Hydrologic cycle and oceans

Transcription

1 Hydrologic cycle and oceans Schlesinger and Bernhardt Chapter 10/9/8 (order is important) General hydrologic cycle- Water important properties and their relevance to biogeochemical cycles Important concepts with respect to the hydrologic cycle Reservoirs and fluxes Freshwater Oceans Circulation Importance for distributing heat Importance for nutrient cycling Interannual variations Composition General and salinity General inputs from rivers and residence time of constituents Geologic controls on compositions Biotic controls on composition O, P, N etc. Anthropogenic impacts Climate change Chemical inputs 1

2 Assignment 3 Water- critical for life as we know it H bonds Cohesion-High surface tension Complex infrared adsorption (most important temperature regulating gas) Excellent universal solvent 2

3 Importance in the atmosphere Light coming in Light going out IR Visible 0.4 to 0.7 um UV 0.2 to 0.4 um Stevens and Bony, 2013 Different forms have different absorbance. Scatters solar radiation so strong planetary albedo 3

4 High molar heat capacity or specific heat capacity amount of heat per unit mass required to raise the temperature 1 o C Water is > most common solids and liquids Absorbs heat from the sun during day and releases at night without much T change Mediates earth temperature and climate Large latent heat of evaporation and condensation amount of energy released or absorbed by a chemical substance during a change of state occurring without a change in temperature Important for transferring energy- evaporation takes E moves with H 2 O condensation releases E Maximum density at 4 o C- expands upon freezing Atmosphere TOT= 8 days (13000/( ) Global water cycle (km 3 ) 12,700 26, ,000 Transfer from ocean to land 35% of land ppt 413,000 4

5 Components of the Cryosphere Trenberth et al Permafrost 24% of land surface in n hemisphere Glaciers-most important contributor to sea rise Ice shelves and tongues thinning Loss of permafrost becoming an issue Freezing duration of lakes and rivers has shortened. From Jacobson 2000 Most of the water from the Pacific recirculates between different parts of the Pacific with little net transport towards land.. Two thirds of net transport of water to land comes from Atlantic with rest from Indian Ocean -Bengtsson 5

6 Fluxes-extremely variable across space and time Processes to consider Precipitation Evaporation Sublimation Transpiration Runoff Importance in regulating other cycles From Jacobson TRMM/ 3hr-7day-rainfall Annual precipitation map US ml Seasonal Spatial variability Wet deposition flux 6

7 Precipitation hard to model and predict Solid and dashed lines rain gauge Dots-models Allan and Soden, 2008 Atm Warming and the Amplification of Precipitation Extremes, Science, 321, 1481 Chahine 1992 Chanine-Water and climate Five components that play major role Atmosphere moisture, clouds, snow and ice, land surface and oceans Must be thought of as whole and behavior recognized as non linear Bengtsson Global atmospheric water cycle Passive component in the troposphere as it is uniquely determined by temperature and should therefore be seen as a part of the climate feedback system. Stevens and Bony-Water in the atmosphere Water orchestrates and amplifies the effect of agents capable of acting independently of surface temperature. 7

8 Water and other biogeochemical cycles Carbon- Photosynthesis Nitrogen- Atmospheric deposition Sulfur-cloud condensation nuclei Phosphorus-runoff Human use and impacts on the hydrologic cycle Transport Irrigation Drinking/bathing Industry Electrical utility cooling Other major uses? 8

9 UNITED STATES USE OF WATER Freshwater-terms Watershed Aquifer Hyporheic zone Eutrophication Acidification Residence time/turnover time Turnover of a lake 9

10 Freshwater chemistry Cations dominated by Ca2+, Mg2+, Na+, K+ Anions HCO3-, CO3-, SO42-, and Cl- Will depend on where you are N, P, Fe important for nutrient cycles Dissolved organic compounds, particulates and organic matter Aquatic algae N:P 3 to 20 Allocthonous/Autochthonous Where do lakes receive water? What about C, N, P? other elements? How does their chemistry change with depth? 10

11 Carbon storage in lakes ΔS =[Air+Pw+Pb+Ai]-[Rw+Rb+B+Ho] ΔS= change in C storage Uptake of CO2 by gas exchange Pw-water column photosynthesis Pb-benthic photosynthesis Ai=allocthonous input Rw=water column respiration Rb=benthic respiration B=Burial Ho= output by out flows Nutrient limitation P and N Fe and Cu Light impacts 11

