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Abong'o DA, Onyatta JO, Mbugua H. "The Effect of Septic Tanks Sewage Disposal System Distances on Borehole Water Quality in Ongata Rongai, Kajiado County, Kenya." European International Journal of Science and Technology. 2017;6(3):1-10.
Birgen J, Wafula G, Yusuf A, Onyatta J. "Assessment of Sulphur Dioxide Levels in Selected Sites in Athi River, Kenya." International Journal of Trend in Scientific Research and Development (IJTSRD). 2017;1(5):416-422.
Bochaberi JO, Onyatta JO, Okemwa KE. "Kinetics of Cadmium Adsorption in Aqueous Media Using Banana Stem Biomass." International Journal of Scientific Research Engineering & Technology (IJSRET). 2017;6(7):751-755.
Isaboke PA, Njomo N, Onyatta JO. "Spectroscopic Determination of Heavy Metals in Plant Tissues in Kisii County." International Journal of Recent Development in Engineering and Technology. 2018;7(11):45-47.
Kipkorir A, Onyatta JO, Yusuf AO. "Removal of Fluoride Ions from Aqueous Solution Using Water Hyacinth Biomass as a Low-Cost Adsorbent." Elixir International Journal. 2017;110:48158-48161.
Langat SK, Onyatta JO. "The changing conceptions and focus of health research in East Africa ." Africa J. Health. 2006;13:1-5.
Miruka AC, Kariuki DK, Yusuf AO, Onyatta JO. "Efficiency of a Wastewater Treatment Plant in the City of Nairobi." International Journal of Sciences: Basic and Applied Research (IJSBAR). 2018;38(1):152-162.
Munene JM, Onyatta JO, Yusuf AO. "Characterization of Water Hyacinth Powder Using FTIR Spectroscopy and the Adsorption Behaviour of Pb2+, Cd2+, Zn2+, Ni2+ and Cr2+ in Aqueous Solution ." Asian Journal of Applied Chemistry Research. 2020;6(1):47-55. AbstractAsian Journal of Applied Chemistry Research

The adsorption behavior of selected metal ions on water hyacinth powder was investigated by Fourier Transform Infrared (FTIR) spectroscopy. Water hyacinth powder was used as an adsorbent due to its popularity, low cost and ease of availability. Water hyacinth stems were dried and ground to a powder. Batch adsorption experiments were conducted at room temperature by adding known concentrations of Pb 2+, Cd 2+, Cr 3+, Zn 2+ and Ni 2+ to 5 g of water hyacinth powder in different test tubes and allowed to stand for the same time respectively. Adsorption is one of the methods used to remove heavy metals from aqueous solutions and wastewaters. FTIR analysis was performed to identify the functional groups in the water hyacinth powder using the KBr disc method. The study showed a strong broad absorption band in the region of 3300-3200cm-1 which is characteristic of OH stretching vibrations of the adsorbed water molecules at the surface of raw water hyacinth powder particles. Other peaks appeared at 1732cm-1 which corresponded to C= O stretching vibrations while the band at 1396cm-1 could be attributed to CH bonds. The functional groups identified were: CH; OH; C= O or CO. After adsorption there was a disappearance, reduction or a shift in the adsorption bands depending on the type of metal ion. Lead for example showed a strong absorption band in the region of 1732cm-1 which is characteristic of C= O stretching bond structure which is found in esters and carboxylic acids. The disappearance of the peaks indicated that the H atom present in the functional groups of the raw water hyacinth powder could have been substituted …

Murithi, E. M, K. Nyangwara, Onyatta JO, Kirigua V, Kaburu PK, Macharia JM. Urban and Peri-urban Agriculture: Towards a better understanding of low-income producers’ organizations: Nairobi Case Study.. Nairobi: FAO; 2007.
Mustapha, A. O., Kalambuka, H. A., Maina D, Onyatta JO, Kioko J, Masinza S, Kamande J. "Needs For Education And Training In Radiation Protection: Kenya Experience.". In: The Second All African IRPA Regional Radiation Protection Congress 22-26 April 2007 . Ismailia, Egypt; 2007.
Mwaniki OK, Abongo DA, Onyatta JO, Kithure JG. "Investigating the Effects of Formulation and Geographical Location on Degradation of Carbendazim in French Beans, Kenya." The International Journal of Science & Technolodge . 2017;5(2):44-51.
Mwaniki JM, Onyatta JO, Yusuf AO. "Adsorption of Heavy Metal Ions from Aqueous Solutions and Wastewater using Water Hyacinth Powder ." International Journal of Trend in Scientific Research and Development (IJTSRD) . 2019;4(1):1-5.
Nyangwara KM, Kirigua V, Kaburu P, Mugo P, Macharia JM, Onyatta JO, Antipa R, S M. Research Information services for Urban Agriculture and Environment in Cities of Kenya: “Empowering through knowledge sharing”.. Nairobi: International Development Research Centre (IDRC); 2007.
Omoko BJ, Onyatta J, Nyabaro O, Kenanda OE. "Level of Metal Pollutants in Water from Nyakomisaro Stream through Kisii Town.." International Journal of Science and Research . 2016;5(7):464-565.
Onyatta JO, Huang PM. Distribution of cadmium introduced to soil in different size fractions after incubation.. Wuhan, China: International Union of Soil Sciences; 2004.
Onyatta JO, Abong'o DA, Muinde V. "Assessment of heavy metals in selected urban farms in Nairobi County, Kenya.". In: . East and Southern Africa Environment/Analytical chemistry conference in Africa. Mombasa, Kenya; 2016.
Onyatta JO, Huang PM. The fate of cadmium introduced to soils. Anaheim, California, USA: The American Society of Agronomy, the Crop Science Society and the Soil Scince Society of America; 1997.
Onyatta JO, Tum PK, Kithure JGN, Oduor FDO. "Photocatalytic Degradation of Acid Orange II Dye on Selected Commercial Titanium Dioxide Catalysts." International Journal of Advanced Research. 2016;4(10):1149-1155.
Onyatta JO, Huang PM. "Distribution of applied cadmium to different size fractions of soils after inocubation." Bio- Fertility Soils. 2006;42:432-436.
Onyatta JO, Chepkwony CK, Ongoma PO. "The Impact of Urban Activities on Heavy Metal Distribution and Bioavailability Index in Selected Tropical Urban Soils.". In: Molecular Environmental Soil Science at the Interfaces in the Earth's Critical Zone. GMbH : Springer-Verlag; 2009.abstract.pdf
Onyatta JO. Kinetics and Equilibria of Cadmium in Selected kenyan Soils. Huang PM, ed. Saskatoon: University of Saskatchewan; 1997.abstract_thesis.pdf
Onyatta JO, Omoto WO. . Potential for urban and peri-urban agriculture to create employment and reduce poverty.. Nairobi: Kenya Agricultural Research Institute, Urban Harvest-CIP and International Livestock Research Institute (ILRI).; 2004.
Onyatta JO, Yusuf AO, Guto PM, Ooko JO. "The need for galvanizing and the corrosion environments in Kenya.". In: International Zinc Association and Afriken International Ltd Workshop. Norfok Hotel, Nairobi, Kenya; 2017.
Onyatta JO, Huang PM. The influence of potassium chloride on cadmium release from selected tropical soils.. Montpelier, France: World Congress ofSoil Science; 1998.abstract_kcl.pdf
Onyatta JD, Huang PM. "Soil Abiotic and Biotic Interactions and Impact on the Ecosystem and Hutnan Welfare.". 2005. AbstractWebsite

