Abstract

The present study aimed to assess the physicochemical and microbiological quality of shallow groundwater tapped by private boreholes for water sale in Togo’s most urbanized coastal areas. Ninety-six (96) groundwater samples were collected at the water sale points for chemical and microbiological analyses using standard methods. The results showed that groundwater is predominantly acidic with fresh and brackish water of Na-Cl type. High concentrations of dissolved inorganic nitrogen (NO3- , NH4+and NO2-) and permanganate indices indicating potential organic matter were found. Among the major ions, Na+ (46.9%), Cl- (51.0%) and NO3- (50.0%) present the highest percentages of unsuitable concentrations compared to WHO guidelines. These findings indicate the control of the natural impact of seawater and lagoon system and anthropogenic pollution from domestic and urban wastes on groundwater’s physicochemical quality. About 65% of groundwater samples did not comply with the drinking water guidelines for microbial indicators, including total mesophilic flora, thermotolerant coliforms, and sulfite-reducing anaerobes. The results showed the failure of sanitation and hygiene conditions around sampling points and fecal contamination from sewage, pit latrines, septic tanks, and refuse and waste disposal. The degradation of physicochemical quality is higher in the old and high-density built-up areas. Simultaneously, microbial contamination represents a high risk of contracting waterborne or hygiene-sanitation-related diseases in the whole study area. This study provides a global view of shallow groundwater’s physicochemical and microbiological quality in the study area. Limitations and suggestions for future research are discussed.

Highlights

  • Groundwater is the most precious water resource for human survival and socio-economic development all over the world

  • Na+ (46.9%), Cl− (51.0%) and NO3− (50.0%) present the highest percentages of unsuitable concentrations compared to WHO guidelines. These findings indicate the control of the natural impact of seawater and lagoon system and anthropogenic pollution from domestic and urban wastes on groundwater’s physicochemical quality

  • The results showed the failure of sanitation and hygiene conditions around sampling points and fecal contamination from sewage, pit latrines, septic tanks, and refuse and waste disposal

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Summary

Introduction

Groundwater is the most precious water resource for human survival and socio-economic development all over the world. The development of human activities have increased the pressure on groundwater and the degradation of its quality in rural as well as urban areas (Cronin et al, 2007; Umezawa et al, 2008; Chidya et al, 2016; Lapworth et al, 2017; Anornu, Gibrilla, & Adomako, 2017; Akpataku et al, 2019). Groundwater in urban areas is sometimes contaminated with multiple contaminants at higher concentrations than in rural areas, one of the most prevalent pollutants in both regions is nitrate (Kuroda & Fukushi, 2008; Diaw et al, 2020). Many studies have focused on nitrate and other pollutants such as fluoride, arsenic, uranium, heavy metals, and pesticides, which limit the use of groundwater resources regarding human health hazards (Tiktak et al, 2004; Wen et al, 2013; Jadhav et al, 2015; Coyte et al, 2019)

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