An assessment of heavy metal contamination of groundwater in George compound of Lusaka

Abstract

This study investigated groundwater contamination in a suburban area of George Compound located on the outskirts of the city of Lusaka in Zambia. The aim was to assess heavy metal contamination of groundwater and the local people’s awareness about the contamination in the study area. The objectives were fivefold; to (i) ascertain the usage of groundwater from wells among residents of George Compound; (ii) determine the concentration of heavy metals (cadmium, chromium, copper, iron and lead) in groundwater of the sampled wells in George Compound; (iii) examine the extent to which industries in close proximity to George Compound contributed to heavy metal contamination; (iv) find out local people’s level of awareness and knowledge about heavy metal contamination of the groundwater; and (v) find out whether or not past sensitisation campaigns have had an impact on the local people’s level of awareness of groundwater contamination in George Compound. A case study design was employed to ensure a detailed understanding of the situation. The data were collected through interviews, questionnaire, field observations and water quality measurements. Purposive and snowball sampling procedures were used in the selection of a sample of 38 respondents. Water sampling in wet and dry seasons was conducted on 14 purposively sampled wells. Respondents included 14 households with wells and 24 households without. Additionally, four (4) key informants were interviewed. Analysis of data revealed that, in the dry season, there were high levels of chromium (Cr) (0.14 mg/l), cadmium (Cd) (0.91 mg/l), and iron (Fe) (1.22 mg/l) as maximum concentrations above the Zambia Bureau of Standards (ZABS) for drinking water. Conversely, lead (Pb) and copper (Cu) concentration were found to be below the ZABS’s permissible limits. For the wet season, parameters found to have concentrations above the ZABS limits were chromium (0.64 mg/l), cadmium (0.32 mg/l), iron (3.11 mg/l), and lead (0.07 mg/l), while copper (Cu) (0.04 mg/l) was below the limit. The sources of these heavy metals were attributed to the manufacturing industries and illegal waste sites. A total of 45 percent of the sampled residents in George Compound were unaware of the groundwater contamination. It is concluded that groundwater in shallow wells in George Compound is contaminated with heavy metals (cadmium, chromium, iron and lead). This calls for regular groundwater quality monitoring by Water Resources Management Authority (WARMA) and Zambia Environmental Management Agency (ZEMA) for evidence to support strict enforcement of compliance by industries on discharge of effluents that meet ZABS standards in order to reduce health risks among residents.