eutrophication. Availability of excess phosphorus can accelerate eutrophication. The diversity of cancers has also been associated with drinking water containing phosphorous levels. The water from Sulal River may be used for irrigation purposes but not for drinking and domestic purposes. Significant seasonal variations were observed in all parameters analyzed except NO3-N in sediments. This indicates that rainfall had a great effect on some soil physicochemical properties.

Osoro, EM, Wandiga S, Madadi V, Abongo D.  2021.  Polybrominated Diphenyl Ethers Pollution in Urban and Rural Settings’ Ambient Air in Kenya: An Insight into Concentration Levels, Compositional Profile and Seasonal Variation. Africa Journal of Physical Sciences ISSN: 2313-3317. 6 AbstractAfrica Journal of Physical Sciences

Description
Air samples were collected from three urban and one rural sites in Kenya with the aim of establishing pollution levels of Polybrominated Diphenyl Ethers. Forty-eight air Samples were collected by passive air sampling, Soxhlet extracted and analysed for brominated diphenyl ethers using gas chromatography coupled with mass spectrometer. The mean concentration of polybrominated diphenyl ethers residue in air ranged from≤ 0.9 to 152.72±3.19 pgm− 3. The predominant congener was 2, 2′, 4, 4′-tetra-bromodiphenyl ether with mean concentration range of 1.94±0.03 to 152.72±3.19 pgm− 3 followed by 2, 2′, 4, 4′, 5-penta-bromodiphenyl ether with mean concentration range of 1.32±0.06 to 66.83±1.19 pgm− 3. Seasonal variations of the pollutants showed a high level of Polybrominated Diphenyl Ethers in hot dry season in range of 1.94±0.03 to 152.72±3.19 pgm− 3. Air samples from Dandora and Industrial area both from urban location recorded high concentrations of the analysed polybrominated diphenyl ethers compared with the air samples from the rural location.

Osoro, EM, Wandiga S, Madadi V, Abongo D.  2021.  Occurrence and Distribution of Polybrominated Diphenyl Ethers in Water from Nairobi River Basin, Kenya, East Africa. Africa Journal of Physical Sciences ISSN: 2313-3317. 6 AbstractAfrica Journal of Physical Sciences

Description
Polybrominated diphenyl ethers are linked to adverse health effects that includethyroid hormone disruption, neuro-developmental deficit, abnormal pregnancy, and potential carcinogens. This study was aimed at assessing the concentrationsof selected Polybrominated diphenyl ether compounds in water of Nairobi River. Water samples were collected by grab method from nine sites along the river andanalysed for brominated diphenyl ethers using gas chromatography coupled withmass spectrometer. The mean concentration of polybrominated diphenyl ethersresidue in water ranged from< 0.0009 to 72.89±6.15 ng/L. The dominantcongeners were 2, 2′, 4, 4′-tetra-bromodiphenyl ether, 2, 2′, 4, 4′, 5, 5′-hexabromodiphenylether, 2, 2′, 4, 4′, 6-penta-bromodiphenyl ether, 2, 2′, 4, 4′, 5, 5′-hexabromodiphenylether and 2, 2′, 4, 4′, 5, 6′-hexa-bromodiphenyl. The highest meanconcentration of 2, 2′, 4, 4′-tetra-bromodiphenyl ether was 72.89±6.15 ng/L, 2, 2′, 3, 4, 4′-penta-bromodiphenyl ether was 14.08±0.68 ng/L, 2, 2′, 4, 4′, 6-pentabromodiphenylether was 43.67±1.47 ng/L, 2, 2′, 4, 4′, 5, 5′-hexa-bromodiphenylether was 24.78±2.49 ng/L, and 2, 2′, 3, 4, 4′, 5′, 6-hepta-bromodiphenyl ether was11. 75±0.97 ng/L. Consequently, as these compounds are known to bioaccumulatein fatty tissues, continued use of the river water poses a health risk toanimals and humans due to contamination across the food chain.

