Chapter 17

Question 1

1. Why are some substances, such as radon gas, cobalt or selenium, potentially hazardous?

Answer 1

Certain elements, molecules and minerals, whether they are dissolved in water or not, are a medical hazard because they cause illness in living things.

For example, Mercury causes mental illness.

Question 2

2. What controls the distribution of substances in the environment?

Answer 2

1. GEOLOGICAL SOURCE - the rock it came from
2. CLIMATE - which controls weathering
3. BIOLOGY - This controls weathering and the distribution of these substances after they are released.

Question 3

3. What is a major problem with determining the health risk of a substance?

Answer 3

Effects can be short or long term.

Question 4

4. What is meant by background level when it comes to medical geological hazards such as mercury or lead?

Answer 4

This refers to the concentration that occurs naturally.

Question 5

5. Explain the medical hazard associated with radon gas?

Answer 5

In high enough concentrations, it can cause health problems such as cancer.

Question 6

Radon Gas

Answer 6

A naturally occurring radioactive gas emitted by some rocks, mainly metamorphic.

Question 7

Arsenic

Answer 7

“Arsenic is “nasty stuff”” - Mark Smith

Question 8

6. Why is arsenic so hazardous to human health?

Answer 8

It affects many parts of the human body as it is a poison.

Question 9

Black shales

Answer 9

A fine grained, layered clastic sedimentary rock that is formed in deep, still water, often in the ocean

Question 10

7. In what kinds of deposits is arsenic found in the natural environment?

Answer 10

It is found in arsenopyrite - an iron sulfide mineral that precipitates under anaerobic conditions.

Arsenic in arsenopyrite is common in black shales.

Question 11

8. Explain the arsenic hazard in Bangladesh

Answer 11

The presence of black shales in the Himalaya Mounts is a source of arsenic.

The climate in the area promotes weathering. The large rivers between the mountains and the coast transport arsenic south to the population centers.

As a result, there is a high, unhealthy concentration of arsenic in the local groundwater. Groundwater is a major source of drinking water.

Question 12

How are potentiall hazardous substances released in general?

Answer 12

These potentially hazardous substances are usually released from a rock formation as a result of a natural process (i.e. radioactive decay) or as the rock/mineral weathers.

Question 13

Tsunami deposits

Answer 13

Tsunami deposits in coastal BC often include a sand layer with organic layers above and below it.

These organized layers are the remains of the forest soil that was there before and after the tsunami happened.

The organic remains in the soil provides the carbon can be used to absolutely date the tsunami.

Question 14

GEOLOGICAL SOURCE

Answer 14

The rock it came from

Question 15

CLIMATE

Answer 15

This controls weathering

Question 16

BIOLOGY

Answer 16

This controls weathering and the distribution of these substances after they are released.

Question 17

Arsenophyte

Answer 17

an iron sulfide mineral that precipitates under anaerobic conditions.