Week12 - 4/8/2010 Giant Salvinia PSA - Texas Parks and...

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4/8/2010 1 Giant Salvinia PSA - Texas Parks and Wildlife http://www.youtube.com/watch?v=S9Mf95GDGjg http://www.weedscience.ncsu.edu/aquaticweeds/comturf/mature%20salvi nia.jpg http://aquaplant.tamu.edu/database/floating_plants/gia nt_salvinia_pics.htm O 2 Dissolved oxygen gas is a major determinant of redox because it has a tremendous affinity for electrons Redox values >200 mV, allows only certain reactions to occur without the net input of energy http://www.princeton.edu/~lmacdona/iron-oxides.html ht p:/ upload.wikimedia.org/wikipedia/commons/b/b8/Iron_hydroxide_precipitate_in_stream.jpg Acid mine drainage MO Iron: Fe 2+ the reduced form is soluble in water, but the oxidized form of iron (ferric iron, Fe 3+ ) precipitates out Low values = more transferable electrons Temperature ( 0 C) 14 12 10 8 6 4 2 0 2 3 4 5 6 8 9 1 0 2 16 17 18 O 2 (mg L -1 ) 14 12 10 8 6 4 2 0 Depth (m) 7 10 11 Redox (mV) 14 12 10 8 6 4 2 0 175 250 Total Iron (mg L -1 ) 14 12 10 8 6 4 2 0 1000 3000 4000 5000 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb ice Fig. 11.7. Iron concentrations in a dimictic lake Total iron redox O 2
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4/8/2010 2 Organisms and redox Can promote chemical reactions that would not otherwise occur by lowering the activation energy. By using enzymes Microorganisms-lower activation energy to convert ammonia to nitrate ( nitrification ) Photosynthesis (CO 2 to sugar) Potential Energy and Redox Potential energy Activation energy Net energy yield Ammonium Nitrate Oxidizing environment Going with potential energy Activation energy Net energy yield Ammonium Nitrate Reducing environment Going with potential energy Activation energy Net energy cost Ammonium Nitrate Going against potential energy Activation energy Net energy cost Ammonium Nitrate Going against potential energy nitrification Figure 11.5 oxygen 21% of atmospheric gas Concentration in water dependent on Metabolic activity rates (aerobic respiration/ photosynthesis) Diffusion Temperature Proximity to atmosphere Mg/liter -1 , mol/liter, percentage saturation http://www.camp4.com/photos/7/Smallfalls2.jpg http://www.rsbs.anu.edu.au/O2/Images/disolved%20oxygen.gif Weiss, R.F. 1970. The solubility of nitrogen, oxygen and argon in water and seawater. Deep-Sea Res. , 17 : 721-735
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3 http://www.rsbs.anu.edu.au/O2/Images/disolved%20oxygen%20temperature.gif Invasive tilapia in Florida Anhinga Trail in Everglades National Park, Florida http://www.pbase.com/jypsee/glades ht p:/ animaldiversity.ummz.umich.edu/site/resources/Grzim ek_fish/Channoidei/v04_id211_con_supanat.jpg/medium.jpg http://www.fao.org/docrep/003/T0537E/T0537E60.gif Air breathing catfishes oxygen Photosynthesis produces O 2 , respiration consumes it. Know the equations! CH
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Week12 - 4/8/2010 Giant Salvinia PSA - Texas Parks and...

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