aquatic geochemistry: introductionjcsites.juniata.edu/faculty/merovich/limnology_files/do...
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Dissolved Gases
DO and Eutrophication
Ch. 12 / 16 / 18
Dissolved gases
DO 14 PPM in water
– 21% in atmosphere
N2
CO2
~400 PPM atm
Biological processes that affect
DO (and DIC)10 productivity
Cellular respiration
– Reactions here
GPP
– NPP = GPP – Rs
– NPP = 0
– NPP > 0
– NPP < 0
Old edition
Physical factors
1. Temp
2. Pressure
3. Agitation
Fig. 12.7
Uptake of DO
SA: Volume
Tracheal
Tracheal system
ending in external gills
Circulatory system
extended in gills
Spatial / Temporal Variation in
DOSeason, time of day
Location, depth
Depth - clinograde
Organic rain
Reduced chemicals in ground
water
warm
Depth - orthograde
Depth – positive heterograde
Organic rain
Depth – negative heterograde
Other spatial patterns in DO
Lakes: Littoral vs. pelagic
Groundwater
Lake
Aquarium periphyton
Stream
Fig. 12.11
Other spatial patterns in DO
Rivers
– Longitudinal variation (RCC)
– Groundwater, springs, HWs, creeks, streams,
rivers, major rivers, estuaries (customary size
gradient !!)
– Thermal pollution
– Nutrient loading - eutrophication
Seasonal variation in DO
ICE
anoxia
Metalimnetic
Maximum
Groundwater
Lake
Aquarium periphyton
Stream
Space and
time (daily)
DO, Nutrients, and Eutrophication
Nutrient loading
– Sources
N
P
Eutrophication
– Oligotrophic
– Mesotrophic
– Eutrophic
Eutrophication
Where is it more of a problem?
– Lakes
– Streams / rivers
IndicatorsTable 18.1
Chl a indicator
Fig. 18.2
SolutionsHodgson 2005
Dec spiraling distance in
upstream areas and HWs.
Maintain HW structure and
function (retentiveness)
Table 18.3
Trophic cascade theory