African Journal of
Environmental Science and Technology

  • Abbreviation: Afr. J. Environ. Sci. Technol.
  • Language: English
  • ISSN: 1996-0786
  • DOI: 10.5897/AJEST
  • Start Year: 2007
  • Published Articles: 883

Review

A review of heavy metals in soil and aquatic systems of urban and semi-urban areas in Malawi with comparisons to other selected countries

Chikumbusko Chiziwa Kaonga
  • Chikumbusko Chiziwa Kaonga
  • Physics and Biochemical Sciences Department, University of Malawi, The Polytechnic, P/Bag 303, Chichiri, Blantyre 3, Malawi.
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Ishmael BobbyMphangwe Kosamu
  • Ishmael BobbyMphangwe Kosamu
  • Physics and Biochemical Sciences Department, University of Malawi, The Polytechnic, P/Bag 303, Chichiri, Blantyre 3, Malawi.
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Deliwe Dinah Lakudzala
  • Deliwe Dinah Lakudzala
  • Physics and Biochemical Sciences Department, University of Malawi, The Polytechnic, P/Bag 303, Chichiri, Blantyre 3, Malawi.
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Rex Mbewe
  • Rex Mbewe
  • Physics and Biochemical Sciences Department, University of Malawi, The Polytechnic, P/Bag 303, Chichiri, Blantyre 3, Malawi.
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Benard Thole
  • Benard Thole
  • Physics and Biochemical Sciences Department, University of Malawi, The Polytechnic, P/Bag 303, Chichiri, Blantyre 3, Malawi.
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Morris Monjerezi
  • Morris Monjerezi
  • Chemistry Department, Chancellor College, P. O. Box 280, Zomba, Malawi.
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Russel Chrispine Garvin Chidya
  • Russel Chrispine Garvin Chidya
  • Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan.
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Stephen Kuyeli
  • Stephen Kuyeli
  • Malawi Bureau of Standards, P. O. Box 946, Blantyre, Malawi.
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Samson Mkali Idruss Sajidu
  • Samson Mkali Idruss Sajidu
  • Chemistry Department, Chancellor College, P. O. Box 280, Zomba, Malawi.
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  •  Received: 13 June 2017
  •  Accepted: 26 July 2017
  •  Published: 30 September 2017

Abstract

Growth of cities in developing countries comes with increasing transportation and industrial activities which may contribute to accumulation of heavy metals in the environment. This paper provides a review of studies on heavy metals in Malawi`s environment, their potential environmental impacts and possible removal methods with comparisons to other selected countries. The reviewed data from Malawi showed that in water samples, heavy metal concentrations were higher than World Health Organisation (WHO) and Malawi Bureau of Standards (MBS) safe limits especially in streams passing through industrial sites. Reports of heavy metals (especially Cu, Mn and Zn) showed that in industrial effluents, the individual levels of each of them were at least 6 times higher as compared to those in surface water bodies. In rivers there was accumulation of heavy metals (Cu, Cd, Cr, Fe, Mn, Pb, Ni and Zn) by algae whereby bioconcentration factors (BCF) ranged from 1.0 to 42 in some of the studies.  Generally, metal levels in soils and selected organisms were much higher than those in water samples which further confirm possible accumulation. Since some aquatic organisms are consumed by humans, there is potential for the heavy metals to cause cancer and kidney damage. The studies done in Malawi compared well to those conducted elsewhere. The degradation of water resources by heavy metals compromises sustainability of water bodies and vital aquatic ecosystems hence negatively impacting on Integrated Water Resource Management (IWRM) efforts. This calls for periodic heavy metal monitoring and identifying ways of reducing their release into the environment.

Key words: Environment, heavy metals, pollution, public health, Malawi.