References in Pollution - water courses:
https://www.chickens.allotment-garden.org/free-range-poultry/nature-land-free-range-poultry/
https://www.bhwt.org.uk/hen-health/learn-about-hens/diarrhoea/
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0187057
https://www.who.int/water_sanitation_health/dwq/chemicals/nitratenitrite2ndadd.pdf