Eutrophication and stoichiometry- nutrient pollution Flashcards

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1
Q

Where is the biggest dead zone caused by eutrophication?

A

gulf of Oman

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2
Q

What is eutrophication?

A

‘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

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3
Q

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

A

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

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4
Q

What might be anthropogenic causes of eutrophication?

A

Sewage
Fertiliser application
NOx from car emissions
Phosphates from clothe washing

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5
Q

What is the biggest contributor to eutrophication?

A

agriculture- 3/4 (with some variation)

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6
Q

What type of pollution source is agriculcture?

A

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

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7
Q

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

A

stagnant- pollutant can build up as fast flow disperses it

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8
Q

What is the problems related to sewage outlet and eutrophication?

A

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

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9
Q

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

A

stoichiometry

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10
Q

What nutrients are most influential in eutrophication?

A

N
P

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11
Q

What is chemical stoichiometry?

A

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

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12
Q

What is ecological stoichiometry?

A

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

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13
Q

What is the Redfield ratio? (definition)

A

the balance of C N P nutrients in a water body

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14
Q

What is the Redfield ratio? (actual ratio)

A

C- 106
N- 16

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15
Q

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

A

phosphorus

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16
Q

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

A

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

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17
Q

What wont have an effect on eutrophication?

A

adding nitrogen its the relative concentration of C/P

18
Q

How have human actions affected nutrient avaliability?

A

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

19
Q

What are the main effects of nutrient pollution?

A

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

20
Q

What are HABs?

A

harmful algal blooms

21
Q

What is a dead zone?

A

low oxygen/ hypoxic areas

22
Q

How do HABs cause hypoxia?

A

respiration by algae at night when they cant photosynthesise

23
Q

How can you identify HABs?

A

oily
cant be picked up
blue/ red twinge

24
Q

How can you tell is algae isnt HABs?

A

bubbly
can be picked up

25
Q

Why is the future of the oceans looking very gelatinous?

A

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

26
Q

What is dissolved oxygen sag?

A

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

27
Q

What are the 2 main processes involved in DO sag?

A

Respiration
Nitrification

28
Q

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

A

one ten-thousandth

29
Q

What factors affect DO?

A

Temperature
Salinity
Atmospheric pressure
Respiration of microorganisms

30
Q

How can DO be measured?

A

Probes- sensors in situ
BOD/ COD in lab

31
Q

What is BOD COD and TOC?

A

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

32
Q

What is biochemical oxygen demand?

A

DO day 1 – DO day 5
= oxygen demand

33
Q

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

A

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

34
Q

What is the usual BOD to COD ratio?

A

1:2

35
Q

What is hard BOD?

A

Large molecules
May take hours/days to degrade

36
Q

What is soft BOD?

A

Small molecules
Taken up directly

37
Q

What constitutes high BOD in unpolluted rivers?

A

<1mg/L

38
Q

What constitutes high BOD in moderately polluted rivers?

A

2-8 mg/L

39
Q

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

A

20 mg/L

40
Q

What constitutes high BOD in untreated sewage?

A

600 mg/L (in EU)