Publications


2015

Mutai, BK, Muthama JN, Ngaina JN.  2015.  Analysis of the Temporal Evolution of Total Column Nitrogen Dioxide and Ozone over Nairobi, Kenya using Daily OMI Measurements. Ethiopian Journal of Environmental Studies and Management. 8(5):530-540. Abstractanalysis_of_the_temporal_evolution_of_total_column_nitrogen_dioxide_and_ozone_over_nairobi_kenya_using_daily_omi_measurements.pdfAfrican Journals Online(AJOL)

Concurrent measurement and analysis of Nitrogen dioxide (NO2)and Ozone (O3) are essential for improved understanding of ozone distribution. This study sought to analyse the temporal evolution of total column NO2 and O3 over Nairobi using satellite-derived daily data between 2009 and 2013. Seasonality is observed in O3 distribution with minimum and maximum occurring during the dry and wet seasons, respectively. Additionally, a lag of about a month or two occurs between the onset of a season and corresponding minimum or maximum NO2 and O3 concentration. The established association between monthly NO2 and O3 is such that, above average concentration of NO2 is likely to lead to above average levels of O3 during the same month (r=0.79) and below average levels about 5 months later (r=0.39). The Quasi Biennial Oscillation (QBO) is the main phenomenon behind the oscillating biennial feature exhibited by NO2 and O3 interannual trend. The study shows that NO2 and O3 are increasing at annual average rates of about 0.27% and 0.46% per year compared to mean values, respectively. Daily variation of both NO2 and O3 depicts stagnating trends over the entire period of study. This difference is attributed to the fact that, whereas daily NO2 and O3 are influenced by mechanisms that control the slow shift between the dry and wet periods within the course of a year, interannual variability is driven by the differences in each year’s general weather conditions.

Key Words: Evolution, Nitrogen dioxide, Ozone, Total Column, Quasi Biennial Oscillation

J., MN, M. KC, K MB, J.K. N’ang’a.  2015.  Simulation of Potential Impact of Air Pollution from the Proposed Coal Mining Sites in Mui Basin, Kitui County. Africa Journal of Physical Sciences. 2(1):60-72. AbstractAfrica Journal of Physical Sciences

The potential for air pollutants transport, dispersion patterns and impacts within and around the Mui basin, Kitui County is simulated. The spatial-temporal distribution of air pollutants from the proposed coal mines was investigated using Hybrid Single Particle Lagrangian Integrated Trajectories (HYSPLIT) and dispersion analyses. The spatial distribution of wind patterns was investigated using wind rose to explain the observed air pollution
distribution. The analysis was carried out for the dry and wet seasons of the study area namely: December, January, February (DJF), March, April, May (MAM), June, July, August (JJA) and September, October, November (SON) seasons. From the analysis, the season during which the exposure levels would pose much health threat was established based on frequency of winds blowing in certain direction and speed. By spatial analysis of the
proximity of proposed mines and direction of dominant winds, areas most prone to pollution were delineated. The results showed that winds over the area were generally low and southerly. The residents to the northern and northwestern sectors would be at most at risk should the mining commence. Due to low wind speeds during January and the onset of JJA season, residents and workers at the mine would be affected adversely. The results may contribute to the design of effective control strategies to reduce impact of emitted pollutants.

Keywords:
Pollution, Wind rose, HYSPLIT, Trajectory, Dispersion, Exposure

2014

Kimani, SK, Ng’ang’a JK, DW Kariuki, Kinyua J, Kimani FT, Kiboi DM.  2014.  Plasmodium Berghei ANKA: Selection of Pyronaridine Resistance in Mouse Model. African Journal of Biochemistry Research. 8(6):111-117.plasmodium_berghei_anka-selection_of_pyronaridine_resistance_in_mouse_model.pdfacademicjournals

2013

2010

2008

K, PROFNGANGAJOHN.  2008.  Cloud cover estimation over selected locations in East Africa using satellite derived reflectivity data.. Journal of KMS VOL 2,NO.2,Pg 85-91. : Muthama N.J,K.H. Kai,G.O. Ouma,J.K.Nganga,F.J. Opijah Abstract
will be availed soon
FRANKLIN, DROPIJAH, R DRMUKABANAJOSEPH, K PROFNGANGAJOHN.  2008.  Contribution to the Heat Budget in Nairobi Metro-Area by the Anthropogenic Heat Component.. Proceedings: 1st KenGen/IAEA geothermal Conference in Kenya. : J. Kenya Meteorological Soc Abstract
This study quantifies the ejected waste heat from artificial supplies comprising road transport and industrial, commercial, domestic and metabolic heating activities which may enhance the urban temperatures in Nairobi metro area, taking into account the energy intensity of a given activity and the level of the activity, considering expended fossil and biofuels, electrical energy consumption and human metabolism. Translation of linear source strengths to area averages from the road transport sector yields about 4% of the total anthropogenic energy over the city. The contribution from the road sector is likely to rise to 10.8 W m-2 in 2029 as the City expands. The industrial/commercial sector contributes up to 35.5 W m-2 or 57% of the total anthropogenic energy, and could increase to 284 W m-2 by 2029 due to industrialization and economic growth. Domestic utilities account for up to 13 W m-2, which is 21% of the total anthropogenic energy. Depending on the activity engaged in, human metabolism contributes up to 11.4 W m-2, which is about 18% of the total anthropogenic energy supplies. The sum total area-averaged anthropogenic energy consumption over the city centre is currently small, constituting about 11 to 18% of the global radiation for the warmer and colder seasons, respectively. Notably, only a part of this energy is released into the atmosphere as waste heat as most is used for the intended purposes. If the current trends of rising population, increased motor vehicle density and enhanced industrialization persist, the anthropogenic waste heat ejection would be large enough to alter the heat balance of the study area appreciably in future by 2030.
FRANKLIN, DROPIJAH, R DRMUKABANAJOSEPH, K PROFNGANGAJOHN.  2008.  Response of the Moisture Budget to the Growth and Development of Nairobi City . Proceedings: 1st KenGen/IAEA geothermal Conference in Kenya. : Africa J. of Sc. and Tech

