Chemical Evolution of the Continental Terminal Shallow Aquifer in the South of Coastal Sedimentary Basin of Benin (West-Africa) Using Multivariate Factor Analysis

Abdoukarim Alassane^1*, Rim Trabelsi², Léonce F. Dovonon³, Diane J. Odeloui¹, Moussa Boukari¹, Kamel Zouari², Daouda Mama¹

¹Laboratoire d’Hydrologie Appliquée, Faculté des Sciences et Techniques, Université d’Abomey-Calavi, Abomey-Calavi, Bénin.
²Laboratoire de Radio-Analyse et Environnement, Ecole Nationale d’Ingénieurs de Sfax, Université de Sfax, Sfax, Tunisie.
³Laboratoire d’Etude et de Recherche en Chimie Appliquée, Ecole Polytechnique d’Abomey-Calavi, Université d'Abomey-Calavi, Abomey-Calavi, Bénin.

DOI: 10.4236/jwarp.2015.76040                

Abstract

In southern Benin, where population is growing and water demand for domestic activities is increasing, water balance assessment constitutes a serious concern about sustainability of water resources. Major ions have been employed with statistical methods to identify geochemical processes controlling groundwater quality. Multivariate statistical analysis (principal component analysis “PCA” and hierarchical cluster analysis “HCA”) revealed the main sources of groundwater mineralization. According to the hydrochemical data and the methods of treatment, groundwater mineralization in the investigated aquifer is caused by four main processes: 1) mixing with Nokoué lake and Porto-Novo lagoon salt water causing salinity to increase in the southern part of the aquifer; 2) anthropogenic activities; 3) cation exchange process; and 4) soil CO₂ diffusion providing a large proportion of bicarbonates.

Keywords

Hydrogeochemical Process, Pollution, Shallow Groundwater, Continental Terminal, Benin

