Eutrophication and stoichiometry- nutrient pollution

Question 1

Where is the biggest dead zone caused by eutrophication?

Answer 1

gulf of Oman

Question 2

What is eutrophication?

Answer 2

‘the enrichment of water by nitrogen compounds causing an accelerated growth of algae and higher
forms of plant life to produce an undesirable disturbance to the balance of organisms present in the
water and to the quality of water concerned’
by nitrates directive

Question 3

What is the lake classification based on nutrient content and organic material production? (increasing)

Answer 3

Dystrophic- brow water lakes (peat drained)
oligotrophic- nutrient poor
mesotrophic- middle nutrient
Eutrophic- nutrient rich
Hypertrophic- very high in nutrients

Question 4

What might be anthropogenic causes of eutrophication?

Answer 4

Sewage
Fertiliser application
NOx from car emissions
Phosphates from clothe washing

Question 5

What is the biggest contributor to eutrophication?

Answer 5

agriculture- 3/4 (with some variation)

Question 6

What type of pollution source is agriculcture?

Answer 6

diffuse - difficult to control (need to understand how pollutant is transported)

Question 7

What type of water flow is the most problematic with eutrophication?

Answer 7

stagnant- pollutant can build up as fast flow disperses it

Question 8

What is the problems related to sewage outlet and eutrophication?

Answer 8

in high situations in the sewage the dam can be flooded leading to spillage of sewage and effluent into river and coastal areas

Question 9

What must also be considered along side nutrient concentration when looking at eutrophication?

Answer 9

stoichiometry

Question 10

What nutrients are most influential in eutrophication?

Answer 10

N
P

Question 11

What is chemical stoichiometry?

Answer 11

quantitative relationships to determine the amount of products/reactants in a chemical equation or composition

Question 12

What is ecological stoichiometry?

Answer 12

study of the balance of energy and multiple chemical elements in ecological interactions

Question 13

What is the Redfield ratio? (definition)

Answer 13

the balance of C N P nutrients in a water body

Question 14

What is the Redfield ratio? (actual ratio)

Answer 14

C- 106
N- 16

Question 15

What did the eutrophication experiment in the great lakes show was the most pivotal eutrophic nutrient?

Answer 15

phosphorus

Question 16

What nutrient concentration ratios need to be accounted for when looking at eutrophication?

Answer 16

C/P
N/P
C/N
and absolute concentration

Question 17

What wont have an effect on eutrophication?

Answer 17

adding nitrogen its the relative concentration of C/P

Question 18

How have human actions affected nutrient avaliability?

Answer 18

nitrogen- doubled amount of reactive nitrogen
phosphorus- 5 fold increase in 50 yr in production and consumption

Question 19

What are the main effects of nutrient pollution?

Answer 19

Hypoxia/ dead zones
Contaminated beaches
Harmful algal blooms- HABs
Contaminated drinking water
Changes in community structure
Fish kills
Poisoning - dogs and people
Increased water treatment cost
Loss of tourism

Question 20

What are HABs?

Answer 20

harmful algal blooms

Question 21

What is a dead zone?

Answer 21

low oxygen/ hypoxic areas

Question 22

How do HABs cause hypoxia?

Answer 22

respiration by algae at night when they cant photosynthesise

Question 23

How can you identify HABs?

Answer 23

oily
cant be picked up
blue/ red twinge

Question 24

How can you tell is algae isnt HABs?

Answer 24

bubbly
can be picked up

Question 25

Why is the future of the oceans looking very gelatinous?

Answer 25

jellyfish relatively unaffected by nutrient pollution and not specialist feeder will eat anything come into contact with

Question 26

What is dissolved oxygen sag?

Answer 26

reduction in dissolved oxygen plotted over a distance along a water body from a point at which sewage or other pollutants have been discharged

Question 27

What are the 2 main processes involved in DO sag?

Answer 27

Respiration
Nitrification

Question 28

At what rate does oxygen diffuse through water compared to air?

Answer 28

one ten-thousandth

Question 29

What factors affect DO?

Answer 29

Temperature
Salinity
Atmospheric pressure
Respiration of microorganisms

Question 30

How can DO be measured?

Answer 30

Probes- sensors in situ
BOD/ COD in lab

Question 31

What is BOD COD and TOC?

Answer 31

BOD- biological oxygen demand
COD- chemical oxygen demand
TOC- total oxygen demand

Question 32

What is biochemical oxygen demand?

Answer 32

DO day 1 – DO day 5
= oxygen demand

Question 33

What can causes a secondary increase in BOD between days 5-8?

Answer 33

presence of sufficient nitrifying bacteria create NBOD - Nitrogenous biochemical oxygen demand

Question 34

What is the usual BOD to COD ratio?

Answer 34

1:2

Question 35

What is hard BOD?

Answer 35

Large molecules
May take hours/days to degrade

Question 36

What is soft BOD?

Answer 36

Small molecules
Taken up directly

Question 37

What constitutes high BOD in unpolluted rivers?

Answer 37

<1mg/L

Question 38

What constitutes high BOD in moderately polluted rivers?

Answer 38

2-8 mg/L

Question 39

What constitutes high BOD in treated (3 stage) rivers?

Answer 39

20 mg/L

Question 40

What constitutes high BOD in untreated sewage?

Answer 40

600 mg/L (in EU)