2b - It is possible to identify the physical and human factors that affect the water and carbon cycles in an Arctic tundra area.

Question 1

Explain key features of the carbon cycle in the Tundra:

x7

Answer 1

• very low NPP (< 200g/m2/yr) - less veg, slow cycle, stored for long, dark/cold
• stores 4-29 tonnes C/Ha
• 1/3 global carbon that can be cycled is found in Artic Tundra - fast carbon cycle
• carbon sink - 1600GT - low temps = slow decomposition
• in summer plants input carbon rich litter into soil, and activity of micro-org increases = increase CO2 in atmosphere
• sink of carbon in soils is 5x greater then above ground biomass
• carbon locked away for past 500,000 years - frozen in permafrost, active layer frozen for 8m in a yr

Question 2

Explain key features of the water cycle in the Tundra:

x6

Answer 2

• slow cycle - less precipitation (50-350mm) - frozen stores
• sig seasonal changes
• low evap - suns energy in summer on melting snow so that ground temp remains low and inhibit convection = surface frozen most of yr = nothing to evap
• limited groundwater and soil moisture - permafrost/active layer is barrier to infiltration, percolation, recharge and groundwater flow
• limited veg and small growing season = little transpiration
• water stores on surface in summer eg ponds due to permafrost preventing drainage

Question 3

How does the developing oil and gas industry impact the cycles?

Construction of oil/gas infrastructure INCL. settlements, oil drillings rigs, houses exc.

Answer 3

rans-Alaskan Pipeline - takes oil from oilfields in the north→ south eg Prudhoe bay to Port of Valdez:
- W = The pipeline transmits 1.4 mill barrels of oil a day. Has reduced need for takers to transmit oil + has reduced risk of oil spills to the arctic ocean
- C = Pipeline requires hot water to maintain hot temps to prevent oil freeze= promotes melting of permafrost

BP drilling platform in Prudhow Bay - produces 55% of Alaska oil and gas
- W = construction and operation of oil and gas instillations can cause localised melting of permafrost = increased river discharge and increase flood risk, larger lakes, rivers, ponds in summer = increased evap
- C = permafrost melting due to construction = inputs CO2 and Methane into atmosphere, while gas flaring will input CO2. In North slope area of Alaska = 40mill tonnes CO2 and 114000 tones of CH4 released from permafrost/yrA, destroys veg = less C stored and PS

house - built of stilts in order to preserve permafrost underneath
- W = prevents heating in houses from melting the permafrost and create unstable foundations
- C = heath from house would melt permafrost = release CO2 and CH4 originally trapped - GHG which promotes CC and further melting

Question 4

How does the developing oil and gas industry impact the cycles?

Dust deposition by the side of the road creating darkened surfaces, changing amount of absorption of light (albedo effect)

Answer 4

• W = increased evap from increased warming, increase speed of cycle,-faster flows
• C = ground is absorbing for sunlight = low albedo (more uptake in energy) = warming - melting = release CO2 - melts the active layer
• AO2 = sig - increases rate of global warming, fairly small scale - local

Question 5

How does the developing oil and gas industry impact the cycles?

Removal of Vegetation

Answer 5

• W = less interception and evaporation - less precipitation
• C = reduces PS and uptake of CO2 from atmosphere, thawing of soil increases microbial activity, decomposition and emissions of CO2 = regeneration LT
• AO2 = not as sig as there is little veg in Tundra = small scale, very fragile - wont easily recover - hard to regrow

Question 6

How does the developing oil and gas industry impact the cycles?

Strip mining of agregates (sand and gravel) for construction - removing top layer

Answer 6

• W = creates artificial lakes = disrupts drainage of water = floods
• C = exposes permafrost = increased melting- increased CO2 and CH4
• A02 - sig - melting and disrupts water cycle, not loads happening = small scale

Question 7

How can management strategies moderate the impact of the oil and gas industry?
x5

Answer 7

Insulated ice and gravel pads:
- roads and other infrastructural features can be constructed on insulating ice or gravel pads = protects permafrost from melting

Buildings and pipelines elevated on stilts:
- allows cold air to circulate beneath structures = provides insulation against heat-generating buildings, pipework exc. which could melt permafrost

Drilling laterally beyond drilling platforms:
- allow oil and gas to be accessed several Km from drilling site = fewer sites needed for drilling rigs = impact on veg and permafrost from construction reduces

more powerful computers:
- reduced exploration wells needed = reduce impact on environment

Refrigerated supports:
- used on trans-Alaska pipeline - stabilised temp of permafrost = conserve it beneath buildings and other infrastructure

Question 8

Physical factors affecting flows and stores in water cycle?

Answer 8

Temp:
- below freezing for 8 months of yr = stops all flows of water
- 4(ish) months of above 0degrees but still cold = slow flows (transpiration) = all processes are slow

Rock permeability/porosity:
- impermeable rock = no percolation = increased surface runoff = lots of surface water to freeze

Relief:
- mostly flat
- less runoff - creates more surface water stores eg lakes, ponds, puddles
- ideal for mosquitos to live in
- freeze in winter
- AO2 - LESS SIG

Question 9

Physical factors affecting flows and stores in the Carbon cycle?

x4

Answer 9

Temp:
- low temp = unavailable liquid water for most of the year (8 months) - limit plant growth = small biomass
- frozen in winter = no flows of carbon
- low temp and waterlogging = slow decomposition and resp/flows of CO2 (into atmosphere)
- due to frozen winter, permafrost locks away decomposed carbon = big soil carbon sink and permafrost is constantly getting deeper = massive store of methane

Vegetation:
- very little NPP and PS - growing season is <3 months = limited uptake/release CO2 or decomposition - not a sig store
- small and slow growing - 4-29 tonnes C/ha - not sig as little store BUT it requires veg to grow and die/decompose for the soil to be rich in carbon = sig in LT

Organic matter in soil:
- soil stores large amount of carbon
- decomposed veg
- 5x more ground biomass (stores)

Mineral composition of rocks:
- impermeable rock and permafrost - little carbon could be stored - insignificant to the cycle
- rocks covered by permafrost = not exposed. Therefore not weathered so carbon not released
- BUT - impermeable rocks mean that permafrost has built up - allowing carbon to be stored

Question 10

Explain the seasonal changes in the cycles in the Tundra?

Answer 10

a) PS
- melts/freezes water - changes to water cycle drives the carbon cycle - with climate change summers longer = active layer deeper
- when the water cycle thaws, more water can be intercepted = precipitation
- winter dark = little light for PS = less flows of carbon and water - winter is frozen = no flows
- increased temp in summer melts active layer = PS

b) decomposition - flows of carbon
- only happens in summer as plants/animals die and decompose into active layer and freezes throughout winter - stops all flows of carbon
- decomposition happens in summer as water melts = release of CO2 and CH4 - but theme gases are then trapped as freezing occurs in winter = increased store carbon in permafrost (1600 GT)