ENVR101 - Block 1 Biogeochemical Cycles

Lectures Weeks 1-3

Reservoir

Storage pool

Flux

Transfer rate or the processes of an element between reservoirs

Residence time

The average time an element spends in a reservoir depending on the size of the reservoir

Steady state

The inputs and outputs of a reservoir being balanced, the rate going in and the rate going out and the same resulting in no net change over time (net 0)

What are reasons for studying biogeochemical cycles?

Mitigating climate change, resource management, Earth system, interconnectivity, and understanding Earth’s long term stability

Atmospheric Circulation

Large scale movement of air around the planet driven by solar energy. This redistributes thermal energy over the Earth’s surface. Warm air rises at the equator and flows towards the poles, cold, more dense air at the poles.

Where is solar radiation more intense?

More at the equator, less at the poles because the Earth is a sphere

Coriolis effect

The rotation of the earth causing and apparent deflection of moving objects such as air currents and ocean currents. This is because the Earth is a sphere.

What are the three atmospheric circulation cells?

Hedley cell (center), Ferrel cell (30 and 60 degrees latitude in both hemispheres), Polar cell (North and South poles)

What is the ocean conveyor belt?

The system which water moves between the cold depths and warm surface in oceans throughout the entire planet. Regulates temperature, salinity, and nutrients moving water and heat.

What is the other name for the ocean conveyor belt?

thermohaline circulation

Main factor influencing thermohaline circulation

Formation of sea ice increases salinity (density) driving deep water cold currents. When ice melts, it adds fresh water to the ocean, decreasing salinity and affecting the circulation pattern. Saltier water at the ocean surface behaves differently than fresher seawater by drawing up heat from the deep ocean and making it harder for sea ice to regrow.

What is the Ekman Drift?

As the top layer of water begins to travel, it in turn pulls on the water layer beneath it, just as the wind had. Now this second water layer begins to move, and it travels in a direction slightly to the right of the layer above it. This effect continues layer by layer as you move down from the surface, creating a spiral effect in the moving water.

What is the thermal structure of the ocean?

The top surface has maximum radiation and heat but the hot water over the colder water does not normally mix

When did the younger dryas event occur

C.13,000 to 11,500 years ago

What occurred in the Younger Dryas Event?

Caused massive temporary drop in temperature in Europe, East Asia and parts of North America after a collapse in thermohaline circulation

Why is the change of thermohaline circulation important?

May impact the ocean’s ability to hold CO2 and heat which therefore causes implications for carbon cycle and climate change

Pollution

The introduction of substances or energy into the environment, causing adverse changes to ecosystems, wildlife, and/or human health

Biogeochemical cycles

The movement and exchange (fluxes) of elements and compounds between Earth’s reservoirs including the role of living organisms.