|
EARLY WINTER
|
| AERATED |
NON AERATED |
 ice
forms on the dugout and prevents the wind from mixing the
water |
ice
covers the dugout and prevents the wind from mixing the
water |
| despite
the absence of wind, bubbles rising from the aeration
diffuser circulate the water in the entire dugout beneath
the ice cover |
a
small amount of oxygen diffuses through the ice but is not
distributed throughout the dugout |
| dead
algae decompose consuming the oxygen at the bottom of the
dugout |
dead
algae at the bottom of the dugout begin to decompose
consuming the oxygen at the bottom of the dugout |
| the
aeration system replaces the consumed oxygen and maintains a
high concentration of oxygen throughout the entire dugout |
the
oxygen is not replaced and the absence of oxygen in the
water allows plant nutrients (e.g. nitrogen, phosphorus) and
metals (e.g. iron, manganese) which are trapped in the
sediment to dissolve into the water |
| water
quality remains good
|
a
layer of poor quality water which is high in nutrients and
metals begins to form at the bottom of dugout |
|
LATE WINTER
|
| AERATED |
NON AERATED |
| decomposition
of dead algae at the bottom of the dugout continues to use
oxygen |
decompositon
of algae at the bottom of the dugout continues to use oxygen |
| the
aeration system replaces any oxygen consumed by the
decomposition process and ensures a high concentration of
oxygen throughout the entire dugout |
the
absence of oxygen results in the release of hydrogen sulfide (rotten egg smell) |
| water
quality remains good throughout winter season |
more
nutrients and metals are released into the water at the
bottom of the dugout and the layer of poor quality water
increases in thickness |
|
the
user notices taste and odour problems when the poor quality
water reaches the intake and is pumped into the house for
use |
|
SPRING
|
| AERATED |
NON AERATED |
| the
heat from the sun melts the ice |
the
heat from the sun melts the ice and creates a uniform water
temperature throughout the dugout |
| the
wind enhances the mixing being provided by the aeration
system |
the
uniform temperature allows the wind to mix the dugout
bringing nutrient rich water from the bottom to the surface |
| spring
runoff adds a small amount of plant nutrients to the dugout |
spring
runoff adds a small amount of plant nutrients in comparison
with that released from the sediment during the winter |
|
EARLY SUMMER
|
| AERATED |
NON AERATED |
| the
sun heats the surface water but the aeration system keeps
the dugout well mixed and the temperature uniform |
the sun heats the
surface water which begins to float on the colder deeper
water which reduces the ability of the wind to mix the water
to the bottom of the dugout |
| a
small supply of plant nutrients limits algae growth |
a
large supply of the plant nutrients encourages rapid algae
growth |
|
MID-SUMMER
|
| AERATED |
NON AERATED |
| the
aeration system and wind keeps the dugout well mixed |
the
sun continues to heat the surface water preventing any
mixing and limiting the mixing effect of the wind to the top
few feet |
| the
limited amount of algae floating in the water allows the
light to reach the bottom of the dugout encouraging the
growth of rooted weeds at the bottom of the dugout |
the
surface algae bloom becomes thick restricting light
penetration to the top few feet and so rooted weed growth is
limited to the edges of the dugout |
| a
small amount of algae dies and falls to the bottom of the
dugout |
a
large amount of algae dies and falls to the bottom of the
dugout |
|
LATE SUMMER
|
| AERATED |
NON AERATED |
| the
aeration system and the wind combine to maintain high
concentrations of oxygen throughout the dugout |
the
wind mixes only the very top layer of the dugout. The green
algae consume all of the available nitrogen, die and fall to
the bottom of the dugout |
| the
dead algae at the bottom of the dugout decompose and consume
oxygen but the aeration system keeps oxygen concentrations
high and the dugout well mixed |
blue
green algae which can grow without nitrogen become dominant.
The green algae at the bottom of
the dugout begin to decompose using oxygen at the bottom of
the dugout which is not replaced |
| the
high concentrations of oxygen prevents nutrients and metals
from dissolving into the water from the sediment |
the
absence of oxygen in the water allows plant nutrients (e.g.
nitrogen, phosphorus) and metals (e.g. iron, manganese)
which are trapped in the sediment to dissolve into the water |
| water
quality remains high throughout the dugout |
a
layer of poor quality water which is high in nutrients and
metals begins to form at the bottom of dugout |
|
AUTUMN
|
| AERATED |
NON AERATED |
| the
water temperature cools, all algae die and fall to the
bottom of the dugout
|
the
surface water temperature cools creating a uniform
temperature throughout the dugout. The
uniform temperature allows the wind to mix the entire dugout
increasing oxygen concentrations throughout the dugout |
| the
aeration system and the wind continue to maintain high
concentrations of oxygen throughout the dugout |
the
increased concentrations of oxygen improve the water quality
of the dugout |
| water
quality remains high |
all
algae die and fall to the bottom of the dugout where they
begin to decompose and consume the oxygen at the bottom of
the dugout |
