MenuPreviousNext The Organic Chemistry of Water Chapter 8 Pages 8-23 to 8-30

MenuPreviousNext The Organic Chemistry of Water Chapter 8 Pages 8-23 to 8-24 Biogeochemical Cycles nOrganic chemistry deals mainly with chemical compounds consisting primarily of carbon and hydrogen. nInorganic compounds such as dissolved sea salts account for the majority of dissolved solids in seawater. nDissolved organic elements also interact with organisms on a significant scale.  These elements are crucial to life and differ from the sea salts in several ways.

MenuPreviousNext Biogeochemical Cycles nProportions of organic elements in seawater differ from the proportions of sea salts because:  The principle of constant proportions does not apply to these elements.  These nonconservative constituents have concentrations and proportions that vary independently of salinity due to biological and geological activity. The Organic Chemistry of Water Chapter 8 Pages 8-23 to 8-24

MenuPreviousNext Biogeochemical Cycles nAll life depends on material from the nonliving part of the Earth.  The continuous flow of elements and compounds between organisms (biological form) and the Earth (geological form) is the biogeochemical cycle. The Organic Chemistry of Water Chapter 8 Pages 8-23 to 8-24

MenuPreviousNext Biogeochemical Cycles nOrganisms require specific elements and compounds to stay alive.  Aside from gases used in respiration or photosynthesis, those substances required for life are called nutrients. nThe primary nutrient elements related to seawater chemistry are carbon, nitrogen, phosphorus, silicon, iron, and a few other trace metals. nNot all elements and compounds cycle at the same rate. nThe biogeochemical cycle of the various nutrients affects the nature of organisms and where they live in the sea. The Organic Chemistry of Water Chapter 8 Pages 8-23 to 8-24

MenuPreviousNext Carbon nCarbon is the fundamental element of life. nCarbon compounds form the basis for chemical energy and for building tissues. nThe seas have plenty of carbon in several forms. It comes from:  Carbon dioxide in the air.  Natural mineral sources - such as carbonate rocks.  Organisms - excretion and decomposition. The Organic Chemistry of Water Chapter 8 Pages 8-24 to 8-26

MenuPreviousNext Carbon nCarbon cycle. The movement of carbon between the biosphere and the nonliving world is described by the carbon cycle. The Organic Chemistry of Water Chapter 8 Pages 8-24 to 8-26

MenuPreviousNext Nitrogen nNitrogen is another element crucial to life on Earth. nOrganisms require nitrogen for organic compounds such as protein, chlorophyll, and nucleic acids. nNitrogen makes up about 78% of the air and 48% of the gases dissolved in seawater. The Organic Chemistry of Water Chapter 8 Pages 8-26 to 6-27

MenuPreviousNext Nitrogen nGaseous nitrogen must be converted to a chemically usable form before it can be used by living organisms. nBacteria “fixes” nitrogen from the air into usable compounds - nitrate, nitrite and ammonium. nIn these forms, autotrophs take up the nitrogen and incorporate it into their systems as protein. The Organic Chemistry of Water Chapter 8 Pages 8-26 to 6-27

MenuPreviousNext Nitrogen The Organic Chemistry of Water nThe nitrogen cycle. Bacteria and humans carry out many of the important steps of the nitrogen cycle. The cycle has four stages: Assimilation, Decomposition, Nitrification, Denitrification. Chapter 8 Pages 8-26 to 6-27

MenuPreviousNext Phosphorus and Silicon nPhosphorus is another element important to life because it is used in the ADP/ATP cycle, by which cells convert chemical energy into the energy required for life.  Phosphorus combined with calcium carbonate is a primary component of bones and teeth. The Organic Chemistry of Water Chapter 8 Page 8-28

MenuPreviousNext Phosphorus and Silicon nThe phosphorus cycle. Dissolved phosphorous is carried to the sea by runoff and leaching from land. Phosphorus is used by plants, then recycled through animals until it is released from waste and decay. The Organic Chemistry of Water Chapter 8 Page 8-28

MenuPreviousNext Phosphorus and Silicon nSilicon is used similarly by some organisms in the marine environment (including diatoms and radiolarians) for their shells and skeletons.  Silicon exists in these organisms as silicon dioxide, called silica. The Organic Chemistry of Water Chapter 8 Page 8-28

MenuPreviousNext Iron and Trace Metals nIron and other trace metals fit into the definition of a micronutrient.  Micronutrients are substances essential to organisms in very small amounts.  These are essential to organisms for constructing specialized proteins, including hemoglobin and enzymes. Plants need iron to produce chlorophyll.  Other trace metals used in enzymes include manganese, copper, and zinc. The Organic Chemistry of Water Chapter 8 Page 8-29