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	INSAE (2003) Troisieme recensement general de la population et de l'habitation, fevrier 2002: Syntheses des resultats. Rapport, Direction des etudes demographiques, Cotonou, Benin.
[2]	Totin, H.S.V., Alassane, A., Boukari, M., Faye, S. and Boko, M. (2010) Climate and Land Use Change Impacts on Groundwater Quality in the Beninese Coastal Basin of the Transboundary Aquifer System Benin-Nigeria-Togo. International Conference “Transboundary Aquifers: Challenges and New Directions” (ISARM 2010), Paris, 6-8 December 2010, 184.
[3]	Pulido-Leboeuf, P. (2004) Seawater Intrusion and Associated Processes in a Small Coastal Complex Aquifer (Castell de Ferro. Spain). Applied Geochemistry, 19, 1517-1527. http://dx.doi.org/10.1016/j.apgeochem.2004.02.004
[4]	Chekirbane, A., Tsujimura, M., Kawachi, A., Isoda, H., Tarhouni, J. and Benalaya, A. (2013) Hydrogeochemistry and Groundwater Salinization in an Ephemeral Coastal Flood Plain: Cap Bon, Tunisia. Hydrological Sciences Journal, 58, 1097-1110. http://dx.doi.org/10.1080/02626667.2013.800202
[5]	Trabelsi, R., Abid, K. and Zouari, K. (2011) Geochemistry Processes of the Djeffara Palaeogroundwater (Southeastern Tunisia). Quaternary International, 257, 43-55. http://dx.doi.org/10.1016/j.quaint.2011.10.029
[6]	Lakshmanan, E., Kannan, R. and Senthil Kumar, M. (2003) Major Ion Chemistry and Identification of Hydrogeochemical Processes of Ground Water in a Part of Kancheepuram District, Tamil Nadu, India. Environmental Geosciences, 10, 157-166. http://dx.doi.org/10.1306/eg100403011
[7]	Kumar, M., Ramanathan, A.L., Rao, M.S. and Kumar, B. (2006) Identification and Evaluation of Hydrogeochemical Processes in the Groundwater Environment of Delhi, India. Environmental Geology, 50, 1025-1039. http://dx.doi.org/10.1007/s00254-006-0275-4
[8]	Cloutiera, V., Lefebvrea, R., Therrienb, R. and Savardc, M.M. (2008) Multivariate Statistical Analysis of Geochemical Data as Indicative of the Hydrogeochemical Evolution of Groundwater in a Sedimentary Rock Aquifer System. Journal of Hydrology, 353, 3-4. http://dx.doi.org/10.1016/j.jhydrol.2008.02.015
[9]	Maliki, R. (1993) Etude hydrogeologique du littoral beninois dans la region de Cotonou (A.O). These de Doctorat de 3eme cycle, Universite, C. A. Diop de Dakar, Senegal.
[10]	Boukari, M. (1998) Fonctionnement du systeme aquifere exploite pour l’approvisionnement en eau de la ville de Cotonou sur le littoral beninois. Impact du developpement urbain sur la qualite des ressources. These Doctorat es-Science, Universite C. A. Diop de Dakar, Senegal.
[11]	Boukari, M., Oyede, L.M., Alidou, S., Gaye, C.B. and Maliki, R. (1995) Identification des aquiferes de la zone littorale du Benin (Afrique de l’Ouest): Hydrodynamique, hydrochimie et problemes d’alimentation en eau de la ville de Cotonou. Africa Geoscience Review, 2, 121-139.
[12]	Alassane, A. (2004) Etude hydrogeologique du Continental Terminal et des formations de la plaine littorale dans la region de Porto-Novo: Identification des aquiferes et vulnerabilite a la pollution de la nappe superficielle. These de doctorat de 3eme cycle, Universite C. A. Diop de Dakar, Senegal.
[13]	Pallas, P. (1988) Contribution a l’etude des ressources en eau souterraine du bassin cotier du Benin. Confrontation ressources—Besoins. Rapport du Projet PNUD.
[14]	Boukari, M., Viane, P. and Azonsi, F. (2008) Three-Dimensional Modelling of a Coastal Sedimentary Basin of Southern Benin (West Africa). In: Adelana, S.M.A. and MacDonald, A.M., Eds., Applied Groundwater Study in Africa (2008): IAH Selected Papers on Hydrogeology, CRC Press/Balkema, Leiden, 437-456.
[15]	Boukari, M., Alassane, A. and Azonsi, F. (2009) Evaluation par la methode DRASTIC de la vulnerabilite de la nappe phreatique de Cotonou (Benin meridional, Afrique de l’Ouest). Africa Geoscience Review, 16, 175-188.
[16]	Alassane, A., Faye, A., Boukari, M. and Cisse Faye, S. (2009) Aquifer Vulnerability and Its Implication for Community Water Supply of Porto-Novo Region (South-East of Benin). In: Xu, Y.X. and Braune, E., Eds., Sustainable Groundwater Resources in Africa (2009): UNEP Selected Papers on Hydrogeology, Indexed in CRC Press, Taylor and Francis/Balkema, Leiden, 107-117. www.crcpress.com/
[17]	Dovonou, F. (2012) Diagnostic qualitatif et environnemental de l’aquifere superficiel du champ de captage intensif de Godomey au Benin (Afrique de l’Ouest): Elements pour un plan d’actions strategiques de protection des ressources en eau souterraine exploitees. These de doctorat unique, Universite d’Abomey-Calavi, Benin.
[18]	Dovonou, F., Babadjide, C., Alassane, A., Yalo, N., Mama, D. and Boukari, M. (2012) Impact de la pollution chimique et bacteriologique sur l’aquifere superficiel de la zone de captage intensif de Godomey au Sud-Benin. Climat et Developpement, 14, 55-67.