Ochiba, NK, Abong’o DA, Onyatta JO.  2021.  The Assessment of The Effect of Proximity of Septic Tanks on The Levels of Selected Heavy Metals in Borehole Water from Ongata Rongai, Kajiado County, Kenya. International Journal of Scientific Research in Science, Engineering and Technology. 8(4):64-76. AbstractInternational Journal of Scientific Research in Science, Engineering and Technology

Description
The study was carried out to evaluate the levels of heavy metals in groundwater samples from ten selected boreholes in Ongata Rongai town, Kajiado County. The selected heavy metals analyzed were: Zn, Pb, Hg, Mn, Cd and Cr in the dry and wet seasons. The effect of the proximity of septic tanks distance to borehole was also determined. The statistical analyses of the data using a 2-way ANOVA showed 95% confidence level (p< 0.05) interdependence of the distance from the boreholes and contaminant levels. The study showed that heavy metals were below the maximum recommended level and the guideline values of World Health Organization and Kenya Bureau of Standards. The analyses of the selected heavy metals, by Flame Atomic Absorption Spectroscopy, revealed that the detected levels of Mn (0.03±0.01-0.26±0.01 mgl-1) were higher than those recommended by WHO and KEBS of 0.01 mgl-1, while Zn (0.11±0.02-0.73±0.01 mgl-1) are within acceptable levels of WHO (3.0 mgl-1) and KEBS (5.0 mgl-1). There was no strong correlation between the distance of borehole from septic tanks and heavy metal levels in water samples. The low detected values should not be overlooked as the heavy metals are capable of bio-accumulating in body tissues.

2019

Momanyi, VN, Margaret K, Abong’o DA, Warutere P.  2019.  Farmers’ compliance to pesticide use standards in Mwea irrigation scheme, Kirinyaga County, Kenya. Int J Innov Res Adv Stud. 6(10):67-73. AbstractInt J Innov Res Adv Stud

Description
Kirinyaga County is the leading producer of tomatoes in Kenya and farmers heavily rely on pesticides to control pests and diseases. The aim of the study was to evaluate the farmers’ compliance to pesticide use standards. The study was conducted in Kirinyaga County at Mwea Irrigation Scheme between July 2017 and June 2018. The study used a Cross-Sectional design that included 203 farmers (198 from open field, 5 from greenhouse farms) who grow tomatoes and use pesticides consistently for at least 2 years. Out of 20 pesticides mainly applied in open field farms, 16 were applied at significantly (P< 0.05, 0.01, 0.001) higher rates and tomatoes sprayed with 19 of the pesticides were harvested at significantly (P< 0.05, 0.01, 0.001) shorter Pre-Harvest Intervals, than recommended by the manufactures. On the other hand, out of all, 12, pesticides applied on in greenhouses, 3 were applied at significantly higher rates, and tomatoes sprayed with 2 pesticides were harvested at shorter durations than specified by the manufacturers. Farmers did not comply with the laid down standards. Non-compliance was due to ignorance, intentional and reliance on neighbor’s and their own, information. The study recommends frequent education and training for farmers by Ministry of Agriculture Livestock and Fisheries on safe use of pesticides to help improve on compliance to pesticide use standards.

Sila, MJ, Nyambura MI, Abong’o DA, Mwaura FB, Iwuoha E.  2019.  Biosynthesis of Silver Nanoparticles from Eucalyptus Corymbia Leaf Extract at Optimized Conditions, April 2019. Nano Hybrids and Composites Vol. 25. 25:32-45., South Africa Abstract

Abstract:

This study reports the biosynthesis of narrow range diameter silver nanoparticles at optimum conditions using Eucalyptus corymbia as a reducing and stabilizing agent. Optimal conditions for biosynthesis of silver nanoparticles (AgNPs) were found to be; an extraction temperature of 90°C, pH of 5.7 a Silver Nitrate concentration of 1mM and AgNO3 to plant extract ratio of 4:1. UV-Visible spectroscopy monitored the formation of colloidal AgNPs. The UV-Visible spectrum showed a peak around 425 nm corresponding to the Plasmon absorbance of the AgNPs. The size and shape characterization of the AgNPs was done using Transmission Electron Microscopy (TEM) techniques which revealed narrow range diameter (18-20 nm), almost monodispersed AgNPs, spherical in nature and with minimal agglomeration. Energy Dispersive X-ray (EDX) results showed the presence of two peaks at 3.0 and 3.15 keV in the silver region. The Fourier Transform Infrared-Spectra (FTIR) of the plant extract and the AgNPs gave rise to vibrational peaks at 3260 and 1634 wavenumbers which are due to the presence of OH and –C=C-functional groups respectively.

