Kalff 2002

Kalff 2002

Fig. 16-2 (Kalff 2002)

Wetzel 2001

Payne (1986)

Payne (1986)

Chemical stratification in Lake Tanganyika and Malawi (Hecky et al. 1996)

Dep

th (m

)

Chemical stratification in Lake Victoria 1961 – 1990 (Hecky et al. 1996)

Dep

th (m

)

Concentration-depth profile of chlorophyll a in Lake Victoria 1961 -1990(from Hecky 1993)

Attempts to tame a killer lake

Betsy Bodamer

Lake Nyos

General Info• Volcanic Crater Lake• Formed ~400+ years ago• Surface area = 1.58 km2 • Max depth = 210 m• Chemocline ≈50 m• Volume = 179,400,000 m3

• rainfall = 2.5 m/yr • Inflow

– 0-50 m: rainfall & streams– 50-210 m: soda springs

• CO2 rich water

• Outflow– Natural dam/spillway

The 1986 Disaster• ~80 million m3 of CO2 released from

Lake Nyos• Killed ~1800 people and thousands

of animals. • Cause = rapid overturn

• Volcanic or limnetic? Or both?

Degassing Lake Nyos

• 2001: full fledge degassing column was successfully assembled, installed and primed. – continuous– 50 m fountain

• Spray = 90% CO2 and 10% water.

• 50,000 STP m3/day

Trends across latitude in some important characteristics of freshwater systems[Lewis 1987]