An investigation of minerals in the water and source rocks of Rurii spring in Meru county, Kenya: a possible potential economic outlet

Abstract

This study dealt with the investigation of minerals in the water and surrounding rocks of Rurii spring which is located in Meru County, Kenya. The spring is well known for discharging highly carbonated and salty water for many years, but no research has been done previously with regard to this phenomenon. The sampling was done twice during the dry and rainy seasons, in the months of September and November 2012, respectively. Ten samples or replicates of the mineral water, rocks and sediments were collected and analysed in each case. The mineral content and other quality parameters of the water were determined. Rock and sediment samples around the spring were analysed for the major oxides (SiO2, Na2O, K2O, CaO, MgO, Al2O3, Fe2O3, MnO and TiO2). The analytical methods used were AAS, XRF, UV/VIS and Titrimetry. The mineral water was found to be very rich in free CO2 and HCO3 -, with almost two to three litres of carbon dioxide per litre of mineral water at room temperature. The CO2 most likely originates from the earth’s crust and rises through a volcanic vent to the surface where it gets mixed with the water to form H2CO3. Sodium level was 1043±35.0 mg/l and 954.4±20.3 mg/l, while chloride was 950.9±13.1 mg/l and 853.6±10.0 mg/l, during the dry and rainy periods, respectively. This was extremely high and contributed to the salty taste in the water. In general, the water had a very high level of mineral content which was responsible for the large TDS (5056.7±51.2 mg/l and 4923.1±40.7 mg/l) as well as very high electrical conductivity (6014.0±41.0 mg/l and 5986.0±40.0 mg/l), in dry and rainy seasons, respectively. The overall mineral analysis of the water, rocks and sediments revealed abundance of dolomite, CaMg(CO3)2 and feldspar, (K,Na,Ca)Al2Si2O8, containing rocks in the studied area. There was no remarkable difference between the results obtained for the dry and rainy seasons.