[19]	Totin, V.S.H., Boukari, M., Odoulami, L. and Edorh, P. (2012) Qualite bacteriologique des eaux souterraines et sources de pollution dans le bassin sedimentaire cotier du Benin. Climat et Developpement, 13, 16-27.
[20]	Boukari, M., Gaye, C.B., Faye, A. and Faye, S. (1996) The Impact of Urban Development on Coastal Aquifers near Cotonou, Benin. Journal of African Earth Sciences, 22, 403-408. http://dx.doi.org/10.1016/0899-5362(96)00027-9
[21]	Boukari, M., Alassane, A., Dovonon, F.A.L., Tossa, A. and Zogo, D. (2006) Groundwater Pollution from Urban Development in Cotonou City, Benin. In: Xu, Y. and Usher, B., Eds., Groundwater Pollution in Africa: UNEP Selected Papers on Hydrogeology Publication, Taylor and Francis/Balkema, Leiden, 125-138.
[22]	Boukari, M. and Alassane, A. (2007) Les ressources en eaux souterraines du bassin sedimentaire cotier de la Republique du Benin. Africa Geoscience Review, 14, 283-301.
[23]	Chen, K., Jiao, J.J., Huang, J. and Huang, R. (2007) Multivariate Statistical Evaluation of Trace Elements in Groundwater in a Coastal Area in Shenzhen, China. Environment Pollution, 147, 771-780. http://dx.doi.org/10.1016/j.envpol.2006.09.002
[24]	Liu, C.W., Lin, K.H. and Kuo, Y.M. (2003) Application of Factor Analysis in the Assessment of Groundwater Quality in a Blackfoot Disease Area in Taiwan. The Science of the Total Environment, 313, 77-89. http://dx.doi.org/10.1016/S0048-9697(02)00683-6
[25]	Wenning, R.J. and Erickson, G.A. (1994) Interpretation and Analysis of Complex Environmental Data Using Chemometric Methods. Trends in Analytical Chemistry, 13, 446-457. http://dx.doi.org/10.1016/0165-9936(94)85026-7
[26]	Helena, B., Pardo, R., Vega, M., Barrado, E.M., Fernandez, J. and Fernandez, L. (2000) Temporal Evolution of Groundwater Composition in an Alluvial Aquifer Pisuerga River. Spain by Principal Component Analysis. Water Research, 34, 807-816. http://dx.doi.org/10.1016/S0043-1354(99)00225-0
[27]	Jackson, J.E. (1991) A User’s Guide to Principal Components. Wiley, New York. http://dx.doi.org/10.1002/0471725331
[28]	Meglen, R.R. (1992) Examining Large Databases: A Chemometric Approach Using Principal Component Analysis. Marine Chemistry, 39, 217-237. http://dx.doi.org/10.1016/0304-4203(92)90103-H
[29]	Vega, M., Pardo, R., Barrado, E. and Deban, L. (1998) Assessment of Seasonal and Polluting Effects on the Quality of River Water by Exploratory Data Analysis. Water Research, 32, 3581-3592. http://dx.doi.org/10.1016/S0043-1354(98)00138-9
[30]	Direction de l’hydraulique (2000) Vision Eau 2025, Benin. Rapport, Direction de l’Hydraulique, Benin.
[31]	IRB (1987) Etude de cartographie geologique et prospection minerale de reconnaissance au Sud du 9eme parallele. Rapport. Istituto Recerche Breda, FED-OBEMINES.
[32]	Le Barbe, L., Ale, G., Millet, B., Borel, Y. and Gualde, R. (1993) Les ressources en eaux superficielles de la Republique du Benin. ORSTOM Editions, Paris.
[33]	Slanski, M. (1968) Contribution a l’etude geologique du bassin sedimentaire cotier du Dahomey et du Togo. These, Universite de Nancy, Nancy.
[34]	Dray, D., Giachello, L., Lazzaroto, V., Mancini, M., Roman, E. and Zuppi, G. (1989) Etude isotopique de l’aquifere cretace du bassin sedimentaire cotier beninois. Actes du seminaire sur le developpement des techniques isotopiques et nucleaires, 3, 167-177.
[35]	Oyede, L.M. (1991) Dynamique sedimentaire actuelle et messages enregistres dans les sequences quaternaires et neogenes du domaine margino-littoral du Benin (Afrique de l’Ouest). XIIeme Congres INQUA, Montreal, Abstract 237.
[36]	Palmer, C. (1911) The Geochemical Interpretation of Water Analysis. USGS Bulletin, 479, 4-31.
[37]	Addinsoft, Inc. (2006) XLSTAT for Windows (Computer Program Manual).
[38]	Mellinger, M. (1987) Multivariate Data Analysis: Its Methods. Chemometrics and Intelligent Laboratory Systems, 2, 29-36. http://dx.doi.org/10.1016/0169-7439(87)80083-7
[39]	Willet, P. (1987) Similarity and Clustering in Chemical Information Systems. Research Studies Press, Wiley, New York.
[40]	Stephen Fisher, R. and Mullican, W.F. (1997) Hydrochemical Evolution of Sodium-Sulfate and Sodium-Chloride Groundwater beneath the Northern Chihuahuan Dezert, Trans-Pecos, Texas, USA. Hydrogeology Journal, 5, 4-16. http://dx.doi.org/10.1007/s100400050102
[41]	WHO (1993) Guidelines for Drinking Water Quality. 2nd Edition, Geneva. http://www.who.int/water_sanitation_health/dwq/gdwq2v1/en/
[42]	Guler, C., Thyne, G.D., McCray, J.E. and Turner, A.K. (2002) Evaluation of Graphical and Multivariate Statistical Methods for Classification of Water Chemistry Data. Hydrogeology Journal, 10, 455-474. http://dx.doi.org/10.1007/s10040-002-0196-6