36.2 Energy flows through ecosystems. There is a limited amount of energy in an ecosystem. It is divided among the different trophic levels . This energy budget influences the types and numbers of organisms in an ecosystem.
1.) Energy Pyramid- depicts energy loss from one trophic level to the next.
Figure 36-7This generalized energy pyramid indicates that only 10 percent of the energy available at a trophic level is typically converted to new biomass in the next trophic level.
Water, Carbon, Nitrogen Oxygen and Phosphorus
3 basic steps of Chemical cycling:
1.) Producers use chemicals from the environment to make sugar. (photosynthesis)
2.) Consumers feed on producers, take in nutrients, release wastes into the environment.
3.) Decomposers break down dead organisms, returning inorganic chemicals to the soil, water, air producers.
The Nitrogen Cycle
Nitrogen Fixation: process by which some bacteria convert nitrogen gas (N2) ammonia(NH3)
These bacteria live in the soil or on the roots of certain plants (beans or legumes).
The ammonia picks ups another H+ ion in the soil forming ammonium (NH4+)
Nitrification – process done by nitrifying bacteria. Converts ammonium (NH4+) to
3 major processes move water between land, bodies of water, and the atmosphere:
1.) evaporation: liquid gas
2.) condensation: gas liquid
3.) precipitation: rain, snow, hail and sleet
Figure 36-12The three major processes of evaporation (including transpiration), condensation, and precipitation continuously move water between the land, bodies of water, and the atmosphere.
Figure 36-10Many life processes and human activities contribute to the cycling of carbon in the biosphere.
Figure 36-14The greenhouse effect is a natural process that stops all of the sun's heat from escaping rapidly back to space. This process can be altered by human activities that affect the levels of greenhouse gases in the atmosphere.
Figure 36-18Free chlorine atoms in the atmosphere react with and destroy ozone molecules. Over time, the loss of ozone has resulted in an ozone "hole"—an area of very low ozone concentrations located over Antarctica.
The following pictures are provided courtesy of NASA. They show the extent of ozone thinning. Dark blue colors correspond to the thinnest ozone, while light blue, green, and yellow pixels indicate progressively thicker ozone.
October 1999 (average)Historically, the Antarctic ozone hole is largest during October. This image shows the data from the Total Ozone Mapping Spectrometer (TOMS) Earth Probe, for the month of October 1999
September 3rd 2000The ozone hole grew quicker than usual and exceptionally large. By the first week in September the hole was the largest ever at that time 11.4 million square miles. For the first time it reached towards South America and to regions of high population.
September 17th 2001Satellite data show the area of the 2001 Antarctic ozone hole peaked at a size roughly equal to that of recent years about the same area as North America. Researchers have observed a leveling-off of the hole size and predict a slow recovery.
Bioaccumulation: isthe process by which substances not readily broken down or excreted can build up and be stored in living tissue (usually in fatty tissue.)
Biomagnification: is the process by which substances become more concentrated in the bodies of consumers as one moves up the food chain (trophic levels).
Figure 36-17In this Great Lakes food chain, the concentration of PCBs measured in herring gull eggs was almost 5000 times higher than that measured in phytoplankton. The concentration increased at each successive trophic level.
PCBs, or polychlorinated biphenyls, are a group of man-made chemicals.
Introduced in 1929 and widely used in electrical transformers, cosmetics, varnishes, inks, carbonless copy paper, pesticides and for general weatherproofing and fire-resistant coatings to wood and plastic.
The federal government banned the production of PCBs in 1976
PCBs can effect the immune system, fertility, child development and possibly increase the risk of certain cancers
DDT is a pesticide that was widely used until being banned in the U.S. in 1972
DDT accumulates in living tissue, particularly in fat tissue
High concentrations in some bird species caused failure of eggs by thinning the shells
U.S. Department of the Interior, U.S. Geological Survey, Center for Coastal GeologyThis page is: http://sofia.usgs.gov/sfrsf/rooms/mercury/achilles_heel/cause.html