Natural Resources Management

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  • Publication
    Publication
    Environmentally persistent free radicals and particulate emissions from the thermal degradation of Croton megalocarpus biodiesel
    (Springer, 2018-09-01) Mosonik, Bornes; Kibet, Joshua; Ngari, Mwaniki; Nyamori, Vincent
    Pyrolysis of biodiesel at high temperatures may result in the formation of transient and stable free radicals immobilized on particulate emissions. Consequently, free radicals adsorbed on particulates are believed to be precursors for health-related illnesses such as cancer, cardiac arrest, and oxidative stress. This study explores the nature of free radicals and particulate emissions generated when Croton megalocarpus biodiesel is pyrolyzed at 600 °C in an inert environment of flowing nitrogen at a residence time of 0.5 s at 1 atm. The surface morphology of thermal emissions were imaged using a field emission gun scanning electron microscope (FEG SEM) while the radical characteristics were investigated using an electron paramagnetic resonance spectrometer (EPR). A g-value of 2.0024 associated with a narrow ∆Hp-p of 3.65 G was determined. The decay rate constant for the radicals was low (1.86 × 10−8 s−1) while the half-life was long ≈ 431 days. The observed EPR characterization of Croton megalocarpus thermal particulates revealed the existence of free radicals typical of those found in coal. The low g-value and low decay rate constant suggests that the free radicals in particulates are possibly carbon-centered. The mechanistic channel for the formation of croton char from model biodiesel component (9-dodecenoic acid, methyl ester) has been proposed in this study.
  • Publication
    Publication
    Improved region-specific emission factors for enteric methane emissions from cattle in smallholder mixed crop: livestock systems of Nandi County, Kenya
    (CSIRO PUBLISHING, 2018-08-01) Ndung’u, P. W.; Bebe, B. O.; Ondiek, J. O.; Butterbach-Bahl, K.; Merbold, L.; Goopy, J. P.
    National greenhouse-gas (GHG) inventories in most developing countries, and in countries in Sub-Saharan Africa in particular, use default (Tier I) GHG emission factors (EFs) provided by the Intergovernmental Panel on Climate Change (IPCC) to estimate enteric methane (CH4) emissions from livestock. Because these EFs are based on data primarily from developed countries, there is a high degree of uncertainty associated with CH4 emission estimates from African livestock systems. Accurate Tier II GHG emission reporting from developing countries becomes particularly important following the Paris Climate agreement made at COP21, which encourages countries to mitigate GHG emissions from agricultural sources. In light of this, the present study provides improved enteric CH4 emission estimates for cattle in Nandi County, Western Kenya, representing a common livestock production system found in East Africa. Using the data from measurements of liveweight and liveweight change, milk production and locomotion collected from 1143 cattle in 127 households across 36 villages over three major agro-ecological zones covering a full year, we estimated total metabolic energy requirements. From this and assessments of digestibility from seasonally available feeds, we estimated feed intake and used this to calculate daily CH4 production by season, and, subsequently, created new EFs. Mean EFs were 50.6, 45.5, 28.5, 33.2 and 29.0 kg CH4/head.year for females (>2 years), males (>2 years), heifers (1–2 years), young males (1–2 years) and calves (<1 year) respectively, and were lower than the IPCC Tier I estimates for unspecified African adult cattle, but higher for calves and young males. Thus, using IPCC Tier 1 EFs may overestimate current enteric CH4 emissions in some African livestock systems.
  • Publication
    Publication
    Propagation And Regeneration Of Important Indigenous Tree Species In Kakamega Forest, Kenya
    (EduPedia Publications (P) Ltd, 2018-08-01) Busuru, Carolyne; G., Obwoyere; Kirui, Bernard
    study evaluated regeneration potential of P. africana vis a vis Olea capensis and Croton megalocarpus, identified the seed for propagation and suitable sowing media that gives optimum germination results. An experiment was set to evaluate these. Seeds were collected prepared, germinated under the different media types and germination percent monitored. The data was collected on mean germination percent in different media ratio and statistical analyses conducted. The results indicated that There was significant difference in the timing of the collection of seeds (F 2, 60, f=24.47, P<0.001). Germination rate was significantly lower in stored seeds compared to the other two seed collection stages i.e. mature green seeds and mature ripe. There was a significant ‘medium’ effect on the germination of C. megalocarpus (F6,62, f=4.84, p<0.001), Prunus africana (Chi- square test = 14.10, d. f= 6, p = 0.029) and O. capensis (Chi –square test = 18.33, d. f= 6, p = 0.005). From the results, it was concluded that the best seed for propagation of P. africana is seed freshly harvested, mature and ripe even without any pre-treatment. It is therefore recommended that P. africana seed should be sown in sand: sawdust 1:1 immediately after harvesting for optimum germination.
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    Publication
    Wildlife Population Change in Africa from the Eyes of the Public—The Case of Mara Enoonkishu Conservancy in Southern Kenya
    (Scientific Research Publishing, 2016-06) Masiga, Dorothy Syallow; Mwaura, Francis; Mukhovi, Mikalitsa S.
    The aims of the study were to: 1) determine the wildlife population trends in the Mara Enoonkishu Conservancy from the eyes and minds of the public, 2) assess the recent trends in wildlife populations based on actual scientific counts, and 3) compare the two patterns and establish whether they are similar or not. The solicitation of public views was based on household surveys using a standard questionnaire which was administered to 115 randomly selected respondents. The dominant wildlife species according to 39% of the respondents was the elephant followed by the zebra with 35%. 40% of the respondents indicated that the rhino population had declined followed by wild dogs (7%) and cheetah (6%). The actual counts showed that the herbivores with increasing populations included the rhino (r2 = 0.9992), impala (r2 = 0.9824), Thomson’s gazelle (r2 = 0.6965), Grant’s gazelle (r2 = 0.7052), elephant (r2 = 0.5798), and topi (r2 = 0.4426) while the increasing predators included the lion (r2 = 1.000), cheetah (r2 = 0.9093) and hyena (r2 = 0.8462). The actual wildlife counts appeared to tally with the public views only for the elephant and zebra. The actual counts contradicted the public views in terms of the rhino, lion and gazelles whose numbers were on the increase but the people did not appear to notice. Based on this, it was concluded that the public view on the wildlife population trend was not similar to the actual wildlife population status on the ground based on scientific monitoring