· involve both biotic and abiotic processes and storage reservoirs
· Carbon – building block of organic compounds
· Hydrogen
· Oxygen – used in respiration; obviously, with H above, makes water
· Nitrogen – with oxygen, makes proteins
o fertilizer, made from atmospheric nitrogen
· Phosphorus – important in energy cycle of cells (ATP, ADP)
o fertilizer, from marine sediments produced in rich ancient upwelling zones (uncommon in geologic record)
o often the limiting nutrient in lakes, streams, estuaries – thus increased input causes eutrophication
· Sulfur – component of proteins
· also Calcium (skeletal material), Sodium, Potassium (blood chemistry)
· often, too little = problem, too much = problem; threshold level for effect may exist
· example: Zinc often in vitamin tablets, but too much (e.g. from mining smelter pollution) = heavy metal poisoning
· Selenium (Se): narrow range of healthy concentration in humans, but
o leached from dryland soils and concentrated in irrigation wastewater, California Central Valley
o wastewater used to make Kesterson Wildlife Refuge, but high selenium in water toxic to waterfowl
o irrigation caused change in biogeochemical cycle, decreased Se in soil reservoir, increased Se in surface water reservoir
· food-chain concentration: (also called biomagnification): increased concentration of element or compound in an organism’s tissue above that of its food source because of metabolic processes. Passed on at each step up food chain
· many pollutant elements and compounds naturally occurring, concentrated by human activity
o may be beneficial to humans, plants, animals within some range
o harmful in too high of concentrations
o e.g., mercury in industrial waste concentrated in food chain (Minamata Bay, Japan, p. 370-371 text)
o e.g., copper concentrated in mine waste through ore processing
· human-made pollutants
o many organic compounds (e.g. PCBs, CFCs, organophosphate pesticides, etc.)
o human-made radioactive isotopes of naturally occurring elements (e.g., cesium-137)
o human-made elements formed in nuclear reactors (e.g. plutonium-239)
· natural pollution? examples:
o deadly hydrogen sulfide gas from volcanic eruptions
o global acid rain from large meteorite impact in certain rock types
o poison springs – water dissolves material in toxic concentrations from certain rock types
· Reservoirs (mass of storage in billions of metric tons of carbon; 1 metric ton = 1000 kg):
o atmosphere (720)
o oceans (39,000)
o soil (1500)
o marine sediments and sedimentary rocks (100,000,000)
· by far the largest reservoir, but slow flux in and out
o biomass (560) – mostly plants
o fossil fuels (4000)
· Transfer processes (mass flow in billions of metric tons of carbon per year)
o volcanism (0.1/yr to atmosphere)
o land photosynthesis-respiration (120/yr in and out of plants)
o ocean (phytoplankton) photosynthesis-respiration (107/yr in and out of phytoplankton)
o marine sediment deposition (?)
o rock weathering and erosion (0.6/yr to oceans)
· CO2 dissolved in water during weathering reactions is carried to oceans
o land-use changes (1.6/yr to atmosphere)
o fossil fuel burning (5.4/yr to atmosphere) – large flux
Atmospheric CO2
increase from 270 ppm (pre-Industrial Revolution) to present 370 ppm
· measurement on top of Mauna Loa, island of Hawaii since 1958 shows increase at increasing rate (Fig. 20-16 text, p. 479)
· largely fossil fuel burning
· annual “global biosphere breathing” cycles also clearly shown in Fig. 20-16
o winter increase in CO2 (more global respiration)
o summer decrease in CO2 (more global photosynthesis)