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Analysis of Spatial and Temporal Levels of Heavy Metals in Water, Sediments and Fish in Sosiani River
(Science and Education publishing (SciEP), 2019-10-09) Shieunda, Ogara Rose; Neyole, Edward; Omuterema, Stanley; Orata, Francis
The objective of the study was to examine spatial and temporal levels of heavy metals in water, sediments and fish in Sosiani River. This study was an experimental design approach in which a scientific analysis was done involving sample collection, preparation and laboratory work to determine Pb, Cd and Cr concentrations in fish water and sediments. The main Sosiani river flows from the Keiyo escarpment at the far South East through Uasin Gishu plateau to Turbo which is in the North West. The units of analysis used in the study included two species of fish, water and sediment; whereby water and sediment were sampled from eleven sampling locations (SR0 – SR10) and fish from ten sampling points (SR1 – SR10) along river Sosiani catchment. Sample analysis was done using Atomic Absorption Spectrometry. Data analysis was done using the statistical program for social sciences (SPSS) version 23. Inferential (ANOVA), regression and descriptive statistics were used to analyse data. Spatial and temporal levels of heavy metals in water, sediments and fish were the outcomes. In the upper Sosiani, SR3 (Chepkorio) registered the highest lead levels in the wet season of 0.127 mg/l. In both dry and wet seasons, and in all the sites, lead values in water were above the NEMA and WHO thresholds of 0.01 mg/l. In the analysis of cadmium concentrations, it was observed that in wet season water had all 50% of the sites above the NEMA and WHO thresholds while all the sites were had values below the limits during the dry season. Cr in water was high for 90% of the sites. Sediment had the highest lead values of 1.744mg/l. Barbus (Barbusbarbus) fish had high lead, cadmium and Cr values in both wet and dry seasons. In both seasons, catfish (Clariusgariapinus) had low values of lead and cadmium below the NEMA and WHO limits for most of the sites but high levels of Chromium. Spatial and temporal variations in heavy metal concentration were observed between the water, sediment and the two species of fish within the catchment. This study recommended mandatory measures (enforcement) to control the increased heavy metal concentration downstream the basin.
Effects of supplemental irrigation on yield, water use efficiency and nitrogen use efficiency of potato grown in mollic Andosols
(Springer Nature, 2021-08-18) Satognon, Felix; Owido, Seth F. O.; Lelei, Joyce J.
Low soil fertility and reduced seasonal rainfall contribute to low potato (Solanum tuberosum L.) yield in Kenya. Nitrogen (N) deficiency is the major problem facing by the smallholder farmers of Kenya due to lack of fallow. Hence an introduction of supplemental irrigation with an adequate application of this nutrient could increase potato yield. The objective of this study was to determine the effects of supplemental irrigation and N-fertilisation on potato tuber yield, water use efficiency (WUE) and nitrogen use efficiency (NUE). The experiment was conducted in Nakuru County, Kenya for two seasons. The experimental soils are classified as mollic Andosols. The treatments comprised two irrigation treatments of full supplemental irrigation (FI) and rainfed production (RF) and four N levels of four N levels of 0 (N0), 60 (N1), 90 (N2) and 130 kg N/ha (N3).ResultsThe results showed that total tuber yield, marketable tuber yield and NUE were significantly (P < 0.001) affected by irrigation × N-fertilisation while WUE was only affected (P < 0.001) by N-fertilisation. The highest total tuber yield, 58.28 tonnes/hectare (t/ha), was recorded under FI combined with N3. Treatment FI significantly increased marketable tuber yield by approximately 125.58% in all N treatments compared to RF. The highest NUE of potato (236.44 kg/kg of N) was obtained under FI combined with N3 but not significantly different from the NUE of potato obtained under FI with N2. N-fertilisation N3 produced the highest WUE of 14.24 kg/m3. Significant correlation was obtained between tuber yield and number of tubers/plant (r = 0.75, P < 0.001), NUE (r = 0.95, P < 0.001) and WUE (r = 0.72, P < 0.001).ConclusionHigh potato yield and marketable tuber yield can be achieved in mollic Andosols when water deficits of the growing season are eliminated with supplemental irrigation and an application of 130 kg N/ha.
