Lecture 8 + 9

Question 1

nitrogen is often a _____ nutrient to primary producers (plants, algae and bacteria)

Answer 1

nitrogen is often a limiting nutrient to primary producers (plants, algae and bacteria)

Question 2

Nitrogen largely enters the ecosystem through ______, but some also enters through geologic reservoirs.

Answer 2

Nitrogen largely enters the ecosystem through microbial fixation, but some also enters through geologic reservoirs.

Question 3

Nitrogen leaves ecosystems through _________ (back to the atmosphere) and through burial and __________

Answer 3

Nitrogen leaves ecosystems through denitrification (back to the atmosphere) and through burial and sedimentation

Question 4

Industrial Synthesis of NH3

Answer 4

Haber-Bosch Process (demonstrated in 1909)

• In the presence of a Fe oxide catalyst
• at 20 MPa (200 atmospheres) and 450°C

N2 + 6 H+ + 6 e– → 2 NH3

Question 5

cultural eutrophication

Answer 5

Indirect human fertilization of surface waters is called cultural eutrophication

Question 6

nitrate

Answer 6

NO3

Question 7

Upper limit for nitrate in groundwater for drinking is _____

Answer 7

Upper limit for nitrate in groundwater for drinking is 10 mg L-1

Above this concentration, alternative drinking water (e.g., bottled) is necessary