Abstract
High water demand for domestic use in Douala with over 3 million inhabitants is met mainly by shallow groundwater. Field measurements and water sampling in January 2015 were carried out to examine the major controls on the groundwater composition and spatial view of ions in the water, timing of recharge and link between the recharge process and quality of the water. Fifty-two water samples were analysed for major ions and stable hydrogen and oxygen isotopes. Low pH values (3.61–6.92) in the groundwater indicated an acidic aquifer; thus, prone to acidification. The dominant water type was Na–Cl. Nitrate, which exceeded the WHO guide value of 50 mg/l in 22% of the groundwater, poses a health problem. Mass ratios of Cl−/Br− in the water ranged from 54 to 3249 and scattered mostly along the mixing lines between dilute waters, septic-tank effluent and domestic sewage. A majority of the samples, especially the high NO3 − shallow wells, clustered around the septic-tank effluent-end-member indicating high contamination by seepage from pit latrines; hence, vulnerable to pollution. Stable isotopes in the groundwater indicated its meteoric origin and rapid infiltration after rainfall. The δ18O values showed narrow ranges and overlaps in rivers, springs, open wells and boreholes. These observations depict hydraulic connectivity, good water mixing and a homogeneous aquifer system mainly receiving local direct uniform areal recharge from rainfall. The rapid and diffused recharge favours the leaching of effluent from the pit toilets into the aquifer; hence, the high NO3 − and Cl− in shallow wells. Silicate weathering, ion exchange and leaching of waste from pit toilets are the dominant controls on the groundwater chemistry. Drilling of deep boreholes is highly recommended for good-quality water supply. However, due the hydraulic connection to the shallow aquifer, geochemical modelling of future effects of such an exploitation of the deeper aquifer should support groundwater management and be ahead of the field actions.
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References
Ako AA, Nkeng GE, Takem GEE (2009) Water quality and occurrence of water-borne diseases in the Douala 4th District, Cameroon. Water Sci Technol 59:2321–2329
Ako AA, Shimada J, Hosono T, Ichiyanagi K, Nkeng GE, Eyong GET, Roger NN (2012) Hydrogeochemical and isotopic characteristics of groundwater in Mbanga, Njombe and Penja (Banana plain)-Cameroon. J Afr Earth Sci 75:25–36
Akoachere J-FTK, Omam L-A, Massalla TN (2013) Assessment of the relationship between bacteriological quality of dug-wells, hygiene behaviour and well characteristics in two cholera endemic localities in Douala, Cameroon. BMC Public Health 13:692
Ala MA, Selley RC (1997) The West African coastal basins. In: Selley RC, Hsu KJ (eds) African basins sedimentary basins of the world, 3. Elsevier, Amsterdam, pp 173–186
Alcalá FJ, Custodio E (2008) Using the Cl/Br ratio as a tracer to identify the origin of salinity in aquifers in Spain and Portugal. J Hydrol 359:189–207
Asaah VA, Abimbola AF, Suh CE (2006) Heavy metal concentrations and distribution in surface soils of the Bassa Industrial Zone 1, Douala, Cameroon. Arab J Sci Eng 31:147–158
Davis SN, Whittemore DO, Fabryka-Martin J (1998) Uses of chloride/bromide ratios in studies of potable water. Ground Water 36:338–350
Davis SN, Fabryka-Martin JT, Wolfsberg LE (2004) Variations of bromide in potable ground water in the United States. Ground Water 42:902–909
Diaw M, Faye S, Stichler W, Maloszewski P (2012) Isotopic and geochemical characteristics of groundwater in the Senegal River delta aquifer: implication of recharge and flow regime. Environ Earth Sci 66:1011–1102
Djeuda-Tchapnga HB, Tanawa E, Ngnikam E (2001) L’eau au Cameroun, T1: Approvisionnement en eau potable. Presses Universitaires de Yaounde, Yaounde, pp 115–129
El Moujabber M, Bou Samra B, Darwish T, Atallah T (2006) Comparison of different indicators for groundwater contamination by seawater intrusion on the Lebanese coast. Water Resour Manage 20:161–180
Eneke GT, Ayonghe SN, Chandrasekharam D, Ntchancho R, Ako AA, Mouncherou OF, Thambidurai P (2011) Controls on groundwater chemistry in a highly urbanised coastal area. Int J Environ Res 5:475–490
