Editing Carbon dioxide (section)

==== Outdoor areas with elevated concentrations ====
Local concentrations of carbon dioxide can reach high values near strong sources, especially those that are isolated by surrounding terrain. At the Bossoleto hot spring near [[Rapolano Terme]] in [[Tuscany]], Italy, situated in a bowl-shaped depression about {{cvt|100|m}} in diameter, concentrations of {{CO2}} rise to above 75% overnight, sufficient to kill insects and small animals. After sunrise the gas is dispersed by convection.<ref>{{Cite book |title=Plant responses to elevated {{CO2}}: Evidence from natural springs |vauthors=van Gardingen PR, Grace J, Jeffree CE, Byari SH, Miglietta F, Raschi A, Bettarini I |publisher=Cambridge University Press |year=1997 |isbn=978-0-521-58203-2 |veditors=Raschi A, Miglietta F, Tognetti R, van Gardingen PR |location=Cambridge |pages=69–86 |chapter=Long-term effects of enhanced {{CO2}} concentrations on leaf gas exchange: research opportunities using {{CO2}} springs}}</ref> High concentrations of {{CO2}} produced by disturbance of deep lake water saturated with {{CO2}} are thought to have caused 37 fatalities at [[Lake Monoun]], [[Cameroon]] in 1984 and 1700 casualties at [[Lake Nyos]], Cameroon in 1986.<ref>{{Cite book |title=Plant responses to elevated {{CO2}}: Evidence from natural springs |vauthors=Martini M |publisher=Cambridge University Press |year=1997 |isbn=978-0-521-58203-2 |veditors=Raschi A, Miglietta F, Tognetti R, van Gardingen PR |location=Cambridge |pages=69–86 |chapter={{CO2}} emissions in volcanic areas: case histories and hazards}}</ref>