Determination of Arsenic Levels in Water and Soils from Ahero Rice Irrigation Scheme and in Ahero, Mwea and Imported Rice

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dc.contributor.authorAduda, Lucy
dc.date.accessioned2021-02-10T09:35:40Z
dc.date.available2021-02-10T09:35:40Z
dc.date.issued2020-11
dc.descriptionA Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science (Chemistry) in the School of Pure and Applied Sciences of Kenyatta University, November, 2020en_US
dc.description.abstractArsenic contamination in irrigation water and soils is a major environmental health hazard in the world. There is a major potential risk to human health through consumption of agricultural produce grown in fields irrigated with arsenic contaminated water and soils. Arsenic Levels have been analyzed in different crops such as rice, wheat, maize and vegetables in different countries. Rice (Oryza sativa L.) is a crop cultivated mainly in irrigated water hence its bioavailability to arsenic is much more than in other crops. This study investigated the levels of arsenic in water and soils in Ahero rice irrigation scheme and in locally produced and imported rice. Hydride Generation Atomic Absorption Spectrometer was used in the analysis. Locally produced rice (Sindano and Pishori) was sampled from Ahero and Mwea irrigation schemes while imported rice from India, Thailand, and Pakistan was obtained from various market outlets Githurai, Eastleigh, Ngara and Kenyatta. The level of arsenic in irrigation water and paddy soils was found to be 0.0230 ±0.010 mg/L and 0.1504 ± (0.08) mg/kg respectively. There was a strong positive correlation in arsenic levels in rice and soils from Ahero irrigation scheme (r2=0.97, P<0.0001). A weak correlation was found between irrigation water and rice (r2=0.16). The mean arsenic concentration in rice from Ahero and Mwea irrigation scheme was 0.059±0.040 and 0.0371 ±0.03 mg/kg respectively. There was no significant difference in the arsenic levels in Sindano rice from Ahero and Basmati (Pishori) rice from Mwea Irrigation scheme. Basmati rice from Thailand had mean arsenic content of 0.126±0.001 mg/kg. The arsenic concentration was significantly higher than in Basmati rice from Pakistan and India, with a mean of 0.075 ±0.001 and 0.062 ±0.01 mg/kg respectively. The levels in the imported Basmati rice were significantly higher than locally produced Pishori rice, a Basmati variety. Indian Sindano rice recorded significantly lower levels (0.088±0.02 mg/kg) than those from Thailand (0.153 ±0.02) and Pakistan (0.175 ±0.02 mg/kg). Arsenic levels was significantly higher in imported Sindano rice from Pakistan and Thailand compared to locally grown Sindano rice (p<0.0001). However, there was no significant difference in the levels in Indian Sindano rice and the locally produced sindano rice (p>0.05). The levels of arsenic in rice from this study were within the WHO recommended levels in rice grain of 1.0 mg/kg dry weight. Though the levels are safe as per this study, chronic exposure from rice consumption could be a human health risk. The information from the study will form a basis of setting limits of arsenic levels in rice sold in the Kenyan markets.en_US
dc.description.sponsorshipKenyatta Universityen_US
dc.identifier.urihttp://ir-library.ku.ac.ke/handle/123456789/21411
dc.language.isoenen_US
dc.publisherKenyatta Universityen_US
dc.subjectDeterminationen_US
dc.subjectArsenic Levelsen_US
dc.subjectWater and Soilsen_US
dc.subjectAhero Rice Irrigation Schemeen_US
dc.titleDetermination of Arsenic Levels in Water and Soils from Ahero Rice Irrigation Scheme and in Ahero, Mwea and Imported Riceen_US
dc.typeThesisen_US
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