PHYSICO-CHEMICAL QUALITY AND METAL CONTAMINATION OF WELL WATER IN THE SIXTHNEIGHBORHOOD OF COTONOU, SOUTH BENIN
Authors:   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin., Sako Avocefohoun Alphonse , Youssao Abdou Karim Alassane ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin.,   Ultra Trace AnalysisAquitaine (UT2 A)/University of Pau and Pays de lAdour (UPPA), France., Kolawole Balogoun Clement ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin., Nonvignon Magloire Gbaguidi Acakpo ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin.,   Ultra Trace AnalysisAquitaine (UT2 A)/University of Pau and Pays de lAdour (UPPA), France., Martin Vitus Mickael Saizonou Kpessou ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin., Sourou Montcho Papin ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin.,   Laboratory of Analytical Chemistry , Bio- Inorganic and Environment / University of Pau and Pays de lAdour (UPPA) - Multidisciplinary Institute of Research on Environment and Materials (IPREM 12- UMR 5254), France., Theotime Mahudjro Hounsou Francis ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin., Kader Alassane Moussa Abdoul ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin., Azokpota Emmanuel ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin., Firmin Dovonon Leonce ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin., Seby Fabienne ,   Ultra Trace AnalysisAquitaine (UT2 A)/University of Pau and Pays de lAdour (UPPA), France.,   Laboratory of Analytical Chemistry , Bio- Inorganic and Environment / University of Pau and Pays de lAdour (UPPA) - Multidisciplinary Institute of Research on Environment and Materials (IPREM 12- UMR 5254), France., Henri Soclo Houenoukpo ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin.,   Ultra Trace AnalysisAquitaine (UT2 A)/University of Pau and Pays de lAdour (UPPA), France., Donard Olivier ,   Ultra Trace AnalysisAquitaine (UT2 A)/University of Pau and Pays de lAdour (UPPA), France.,   Laboratory of Analytical Chemistry , Bio- Inorganic and Environment / University of Pau and Pays de lAdour (UPPA) - Multidisciplinary Institute of Research on Environment and Materials (IPREM 12- UMR 5254), France., CK Sohounhloue Dominique ,   Laboratory of Study and Research in Applied Chemistry (LERCA)/ Ecotoxicology and Quality Study Research Unit (UREEQ)/Abomey- Calavi Polytechnic School (EPAC/UAC), Benin.
Published: November 2022

In this research work, we have studied the physico-chemical characterization and searched for twenty-six metallic elements in the well waters of the sixth neighborhoodofCotonou. Well water was sampled in ten neighborhoods of this neighborhood.Physico-chemical parameters such as pH, temperature, conductivity, total dissolved salts (TDS) and salinity were measured on site while ammonium, phosphate, chloride, nitrite and nitrate ions are determined in the laboratory. Twenty-six metallic elements were measured after acid digestion of the water samples using the inductively coupled plasma source mass spectrometer (ICP-MS). The results showed that groundwater in the sixth neighborhood is in a degradation of its physico-chemical quality. The conductivity values varying between 2.06 and 1270 ÂµS/Cm with an average of 872.41 and a standard deviation of 393.90 show that these waters are highly mineralized (the WHO qualifies waters with a conductivity greater than 200ÂµS/Cm of very highly mineralized water). Ammonium and nitrite ions varying respectively between 0.6 and 7.1 mg/L with an average of 2.21 mg/L and 0.02 and 0.61 mg/L with an average of 0.22 mg/L are at abnormal concentrations in groundwater. The ammonium ion contents are beyond the standard value.As for metallic elements, aluminum, which is a trace element, is strongly present in water with an atypical observation of 5.008 mg/L. This value exceeds more than 25 times the standard defined by the WHO which is 0.2 mg/L. Iron is also present with an abnormal concentration of 2.711 mg/L as maximum value. Even if the values of the trace metals whose toxicities approved are lower than the standards, some atypical values are recorded and significant correlations established between these different chemical elements results from the common origins for the positively correlated metals and different origins for those which are negatively correlated.