Hydrogeology Journal

, Volume 18, Issue 4, pp 985–995 | Cite as

A hydrogeochemical survey of Kilimanjaro (Tanzania): implications for water sources and ages

  • Jeffrey M. Mckenzie
  • Bryan G. Mark
  • Lonnie G. Thompson
  • Ulrich Schotterer
  • Ping-Nan Lin
Report

Abstract

Kilimanjaro, Tanzania, the highest mountain in Africa, has undergone extensive hydrologic changes over the past century in an area where water resources are critical. A hydrochemical and isotopic synoptic sampling program in January 2006 is used to characterize hydrogeology, hydrology, and water quality of the area. Samples were collected from the summit and southern side of Kilimanjaro and the Moshi region (Tanzania). Sample sources included four glaciers, seven groundwater wells, 12 rivers, 10 springs, precipitation, and a lake. Analyses included major ion chemistry, stable isotopes of water (18O and D); in addition, seven samples were analyzed for tritium. The samples generally have good water quality with the exception of three samples with elevated fluoride concentrations (>3 mg/L) and elevated nitrate concentrations (>2.5 mg/L NO3 as N). There is a strong elevation control on stable isotopes, with an apparent elevation effect of – 0.1 ‰ δ18O per 100 m rise in elevation (R 2 = 0.79). The results, including the tritium values, show that the hydrogeologic system is comprised of both local and regional flow systems, and that regional rivers are receiving significant inflow from shallow groundwater, and at very high elevations the hydrologic system is derived from groundwater, precipitation, and glacial melt water.

Keywords

Volcanic aquifer Hydrochemistry Groundwater age Kilimanjaro Tanzania 

Transport des bactéries dans un sédiment aquifère: expérimentation et modélisation

Résumé

Le Kilimandjaro en Tanzanie, plus haute montagne d’Afrique, a subi des changements hydrologiques ces derniers siècles dans une zone où la ressource en eau est critique. Une campagne d’échantillonnage pour analyses chimiques et isotopiques a été réalisée en janvier 2006 afin de caractériser l’hydrogéologie, l’hydrologie et la qualité des eaux de cette région. Les échantillons ont été collectés au sommet et sur le flanc sud du Kilimandjaro ainsi que dans la région de Moshi (Tanzanie). Les points échantillonnés inclus 4 glaciers, 7 forages, 12 rivières, 10 résurgences, les précipitations et un lac. Les analyses des ions majeurs et des isotopes stables de la molécule d’eau (18O et D) ont été réalisées sur tous les échantillons et le tritium a été mesuré sur 7 eaux. Les eaux sont en général de bonne qualité à l’exception de trois échantillons présentant de fortes concentrations en fluor (>3 mg/L) et nitrate (>2.5 mg/L NO3 - N). Les variations des isotopes stables sont contrôlées par l’effet d’altitude suivant un gradient de – 0.1 ‰ δ18O pour 100 m d’altitude (R 2 = 0.79). Les résultats, incluant les valeurs de tritium, montrent que le système hydrogéologique comporte un flux local et un flux régional. Les rivières ont un apport significatif d’eau souterraine. Pour les plus hautes altitudes, le système hydrologique comporte les eaux souterraines, des précipitations et la fonte des glaciers.

Transporte de bacterias en el sedimento de un acuífero: experimentos y modelado

Resumen

El Kilimanjaro, Tanzania, la montaña más alta en África, ha experimentado cambios hidrológicos extensivos durante el siglo pasado en un área donde los recursos hídricos son críticos. En enero de 2006 se utilizó un programa de muestreo sinóptico hidroquímico e isotópico para caracterizar la hidrogeología, hidrología y calidad de agua del área. Las muestras fueron colectadas en la cima y en el lado lado sur del Kilimanjaro y de la región de Moshi (Tanzania). Las fuentes de muestreo incluyeron cuatro glaciares, siete pozos de aguas subterráneas, 12 ríos, 10 manantiales, la precipitación, y un lago. Los análisis incluyeron la los iones químicos mayoritarios, isótopos estables del agua (18O and D); además siete muestras fueron analizadas para tritio. Las muestras tienen generalmente buena calidad de agua con excepción de tres muestras con una elevada concentración de fluoruro (>3 mg/L) y elevada concentraciones de nitrato (>2.5 mg/L NO3 como N). Existe un control de la altitud sobre los isótopos estables, con un efecto de altitud aparente de – 0.1 ‰ δ18O por 100 m de aumento de la altitud (R 2 = 0.79). Los resultados, incluyendo los valores de tritio muestran que el sistema hidrogeológico está compuesto por un sistema de flujo regional y uno local; y que los ríos regionalmente están recibiendo una significativo ingreso del agua subterránea somero a partir de aguas subterráneas poco profundas, y a muy grandes altitudes en el sistema hidrológico es proveniente de aguas subterráneas, la precipitación, y el derretimiento de agua glacial.

Transporte de bactérias nos sedimentos de um aquífero: experiências e modelação

Resumo

Kilimanjaro, na Tanzânia, é a mais alta montanha de África, e tem sofrido grandes mudanças ao longo do último século, numa área em que os recursos hídricos são críticos. Um programa sinóptico de amostragem hidroquímica e isotópica, realizado em Janeiro de 2006, foi usado para caracterizar a hidrogeologia, hidrologia e a qualidade da água da região. As amostras foram recolhidas no cume, no lado sul do Kilimanjaro e na região de Moshi (Tanzânia). A origem das amostras incluiu quatro glaciares, sete furos de água subterrânea, 12 rios, 10 nascentes, água de precipitação e um lago. As análises incluíram a química dos iões principais e isótopos estáveis da água (18O e D); para além disso, foi analisado o trítio em sete amostras. As amostras apresentaram, no geral, água de boa qualidade, com excepção de três amostras com concentração elevada de flúor (>3 mg/L) e de nitrato (>2.5 mg/L NO3 como N). Há um forte controlo da altitude nos isótopos estáveis, com um efeito aparente da altitude de – 0.1 ‰ δ18O por 100 m de aumento da cota (R 2 = 0.79). Os resultados, incluindo os valores de trítio, evidenciam que o sistema hidrológico é formado por sistemas de fluxo tanto locais como regionais, que os rios da região recebem descarga significativa das águas subterrâneas pouco profundas e que em regiões de cota muito elevada o sistema hidrológico deriva da água subterrânea, da precipitação e da água proveniente do degelo dos glaciares.

Notes

Acknowledgements

The authors thank the Ohio State University Department of Geography, Byrd Polar Research Center, McGill University, E. Mosley-Thompson, S. Lee, and K. Welch for their assistance in data collection and analysis. The research was supported by a grant from the Climate, Water & Carbon TIE at The Ohio State University.

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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Jeffrey M. Mckenzie
    • 1
  • Bryan G. Mark
    • 2
    • 3
  • Lonnie G. Thompson
    • 2
  • Ulrich Schotterer
    • 4
  • Ping-Nan Lin
    • 2
  1. 1.Department of Earth and Planetary ScienceMcGill UniversityMontrealCanada
  2. 2.Byrd Polar Research CenterThe Ohio State UniversityColumbusUSA
  3. 3.Department of GeographyThe Ohio State UniversityColumbusUSA
  4. 4.Department of Climate and Environmental PhysicsUniversity of BernBernSwitzerland

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