Isotope analysis of groundwater, surface water and rain in Lodwar and its environs, Turkana County, Kenya

This study aimed to analyze water sources within the Turkwel River basin in Turkana County, focusing on isotope analysis of groundwater, surface water, and rain. The isotope study represented the first comprehensive effort to understand water sources in northwestern Kenya. Water sources included
rainwater, rivers, water pans, Lake Turkana, and groundwater from springs, scoop holes, wells, and boreholes, adhering to International Atomic Energy Agency (IAEA) and American Public Health Association (APHA) guidelines. A total of 112 georeferenced water samples were collected during the peak of the wet season in May 2018 as follows: rain (1), Turkwel River (4); Kawalase river (2); water pans (5); Lake Turkana (2) – one at the Turkwel delta and one at its shores at Eliye Spring, and; groundwater (98) - comprising one spring (Eliye Spring), seven scoop holes (all <1m bgl) in dry ephemeral streams, 52 samples from wells operated by handpumps, and 38 boreholes.
Duplicate samples were taken from each source using 500 ml polyethylene bottles and were georeferenced using GPS. Samples were labeled, preserved in cooler boxes at 4°C, and further refrigerated at the University of Nairobi before being exported to Elemtex Lab, UK, for isotope analysis. δ18O and δ2H were measured using high temperature conversion elemental analyzers coupled to isotope ratio mass spectrometers, while δ3H was measured via liquid scintillation counting after electrolytic enrichment. Quality control measures included strict adherence to established protocols for isotope sampling. Samples with EC values greater than 1000 ppm were excluded from tritium determination.

Related publications:

Tanui, F., Olago, D., Dulo, S. Ouma, G., & Kuria, Z. (2020). Hydrogeochemistry of a strategic alluvial aquifer system in a semi-arid setting and its implications for potable urban water supply: The Lodwar Alluvial Aquifer System (LAAS), Groundwater for Sustainable Development, Volume 11. https://doi.org/10.1016/j.gsd.2020.100451