plants convert CO2 (atmospheric carbon) into complex carbohydrates (glucose C6H12O6).
oxygen consuming producers, consumers & decomposers break down complex organic compounds & convert organic carbon back into CO2.
Energy Flow through Food Webs
Only about 10% of usable energy is transferred from one trophic level to the next. Reason: usable energy lost as heat (2nd law of Thermodynamics), not all biomass is digested & absorbed, predators expend energy to catch prey.
the living components of an ecosystem
the nonliving components of an ecosystem.
atmospheric nitrogen (N2), which cannot be used directly by plants, is first converted into ammonia by bacteria.
ammonia is converted to nitrate ions (NO3-)
inorganic nitrogen (nitrate) is converted into organic molecules such as DNA/amino acids & proteins.
decomposers covert organic waste into ammonia
bacteria convert ammonia into atmospheric nitrogen (N2).
does not exist at the Earth's surface as a gas; released into ecosystems through the weathering of phosphate rocks, it is a major limiting factor for plant growth. The phosphorus cycle is relatively slow, without an atmospheric step.
organisms that make their own food. Photosynthetic life (plants).
in arid regions, water evaporates leaving salts behind. (ex. fertile crescent, southwestern US)
water completely saturates soil starves plant roots of oxygen, rots roots
all of the land that drains into a body of water
underground layers of porous rock allow water to move slowly.
El Nino Southern Oscillation, trade winds weaken & warm surface water moves toward South America. Diminished fisheries off South America, drought in western Pacific, increased precipitation in southwestern North America, fewer Atlantic hurricanes.
near the coast, overpumping of groundwater causes saltwater to move into the aquifer
A "normal" year, easterly trade winds and ocean currents pool warm water in the western Pacific, allowing upwelling of nutrient rich water off the West coast of South America.
Doubling Time (rule of 70)
doubling time is equal to 70 divided by the percent rate of growth. (ex. a population growing at 5% annually doubles in 70 ÷ 5 = 14 years)
Replacement Level Fertility
the number of children a couple must have to replace themselves (averages 2.1 in more developed nations, 2.7 in less developed nations)
Demographic Transition Model: Preindustrial stage
birth & death rates high, population grows slowly, infant mortality high.
Demographic Transition Model: Transitional stage
death rate (infant mortality) lower, birth rates remain high, better health care, population grows fast.
source from specific location such as pipe or smokestack
Non-Point Source Pollution
source spread over an area such as agricultural/feedlot runoff, urban runoff, traffic.
rapid algal growth (algal bloom) caused by an excess of nitrogen & phosphorus (phosphorus usually limits), blocks sunlight, causing the death/decomposition of aquatic plants, decreasing dissolved oxygen (DO), suffocating fish
water with very low dissolved oxygen levels, the end result of eutrophication, for example
Primary Sewage Treatment
first step of sewage (wastewater) treatment; eliminates most particulate material from raw sewage using grates, screens, and gravity (settling).
Secondary Sewage Treatment
second step of sewage treatment; bacteria break down organic waste, aeration accelerates the process
Tertiary Sewage Treatment
final step of sewage treatment; ponds/wetlands used to remove nutrients nitrogen & phosphorus.
Biological Oxygen Demand, amount of dissolved oxygen needed by aerobic decomposers to break down organic materials.
a measure of the cloudiness of water, caused by suspended solids (sediment).
the result of dissolved calcium ions (Ca2+) and magnesium (Mg2+).
Corporate Average Fuel Economy standards enacted into law in 1975, established fuel efficiency standards for passenger cars and light trucks.
Primary Air Pollutants
produced by humans & nature (CO, CO2, SO2, NO, hydrocarbons, particulates)
Secondary Air Pollutants
formed via the atmospheric reaction of primary air pollutants.
Particulate Matter (PM2.5 & PM10):
sources include burning fossil fuels and car exhaust. Effects include reduced visibility, respiratory irritation. Methods of reduction include filtering, electrostatic precipitators, and using alternative sources of energy.
formed by chemical reactions involving sunlight (NOx, hydrocarbons, O2).
Secondary pollutant, NO2 + UV -->NO + O; O + O2-->O3, with VOCs. Causes respiratory irritation and plant damage. Reduced by reducing NO emissions and VOCs.
Nitrogen Oxides: (NOx)
Major source is auto exhaust. Primary and secondary effects include acidification of lakes, respiratory irritation, leads to smog and ozone. Reduced using catalytic converters. Equation for acid formation: NO + O2-->NO2 + H2O-->HNO3 (nitric acid)
caused by sulfuric and nitric acids formed from NOx and SOx resulting in lowered pH of surface waters
(SOx) Primary source is coal burning. Primary and secondary effects include acid deposition, respiratory irritation, plant damage. Reduction methods include: scrubbers, burn low sulfur fuel. Equation for acid formation: SO2 + O2 -->SO3 + H2O -->H2SO4 (sulfuric acid)
(CO2) Sources include the combustion of fossil fuels. Effects: greenhouse gas-contributes to global warming. Reduction accomplished by increased fuel efficiency (gas mileage), mass transit (reduction).
(CO) Sources include incomplete combustion of fossil fuels. Effects: binds to hemoglobin reducing bloods ability to carry O2. Reduction accomplished by catalytic converters, oxygenated fuel, mass transit (reduction).
Most significant (not anthropogenic) - H2O. Also (and largely anthropogenic) - CO2, methane (CH4), and CFCs. Trap outgoing infrared energy (heat) causing earth to warm.
Effects of Global Warming
rising sea level (due primarily to thermal expansion, not melting ice), extreme weather, droughts (famine), and extinctions
caused by CFCs, methyl chloroform, carbon tetrachloride, halon, methyl bromide all of which attack stratospheric ozone. Negative effects of ozone depletion include increased UV, skin cancer, cataracts, and decreased plant growth
Municipal Solid Waste
: is mostly paper and mostly put into landfills
problems include leachate, which is solved using a liner with a collection system; methane gas, which may be collected and burned; and the volume of garbage, which may be compacted and/or reduced
Advantages-volume of waste reduced by 90% and waste heat can be used. Disadvantages-toxic emissions (polyvinyl chloride, dioxin), scrubbers and electrostatic precipitators needed, ash disposal
an abandoned industrial site
return a contaminated area to its original state
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