Open Defaecation and Its Effects on the Bacteriological Quality of Drinking Water Sources in Isiolo County, Kenya
(Sage Journals, 2017-09-09) Okullo, Joab Odhiambo; Moturi, Wilkister Nyaora; Ogendi, George Morara
Background information: The post-2015 Sustainable Development Goals for sanitation call for universal access to adequate and equitable sanitation and an end to open defaecation by 2030. In Isiolo County, a semi-arid region lying in the northern part of Kenya, poor sanitation and water shortage remain a major problem facing the rural communities.Objective: The overall aim of the study was to assess the relationship between sanitation practices and the bacteriological quality of drinking water sources. The study also assessed the risk factors contributing to open defaecation in the rural environments of the study area.Methods: A cross-sectional study of 150 households was conducted to assess the faecal disposal practices in open defaecation free (ODF) and open defaecation not free (ODNF) areas. Sanitary surveys and bacteriological analyses were conducted for selected community water sources to identify faecal pollution sources, contamination pathways, and contributory factors. Analysis of data was performed using SPSS (descriptive and inferential statistics at α = .05 level of significance).Results: Open defaecation habit was reported in 51% of the study households in ODNF villages and in 17% households in ODF villages. Higher mean colony counts were recorded for water samples from ODNF areas 2.0, 7.8, 5.3, and 7.0 (×103) colony-forming units (CFUs)/100 mL compared with those of ODF 1.8, 6.4, 3.5, and 6.1 (×103) areas for Escherichia coli, faecal streptococci, Salmonella typhi, and total coliform, respectively. Correlation tests revealed a significant relationship between sanitary surveys and contamination of water sources (P = .002).Conclusions: The water sources exhibited high levels of contamination with microbial pathogens attributed to poor sanitation. Practising safe faecal disposal in particular is recommended as this will considerably reverse the situation and thus lead to improved human health.
Simulation of the Hydraulics and Treatment Performance of Horizontal Subsurface Flow Constructed Wetland Treating Greywater
(Science Publishing Group, 2018-05-10) Raude, James Messo; Mutua, Benedict Mwavu; Kamau, David Ngugi
Constructed wetlands (CWs) have evolved as some of reliable wastewater treatment technologies. Various types of CWs differ in their main design characteristics and in processes responsible for pollutant removal. Classification of CWS is based on the type of vegetation used and hydrological parameters involved and can thus be classified as free water surface or subsurface flow systems. Further, subsurface flow systems can be classified according to flow direction as vertical or horizontal. This study considers horizontal subsurface flow constructed wetlands (HSFCWs) which introduces the mechanistic, dynamic compartmental model-Constructed Wetlands 2D (CW2D). The model has successfully been utilized to evaluate the performance of vertical flow constructed wetlands and is being tested on HFCWs. An outdoor pilot scale HSFCW system was established in Nakuru, Kenya. CW2D was calibrated, validated and used to simulate hydraulic performance of HSFCW system. The model was used in predicting effluent concentrations of the main greywater pollutants. In general, the results obtained showed a good match with the measured data. CW2D is an effective tool for evaluating the performance of CWs and can provide insights in treatment problems at an existing CW. The same methodology can be used to optimize existing systems.
Mangrove cover and cover change analysis in the transboundary area of Kenya and Tanzania during 1986–2016
(Taylor & Francis group, 2019-05-20) Mungai, Fredrick; Kairo, James; Mironga, John; Kirui, Bernard; Mangora, Mwita; Koedam, Nico
Mangrove forests are among the most threatened ecosystems on earth. Some of these forests traverse national boundaries complicating their management due to differences in governance structures between countries. To improve the management of transboundary species regular monitoring is essential. Remotely sensed data were used to estimate forest cover and analyze conditions of mangroves in the proposed transboundary conservation area (TBCA) between Kenya and Tanzania. Image analysis was performed using unsupervised and supervised classification methods. The transboundary mangroves cover an estimated 11,906 ha; 55% being in Kenya, 45% in Tanzania. Ceriops tagal, Avicennia marina, and Rhizophora mucronata species co-dominate the mangroves of the transboundary area. The hotspot for loss and degradation of mangrove in the TBCA is Vanga in Kenya with a loss of 27 ha/yr. Harvesting of mangrove wood products have contributed to the loss of mangroves in the transboundary area. TBCA formation could play a critical role in ensuring sustainable mangrove resources utilization.