Phosphate fertilizers are applied to correct phosphorus deficiency in acidic tropical soils of variable charge, which account for a large proportion of the world's arable land. They are commonly applied in bands or mixed with seeds. Within the vicinity of the phosphate fertilizer zone, the concentration of phosphate is high and can cause dissolution of soil minerals. Hence a study was conducted to investigate the degree to which phosphate may effect release of cadmium (Cd) from soil,rate of release, and formation of phosphate reaction products. Since phosphate fertilizers contain a wide range of Cd concentrations, perturbation of phosphate reaction product formation by Cd was also investigated. The surface soils used in this study were selected from tropical soils in Kenya varying widely in physicochemical properties. The study shows that 1M NH4HzP04 solution induced the release of Cd from natural soils and the soils treated with Idaho monoammonium phosphate (MAP)-fertilizer.The enhanced release of Cd by the phosphate was attributed to the combined effect of Cd introduced to the soils and the Cd released from the soils through the attack of protons and the complexation of phosphate. Phosphate-induced Cd release from natural soils and treated soils increased during the short reaction period of0.25 to 1h, then decreased with time,and tended to approach a plateau. Decrease in Cd concentration was apparently due to readsorption of the Cd released on the surface of the soil particles and/ or formation of sparingly soluble reaction products in the solution. The amounts of Cd released by NH4HzP04 increased with increments in concentration of NH4H2P04. XRD analysis showed that NH4-taranakite formed in the soils treated with 1M NH4H2P04 solution. However, taranakite did not form when monoammonium phosphate was spiked with Cd even at 6.4 x 10-3M Cd(CI0 4h, indicating that Cd perturbed taranakite formation. The study indicates that at the fertilizer granule-soil interface wherein concentration of orthophosphate is high, more Cd was mobilized compared to bulk soil. The study further shows that NH 4taranakite can form in acidic tropical soilsbut the formation may be perturbed if the MAP-fertilizer applied contains significantly high Cd as an impurity.

Onyatta JO, Huang PM. Phosphate-induced cadmium release from selected soils. . Bangkok, Thailand: World Congress ofSoil Science; 2002.
Onyatta JO, Yusuf AO, Ooko JO. "Atmospheric Corrosion Studies in Kenya: Past, Present and Future." African Corrosion Journal. 2016;2(1):25-31.
Onyatta JO, Huang PM. Cadmium status in selected Kenyan soils. St. Louis, Missouri, USA: The American Society of Agronomy, the Crop Science Society and the Soil Scince Society of America; 1995.
Onyatta JO, Huang PM. "Phosphate-induced cadmium release from soils.". In: Soil Abiotic and Biotic Interactions and the Impact of the Ecosystem and Human Welfare. Enfield, NH USA: Science Publishers; 2005.
Onyatta JO. Urban micro-farming and HIV/AIDS mitigation-Gardens of Hope. Johannesburg/Cape Town S.A: RUAF, The Netherlands and Abalimi Bezakhaya, South Africa; 2005.
Ooko JO, Onyatta JO, Yusuf AO, Guto PM. "Use of Accelerated Tests to Estimate Rate of Corrosion of Roofing Sheets." International Journal of Sciences: Basic and Applied Research. 2018;37(3):1-8.
Oyagi MO, Onyatta JO, Kamau GN, Guto PM. "Simultaneous Determination of Trace Lead (II), Cadmium (II) and Cobalt (II) by Differential Pulse Anodic Stripping Voltammetry Using Polyacrylic acid/Glassy Carbon Electrode." International Journal of Sciences: Basic and Applied Research. 2015;23(2):324-334.

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