Chemistry of the Environment: element cycles and toxicology

lithosphere

the crust of the Earth; soil, rocks, all other surface materials

hydrosphere

all of the water on the earth (liquid, frozen, and vapor)

atmosphere

air above surface of earth

biosphere

all biological matter on Earth (living and dead)

geosphere

non-biological spheres of the environment (lithosphere, hydrosphere, and atmosphere)

residence time

The average amount of time that an \n atom or a molecule remains in a \n compartment before it is removed in \n some way

% oxygen in the atmosphere

21%

% nitrogen in the atmosphere

78%

residence time of oxygen in the atmosphere

5000 years

residence time of nitrogen in the environment

10 million years

nitrogen fixation

process of converting free nitrogen in the air into chemically combined nitrogen

% CO2 in the atmosphere

0.039%

Hazardous chemical are:

Flammable

Explosive

Corrosive

Toxic

Allergenic

Toxin/poison

substance that causes injury, illness, or death of a living organism

Toxicology

study of poisons, their effects, detection, identification, and antidotes

biotoxins

toxic substances produced by organisms for defense or other reasons

“Silent Spring”

written by Rachel Carson; brought attention to widespread use of pesticides; partially led to ban of DDT in US

environmental toxicology

study of toxins in the environment

environmental health toxicology

study of the effect of toxins on human health

ecotoxicology

study of the effects of toxins on an ecosystem in the environment

threshold dose

a dose below which a toxin shows no observable effect

LD50

the dose at which 50% of the individuals die (mg toxin/kg body mass)

acute toxicity

• manifests its effect in a relatively short period of time
• type of toxicology results from relatively brief periods of exposure to a toxin

chronic toxicity

• manifests itself over a longer period of time
• type of toxicology results from long periods of exposure to a toxin

No Observed Effect Level (NOEL)

the highest dose at which no effect is observed (lies slightly above the threshold dose)

Carbon dioxide dissolves in water to form…

carbonic acid

Continuous processes operating with little change for long periods of time are called…

sustainable

Limestone is a very compressed form of…

calcium carbonate

Nitrogen fixation is the process that converts…

Atmospheric nitrogen gas to useful compounds of nitrogen

Photosynthesis is the process by which…

Water and carbon dioxide are converted to carbohydrates and oxygen

Respiration is the…

Breakdown of carbohydrates with oxygen to form water and carbon dioxide

Is nitrogen gas reactive?

no, highly unreactive

is oxygen gas reactive?

yes, highly reactive

The compartments of our planet are

Hydrosphere, lithosphere, atmosphere, and biosphere

The only significant way oxygen (O2) enters the atmosphere is through…

photosynthesis

Which of the following cycles does not have an atmospheric component?

phosphorus

Which of the following produces useful nitrogen compounds to fertilize crops?

• Nitrogen fixation through lightning discharges
• Nitrogen fixation with nitrogen-fixing bacteria such as Rhizobium
• Fertilizers produced by the Hager Process from elemental nitrogen and hydrogen

Poisons that show up in the environment due to the activities of our society are known as

environmental toxins

Substances which in low concentrations can cause death in test animals are known as

toxins

Toxins in the environment are generally broken down by

Water, light, and microorganisms

The sulfur cycle is similar to the

phosphorus cycle