Eutrophication Key Terms

Question 1

Eutrophication

Answer 1

An increase in the external nutrients to an ecosystem that results in an increase in plant growth. Affects ecosystems, recreation, economies and lives.

Question 2

Eutrophic

Answer 2

Lake or body of water rich in nutrients and so supporting a dense plant population, the decomposition of which kills animal life by depriving it of oxygen

Question 3

Nutrient

Answer 3

Essential elements that tent to limit plant growth. Plants need oxygen but it is not considered a nutrient - nutrients are things that limit

Question 4

Phytoplankton

Answer 4

Increased nutrient supply can result in increased phytoplankton growth -> more phytoplankton .. this can cause problems

Question 5

Limiting nutrient

Answer 5

C, N, P, Fe (fertilizer ingredients)

Question 6

Liebigs Laws

Answer 6

Tells us which nutrient to reduce, the limiting nutrient is the one in shortest relative to need - must control this to reverse eutrophication

Question 7

Control (in an experiment)

Answer 7

One that is limited

Question 8

Paleo-reconstruction

Answer 8

Shows us lake aging - history of algae production

Question 9

Sediment core

Answer 9

Collected during reconstruction

Question 10

Point source

Answer 10

Comes from points - pipes, domestic sewage - is easier to measure

Question 11

Non-point source

Answer 11

From water shed activities, live stock production, urbanization

Question 12

Biological Oxygen Demand (BOD)

Answer 12

The amount of oxygen consumed by respiration per unit time - depends on 2 main things: concentration of organic matter in water & how easily organic matter is decomposed (labile)

Question 13

Labile

Answer 13

Readily digested, easily decomposed by bacteria - raw sewage

Question 14

Refractory

Answer 14

Poorly digested, not easily decomposed by bacteria - leafs and wood

Question 15

Cyanobacteria

Answer 15

Fresh water toxic phytoplankton

Question 16

Dinoflagellates

Answer 16

Marine toxic phytoplankton - huge issue can kill a lot animals

Question 17

Toxic Red Tide

Answer 17

Harmful algal bloom caused by dinoflagellates

Question 18

Fish Kill

Answer 18

More nutrients aren’t always a good thing - increased nutrients leads to increased fish

Question 19

Dead Zone

Answer 19

Areas of large bodies of water where the bottom water is anoxic. These are occurring in many areas along the coast of major continents, large rivers and large lakes.

Question 20

Anoxic

Answer 20

Very low or completely zero concentrations of dissolved oxygen

Question 21

Sewage Diversion

Answer 21

Lake Washington success story

Question 22

What 4 elements limit plant growth?

Answer 22

C, N, P, Fe

Question 23

Why do we need to determine which nutrient is limiting to control eutrophication?

Answer 23

The limiting nutrient is the one thats shortest in supply - this is how reverse it, limiting one is the one that will have the effect.

So we can limit the growth of phytoplankton and potential dead zones

Question 24

Where does C, N and P come from externally in lakes

Answer 24

c: atmosphere & watershed, n: watershed & atmosphere, p: watershed

Question 25

Which element was it surprising to find was limiting in lake water using lab experiments? Why was this not correct? How did it not represent what was actually happening in the lake?

Answer 25

Carbon - in nature Carbon is found in the air (wind + air = carbon gets in through air) - in the lab/flask the top is too small for this to happen - When water is in a flask, ripples are eliminated and waves are non existent

Question 26

Why is iron limited in the ocean but not inland lakes?

Answer 26

Fe limited in the ocean because it far from dirt and run off

Question 27

Is Eutrophication a natural process? What evidence was used to support the answer?

Answer 27

Mostly, no - in class question about roads and run off, see graph below (showed no natural Eutrophication for centuries until Romans built roads near lake) -

Question 28

What is the main way building a road near a lake contributes to eutrophication?

Answer 28

Muddy water has lots of plant food in it, high P - building a road takes P out

Question 29

What are three negative things caused by dumping raw sewage? How does decomposition come into play?

Answer 29

1. Decomp consumes oxygen (bad for river bc fish want the oxygen) 2. Decomp releases inorganic nutrients 3. Spreads disease

dump waste (inorganic matter) in lake–> Bacteria comes in to decomposes that stuff it uses oxygen

• -> The more waste we dump will generate more bacteria to decompose and use up oxygen
• -> Increasing the Biological Oxygen Demand because bacteria need oxygen to decompose these organic waste-
• > AS they bacteria is decomposing the wastes, they are also respiring which releases inorganic nutrients(#2)

Question 30

What two main factors affect the BOD of organic matter in water?

Answer 30

Concentration of organic matter in water and how easily organic matter is decomposed

Question 31

Do we want sewage to have a higher or lower bod?

Answer 31

Lower BOD

Question 32

Preliminary, primary, secondary and tertiary phases of sewage plant. Know each and which reduces BOD.

