Tryptophan fluorescence Research Papers - Academia.edu (original) (raw)

Each day, 1.8 billion individuals around the world drink water contaminated with faeces (WHO, 2017). In sub-Saharan Africa alone, this represents a leading cause of mortality, as diarrhoeal diseases killed 643,000 people in 2015 (WHO, 2016). In the coastal megacity of Dakar, Senegal, the Thiaroye shallow aquifer is a complex system in which multiple sources of pollution and a lack of sufficient sanitation infrastructure have contributed to an extreme degradation of groundwater quality. This study is an investigation of faecal contamination patterns across the aquifer. It is based on data collection conducted in the greater Dakar region under the Dakar urban observatory of the AfriWatSan project, in June-July 2018. Within the AfriWatSan framework, this study seeks to explore faecal contamination patterns across the Thiaroye aquifer, based on standard culture-based methods and tryptophan-like fluorescence (TLF). TLF is a fluorescence based method currently being developed by the British Geological Survey for real-time screening of faecally contaminated drinking water in urban Africa. The method offers several key advantages over traditional methods as it is portable, real-time and easy to use.
97 samples were collected with 48 parameters including hydrochemical parameters and environmental risks. This study first seeks to explore the relationships between different variables, with a specific focus on TLF performance as a faecal matter detection method. It then explores spatial patterns of contamination, before adopting an unsupervised machine learning approach to classification with Agglomerative Hierarchical Clustering (HAC).
While TLF fails to accurately predict current contamination across the Thiaroye aquifer, this data exploration and modelling exercise provides additional information about the Thiaroye aquifer groundwater quality. In order to achieve a more accurate representation of the contamination, further research will need to incorporate groundwater flow modelling, and to investigate vertical contamination flows.
Research was conducted under the AfriWatSan project, funded by The Royal Society (UK) and Department for International Development (DFID), and supported by the British Geological Survey (BGS), currently developing portable, UV-based fluorimeters for real-time screening of faecally contaminated drinking water in urban Africa.