2007

Otengi, SBB, Stigter CJ, Ng'ang'a JK, Liniger H.  2007.  Soil moisture and maize-bean yields under different management in a six years old hedged Agroforestry system in Semi-Arid Laikipia, Kenya, for two contrasting seasons. AbstractWebsite

Hedged agroforestry (AF) demonstration plots with maize/bean intercrops were studied at Matanya in Laikipia district, Kenya, between 1991 and 1995 inclusive, to understand crop yield behaviour due to selected soil moisture conservation methods applicable in semi-arid areas. The treatments were: Grevillea robusta trees root pruned, compared to unpruned, both in combination with (1) minimum tillage and mulching with 3t/ha maize stalks harvested from the plots with additional stalks collected from the nearby farms, and (2) the locally applied method of deep tillage practiced by the immigrants from wetter regions, acting as the control. Results showed that: (i) plots with root pruned Grevillea robusta trees that were mulched and minimum tilled had most soil moisture available in the shallower layers, during the wettest and the driest season on which this paper is based; (ii) the variation of soil moisture with distance from the Grevillea robusta trees showed patterns that were quite similar for plots with root pruned trees in the dry and the wet season; (iii) beans had greater seed yields and maize had more (stover) biomass and (only in the wettest season) grain in plots with pruned trees, minimum tilled and mulched, than in other AF plots. In the wettest season this resulted in identical maize yields but lower bean seed yields compared to those in the mulched and sometimes also the local control plots without trees. In the driest season bean yields remained the same but maize biomass yields improved above the control yields for the most successful agroforestry intervention applied; (iv) competition between the six year old Grevillea robusta trees and the crops was indirectly confirmed to be stronger than in earlier experiments in the same plots. This way the agroforestry demonstration plots were very successful in showing the consequences of the ageing agroforestry system, where the soil moisture conservation measures of pruning and mulching kept their effects. Statistical analysis only weakly confirmed the positive effect of root pruning on reducing competition for soil moisture between crops and trees that were very clearly shown to exist by the physical error analysis.

Otengi, SBB, Stigter CJ, Ng'anga JK, Liniger H.  2007.  Soil moisture and its consequences under different management in a six year old hedged agroforestry demonstration plot in semi-arid Kenya, for two successive contrasting seasons. AbstractWebsite

Hedged agroforestry (AF) demonstration plots with maize/bean intercrops were studied at Matanya in Laikipia district, Kenya, between 1991 and 1995 inclusive, to understand crop yield behaviour due to selected soil moisture conservation methods applicable in semi-arid areas. The treatments were: Grevillea robusta trees root pruned, compared to unpruned, both in combination with (1) minimum tillage and mulching with 3t/ha maize stalks harvested from the plots with additional stalks collected from the nearby farms, and (2) the locally applied method of deep tillage practiced by the immigrants from wetter regions, acting as the control. Results showed that: (i) plots with root pruned Grevillea robusta trees that were mulched and minimum tilled had most soil moisture available in the shallower layers, during the wettest and the driest season on which this paper is based; (ii) the variation of soil moisture with distance from the Grevillea robusta trees showed patterns that were quite similar for plots with root pruned trees in the dry and the wet season; (iii) beans had greater seed yields and maize had more (stover) biomass and (only in the wettest season) grain in plots with pruned trees, minimum tilled and mulched, than in other AF plots. In the wettest season this resulted in identical maize yields but lower bean seed yields compared to those in the mulched and sometimes also the local control plots without trees. In the driest season bean yields remained the same but maize biomass yields improved above the control yields for the most successful agroforestry intervention applied; (iv) competition between the six year old Grevillea robusta trees and the crops was indirectly confirmed to be stronger than in earlier experiments in the same plots. This way the agroforestry demonstration plots were very successful in showing the consequences of the ageing agroforestry system, where the soil moisture conservation measures of pruning and mulching kept their effects. Statistical analysis only weakly confirmed the positive effect of root pruning on reducing competition for soil moisture between crops and trees that were very clearly shown to exist by the physical error analysis

