Impact of organic pollutants from urban slum informal settlements on sustainable development goals and river sediment quality, Nairobi, Kenya, Africa

The UN Sustainable Development Goals highlight the myriad of socio-economic and environmental challenges occurring as a result anthropogenic chemical pollution. Urban sediments from informal settlements (slums) on Nairobi, Ngong Mathare Rivers (n = 25), were evaluated for sediment quality. Microtox bioassay identified 8 sites toxic, 9 moderately toxic non-toxic. Slum characterised by high total organic carbon Rock-Eval pyrolysis revealed bound mix raw sewage domestic refuse. Sediments Kiambio, Kibera, Kawangware slums contained coprostanol at 55–298 μg/g epicoprostanol 3.2–21.7 confirming appreciable incorporation untreated human faeces. Hormones, antianalgeiscs, antiinflamatories, antiepileptics antibiotics most affected > Kiambio Kibera Mukuru slums. Carbamazepine, ibuprofen, diclofenac acetaminophen concentrations are amongst highest reported in Kenyan river positively correlated with faecal steroids (sewage). Common persistent pollutants, such organochlorine insecticides ΣDDT 1–59 μg/kg, mean 21.2 Σ16PAH 182–2218 822 μg/kg Σ30 PCB 3.1–157.1 21.4 between probable effect likely unlikely quality guidelines (SQG). PAH source ratios parent to alkyl-PAH distribution suggested vehicle exhaust, power stations (heavy oil), kerosene (cooking oil) other pollution sources. Trace metal As, Cd, Cr, Hg Ni below SQG whereas Pb exceeded SQG. This multi-contaminant characterisation Nairobi supports development implementation policies improve urban infrastructure protect ecological health. It demonstrates need geochemists engage science-policy interface associated both global national frameworks, particular reference Goals, New Agenda, Kenya’s Vision 2030.