Water quality and human health risk assessment of Kaning'ina natural springs in Mzuzu city, Malawi

Abstract

The availability of water in good quantity and quality is important for sustenance of human and environmental health worldwide. This study assessed the drinking, irrigation and human health risks resulting from using water abstracted from seven purposively selected natural springs (5) and community taps (2) in Kaning’ina Forest, Mzuzu City, Malawi. Biological and physico-chemical parameters, namely: pH, Turbidity, TDS, Electrical conductivity (EC), Na+, K+, Ca2+, Mg2+, CO32–, HCO3–, SO42–, NO3–, Fe2+, E. coli, and Total coliforms, were analysed using standard methods. An appraisal of irrigation water quality was performed based on levels of sodium adsorption ratio, %Na+, residual sodium carbonate, magnesium hazards, permeability index and EC. Health risks were analysed utilising WHO WSPs. A SEBA current meter was used to assess discharge rates. Levels of biological and physico-chemical parameters were: pH (6.82 – 7.21), Turbidity (2.47 – 15.07 NTU), TDS (11.33 – 15.70 mg/L), EC (22.60 – 31.77 μS/cm), Na+ (2.47 – 3.70 mg/L), K+ (0.60 – 1.20 mg/L), Ca2+(28.47 – 67.27 mg/L), Mg2+(1.68 – 2.82 mg/L), CO32– (no detection), HCO3– (45.24 – 55.92 mg/L), SO42– (1.77 – 2.53 mg/L), NO3– (3.27 – 4.15 mg/L), E. coli (232. 67 – 648.00 CFU) and total coliforms (430.67 – 1302.00 CFU). The discharge rates (0.001 – 0.004 m3/s) of the springs revealed to be adequate for the abstraction of water for bottling purposes. Although levels of physico-chemical parameters were within allowable limits of WHO standards e.g., pH (6.5 – 8.5) for drinking water except turbidity in three springs, levels of biological parameters were above the permissible limits in all samples. 100% water samples were suitable for irrigation. The WSP demonstrated the reliability of the application of the model to small drinking-water systems. While the natural springs of Kaning’ina Forest Reserve contain good water for irrigation purposes, the water samples are not suitable for drinking and must be treated prior to consumption to protect human health. The natural water resource needs to be protected for sustainability and maintenance of environmental quality.

Keywords: human health risks, irrigation, Kaning’ina, spring discharge, water quality.