Ch. 17. Hazardous Gas Flashcards
(8 cards)
Why are some substances, such as radon gas, cobalt or selenium, potentially hazardous?
Because they are usually released from a rock formation as a result of a natural process or as the rock/mineral weathers and can contaminate water and certain geological rock formations and certain elements, molecules and minerals whether they are dissolved in water or not they are a medical hazard because they cause illness in living things.
What controls the distribution of substances in the environment?
- The geological source - the rock it came from
- Climate, which controls weathering
- Biology. This controls weathering and the distribution of these substances after they are released
What is a major problem with determining the health risk of substance?
The major problem is determine how much is harmful and what are the effect. Effects can be short or long term.
What is meant by background level when it comes to medical geological hazards such as mercury or lead?
The background level of a potentially harmful substance refers to the concentration that occurs naturally.
Explain the medical hazard associated with radon gas?
Radon gas is a naturally occurring radioactive gas emitted by some rocks, mainly, metamorphic. The hazard is that in high enough concentrations it can cause health problems such as cancer.
Why is arsenic so hazardous to human health?
Arsenic is nasty stuff, main ingredient in rat poison. It affects many parts of the human body as it is a poison.
In what kinds of deposits is arsenic round in the natural environment?
Arsenic is found in arsenopyrite an iron sulfide mineral that precipitates inner anaerobic conditions. Anaerobic means no oxygen. Arsenic is arsenopyrite is common in black shales. This is a fine grained, layered clastic sedimentary rock that formed in deep, still water, often in the ocean.
Explain the arsenic hazard in Bangladesh.
The presence of black shales in the Himalaya mountains is a source for arsenic. The climate in the area promotes weathering. The large rivers between the mountains and the coast transport arsenic south, the population centres. As a result there is high, unhealthy concentration of arsenic in the local groundwater. Ground water is a major source of drinking water.