Muraga, JM.  2019.  Assessment Of Dissolved Ions And Microbial Coliforms In Water From Selected Sites Of The Upper Athi River Subcatchment Area, Kenya.. , Nairobi: University of Nairobi Abstract

Description
The Upper Athi River sub-catchment area has experienced exponential growth of human population since the turn of the century. This has led to establishment of satellite towns such as Ngong, Kiserian, Ongata Rongai, Mlolongo, Kitengela and Ruai. These towns have either no or inadequate supply of water from the local governments, that is, Kajiado, Machakos and Nairobi. Communities in this area of study have therefore resorted to obtaining ground water through drilling boreholes and digging shallow wells for their domestic needs. This is done without proper information on whether the water meets quality standards set out by Kenya Bureau of Standards (KEBS). This study therefore sought to assess the water quality in this area to determine whether ground water meets these standards. It also compared these levels of dissolved ions and coliforms to those of river water in the recharge area of the Upper Athi sub-catchment area. Twenty one water samples comprising of eleven boreholes, five shallow wells and five river water samples were collected from the Upper Athi sub-catchment area in the months of December 2011 which was a dry month and in May 2012 which was a wet month. The samples were analysed for dissolved ions and microbial coliforms. The metal ions analysed included Ca, Cd, Cr, Cu, Fe, Mg, Mn, Na, Pb and Zn while anions included Cl-, CO32-/HCO3-, F-, NO2-/NO3- and SO42- as well as faecal coliforms. Physical parameters analysed included pH, electrical conductivity (EC) turbidity, total dissolved solids and colour. The analysis of cations was carried out using atomic absorption spectrophotometry while chlorides …

2018

Abong’, DA, Wandiga SO, Jumba IO.  2018.  Occurrence and distribution of organochlorine pesticide residue levels in water, sediment and aquatic weeds in the Nyando River catchment, Lake Victoria, Kenya. African Journal of Aquatic Science. 43(3):255-270. AbstractAfrican Journal of Aquatic Science

Description
Samples of water, sediments and aquatic weeds were collected from 26 sites in the Nyando River catchment of the Lake Victoria basin in 2005–2006. The objective was to investigate levels of organochlorine pesticides that have either been banned or are restricted for use in Kenya. The pesticides investigated were lindane, aldrin, endosulfan, endrin, dieldrin, DDT, heptachlor and methoxychlor. These pesticides had previously found wide applications in public health and agriculture in Kenya for control of disease vectors and crop pests respectively. Results showed that mean concentrations were highest for methoxychlor (8.817 ± 0.020 µg l−1) in water, sediments (92.893 ± 3.039 µg kg−1), and weeds (39.641 ± 3.045 µg kg−1), the weeds also tended to accumulate aldrin (15.519 ± 3.756 µg kg−1). The results show that the pesticides are still in use and are detected in the catchment. Stringent management and …

2017

O, OD, O WANDIGAS, A A’oD.  2017.  Synergistic Effects of Titanium (IV) Oxide Modified Clay for Disinfection and Purification of Water. European International Journal of Science and Technology . 6(5):7-32.
K, OE, V.O M, A A’oD, A O.  2017.  Assessment of the Level of Organochlorine Pesticides Contamination in Kales, Water and Soil from Naivasha, Kenya. . International Journal of Scientific Research in Science, Engineering and Technology . 3(5):205-213.
JK, A, O WANDIGAS, A A’oD, O MV, EM O.  2017.  Organochlorine Pesticides Residue Levels in Air and Soil from Nairobi and Mount Kenya regions, Kenya. Journal of Applied Chemistry. 10(7):5-11.
J, KC, O OFD, DA A.  2017.  Assessment of Domestic Water Quality of Dams in Chepalungu Sub-county, Bomet County, Kenya.. The International Journal of Science & Technology. 5(6):144-130.
A, A’oD, J.O O, M H.  2017.  The Effect of Septic Tanks Sewage Disposal System Distances On Borehole Water Quality in Ongata Rongai, Kajiado County, Kenya:. The Effect of Septic Tanks Sewage Disposal System Distances On Borehole Water Quality in Ongata Rongai, Kajiado County, Kenya. 6(3):1-10.
Mwaniki O K, A A’oD, O OJ, G KJ.  2017.  Investigating the Effects of Formulation, and Geographical Location on Degradation of Carbendazim in French Beans, Kenya. The International Journal of Science & Technology . 5(2):44-51.

