Botkin Environmental Science Earth as Living Planet 8th txtbk

Glossary G-13
Nonpoint sources Pollution sources that are diffused and
intermittent and are influenced by factors such as land
use, climate, hydrology, topography, native vegetation, and
geology.
Nonrenewable energy Energy sources, including nuclear and
geothermal, that are dependent on fuels, or a resource that
may be used up much faster than it is replenished by natural
processes.
Nonrenewable resource A resource that is cycled so slowly by
natural Earth processes that once used, it is essentially not
going to be made available within any useful time framework.
No-till agriculture A combination of farming practices that
includes not plowing the land and using herbicides to keep
down weeds.
Nuclear cycle The series of processes that begins with the
mining of uranium to be processed and used in nuclear
reactors and ends with the disposal of radioactive waste.
Nuclear energy The energy of the atomic nucleus that, when
released, may be used to do work. Controlled nuclear
fission reactions take place within commercial nuclear
reactors to produce energy.
Nuclear fuel cycle Processes involved with producing nuclear
power from the mining and processing of uranium to
control fission, reprocessing of spent nuclear fuel, decommissioning
of power plants, and disposal of radioactive
waste.
Nuclear reactors Devices that produce controlled nuclear
fission, generally for the production of electric energy.
Obligate symbionts A symbiotic relationship between two
organisms in which neither by themselves can exist without
the other.
Observations Information obtained through one or more
of the five senses or through instruments that extend the
senses. For example, some remote sensing instruments
measure infrared intensity, which we do not see, and
convert the measurement into colors, which we do see.
Ocean thermal conversion Direct utilization of solar energy
using part of a natural oceanic environment as a gigantic
solar collector.
Off-site effect An environmental effect occurring away from
the location of the causal factors.
Off-stream use Type of water use where water is removed
from its source for a particular use.
Oil shale A fine-grained sedimentary rock containing
organic material known as kerogen. On distillation, it yields
significant amounts of hydrocarbons, including oil.
Oil spill The accidental release of oil from a ship transporting
oil, an oil pipeline leak, or release of oil from a well during
or after drilling.
Old-growth forest A nontechnical term often used to mean a
virgin forest (one never cut), but also used to mean a forest
that has been undisturbed for a long, but usually unspecified,
time.
Oligotrophic Referring to bodies of water having a low
concentration of the chemical elements required for life.
Omnivores Organisms that eat both plants and animals.
On-site effect An environmental effect occurring at the location
of the causal factors.
Open dump An area where solid waste is disposed of by simply
dumping it. It often causes severe environmental problems,
such as water pollution, and creates a health hazard. Illegal
in the United States and in many other countries around
the world.
Open system A type of system in which exchanges of mass or
energy occur with other systems.
Open woodlands Areas in which trees are a dominant vegetation
form but the leaves of adjacent trees generally do
not touch or overlap, so that there are gaps in the canopy.
Typically, grasses or shrubs grow in the gaps among the
trees.
Operational definitions Definitions that tell you what you
need to look for or do in order to carry out an operation,
such as measuring, constructing, or manipulating.
Optimal carrying capacity A term that has several meanings,
but the major idea is the maximum abundance of a population
or species that can persist in an ecosystem without
degrading the ability of the ecosystem to maintain (1) that
population or species; (2) all necessary ecosystem processes;
and (3) the other species found in that ecosystem.
Optimum sustainable population (OSP) The population
size that is in some way best for the population, its ecological
community, its ecosystem, or the biosphere.
Optimum sustainable yield (OSY) The largest yield of a
re newable resource achievable over a long time period
without decreasing the ability of the resource, its ecosystem
or its environment to maintain this level of yield. OSY
differs from maximum sustainable yield (MSY) by taking
the ecosystem of a resource into account.
Ore deposits Earth materials in which metals exist in high
concentrations, sufficient to be mined.
Organelle Specialized parts of cells that function like organs
in multi-celled organisms.
Organic compound A compound of carbon; originally used
to refer to the compounds found in and formed by living
things.
Organic farming Farming that is more “natural” in the sense
that it does not involve the use of artificial pesticides and,
more recently, genetically modified crops. In recent years
governments have begun to set up legal criteria for what
constitutes organic farming.
Output With respect to basic operation of system, refers to material
or energy that leaves a particular storage compartment.
Overdraft Groundwater withdrawal when the amount pumped
from wells exceeds the natural rate of replenishment.
Overgrazing Exceeding the carrying capacity of land for an
herbivore, such as cattle or deer.
Overshoot and collapse Occurs when growth in one part of
a system over time exceeds carrying capacity, resulting in a
sudden decline in one or both parts of the system.
Ozone (O 3 ) A form of oxygen in which three atoms of
oxygen occur together. It is chemically active and has a
short average lifetime in the atmosphere. Forms a natural
layer high in the atmosphere (stratosphere) that protects us
from harmful ultraviolet radiation from the sun, is an air