Biogeochemical Cycles

Transcription

1 s Hydrologic cycle cycle Carbon cycle Contents 2 Did you know? 3 (bio) (chemical) (geo;, ) biogeochemical cycles Biogeochemistry = the study of the exchange or flux of materials between living and nonliving components of the biosphere (Hutchinson, 1944, 1950) 3 4

2 1. (biotic components) 3 Producers ( ) Macroconsumers () Phagotrophs ( ) Consumers Microconsumers () Saprotrophs ( ) Osmotrophs ( ) Decomposers 5 2. (aboptic components) 3 Inorganic substances (C, N, CO 2, H 2 O etc) Organic compounds (,, ) Climate regime ( ) 6 3. Time Space atmosphere, hydrosphere, biosphere, lithosphere 2 7 8

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4 4 1. (Hydrologic cycles) 2. (Atmospheric cycles; gaseous types) CO 2, N 2 3. (Lithospheric cycles; sedimentary types) P, S 4. (Biological cycles) Hydrologic s 90% (external medium) (universal solvent) etc. Hydrologic s 15 (Lean & Hinrichsen 1994) 16

5 Hydrologic s 0.001% The Earth's atmosphere consists by volume of nitrogen (79.1%), oxygen (20.9%), carbon dioxide (about 0.03%) and traces of the noble gases (argon, krypton, xenon, helium) plus water vapour, traces of ammonia, organic matter, ozone, various salts and suspended solid particles. 0.63% 0.016% 97.5% (NH 3 ), (NO 3 ), (NO 2 )

6 4 1. ( ) 2. Ammonification () 3. Nitrification ( ) 4. Denitrification ( ) 3 21 lightning + N 2 + O 2 > 2NO 2NO + O 2 > 2NO 2 2NO 2 + H 2 O > HNO 3 + HNO 2 HNO 3 > H + + NO 3 (nitrate ions) & HNO 2 > H + + NO 2 (nitrite ions) 22 Freeliving organisms Cyanobacteria Cyanobacteria 23 24

7 Freeliving organisms Symbiotic nodule bacteria Azotobacter Clostridium in the sea The availability of nitrogen is one of the crucial factors constraining oceanic primary productivity and, ultimately, controlling global atmosphereocean carbon balances. fixing organisms should be keystone microorganisms in nitrogenlimited waters, and yet only a few nitrogenfixing microorganisms have been previously reported from oceanic waters. ase genes and nitrogenase gene transcripts (mrna), indicative of active transcription of the nitrogenase genes, were detected from surface waters at station ALOHA in the North Pacific Subtropical Gyre. ase genes were expressed in a distinct daily pattern throughout the upper 150 meters of the water column. Analysis of the gene sequence led to identification and cultivation of a novel unicellular cyanobacterium, which appears to be an important, previously unrecognized nitrogen fixer particularly in the North Pacific Subtropical Gyre. These results have important implications for the global controls on primary productivity by the availability of nitrogen

8 Alanine(an amino acid) + deaminating enzyme > ammonia + pyruvic acid Ammonification RNH 2 (Organic N) + heterotrophic (ammonifying) bacteria > NH 3 (ammonia) + R ph < 7.5 Nitrification (aerobic condition) Denitrification (anaerobic condition) NO N 2 O Hole in pipe NO N 2 O NH 4 + NO 3 N 2 NO 2 NO 2 NO 3 N 2 O N 2 Nitrification Denitrification 31 32

9 0.03% Carbon Carbon Important carbon molecules CO 2 (carbon dioxide), CH 4 (methane), HCO 3 (bicarbonate), CaCO 3 (calcium carbonate), CH 2 O (carbohydrate) ocean holds 98% of free carbon (43,000 X kg) (photosynthesis) 2. (respiration and decomposition) 3. (combustion) 4. (weathering) Carbon 36

10 1. (photosynthesis) Photosynthesis 2. (respiration and decomposition) Decomposition Respiration 37,, 38 Decomposition Respiration (methanogenesis) (fermentation) 3. (combustion) Combustion CO 2, CO 39 40

11 4. (weathering) Weathering CaCO 3 + 2H + CO 2 + H 2 O + Ca