The main aim of investigating activity concentrations together with distribution of radionuclides naturally in soil from Kargi was to evaluate radiological health hazard together with environmental radioactivity. Rese...The main aim of investigating activity concentrations together with distribution of radionuclides naturally in soil from Kargi was to evaluate radiological health hazard together with environmental radioactivity. Research shows radionuclides as one source of exposure due to radiation with detrimental effects health wise for populations found in areas considered high background radiation. After collecting 117 soil samples from the area, analysis was done in order to measure their natural radioactivities due to <sup>40</sup>K, <sup>232</sup>Th and <sup>226</sup>Ra radionuclides. Measurements method of gamma spectrometry employing a high purity germanium (HPGe) detector was employed basically to evaluate the radiological hazard of radioactivities. For <sup>40</sup>K, <sup>232</sup>Th and <sup>226</sup>Ra, mean calculated activities were 353.19 ± 110.07, 7.98 ± 3.98 and 7.37 ± 2.60 Bq<span style="white-space:nowrap;">·</span>kg <sup>-1</sup> respectively. Mean values of absorbed and effective dose rates, external and internal hazard indices together with radium equivalent activity were 23.82 ± 6.59 nGy<span style="white-space:nowrap;">·</span>h <sup>-1</sup> and 0.14 ± 0.04 mSv<span style="white-space:nowrap;">·</span>y <sup>-1</sup>, 0.12 ± 0.03 and 0.14 ± 0.04 and 45.90 ± 12.65 Bq<span style="white-space:nowrap;">·</span>kg <sup>-1</sup> respectively. Comparing with approved global values, the values were found to be below the given global limits. Evidence of involvement of metasomatic activity of the radioelements or fractionation during weathering is seen as calculations give a higher value Th/U. Excess cancer risk, calculated from the samples showed lower values as compared to global standard values hence minimal chance of getting cancer disease. The area is safe from cancer causing radionuclides.展开更多
Constraints and probable pathway towards increasing tree density and diversity within farmlands as a means of reducing human dependency on Mt. Marsabit forest for wood are addressed. The forest provides a carbon sink ...Constraints and probable pathway towards increasing tree density and diversity within farmlands as a means of reducing human dependency on Mt. Marsabit forest for wood are addressed. The forest provides a carbon sink to counteract the risks and hazards associated with climate change. A structured questionnaire was administered to a sample of 205 respondents that were selected from a population of 3075 farming households using a systematic random sampling procedure. While majority of the farms （53%） had low tree density （1-10 trees）, only 8% of the farms had high density （≥ 20 trees）. About 50% and 15% farms had Grevelia robusta and Eucalyptus cammudelensis, which were grown for timber production, respectively. Broad leafed trees, like Croton megalocarpus and Moringa stenoptella had been established in 17% of the farmlands, respectively. With only 20% of the households having a fence around the crop fields, coupled by widely inter-household sharing of crop residues for grazing, tree browsing by livestock was a constraint to tree establishment. The challenges present an opportunity to establish governance structures and processes for communal responsibility and management of tree resources in the farms. A plausible approach entails the Adaptive Collaborative Management （ACM） as a process that facilitates to experiential learning and negotiation for probable actions and policies in management of natural resources.展开更多
文摘The main aim of investigating activity concentrations together with distribution of radionuclides naturally in soil from Kargi was to evaluate radiological health hazard together with environmental radioactivity. Research shows radionuclides as one source of exposure due to radiation with detrimental effects health wise for populations found in areas considered high background radiation. After collecting 117 soil samples from the area, analysis was done in order to measure their natural radioactivities due to <sup>40</sup>K, <sup>232</sup>Th and <sup>226</sup>Ra radionuclides. Measurements method of gamma spectrometry employing a high purity germanium (HPGe) detector was employed basically to evaluate the radiological hazard of radioactivities. For <sup>40</sup>K, <sup>232</sup>Th and <sup>226</sup>Ra, mean calculated activities were 353.19 ± 110.07, 7.98 ± 3.98 and 7.37 ± 2.60 Bq<span style="white-space:nowrap;">·</span>kg <sup>-1</sup> respectively. Mean values of absorbed and effective dose rates, external and internal hazard indices together with radium equivalent activity were 23.82 ± 6.59 nGy<span style="white-space:nowrap;">·</span>h <sup>-1</sup> and 0.14 ± 0.04 mSv<span style="white-space:nowrap;">·</span>y <sup>-1</sup>, 0.12 ± 0.03 and 0.14 ± 0.04 and 45.90 ± 12.65 Bq<span style="white-space:nowrap;">·</span>kg <sup>-1</sup> respectively. Comparing with approved global values, the values were found to be below the given global limits. Evidence of involvement of metasomatic activity of the radioelements or fractionation during weathering is seen as calculations give a higher value Th/U. Excess cancer risk, calculated from the samples showed lower values as compared to global standard values hence minimal chance of getting cancer disease. The area is safe from cancer causing radionuclides.
文摘Constraints and probable pathway towards increasing tree density and diversity within farmlands as a means of reducing human dependency on Mt. Marsabit forest for wood are addressed. The forest provides a carbon sink to counteract the risks and hazards associated with climate change. A structured questionnaire was administered to a sample of 205 respondents that were selected from a population of 3075 farming households using a systematic random sampling procedure. While majority of the farms （53%） had low tree density （1-10 trees）, only 8% of the farms had high density （≥ 20 trees）. About 50% and 15% farms had Grevelia robusta and Eucalyptus cammudelensis, which were grown for timber production, respectively. Broad leafed trees, like Croton megalocarpus and Moringa stenoptella had been established in 17% of the farmlands, respectively. With only 20% of the households having a fence around the crop fields, coupled by widely inter-household sharing of crop residues for grazing, tree browsing by livestock was a constraint to tree establishment. The challenges present an opportunity to establish governance structures and processes for communal responsibility and management of tree resources in the farms. A plausible approach entails the Adaptive Collaborative Management （ACM） as a process that facilitates to experiential learning and negotiation for probable actions and policies in management of natural resources.
