Lec 21: Human Impact - Microbes and Mercury Flashcards
What are the 2 forms of mercury?
- Inorganic and organic (methylmercury)
How is mercury naturally released into the environment?
- volcanic activity
- weathering of rocks
Why is it believed that volcanic activity was the main late-triassic extinction trigger?
because high contents of mercury were found in extinction-age rocks, and volcanoes are the main source of nonanthropogenic mercury
Which human activities release mercury?
- coal combustion
- mining
how does mercury become methylmercury?
by bacteria that live in aquatic systems
how does the majority of mercury exposure occur?
through fish consumption
Which type of bacteria were believed to be methylators?
sulfate reducing bacteria
Where are genes responsible for methylation found?
in many different kinds of microbes
How does dam construction affect methylmercury presence in water?
flooding of soils causes inorganic mercury to be exposed to bacteria, which methylate it.
