Transcript ASSESSING AQUATIC ECOSYSTEMS AND MEASUREMENT

Assessing Aquatic
Ecosystems
&
Measurement
Aquatic Ecosystem
Assessment
• The health of an aquatic ecosystem
can be determined by examining a
variety of factors, including:
– Water quality (physical & chemical
parameters)
– Aquatic macroinvertebrates
– Habitat
USGS: Water Science for Schools - http://ga.water.usgs.gov/edu/waterquality.html
Sources of Contamination
Water Quality
• Physical
– Stream flow, turbidity, temperature
• Chemical
– Dissolved oxygen (D.O.)
– pH
– Alkalinity
– Conductivity
– Phosphorous
– Nitrates
– Chlorine and chloride
– Heavy metals
– Organic compounds
Measuring Stream Flow
Turbidity – tied to Conductivity
• Measure of
water clarity
• Based on
suspended
material in
water (soil,
plankton,
microbes, etc.)
Turbidity
• Affected by:
– Weather
– Stream flow & velocity
– Erosion
– Run-off & discharge
– Excessive algal growth
Turbidity
• Turbidity has an effect on:
– Water color & light penetration
– Temperature & dissolved oxygen
– Survival of fish & invertebrates
Temperature
• Optimal temp. range depends on species
• Temp. of lower order (closer to
headwaters) streams is usually < 20°C
• Affected by:
– Water sources & discharges
– Weather & seasons
– Riparian vegetation
Temperature
• Temp. affects:
– Rate of biological & chemical reactions
• Higher temps…?
– Dissolved oxygen levels
• Higher D.O….?
– Sensitivity of aquatic life
Dissolved Oxygen (DO)
• Affected by:
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Photosynthesis & Respiration
Riparian vegetation
Input of organic material
Temperature
Stream flow
Turbidity
Decomposition
Dissolved Oxygen (DO)
• Most aquatic life requires DO levels
of 5 - 6 ppm to thrive
• Levels < 3 ppm are stressful
pH
• Measure of the alkalinity or acidity of the water
• Tolerance varies based on species
• Optimal range for most aquatic life is a pH of 6.5
– 8.0
pH…
• Affected by:
– Stream geology
– Alkalinity
– Acid precipitation
– Wastewater discharges
– Mining of coal or metals
• pH has an effect on:
– Biological and chemical processes
– Solubility of elements & compounds
– Survival of aquatic life
Alkalinity
• Measure of the buffering capacity
• Helps maintain pH of stream
• Highly dependent on stream geology
– Produced by leaching of
carbonate/bicarbonate from rocks
• Levels between 100 – 200 ppm will
stabilize pH
Conductivity – (tied to Turbidity)
• General measure of water quality
• Related to ion concentration
• Affected by:
– Geology of stream
– Discharges to stream (ex: sewage)
• U.S. streams range from 50–1500 µs/cm
• 150–500 µs/cm good range for most fish
& macroinvertebrates
Phosphorus – (tied to
Nitrogen)
• Essential nutrient for plants, algae,
and animals
• Phosphorus is usually found as part
of phosphate (PO43-)
• Aquatic ecosystems have both
inorganic and organic PO43-
• Plants require inorganic PO43-;
animals can use both
The Phosphorus Cycle
Land
Animal tissue
animals
Urine and feces
Soluble soil
Decomposers
phosphate
(bacteria and
Loss in
fungi)
drainage
Rocks and
minerals
Phosphates
Decomposers in solution
(bacteria and
fungi)
Animal tissue
and feces
Plants and
Aquatic
algae
animals
Precipitates
Plants
Tri-C Eastern Campus
BIO 2806 - Environmental Science for Educators: Promoting Watershed Stewardship
Loss to deep sediment
July 2007
Phosphorus
• Usually in short supply in aquatic
ecosystems
– Unpolluted waters < 0.03 mg/L
– Critical level is 0.1 mg/L
• Sources of phosphorus:
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Soils and rocks
Decomposition
Wastewater
Run-off (fertilizers and waste)
Eutrophication
• Increased phosphorus can lead to
overgrowth of algae & aquatic plants…
…which leads to a chain of events that
ends in oxygen depletion.
Nitrates – tied to
Phosphates
• A form of nitrogen found in aquatic
ecosystems in the following forms:
ammonia (NH3), nitrates (NO3-), nitrites (NO2)
• Nitrates are an essential nutrient for
plants and algae
• Natural levels in water < 1 mg/L
The Nitrogen Cycle
Atmospheric
nitrogen
Carnivores
Herbivores
Plankton Birds
with
nitrogenfixing
bacteria Fish
Plants
NitrogenDeath, excretion, feces fixing
bacteria
Decomposing bacteria
(plant roots)
Amino acids
Excretion
NitrogenAmmonifying bacteria
fixing
Loss to deep sediments
bacteria
Nitrifying bacteria
(soil)
Denitrifying
Tri-C Eastern Campus BIO 2806 - Environmental Science for Educators: Promoting Watershed Stewardship
July 2008
Soil nitrates
bacteria
Nitrates
• High levels along
w/ phosphorus can
lead to
eutrophication
• Sources of
nitrates:
– Decomposition
& wastes
– Wastewater
– Run-off (waste
& fertilizers)
Chlorine & Chloride
• Low levels of chloride may be found
naturally (<16 mg/L is normal)
• Sources of chloride (Cl-):
– Soil, rocks, minerals
– Decomposition & wastes
– Street salt, wastewater, industry
• Chlorine (Cl2)should not be present
– Indicates input from municipal water
source
Other Water Quality Concerns
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Metals (copper, iron, mercury, etc.)
Pesticides
Organics (PCBs, PAHs, etc.)
Fecal coliform bacteria
Ways to Assess Water Quality
• Chemical tests:
• Physical tests:
• Biological tests:
Measurement in the Field
• Always use Metric!
• Length
– 1 mm ~ width of a dime
– 1 cm ~ as wide as your pinky (10x dime)
– 1 m ~ as tall as a doorknob (100x pinky)
• Temperature – Celsius!
• Volume
– 1 mL = 1 cm3 ~ 10 drops of water
– 1 L – 1 quart (~4 cups)
“Micro Hike”
• Measuring length & discussing
relative size
• Let’s measure some things!
“Micro Hike” Lesson
• C.L.O.S.E. II students…
“What’s Hot & What’s Not”
• Measuring Temperature and
discussing relative temperatures
– What is the temperature under your
arm in Celsius? Add 1° and this is your
body temperature.
– What is the temperature of the ice
water in Celsius?
– What is the temperature of the tap
water in Celsius?
“What’s Hot & What’s Not
Lesson”
• C.L.O.S.E. II students…
Reading graduations
• Do not think that this is easy for
students…
“A Drop in the Bucket”