RELATIONSHIP BETWEEN FLUORIDE LEVELS AND PHYSICALCHEMICAL PARAMETERS IN SELECTED MEDIA IN UPPER RIVER NJORO CATCHMENT NAKURU COUNTY, KENYA

Abstract

Water is vital for life, but its quality determines its suitability for consumption. In 2020, 2 billion people lacked safe water services. Fluoride in water can be beneficial or harmful; the World Health Organization (WHO) recommends a maximum of 1.5 mg/L to prevent health risks. Globally, fluoride contamination is a problem, especially in India, China, and Africa. In Kenya's Rift Valley, high fluoride levels cause fluorosis. This study was conducted to assess fluoride levels in the Njoro catchment, Nakuru County, Kenya, due to concerns about potential health risks from elevated fluoride levels in the region. Water sources in the River Njoro catchment have varying fluoride concentrations, posing risks of skeletal and dental fluorosis. The study assessed fluoride levels in sediments, springs, and river waters in the upper River Njoro catchment, Nakuru County, guided by the following objectives: determining fluoride levels in sediments, springs, and river water, analyzing pH, temperature, electrical conductivity, and total dissolved solids in springs and river waters, and investigating the relationship between fluoride levels and physical-chemical parameters. This study assessed fluoride levels in the upper River Njoro catchment area, spanning from Nessuit upstream to Tumaini Bridge downstream. A longitudinal profile survey design was utilized, incorporating stratified sampling across upper, middle, and lower catchments. Data were collected from fifteen sites, including river water, spring water, and sediment samples, during both dry and wet seasons. Water and sediment samples were analyzed at the University of Eldoret for fluoride and physical-chemical parameters. Sampling involved triplicate collections, with physical-chemical measurements taken in situ and fluoride concentrations determined using ion-selective electrodes. Sediment samples were collected and processed following standardized methods. Statistical analysis, performed using Genstat software, involved ANOVA and correlation statistics to identify significant differences and relationships between fluoride levels and physical-chemical parameters. River water fluoride concentrations ranged from 0.38 to 1.77 mg/L, with the highest mean at site S8. River sediments showed fluoride levels between 0.50 and 2.91 mg/kg, with higher concentrations in lower strata. Spring water fluoride ranged from 1.20 to 2.44 mg/L, while sediments at spring sites had levels from 0.77 to 1.55 mg/kg. This study revealed significant variations in fluoride levels across river and spring waters in the upper River Njoro catchment, with some sites exceeding WHO standards. Fluoride levels negatively correlated with pH and positively with total dissolved solids (TDS) and electrical conductivity (EC). Spring water generally had higher fluoride concentrations than river water, suggesting geological or hydrological influences. The findings underscore the urgent need for targeted interventions to mitigate fluoride contamination and ensure safe water access for the local population. Continuous monitoring and remediation efforts, alongside public awareness campaigns, are essential to prevent further exposure and protect community health.