Which condition is caused by nitrate contamination in water?
High nitrate in drinking water can cause infant methaemoglobinaemia, commonly called blue baby syndrome. Gut microbes reduce nitrate to nitrite, which oxidises haemoglobin iron from the ferrous to ferric state, producing methaemoglobin that cannot bind oxygen effectively. Infants are particularly susceptible because of gastrointestinal and enzymatic features. Minamata and Itai-itai diseases involve mercury and cadmium, respectively, while cholera is an infection. Sensitive developmental stages may respond at concentrations that cause little immediate adult mortality, making reproduction and recruitment essential endpoints. Monitoring should include appropriate controls, spatial replication, temporal variation, and validated analytical methods before broad conclusions are drawn. Community-level consequences can emerge when physiological injury changes survival, reproduction, species interactions, or the flow of energy through food webs. Aquatic effects depend on chemical form, persistence, solubility, dose, and the capacity of organisms to metabolise or excrete the substance. Catchment processes connect land use with rivers, lakes, estuaries, and coastal waters, so prevention at the source is usually more effective than downstream treatment.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology