ISSN 2375-088X
African Journal of Soil Science ISSN 2375-088X Vol. 11 (9), pp. 001-013, September, 2024. Available online at www.internationalscholarsjournals.org © International Scholars Journals
Review
Analysis of heavy metals in soil and water systems of urban and semi-urban areas in Malawi: Insights from comparative research with other nations
Chikumbusko Chiziwa Kaonga1*, Ishmael BobbyMphangwe Kosamu1, Deliwe Dinah Lakudzala1, Rex Mbewe1, Benard Thole1, Morris Monjerezi2, Russel Chrispine Garvin Chidya3,4, Stephen Kuyeli5 and Samson Mkali Idruss Sajidu2
1Physics and Biochemical Sciences Department, University of Malawi, The Polytechnic, P/Bag 303, Chichiri,
Blantyre 3, Malawi.
2Chemistry Department, Chancellor College, P. O. Box 280, Zomba, Malawi.
3Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan.
4Faculty of Environmental Sciences, Mzuzu University, P/Bag 201, Mzuzu, Malawi.
5Malawi Bureau of Standards, P. O. Box 946, Blantyre, Malawi.
Received 13 June, 2024; Accepted 26 July, 2024 and Published 10 September, 2024
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.