12 Hydrology in complex terrane Google Earth Oceans Ocean floor is complex! 12

13 Complexity reflects plate tectonic system Plate tectonic boundaries Continental shelf -cyan Source: 13

14 Visible light o C Thermocline 18-4 o C 4 to 3 o C 95% ocean Thermally stratified Driven by Circulation Wind Salinity-temperature-density Heat content Bottom currents -topography Earth s rotation-coriolis effect( iolis_effect.html) gravity 14

15 Fig 2.6 Ruddiman /woa13fv2/ 15

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17 Surface circulation (wind) Deep ocean ( temperature and dens Bit.ly/SN_DeepWater Ocean currents- thermohaline circulation or global conveyor Profound impacts on global climate 17

18 Surface currents measured by the TOPEX Poseidon satellite Polar (ice) Warm temperate Highland Warm ocean current Subarctic (snow) Cool temperate Dry Tropical Major upwelling zones Circulation and biological cycles Cold ocean current River Fig. 6.4, p. 124 Nutrient map example Conveyor ON 18

19 Conveyor OFF :// Interannual variability El nino La nina NOAA website La Nina El Nino Trade winds weaken Upwelling affected Less CO2 released to the atmosphere 19

20 Chemistry Salinity- 3.5% 35 g/kg H2O Major ions Influenced by -biological activity -river input -atmospheric deposition -water rock interactions -continental shelf -evaporative loss -upwelling -humans 20

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22 Major constituents 11 constituents make up 99.9% of dissolved salts (Major ions > 1ppm) ph Origins - Scrubbing the initial earth s atmosphere weathering of the crust S and B Table 9.1 and figure 9.6 biolimitations Table 9.1 Schlesinger and B pg 351 Driven by sources and sinks.. 22

23 Gas exchange One layer stagnant boundary layer Well mixed atmosphere Well mixed ocean Thin film at liquid surface where diffusion important Uptake f (Henry s law, wind, turbulence, temperature) Biota are important Global ocean chlorophyll August 2017 May 2017 March 2017 January

24 Distribution of oxygen and temperature in the N Pacific Ocean (Craig and Hayward, 1987) Maximum photosynthesis where nutrients are mineralized The ocean and carbon cycling Carbon cycling in the oceans abiotic and slow biologic quickly Primary production in the oceans importance of plankton Redfield ratio 24

25 CO 2 storage Ca HCO3- > CaCO3 + CO2 + H2O CO2 + H2O > HCO3- + H+ 6CO2 + 6H2O +light > C6H12O6 +O2 Redfield ratio 106CO NO 3- +HPO H 2 O +18H+ (CH 2 O)106(NH 3 )16(H 3 PO 4 ) + 138O 2 25

26 Tiny important organisms- Plankton Phytoplankton and Zooplankton Diatoms (Si) Radiolarian (Si) Foraminifera(Ca) Coccolithoporids (Ca) Cyanobacteria-blue green algae Picoplankton- < 1 µm Understanding processes use of 17 O Use of satellite data for understanding Figure 9.8 (B and S) Nutrient cycling Plankton 106 C: 16 N: 1 P (Redfield ratio- Redfield et al 1963 Upwelling 800C: 16N: 1 P Nitrogen phosphorus ratio in oceans 14.7:1 Liebig s Law Oceans N/P limited depending on location Fe limitation N, Fe, Si considered most limiting however recent work suggest P limitations Increase Fe Increase N fixation cause P limitation Impacts of atmospheric nutrient deposition on marine productivity Global Biogeochemical cycles 2011EOS v Phosphorus deficiency in the Atlantic an emerging paradigm 26

27 To fix N need Mo and Fe From Schlesinger Look at S and B numbers are different Recycling important Linking of cycles Photosynthesis Respiration O 2 + Organic matter= NH CO2 + H20 From Schlesinger 27

28 Model-estimated anthropogenic ( minus preindustrial) atmospheric deposition fluxes for carbon, nitrogen, and sulfur (mol m 2 y 1); alkalinity; and potential alkalinity, assuming complete nitrification of NH4+ + NH3 (eq m 2 y 1). Doney S. C. et.al. PNAS 2007;104: by The National Academy of Sciences of the USA Ocean acidification NAS report Oceans absorb CO2 (1/3 rd human releases of that released from geologic storage CO 2 + H 2 O HCO 3- + H + 28

29 Iron limitation Fe more important than P? Ocean iron addition experiment 29