Fantong WY, Fouepe AT, Ketchemen-Tandia B et al (2016) Variation of hydrogeochemical characteristics of water in surface flows, shallow wells, and boreholes in the coastal city of Douala (Cameroon). Hydrolog Sci J. doi:10.1080/02626667.2016.1173789
Fisher RS, Mullican WF III (1997) Hydrochemical evolution of sodium-sulfate and sodium-chloride groundwater beneath the northern Chihuahuan Desert, Trans-Pecos, Texas, USA. Hydrogeol J 5:4–16
Foster SD, Hirata R, Howard KWF (2010) Groundwater use in developing cities: policy issues arising from current trends. Hydrogeol J 19:271–274
Gibrilla A, Osae S, Akiti TT, Adomako D, Ganyaglo SY, Bam EPK, Hadisu H (2010) Origin of dissolve ions in groundwaters in the northern Densu river basin of Ghana using stable isotopes of 18O and 2H. J Water Res Prot 2:1010–1019
Han G, Liu C-Q (2004) Water geochemistry controlled by carbonate dissolution: a study of the river waters draining karst-dominated terrain, Guizhou Province, China. Chem Geol 204:1–21
Hounslow AW (1995) Water quality data: analysis and interpretation. Lewis Publishers, Boca Raton
Katz BG, Eberts SM, Kauffman LJ (2011) Using Cl/Br ratios and other indicators to assess potential impacts on groundwater quality from septic systems: a review and examples from principal aquifers in the United States. J Hydrol 397:151–166
Ketchemen-Tandia B, Ntamak-Nida MJ, Boum-Nkot S et al (2007) First results of the isotopic study (18O, 2H, 3H) of the Douala Quaternary aquifer (Cameroon). In: IAEA (ed) Advances in isotope hydrology and its role in Sustainable water resources management (IAEA-CN 151/37). IAEA, Vienna
Ketchemen-Tandia B, Ngo Boum S, Ebonji Seth CR, Nkoue Ndong GR, Wonkam C (2013) Stable isotope composition of rainfall in western Cameroon. In: (IAEA) Isotopes in hydrology, marine ecosystems and climate change studies. Proceedings of an International Symposium, 27 March–1 April 2011 Monaco, pp 113–120
Lapworth DJ, MacDonald AM, Tijani MN, Darling WG, Gooddy DC, Bonsor HC, Araguás-Araguás LJ (2013) Residence times of shallow groundwater in West Africa: implications for hydrogeology and resilience to future changes in climate. Hydrogeol J 21:673–686
Mafany GT (1999) Impact of the geology and seawater intrusion on groundwater quality in Douala. M.Sc. Thesis, Buea University
Mansouri A, Lurie AA (1993) Concise review: methemoglobinemia. Am J Hematol 42:7–12
Marchand D, Rayan M C, Bethune D N, Chu A (2002) Groundwater–surface water interaction and nitrate origin in municipal water supply aquifers, Sanjose, Costa Rica
Mbonu M, Travi Y (1994) Labelling of precipitation by stable isotopes (18O, 2H) over the Jos Plateau and the surrounding plains (north-central Nigeria). J Afr Earth Sci 19:91–98
McArthur JM, Sikdar PK, Hoque MA, Ghosal U (2012) Waste-water impacts on groundwater: Cl/Br ratios and implications for arsenic pollution of groundwater in the Bengal Basin and Red River Basin, Vietnam. Sci Total Environ 437:390–402
Monteny BA, Casenave A (1989) The forest contribution to the hydrological budget in tropical West Africa. Ann Geophys 7:427–436
Mtoni Y, Mjemah IC, Bakundukize C, Camp MV, Martens K, Walraevens K (2013) Saltwater intrusion and nitrate pollution in the coastal aquifer of Dar es Salaam, Tanzania. Environ Earth Sci 70:1091–1111
Ndjama J, Kamgang KBV, Siga-Nkamdjou L, Ekodeck G, Tita MA (2008) Water supply, sanitation and health risks in Douala, Cameroon. Afri J Environ Sci 2:422–429
Neh AV, Ako AA, Ayuk AR II, Hosono T (2015) DRASTIC-GIS model for assessing vulnerability to pollution of the phreatic aquiferous formations in Douala-Cameroon. J Afr Earth Sci 102:180–190
Oga MS, Marlin C, Dever L, Filly A, Njitchoua R (2008) Hydrochemical and isotopic characteristics of coastal ground-water near Abidjan (southern Ivory Coast). In: Adelana SAM, MacDonald AM (eds) Applied groundwater studies in Africa. Taylor and Francis, London, pp 371–389
Pradeep K, Nepolian M, Anandhan P, Chandran Kaviyarasan R, Prasanna Prasanna MV, Prasanna S (2016) A study on variation in dissolved silica concentration in groundwater of hard rock aquifers in Southeast coast of India. IOP Conf Ser Mater Sci Eng 121:012008. doi:10.1088/1757-899X/121/1/012008