2016

E, TJP, O WANDIGAS, A A’oD.  2016.  Methane and heavy metals Levels from leachates at Dandora dumpsite, Nairobi County, Kenya. IOSR Journal of Applied Chemistry. 9(9):39-46.janniffer_publication.pdf
EM, O, O WANDIGAS, DA A, O MV, W MJ.  2016.  Organochlorine Pesticides Residues in Water and Sediment from Rusinga Island, Lake Victoria, Kenya. IOSR Journal of Applied Chemistry. 9(9):56-63.osoro_publication.pdf

2015

D.A, A’o, O WANDIGAS, O JI, den J VBP, B NB, O MV, A WG, P N-K, H K.  2015.  Occurrence, abundance and distribution of benthic macroinvertebrates in the Nyando River catchment, Kenya. African Journal of Aquatic Science. 40(4):373–392.benthic_macroinvertevertebrates_in_nyando_river.pdf
D.A, A’o, O WANDIGAS, O JI, den J VBP, B NB.  2015.  Organochlorine pesticide residue levels in soil from the Nyando River Catchment, Kenya . Africa Journal of Physical Sciences. 2(1):18-32.

2014

2009

Abong'o, D, Wandiga SO.  2009.  Occurrence, distribution and environmental impact of organochlorine pesticide resedues in the Lake Victoria catchment: a case study of River Nyando drainage basin. AbstractFull text link

The study was to investigate the impacts on the ecosystem health in relation to levels and distribution of organochlorine pesticides that have either been banned or restricted for use in Kenya. The pesticides targeted were DDT, lindane, aldrin, dieldrin, heptachlor, endrin, endosuphan, and methoxychlor. Prior to their ban or restriction in use, they had found wide applications in public health and agriculture for control of disease vectors and crop pests respectively.

A study was conducted in which 880 samples of soil, water, sediments, aquatic weeds and benthic macroinvertebrates were collected from 26 locations representative of the River Nyando drainage basin catchment area of 3450 km2 and a total length of 170 km of the Lake Victoria Catchment over a period of two years. Soils from six farms were sampled in areas where maize, tea, sugar cane, col fee, rice and vegetables have been grown over the years. The objective was to investigate the impacts on the ecosystem health in relation to levels and distribution of oraganochlorine pesticides that have either been banned or are restricted for use in Kenya. The pesticides targeted were DDT, lindane, aldrin, dieldrin, heptachlor, endrin, endosulfan and methoxychlor. Pior to their ban or restriction in use, they had found wide applications in public health and agriculture for control of disease vectors and crop pests respectively. Analysis of 48 soil samples revealed presence of all the targeted pesticides. Mean concentrations (pg/kg) recorded decreased in the order methoxychlor (138.97±1.517 pg/kg), total (X) endosulfan (30.267±2.098pg/kg), £DDT (17.513± 1.689 pg/kg), dieldrin (14.073±0.440 pg/kg), endrin (10.155±0.860 pg/kg), lindane (8.985±1.318 pg/kg) and ^Heptachlor (0.681±0.021 pg/kg), respectively. The distribution showed that dieldrin was in use in vegetable farms in Kedowa area, tea farms in Nandi District and in Ahero rice paddies; while p-endosulfan was commonly used on tea farms in Nandi. Water analysis from the 26 sampling sites showed the highest mean concentrations were detected for methoxychlor (8.817±0.020 pg/L), ^endosulfan (1.648± 0.04 pg/L), dieldrin (1.1561± 0.042 pg/L), endrin (0.281± 0.003 pg/L), £DDT (0.242±0.009 pg/L), £heptachlor (0.148±0.01 lpg/L) and lindane (0.144±0.006pg/L) respectively. The detected levels in sediments were considerably higher than those found in water in the order, methoxychlor (92.893±3.039 pg/kg ), lindane (33.917±2.360 pg/kg), aldrin (26.676±0.981 pg/kg ), dieldrin (23.62±4.810 pg/kg) and P-endosulfan, (10.502±0.800 pg/kg), respectively. The analysis of aquatic weeds recorded methoxychlor (39.641±3.045 pg/kg) as the highest residue concentrations, followed by aldrin (15.519±3.756 pg/kg). These higher levels may be as a result of continued use of the pesticide in the drainage basin. The levels of pesticides were higher in sediment, weeds and soil than in water. The pooled results show that the targeted pesticides are still in use in the basin and could be impacting negatively on the ecosystem health of the area. A study of the composition of the benthic macroinvertebrates showed presence of four invertebrate phyla in River Nyando. These were Arthropoda, Mollusca, Plathelminthes and Annelida. A diversity of 16 families and eleven orders was recorded, with the order Ephemeroptera being abundant upstream followed by Hemiptera, Plecoptera and Trichoptera respectively. The downstream sections mainly the rice farming areas were dominated by Hirudinae (leaches) and Oligochaeta, suggesting that they are less sensitive to environmental pollution. Using Multivariate analytical techniques, Redundancy Analysis and Canonical Correspondence Analysis, correlation statistics showed that the occurrence of organochlorine pesticides strongly affects the distribution of the benthic macro invertebrates at all the sampling locations within the drainage basin. The high concentrations of pesticide residues were detected mostly in the soils and water from rice farms, these magnitudes were followed by those from tea farms. This implies that the rice farmers use most pesticides followed by tea farmers and there the proximity of the rice paddies to Lake Victoria could pose a greater impact to ecosystem health in the entire catchment than the upstream tea, sugar cane, maize and coffee farms owing to pesticide discharge; and this call for stringent management measures to be put in place to safeguard the environment.

