elss sg4 Flashcards
arctic tundra location and facts
- it is 8 million km squared, cast study is prudhoe bay on the northern slope of alaska.
- average temp - -12 degrees celcius, annual temp rangeof 33, average precipitation is 137mm mainly as snow. inter lasts fir 8 to 9 months, temps can plunge to 40 degrees, sun remain belows horizon. Long hours of daylght in summer, temps going up to 10 degrees.
- net primary productivity - less than 200 g/m2/year.
- structure of ground - actuve layer - ground that is seasonably frozen, thaws in summer, 30-200cm, permafrost - layer permanently frozen for oevr 2 years, 1500 metres deep. Talik -unfrozen ground beneath permafrost.
flows and stores of water in arctic tundra
flows:
1 - precipitation is small - little precipitaion due to little water, it is all frozen
2 - evapotranspiration is small - limited transpiration due to little veg and short growing season, little evaporation due to temps so low.
3 - run off - varies, occurs as surface run off, infilatrated water usuallt freezes in permafrost
4 - infiltration - small - more in summer soil is frozen in winter so no infiltration.
stores:
1 - atmosphere - small store: water is frozen, little evapotranspiration.
2 - soil and ground water - small store: permafost = barrier to infiltraton so no groundwater, some stored in soil in summer months.
3 - vegetation - varies, in summer there is more in veg as it grows quick, less in winter = plants frozen.
4 - surface stores - varies - stored in lakes and podns in sumemr due to thawing.
MOST WATER STORED IN CRYOSPHERE
flows and stores of carbon in arctic tundra
flows:
1 - photosynthesis - small flux - growing season lasts for barely 3 months, no sungliht in winter months and veg is frozen so no photosynthesis.
2 - respiration - small flux - low temps and waterlogged slow respiration and flows of co2 into atmosphere
3 - decompostion/soil respiration - low temps and waterlogging slow decomposition, it remains frozen and cannot decompose. More soil respiration in summer months.
stores:
1 - atmosphere - small store - there is 2 times more carbon in permafrost than the atmosphere, little respiration and decomposition =no flux of CO2 into atmosphere.
2 - biomass - varies - no trees to store carbon, little veg in summer but more stores in summer.
3 - permafrost - large store - carbon storage in permafrost globally in the region of 1600 GT, twice the amountof the atmosphere, 5 times above the ground biomass.
impact of developing oil and gas in arctic tundra
place specific facts: north slope has produced 18 million barrels of oil, TAP is 800 miles long to transport oil across country, oil industry accounts for 25% of alaska’s jobs and 50% of eocnomy, 500,000 oil barrels in 2019.
impact on WC: extraction of oil, relases heat = melting of PF = more surface stores of water and thermokarst landscape = more runoff = higher rver discharge = more flooding. strip mining of sand and gravel for construction creates artificial lakes which disrupt drainage and expose PF to melting mroe.
Impact CC: infrastructure diffuse thermal energy into ground which melts permafrost = more decomposition and more CO2 and methane released = enhanced greenhouse effect. removalof vegetation for constriction = less cover of permafrost = more exposed so more melting and decompostion.
estimated CO2 losses vary from 7-40million/tonnes/year, methane losses range from 24,000-114,000 tonnes/year. Methane is 4 times mroe potent
management strategies at prudhoe bay
1 - roads and infratructure constructed on insulated gravel protecting the permafrost from leting. Large structures built on 1-2m of gravel, reduces transfer of heat into ground.
2 - constructing buildings and pipelines on piles/stils allows cold air to circulate beneath structures, preventing transferring into the ground.
3 - oil/gas pipelines built on stilts to allow cold air to circulate underneath, elevating themprovides insulation against heat generating pipework that would melt the permafrost.
