Bio

Publications


2017

Mwaniki, OK, Abongo DA, Onyatta JO, Kithure JG.  2017.  Investigating the Effects of Formulation and Geographical Location on Degradation of Carbendazim in French Beans, Kenya. The International Journal of Science & Technolodge . 5(2):44-51.

2016

Onyatta, JO, Tum PK, Kithure JGN, Oduor FDO.  2016.  Photocatalytic Degradation of Acid Orange II Dye on Selected Commercial Titanium Dioxide Catalysts. International Journal of Advanced Research. 4(10):1149-1155.
Omoko, BJ, Onyatta J, Nyabaro O, Kenanda OE.  2016.  Level of Metal Pollutants in Water from Nyakomisaro Stream through Kisii Town... International Journal of Science and Research . 5(7):464-565.

2015

Oyagi, MO, Onyatta JO, Kamau GN, Guto PM.  2015.  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. 23(2):324-334.

2009

Onyatta, JO, Chepkwony CK, Ongoma PO.  2009.  The Impact of Urban Activities on Heavy Metal Distribution and Bioavailability Index in Selected Tropical Urban Soils. Molecular Environmental Soil Science at the Interfaces in the Earth's Critical Zone. , GMbH : Springer-Verlagabstract.pdf

2007

Nyangwara, KM, Kirigua V, Kaburu P, Mugo P, Macharia JM, Onyatta JO, Antipa R, S M.  2007.  Research Information services for Urban Agriculture and Environment in Cities of Kenya: “Empowering through knowledge sharing”., 2007. , Nairobi: International Development Research Centre (IDRC)
Murithi, E., M, K. Nyangwara, Onyatta JO, Kirigua V, Kaburu PK, Macharia JM.  2007.  Urban and Peri-urban Agriculture: Towards a better understanding of low-income producers’ organizations: Nairobi Case Study., 2007. , Nairobi: FAO

2006

Langat, SK, Onyatta JO.  2006.  The changing conceptions and focus of health research in East Africa . Africa J. Health. 13:1-5.
Onyatta, JO, Huang PM.  2006.  Distribution of applied cadmium to different size fractions of soils after inocubation. Bio- Fertility Soils. 42:432-436.

2005

Onyatta, JD, Huang PM.  2005.  Soil Abiotic and Biotic Interactions and Impact on the Ecosystem and Hutnan Welfare. 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.  2005.  Urban micro-farming and HIV/AIDS mitigation-Gardens of Hope, August/2005. , Johannesburg/Cape Town S.A: RUAF, The Netherlands and Abalimi Bezakhaya, South Africa
Onyatta, JO, Huang PM.  2005.  Phosphate-induced cadmium release from soils. Soil Abiotic and Biotic Interactions and the Impact of the Ecosystem and Human Welfare. , Enfield, NH USA: Science Publishers

2004

Onyatta, JO, Omoto WO.  2004.  . Potential for urban and peri-urban agriculture to create employment and reduce poverty., 2004. , Nairobi: Kenya Agricultural Research Institute, Urban Harvest-CIP and International Livestock Research Institute (ILRI).
Onyatta, JO, Huang PM.  2004.  Distribution of cadmium introduced to soil in different size fractions after incubation.. 4th International Symposium of the Working Group MO. “Interactions of Soil Minerals with Organic Components and Microorganisms” (ISMOM) and the First Inter-Congress Conference of Commission 2.5 “Soil Physical/Chemical/Biological Interfacial Interactions. :20., Wuhan, China: International Union of Soil Sciences

2003

2002

Onyatta, JO, Huang PM.  2002.  Phosphate-induced cadmium release from selected soils. . 17th World Congress of Soil Science. :14-21., Bangkok, Thailand: World Congress ofSoil Science

1999

1998

Onyatta, JO, Huang PM.  1998.  The influence of potassium chloride on cadmium release from selected tropical soils.. 16th World Congress of Soil Science. :1-5., Montpelier, France: World Congress ofSoil Scienceabstract_kcl.pdf

1997

Onyatta, JO.  1997.  Kinetics and Equilibria of Cadmium in Selected kenyan Soils. (P. M. Huang, Ed.)., Saskatoon: University of Saskatchewanabstract_thesis.pdf
Onyatta, JO, Huang PM.  1997.  The fate of cadmium introduced to soils. The annual meetings of the American Society of Agronomy, the Crop Science Society and the Soil Science Society of America,. , Anaheim, California, USA: The American Society of Agronomy, the Crop Science Society and the Soil Scince Society of America

1995

Onyatta, JO, Huang PM.  1995.  Cadmium status in selected Kenyan soils. The annual meetings of the American Society of Agronomy, the Crop Science Society and the Soil Scince Society of America. :217., St. Louis, Missouri, USA: The American Society of Agronomy, the Crop Science Society and the Soil Scince Society of America

1985

UoN Websites Search