2004

Kasima, E, Yusuf A, Kariuki K, Abong'o D.  2004.  Evaluation of efficiency of Kipevu wastewater treatment plant in Mombasa County, Kenya. Scholar.
Aucha, JK, Wandiga SO, Abong’o DA, Madadi VO, Osoro EM.  2004.  OrganochlorinePesticides Residue Levels in Airand Soilfrom Nairobiand Mount Kenyaregions, Kenya. Researchgate. AbstractFull text link

Thestudy investigates the organochlorine pesticides residue level in air and soilat
sites in Nairobi and Mount Kenya regions, Kenya. Air and soil samples from four sites were
collected and analysed for selected organochlorine pesticides (OCP) using gas
chromatography equipped with electron capture detector and confirmed using GC/MS. The
targeted pesticides were α-HCH, β-HCH, γ-HCH (lindane), α-endosulfan, βendosulfan and
Endosulfansulfate.

Thabano, JRE, bong’o DA, Sawula GM.  2004.  Determination of nitrate by suppressed ion chromatography after copperised-cadmium column reduction. Journal of Chromatography A. 1045(1):153-159. AbstractFull text link

The nitrate-selective copperised-cadmium (Cu-Cd) reduction reaction coupled directly to the highly sensitive nitrite ion chromatographic detection, produced a more precise method for determination of nitrate than any one of the two conventional methods. A borate buffer solution used in the reduction reaction, in place of the conventional ammonium–EDTA buffer solution, eliminated interferences from co-eluting ions in the subsequent ion chromatographic detection of nitrite. Optimised experimental conditions included using a packed-bed Cu-Cd reductor column length of 12.5 cm, a solution flow rate of 3.0 ml/min, and using 10.0 ml of borate buffer solution for each 20.0 ml of nitrate-containing solution. Precision was high for results obtained within a greatly extended linear dynamic range of 0.006–1.20 mg/l NO3−, with a much lower limit of detection of 0.40 μg/l NO3−. Cu-Cd reductor column efficiency was 98.20 ± 6.03%. Validation of the method was undertaken using certified reference materials. The method was successfully applied to analysis of dam water, river water and storm water samples, producing more precise results than either the conventional colorimetric method or the conventional ion chromatographic method.

Thabano, JRE, D.Abongo, Sawula GM.  2004.  determination of nitrates using suppressed ion chromatography after copperised cadmium column reduction . Journal of chromatography A. 1045:153-159.thabano_publication.pdf

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