title: Emerging contaminants in urban groundwater sources in Africa.
abstract: The occurrence of emerging organic contaminants within the aquatic environment in Africa is currently unknown. This study provides early insights by characterising a broad range of emerging organic contaminants (n > 1000) in groundwater sources in Kabwe, Zambia. Groundwater samples were obtained during both the dry and wet seasons from a selection of deep boreholes and shallow wells completed within the bedrock and overlying superficial aquifers, respectively. Groundwater sources were distributed across the city to encompass peri-urban, lower cost housing, higher cost housing, and industrial land uses. The insect repellent DEET was ubiquitous within groundwater at concentrations up to 1.8 μg/L. Other compounds (n = 26) were detected in less than 15% of the sources and included the bactericide triclosan (up to 0.03 μg/L), chlorination by-products - trihalomethanes (up to 50 μg/L), and the surfactant 2,4,7,9-tetramethyl-5-decyne-4,7-diol (up to 0.6 μg/L). Emerging contaminants were most prevalent in shallow wells sited in low cost housing areas. This is attributed to localised vulnerability associated with inadequate well protection, sanitation, and household waste disposal. The five-fold increase in median DEET concentration following the onset of the seasonal rains highlights that more mobile compounds can rapidly migrate from the surface to the aquifer suggesting the aquifer is more vulnerable than previously considered. Furthermore it suggests DEET is potentially useful as a wastewater tracer in Africa. There was a general absence of personal care products, life-style compounds, and pharmaceuticals which are commonly detected in the aquatic environment in the developed world. This perhaps reflects some degree of attenuation within the subsurface, but could also be a result of the current limited use of products containing emerging contaminants by locals due to unaffordability and unavailability. As development and population increases in Africa, it is likely a wider-range of emerging contaminants will be released into the environment.
authors.affiliation: British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK. Electronic address: jare1@bgs.ac.uk.
authors.forename: J P R
authors.initials: JP
authors.lastname: Sorensen
authors.affiliation: British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Lapworth
authors.affiliation: University of Zambia, Great East Road Campus, P.O. Box 32379, Lusaka, Zambia.
authors.forename: D C W
authors.initials: DC
authors.lastname: Nkhuwa
authors.affiliation: British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK.
authors.forename: M E
authors.initials: ME
authors.lastname: Stuart
authors.affiliation: British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK.
authors.forename: D C
authors.initials: DC
authors.lastname: Gooddy
authors.affiliation: British Geological Survey, Maclean Building, Wallingford OX10 8BB, UK.
authors.forename: R A
authors.initials: RA
authors.lastname: Bell
authors.affiliation: University of Zambia, Great East Road Campus, P.O. Box 32379, Lusaka, Zambia.
authors.forename: M
authors.initials: M
authors.lastname: Chirwa
authors.affiliation: University of Zambia, Great East Road Campus, P.O. Box 32379, Lusaka, Zambia.
authors.forename: J
authors.initials: J
authors.lastname: Kabika
authors.affiliation: Lukanga Water and Sewerage Company Limited, P.O. Box 81745, Kabwe, Zambia.
authors.forename: M
authors.initials: M
authors.lastname: Liemisa
authors.affiliation: Lukanga Water and Sewerage Company Limited, P.O. Box 81745, Kabwe, Zambia.
authors.forename: M
authors.initials: M
authors.lastname: Chibesa
authors.affiliation: Robens Centre for Public and Environmental Health, University of Surrey, Guildford GU2 7XH, UK.
authors.forename: S
authors.initials: S
authors.lastname: Pedley
mesh_terms: D000349:Africa; D002947:Cities; D003671:DEET / Q000032:analysis; D019049:Developed Countries; D004553:Electric Conductivity; D005843:Geography; D060587:Groundwater / Q000737:chemistry*; D008962:Models, Theoretical; D012307:Risk Factors; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014876:Water Pollution / Q000032:analysis
chemical_list: D014874:Water Pollutants, Chemical; D003671:DEET
keywords: Africa; DEET; Emerging contaminants; Groundwater; Urban tracer; Vulnerability