R, DRMUKABANAJOSEPH, K PROFNGANGAJOHN, FRANKLIN DROPIJAH.  2007.  Rainfall Distribution over Nairobi Area. Journal of KMS VOL 2,NO.2,Pg 85-91. : J. Kenya Meteorological Soc

2006

2005

K, PROFNGANGAJOHN.  2005.  Evaporation from soils below sparse crops in contour hedgerow agroforestry in semi-arid Kenya. Agricultural and Forest Meteorology, Vol. 130, pp. 149-162.. Journal of the African Meteorological Society, Vol. 6 No.1 pp. 25-35.. : SMA
K, PROFNGANGAJOHN, FRANKLIN DROPIJAH.  2005.  Simulation of the influence of surface heterogeneity on air flow and convection over Nairobi area: Implication on airquality in the city.. Journal of the African Meteorological Society, Vol. 6 No.1 pp. 25-35.. : SMA

2001

2000

1998

Stigter, CJ, den Van B, Daane JRV, Adam HS, Mohammed AE, Ng'ang'a JK, Mungai DN.  1998.  The “picnic” model for research training at African Universities: evaluation and preliminary comparison. AbstractThe “picnic” model for research training at African Universities: evaluation and preliminary comparison

What distinguishes the “Picnic” model for research training at African universities from more classical models is reviewed and it is shown how the “Picnic” model deals with remaining drawbacks from the now popular “Sandwich” model. Starting with managerial experiences, criteria guiding this evaluation are used as sub-headings: realistic planning; adequate resource provision; partnership instead of aid; long term impact; high quality supervision; quality and quantity of student input; open and interactive communication; willingness to adapt to local circumstances; ongoing critical reflection; gradual expatriate withdrawal. The training output of the “Picnic” model tests in the four TTMI-countries is assessed after the actual and prospective jobs of its former students. The on-farm quantification of protecting systems/structures led in many TTMI PhD-research cases to improved design criteria for such systems/structures, with direct increases of yield or its preservation. In comparison with the “Sandwich” model, the “Picnic” model particularly incorporates institutional strengthening in the aim that the southern countries will become able to provide adequate education at the postgraduate level, teaching their students how to apply knowledge in their own environment. Degrees obtained at southern universities, therefore, have distinct advantages but joint responsibilities of universities for such degrees are difficult to organize, given the presently existing modes of output-related financing of Dutch universities. In a situation of institutional deterioration, such as Africa is experiencing, the best hope probably lies in strengthening networks of individuals and a collective sense of academic commitment, pending the revival of universities themselves. Emergency research related to the protection of the African agricultural environment by African universities, training NARS staff, must in the long run contribute to restoring an agricultural basis for part of the economies of the many poor African countries. Knowledge developed locally remains the most powerful vehicle for change from within.

1996

1995

1992

1990

K, PROFNGANGAJOHN.  1990.  Nganga, J.K., 1990: Air pollution problem in African cities. African Urban Quarterly. Vol 5: No. 1, pp. 30-33.. African Urban Quarterly. Vol 5: No. 1, pp. 30-33.. : SMA Abstract
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1989

1988

1987

K, PROFNGANGAJOHN.  1987.  Okumu, A. M. Das, P. K. and Nganga, J. K., 1987: Some aspects of Somali current. @pp. 22- 126.. Some aspects of Somali current. @pp. 22- 126.. : SMA Abstract
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K, PROFNGANGAJOHN.  1987.  Nganga, J. K. 1987: Meteorological Application to air pollution research in tropical regions. An invited paper. Proceedings of the First Technical Conference for Meteorological Reseach in Eastern and Southern Africa, Nairobi, Kenya, 6-9 January 1987, pp. . Proceedings of the First Technical Conference for Meteorological Reseach in Eastern and Southern Africa, Nairobi, Kenya, 6-9 January 1987, pp. 283-286.. : SMA Abstract
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1986

K, PROFNGANGAJOHN.  1986.  Nganga, J.K., and Ngugi, G. K, 1986: Indices of comfort in some Towns in Kenya, w. pp. 190- 199.. Indices of comfort in some Towns in Kenya, w. pp. 190- 199.. : SMA Abstract
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1985

1984

K, PROFNGANGAJOHN.  1984.  Patnaik, J.K., Kiangi, P.M.R. and Nganga, J.K. 1984: The Three Dimensional Temperature Field over Africa; IbkJ., pp. 166 - 1 7 1.. The Three Dimensional Temperature Field over Africa; IbkJ., pp. 166 - 1 7 1.. : SMA Abstract
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1981

K, PROFNGANGAJOHN.  1981.  Nganga, J.K., : On the Frequency and Stability Wind Roses in a Tropical Region. Journal of Air, Water and Soil Pollution, Vol. 16: pp. 385 - 386.. Journal of Air, Water and Soil Pollution, Vol. 16: pp. 385 - 386.. : SMA Abstract
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1980

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