Hydrosphere II

Question 1

Where are wetlands mainly found in Canada?

Answer 1

Northern Ontario, northern prairies

Question 2

What are the two types of wetlands?

Answer 2

Coastal and riparian, inland

Question 3

Give 3 examples of coastal and riparian wetlands.

Answer 3

Tidal salt marshes, tidal freshwater marshes, mangrove wetland

Question 4

Give 3 examples of inland wetlands.

Answer 4

Inland freshwater marshes, peatlands, seeps, southern deepwater swamps, riparian wetlands

Question 5

What is aeration?

Answer 5

The status or amount of air (gases) in a soil volume. This can include gases other than oxygen.

Question 6

What is a wetland?

Answer 6

Wetlands are transitional lands between terrestrial and aquatic systems where the water table is usually at or near the surface, or the land is covered by shallow water.

Question 7

What are the 3 criteria to qualify as a wetland?

Answer 7

Must have one or more of:
1. Hydrology: saturated with water at some time during the growing season
2. Plants: must support predominantly hydrophytes at least periodically
3. Soil: the substrate is permanently undrained, anaerobic soil.

Question 8

In anaerobic conditions, oxygen is removed from groundwater by […]

Answer 8

The respiration of microbes, roots, and soil fauna

Question 9

What is the difference between a bog and a fen in terms of hydrology?

Answer 9

A fen is a younger version of a bog. Bogs get water from the rain and are not connected to lakes or streams, so they are generally nutrient poor and how low plant diversity. Fens are connected to flowing water, so they are more nutrient rich.

Question 10

Describe the characteristics of wetlands when precipitation is high and groundwater is low.

Answer 10

The wetlands have water with a high residence time, they are closed systems, and they are biogeochemically isolated from catchments. So there’s not many nutrients. These are precipitation-dominated wetlands.

Question 11

Describe the characteristics of wetlands when precipitation is low and surface flow is high.

Answer 11

The wetlands have water with a shorter residence time, and there are more sediments and nutrients. These are surface flow wetlands.

Question 12

Describe the characteristics of wetlands when surface flow is low and groundwater is high.

Answer 12

There are groundwater wetlands. Residence time is shorter and it’s moving at a good pace, allowing plants to survive that wouldn’t otherwise grow there.

Question 13

Describe how hydrophytes are adapted to be able to survive saturated, anoxic environments.

Answer 13

To get aeration from the roots, they have aerenchymas tissue, which are porous. This are a pathway for the exchange of oxygen to plant organs from the air downwards and helps with buoyancy.

Question 14

Why are hydric soils?

Answer 14

Hydric soils are soils that usually alternate between periods of anaerobic and aerobic conditions that produce redoximorphic features.

Question 15

Describe the redoximorphic features of hydric soils.

Answer 15

When the soil is anaerobic, the iron (Fe2+) in the soil takes on a grey colour. When the soil is aerobic, ferric iron (Fe3+) turns red in the presence of oxygen.

Question 16

Describe how wetland decomposition and respiration varies between aerobic and anaerobic soils.

Answer 16

In aerobic soils, microbes use oxygen as an electron acceptor to oxidize organic matter and convert it to ATP, with CO2 as a byproduct. In anaerobic soils, microbes use Fe3, No3, CO2, SO42- as alternate electron acceptors to produce ATP, and release CO2 and CH4 as a byproduct. The anaerobic process is slower.

Question 17

The major gas produced via respiration in wetlands is […]

Answer 17

Methane (CH4)

Question 18

What are the 3 ways by which CH4 can leave the wetlands after it is produced.

Answer 18

It can be released through plant leaves and roots, via gas bubbles, and from the water surface

Question 19

Describe the 4 steps of the cycle of carbon exchange in a wetland.

Answer 19

1. Beginning with respiration: CO2 is reduced to CH4 during oxidation.
2. CH4 is released via plant leaves/roots/gas bubble/water surface.
3. Plants pump air O2 from leaves to roots to soil
4. CH4 produced during anaerobic respiration can be oxidized back to CO2 in the more aerobic root zone.

Question 20

How does peat accumulate in the soil?

Answer 20

It accumulates because net primary productivity exceeds decomposition and other soil carbon losses, so it compacts. It is deposited and some is decomposed, burial, and compaction.

Question 21

Why does peat accumulate under saturated conditions?

Answer 21

The decomposition rate is lower than the net primary productivity. This is because they receive a high concentration of nutrients, creating rapid growth. Meanwhile, since anaerobic decomposition is slower, is can’t keep up.

Question 22

What is the fate of the majority of the wetlands and peatlands in Canada?

Answer 22

The majority of them have been drained for agriculture, forestry, and to stabilize building or road construction.