Rao MS, Purushothaman P, Krishan G, Rawat YS, Kumar CP (2014) Hydrochemical and isotopic investigation of groundwater regime in Jalandhar and Kapurthala districts, Punjab, India. Int J Earth Sci Eng 7:6–15
Regnoult JM (1986) Synthese Geologique du Cameroun. Ministere de Mine et de L’energy, Yaounde
Revelle R (1941) Criteria for recognizing seawater in groundwater. Trans Am Geophys Union 22:593–598
Sadeq M, Moe CL, Attarassi B, Cherkaoui I, ElAouad R, Idrissi L (2008) Drinking water nitrate and prevalence of methemoglobinemia among infants and children aged 1–7 years in Moroccan areas. Int J Hyg Environ Health 211:546–554
Sappa G, Ergul S, Ferranti F (2014) Distribution of Ca and mg in groundwater flow systems in carbonate aquifers in Southern Latium Region (Italy): implications on drinking water quality. In: Razowska-Jaworek L (ed) Calcium and magnesium in groundwater: occurrence and significance for human health. Taylor and Francis, London, pp 93–106
Schoeller H (1965) Qualitative evaluation of groundwater resources. In: Methods and techniques of groundwater investigations and development. Water Resource Series No 33. UNESCO, Paris, pp 44–52
Takem GE, Chandrasekharam D, Ayonghe SN, Thambidurai P (2010) Pollution characteristics of alluvial groundwater from springs and bore wells in semi-urban informal settlements of Douala, Cameroon, Western Africa. Environ Earth Sci 61:287–298
Tamfu SF, Batupe M, Pauken RJ, Boatwright DC (1995) Geologic setting, stratigraphy and hydrocarbon habitat of the Douala Basin Cameroon. AAPG Search and Discovery Article #91020, AAPG Annual Convention, Houston, Texas, May 5–8
Taylor RG, Howard KWF (1996) Groundwater recharge in the Victoria Nile basin of East Africa: support for the soil moisture balance method using stable isotope and flow modelling studies. J Hydrol 180:31–53
Tening AS, Chuyong GB, Asongwe GA, Fonge BA, Lifongo LL, Tandia BK (2013) Nitrate and ammonium levels of some water bodies and their interaction with some selected soil properties in Douala metropolis, Cameroon. Afr J Environ Sci Technol 7:648–656
Thorncroft CD, Nguyen H, Zhang C, Peyrille P (2011) Annual cycle of the West African monsoon: regional circulations and associated water vapour transport. Q J R Meteorol Soc 137:129–147
Tredoux G, Talma AS (2006) Nitrate pollution of groundwater in South Africa. In: Xu Y, Usher B (eds) Groundwater pollution in Africa. Taylor and Francis, London, pp 15–36
Vengosh A, Pankratov I (1998) Chloride/bromide and chloride/fluoride ratios of domestic sewage effluents and associated contaminated ground water. Ground Water 36:815–824
WHO (2011) Guidelines for drinking-water quality, 4th edn. World Health Organization, Geneva
Wirmvem MJ, Mimba ME, Kamtchueng BT et al (2015) Shallow groundwater recharge mechanism and apparent age in the Ndop plain, northwest Cameroon. Appl Water Sci. doi:10.1007/s13201-015-0268-0
Wirmvem MJ, Ohba T, Kamtchueng BT, Taylor ET, Fantong WY, Ako AA (2016) Variation in stable isotope ratios of monthly rainfall in the Douala and Yaounde cities, Cameroon: local meteoric lines and relationship to regional precipitation cycle. Appl Water Sci. doi:10.1007/s13201-016-0413-4
Acknowledgements
The corresponding author is an International Research Fellow of the Japan Society for the Promotion of Science (JSPS). This work was fully supported by JSPS KAKENHI Grant Number 26·04331. We thank Dr Jonathan N. Hogarh of Nkwame Nkrumah University of Science and Technology for his constructive comments. The corresponding author dedicates the paper to Professor Samuel N.Y. Fanso Free, a mentor, who passed to the Lord on March 10, 2016. The manuscript was significantly improved by review comments from two anonymous reviewers.
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Wirmvem, M.J., Ohba, T., Nche, L.A. et al. Effect of diffuse recharge and wastewater on groundwater contamination in Douala, Cameroon. Environ Earth Sci 76, 354 (2017). https://doi.org/10.1007/s12665-017-6692-8
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DOI: https://doi.org/10.1007/s12665-017-6692-8