Author(s): Evelin Humerez; Makoto Umeda
Linked Author(s):
Keywords: Condoriri glacier; Water quality; Transport of nutrients; Major ions
Abstract: Many researches related with water quality and the influence of nutrients and major ions have been made in aquatic ecosystems worldwide. However, rivers in the Andes have been insufficiently studied. Condoriri River basin is an interesting case of study since tropical glaciers are very sensitive to climate change and this basin provides drinking water to La Paz and El Alto, the two major cities in Bolivia. The purpose of this study is to analyze the effects of the transport of nutrients and major ions composition over water quality during two different seasons. Field measurements were done in July 2012 (dry season), November 2012 (wet season) and February 2013 (wet season) for the determination of physicochemical parameters like pH and electrical conductivity. Water samples were taken for the analysis of nutrients, major ions compositions, and chlorophyll a. Macrophytes and periphyton were taken for the determination of biomass. Concentrations of nutrients and ions greatly varied through the whole basin. Nutrients are most represented by nitrogen in the forms of nitrate and ammonium, and silicate. According to the results, phosphorus was the limiting factor. The transport of nutrients and major ions were higher during the wet than the dry season in 2012. Transport of nitrate varied from 3. 04 kg/day to 0. 6 kg/day and silicate from 151. 72 kg/day to 28. 23 kg/day, from the upper reaches of the stream to the lowest area of the basin. Macrophytes, periphyton and phytoplankton biomass were affected by the availability of nutrients. Major ions were mainly represented by Ca2+ and SO4 2+, specifically at the glacier effluent. Weathering of rocks like gypsum was estimated as the principal source of solutes. The results of this research can enhance our understandings of the current condition of water quality in the river.
Year: 2013