Answer 32

Preliminary - settle out large stuff
Primary - physical removal (screens, settling, floating); not effective at reducing BOD
Secondary - biological removal, sludge is separated out and brought elsewhere (greatly reduces BOD)
Tertiary - use chemical removal, add chemicals, not practiced everywhere bc its $$$

Question 33

What happens to inorganic and organic P in the secondary treatment? Is it a good or bad thing?

Answer 33

• organic P decreases and inorganic P increases

its a bad thing

Question 34

What was Mr Floaty trying to convey to the public?

Answer 34

We need better regulations and should be flushing right into the river which happens w/ big storms

Question 35

How does green lawn syndrome and septic fields contribute to eutrophication?

Answer 35

Fertilizing lawn ends up in lake

Question 36

How does erosion contribute to eutrophication? Is point source on non-point source?

Answer 36

Erosion occurs with agriculture, livestock production and urbanization - these are all non-point sources that increase nutrients and contribute eutrophication

it has absorbed phosphorus particles
non-point

Question 37

There is a figure of increasing total P as a function of % watershed farmed or developed: What is it telling us?

Answer 37

Where people are P is higher, points on graph are lakes or ponds

Question 38

What organisms in the water increases with eutrophication? What particular kinds in freshwater and marine systems?

Answer 38

Phytoplankton blooms
Fresh - cyanobacteria
Marine - dinoflagellates
Difference between the two, dino can kill a lot of animals

Question 39

How does an increase in P affect the % of cyanobacteria in freshwater systems? How does the increase in P affect biodiversity of algae (algae = phytoplankton here)?

Answer 39

Adding more P along x axis is like more people, biodiversity decreases

Question 40

How does adding nutrients to lakes affect fish density? (note, it is different depending on the initial nutrient level in the lake (low or high), and how much is added).

Answer 40

Fish kill - slide 34, shows that more nutrients isn’t always a bad thing,

Question 41

Lake Eerie - what was dead about it? What organisms would argue that the lake is not dead? Why couldn’t the same solution be used from Lake Washington? What was the solution and did it work?

Answer 41

Solutions - removing P, Lake Eerie phytoplankton decreased, BOD went down, good for fish -> less dead zones (in 1960 it was declared dead due to P being too high)

Because it was caused by phosphorus loading from point sources

Question 42

By what % would doubling the concentration of PO4-3 increase phytoplankton growth rate in lakes given an initial concentration of e.g. 1, 5, 10 and 20μg/L (slide 12)

Answer 42

Example: 5 doubled -> 10
On the graph at 5 you have 1 unit of growth. At 10 you have around 1.3 so the change is .3 so 30%
At 20 its about .1 higher than 10 due to saturating curve

Question 43

Why do we need to determine which nutrient is limiting to control eutrophication

Answer 43

Because when you’re at the saturating curve it will no longer limit the growth. It is an essential element but we already have enough.

Question 44

What is the figure of chlorophyll vs total P of field observations of lake surveys telling us? (that is, what was the point of this figure?)

Answer 44

It shows us the relationship between phosphorus and chlorophyll. The more chlorophyll means the more plants. It shows that the higher the level of phosphorus the higher the level of chlorophyll.

Question 45

T / F
Higher levels of phosphorous lead to more phytoplankton growth

Increasing total phosphorous by 10 times leads to less than a 10 times increase in Chlorophyll

Phosphorous is limiting in the lakes surveyed

Answer 45

True

False

True

Question 46

How would you test whether a nutrient is limited using a laboratory experiment?

Answer 46

You would fill lake water into flasks and then add either C,N, or P into them with one remaining control. Then you would see which one produced the most phytoplankton

Question 47

What was the controversy concerning nutrient limitation?

Answer 47

“Junk Science” it was a selective use of evidence to support a pre-determined position. It was funded by companies that would be affected by the outcome.

Question 48

What nutrient(s) are most limiting in freshwater, coastal marine, and open water marine Systems?

Answer 48

FRESHWATER: Phosphorous
COASTAL MARINE: Nitrogen
OPEN WATER MARINE: Nitrogen, Phosphorus, Iron

Question 49

What is in raw sewage?

Answer 49

high in organic matter (called detritus)
high in N and P (organic and inorganic)
high in disease-causing microbes (bacteria, viruses, etc.)

Question 50

How do septic tanks contribute to eutrophication? Is this point or non-point?

Answer 50

septic tanks are mini-sewage treatment plants behind your house, The nutrients are going underground and eventually seep into the water system. They are basically inefficient mini-treatment plants.
non-point

Question 51

Medium nutrients in a lake affect fish in what part of the lake? Why?

Answer 51

The bottom because there is medium respiration, decreasing the level of dissolved oxygen at the bottom

Question 52

How do the figures of Lake Washington water indicated it was becoming eutrophic?
What happens to the phosphate in the summer?

Answer 52

The chlorophyll levels increased with the amount of phosphorus

Question 53

What was the solution to the phosphorous problem in Lake Erie? Did it work?

Answer 53

Improve watershed discharge -It shifted the main source to non-point source