Environmental Engineering Reference
In-Depth Information
Glossary
A,
area
A
d
, drainage basin area
A
0
, surface area of a lake
A
z
, area at a specific lake depth (
z
)
Aerobic,
oxic, with oxygen
Age class,
organisms within a specific age range
Aggradation,
deposition of excess stream load
(sediment) to its channel
AHOD (oxygen deficit per unit area),
decrease
in O
2
in the hypolimnion per unit area sur-
face; mg O
2
cm
2
day
1
or mg O
2
m
2
day
1
Airlift pump,
pump that uses compressed gas
to move water up a tube; used for ground-
water sampling and hypolimnetic aeration
Akenites,
resting cells
Alarm chemical,
chemical produced by a dam-
aged or stressed prey that alarms other prey
Algae,
nonvascular organisms capable of oxy-
genic photosynthesis, without sterile cells
covering gametangia
Alkaline phosphatase,
enzyme that hydrolyzes
organic phosphorus compounds under basic
conditions, rendering some P obtainable as
soluble inorganic phosphate; used in some P
diversity,
within habitat diversity
Abiotic oxidation,
a chemical oxidation in the
absence of organisms
Absorb,
soak up (compare to adsorb)
Acidity,
the proton ion concentration (pH); also
the ability of a solution to react with a base
Acute toxicity,
poisoning with large pulses over
short periods of time
Adaptive radiation,
evolution of a single species
into many species when they reach a new
habitat or niche
Adsorb,
to take onto a surface
Advective transport,
movement of materials by
movement of parcels of water (as opposed
to molecular diffusion)
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