Browsing by Author "Gichumbi, J. M."

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  • Publication
    Publication
    Phthalate Levels in Wastewater Treatment Plants of Lake Victoria Basin
    (Applied Ecology and Environmental Sciences., 2021-12-16) Onchiri, R.; Mayaka, A.; Majanga, A.; Ongulu, R.; Orata, F.; Getenga, Z. M.; Gichumbi, J. M.
    Phthalates are examples of EDCs, which have been used as plasticizers for longtime worldwide. However, their occurrence in these environments causes adverse effects such as congenital anomalies, endocrine disruption and chronic toxicity. Wastewater is the source of these phthalates in the environment. The main aim of this study was to determine the levels of dimethyl phthalate (DMP), benzyl butyl phthalate (BBP) and bis (2-ethylhexyl) phthalate (BEHP) in wastewater sampled from wastewater treatment plants (WWTPs) of Nyalenda, Homabay and Kisii, in Kenya during wet and dry seasons. Thermos Scientific Dionex UltiMateTM 3000 HPLC system was used to analyze the residue levels at 0.004 and 0.005 mg/L limits of quantification during wet and dry seasons, respectively. Most sites sampled had detectable levels of DMP, BBP and BEHP. Higher concentrations were detected during wet season compared to dry season. At Nyalenda treatment plant, DMP was detected at 0.99 ± 0.0005 mg/L and 0.79 ± 0.0005 mg/L at the inlet sampling point during the wet and dry seasons, respectively. The concentrations detected were high at the inlet and lowest at the outlet sampling points. The residue levels obtained showed significant differences at 5% confidence limits with Zcalculated for DMP at Nyalenda, Homabay and Kisii WWTPs obtained as 0.2650, 0.2183 and 0.1983, respectively. These Z-score values (Zcalculated) were less than the critical value (Zcritical = 1.96). Similar observations were observed with BBP and BEHP.
  • Publication
    Publication
    Phytochemical analysis and antifungal activity of Tithonia diversifolia and Kigelia africana extracts against Fusarium oxysporum in tomato
    (Acadamic Journals, 2021-05-31) Awere, C. A.; Githae, E. W.; Gichumbi, J. M.
    Fusarium wilt can cause severe losses in many vegetables and flowers, field crops and plantation crops. The main method for controlling Fusarium wilt is through chemical methods which have the disadvantage of polluting the environment and are expensive. Thus, there is a need for more environmentally friendly and cheaper techniques for controlling Fusarium Wilt. This study screened the phytochemical compounds of two plant extracts; Tithonia diversifolia and Kigelia africana and assessed their potency in controlling plant fungal pathogen F. oxysporum, which causes fusarium wilt in tomatoes. The phytochemical analysis revealed that the two plant extracts contained saponins, tannins, terpenoids, flavonoids, glycosides and phenolics except alkaloids and steroids which were only found in T. diversifolia. The mean inhibitory zones ranged from 7.93 to 10.44 mm for T. diversifolia at 25 to 100 g/l. The mean inhibitory zones for K. Africana ranged from 12.07 to 15.56 mm at 25 to 100 g/l. K. Africana extracts had the highest inhibitory (antimicrobial) activity. Combining both extracts was more effective compared to the single extract. The effect of the combined plant extract and positive control was statistically significant (p < 0.05). This study provides scientific evidence that K. africana and T. diversifolia extract possess antifungal activity and can be used as a broad-spectrum in managing microbial diseases. Key words: Plant extracts, phytochemical screening, antimicrobial and antifungal properties, Fusarium oxysporum.