Flow  of  Matter  Vs.  Energy • Matter

Biogeochemical  Cycles

– Law  of   Conservation  of   mass

• Energy – Law  of   Conservation  of   Energy  (First  Law  of   Thermodynamics)

Biogeochemical  Cycles Describe  the  flow  of  essential   elements from  the  environment   through  living  organisms  and  back   into  the  environment. They  are  elements  found  on  earth   that  are  required  for  life.

Reservoirs • Reservoirs  are  places  where   biogeochemicals can  be  found  within  the   earth.     • Reservoirs  may  also  be  referred  to  as   “sinks”  especially  if  a  significant  amount  of   the  element  can  be  found  there.

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Carbon  Cycle (carbon  is  required  for  building  organic  compounds)

1.  Reservoirs – atmosphere  (0.04%  of   atmosphere  is  CO2),  fossil  fuels  (oil,   coal),  biological  organisms,  Ocean   (carbonic  acid). 2.  Processes – photosynthesis,  cellular   respiration,  consumption,   decomposition,  burning  of  fossil   fuels,  ocean  absorption/acidification

Human  impact  on  Carbon  Cycle • Humans  burn  fossil  fuels  adding  more  CO2 to  the  atmosphere • More  atmospheric  CO2 contributes  to   global  warming  (CO2 is  a  GHG) • Ocean  acidification  through  ocean   atmosphere  interaction  creating  carbonic   acid  in  ocean  water.

Nitrogen  Cycle Carbon  Cycle

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Nitrogen  Cycle (Nitrogen  is  required  for  the  manufacture  of     amino  acids  and  nucleic  acids)

1.  Reservoirs – atmosphere  (as  N2);;  soil  (as   NH3 (ammonia),  N03-­ (nitrate));;   Biological  Organisms  (amino   acids,  nucleic  acids,  proteins) Atmosphere  is  78%  N2

Nitrogen  Cycle 2. Processes – plants  absorb  nitrogen  as  either   NH3 (ammonia)  or  as  NO3-­ (nitrates),   animals  obtain  nitrogen  by  eating   plants  and  other  animals.   Nitrogen  Fixation:  N2    to NH3    by  nitrogen-­ fixing  bacteria  (prokaryotes  in  the  soil   and  root  nodules),  N2    to  NO3-­ by   lightning  and  UV  radiation. Nitrification: NH3 converts  to  NO3-­ by   various  nitrifying  bacteria.

Nitrogen  Cycle

Human  Impact  on  Nitrogen  Cycle

Ammonification – Nitrogen  in  living   organisms  (NH4+,  uric  acid,    or   other  compounds)  is  converted  to   NH3 by  decomposing  organisms.

• Humans  manufacture  nitrogen  based  fertilizers   from  natural  gas. • These  nitrogen  based  fertilizers  increase   nitrogen  levels  in  soil  for  crop  production,  but   also  run-­off  into  aquatic  systems • Fertilizer  runoff  causes  eutrophication   – Overgrowth  of  plant  matter  in  water,  causing   decreasing  dissolved  O2 and  fish  deaths • Alternatives  to  nitrogen  fertilizers  avoid  this   issue.    

Denitrification -­ Denitrifying  bacteria   convert  NO3-­ back to  N2  and   releasing  into  the  atmosphere.

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Phosphorus  Cycle

Phosphorus  Cycle 1.  Reservoirs -­ sediments  and  rocks  that   accumulate  on  ocean  floors  return  to   the  surface  as  a  result  of  uplifting  by   geological  processes,  Biological   Organisms,  Soil,  Water,   (Not  present  in  atmosphere!)

Processes  – • plants  absorb  phosphorus from  soils;; • animals  obtain  organic  phosphorus  when  they   consume  plants  and  other  animals,   • plants  and  animals  release  phosphorus  when   they  decompose;;   • animals  excrete  phosphorus  in  their  waste   products.     • phosphorus  accumulates  in  sediment  to  form   sedimentary  rock

Phosphorus  Cycle

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Human  Impact  on  Phosphorus   Cycle • Humans  mine  phosphorus  out  of  the   ground  and  use  it  in  phosphorus  based   fertilizers. • Similar  impacts  compared  to  Nitrogen

Biogeochemical  cycles  also  exist   for  other  elements,  such  as   calcium,  magnesium,  and  sulfur.

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