Carbon Cycle Carbon Pools: 1. Atmosphere, 0.035% CO2 2. Ocean, a carbon sink 3. Earth’s crust, 300 Ma deposits 4. Soils, can be a sink, e.g., MgSiO3 + CO2 MgCO3 + SiO2 also, peat bogs Fig. 22.1

Chlorinated Hydrocarbons --synthetic compounds containing chlorine and carbon, first synthesized in 1874 --used for pesticides after WWII, 1940s to 1970s --DDT most infamous, used for mosquito control to stop malaria in Sri Lanka in early 1950s --malaria dropped from 2 million cases per year to zero!

Problems with DDT --long-lived compound, lasts for decades in soil or water without breaking down --soluble in fat, but does not metabolize so builds up in tissues when consumed --concentrations will increase in long-lived species, perhaps to toxic or harmful levels --in birds, high concentrations block calcium production in eggshell formation, resulting in thin eggs being laid and breaking when incubated --nearly caused the extinction of top predators such as bald eagles, peregrine falcons, and brown pelicans

Biomagnification

Rachel Carson (1907 – 1964) Author of ‘Silent Spring’ (1962) First to draw attention of dangers of pesticides to the public