Poluição Ambiental e Mudanças Climáticas

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Groundwater Quality Assessment around Two Dumpsites: A Case Study of Ojota and Bariga Sites in Lagos, Nigeria

Majekodunmi Grace F, Akanmu James, Adenekan Kifaayah, Mayowa Adenekan, Notiswa Libala

Many Nigerians does not have access to improved drinking water both in rural and urban area but more critical in urban areas of which can be linked to rapid urbanization leading to greater demand for water resource supply and municipal sanitation services in the country. This is particularly true for region experiencing exponential population growth such as the Lagos Metropolitan, the economic hub of Nigeria. Concurrently, waste generation increases at rates that municipalities cannot safely dispose of; which results in the rise of illegal waste dumping in unauthorised dumpsites.

The occurrence of these dumpsites in urban areas were identified as one of the sources of water pollution and poses a health risk to groundwater users as leachate and other contaminants generated from the dumpsites has the potential to migrate downwards into the underlying aquifers. This study assessed the groundwater quality near two dumpsites in the Lagos Metropolitan (The government controlled authorised Ojota the unauthorised Bariga disposal sites).

Samples were collected from boreholes and monitoring wells around the Ojota and Bariga dumpsites respectively between the period of June and August 2021 The pH, Temp, EC, Salinity, TDS, Calcium Hardness, Total Hardness,Chloride content, Alkalinity, Acidity, Heavy metals (Cr, Cu, Fe, Mn, Pb, and Zn) microbial parameters were analysed from the water and leachate sample collected. The results were analysed using the statistical tools in the R-package and compared against the World Health Organization (WHO-2017) and the Nigerian Standard for drinking water quality(NSDWQ-2007).

However, the concentrations of EC, TDS, Chloride, Fe and Zn levels of Bariga dumpsite were observed to be higher which means it contains some contaminants than that of Ojota dumpsite as compared with the standards used (WHO&NSDWQ). Although the result of analysis of EC, TDS on the leachate for Ojota dumpsite was discovered to be high beyond permissible limits showing a level of contamination in the groundwater quality.

From this study, it is evident that lack of well-constructed engineered environmental friendly landfills and indiscriminate dumping of wastes to water channels can possibly lead to high contamination of the groundwater quality,posing a serious threat to the human health and the environment at large. It therefore requires collective efforts between the community residents to avoid indiscriminate dumping of waste and the government ensuring that proper waste management and monitoring is put in place especially in areas where these landfills are currently situated.