Major threats to freshwater ecosystems

Question 1

Give an example of a human impact on the nitrogen cycle

Answer 1

Eutrophication

Question 2

Name two ways in which humans can cause eutrophication in freshwater ecosystems

Answer 2

Fertiliser runoff, sewage discharge

Question 3

Name a natural mechanism of eutrophication

Answer 3

Erosion of nutrient rich sediments

Question 4

What can eutrophication result in?

Answer 4

Shift in species composition in the food chain

Question 5

Name three sources of organic pollution

Answer 5

Domestic sewage, combined sewage overflows, farm waste

Question 6

Define organic pollution

Answer 6

Large quantities of organic compounds (e.g. proteins, carbohydrates, lipids, nucleic acids)

Question 7

Describe how domestic sewage can be a source of organic pollution

Answer 7

Waste is discharged into rivers, increasing N and P

Question 8

Describe two effects farm waste (slurry) as a source of organic pollution

Answer 8

Reduction in O2, anaerobic bacteria decomposes polluting material, increases biochemical oxygen demand (BOD)

Question 9

Define biochemical oxygen demand (BOD)

Answer 9

The amount of dissolved oxygen consumed by aerobic bacteria

Question 10

Why does farm waste often end up in freshwater ecosystems?

Answer 10

The farm is near flowing water to dilute leaks

Question 11

Describe combined sewage overflows (CSO)

Answer 11

Collects runoff in the same system as sewage and industrial wastewater when there is too much for treatment works

Question 12

What causes CSOs to overflow

Answer 12

Heavy rainfall

Question 13

What does CSO overflow result in?

Answer 13

Release of organic and industrial pollutants and surface contaminants into water ecosystems

Question 14

Describe urban stream syndrome

Answer 14

The consistently observed ecological degradation of streams draining urban land.
Looking at the holistic challenges, not in isolation.

Question 15

Give an example of a solution for the protection of freshwater ecosystems

Answer 15

Stewardship

Question 16

Give the five processes necessary for the protection of freshwaters

Answer 16

Diagnosis, treatment, prevention of recurrence, management, communication and commitment

Question 17

Give four responsibilities of environmental agencies in the protection of freshwater

Answer 17

Assess state, identify pressures, assess options, manage environment

Question 18

What indices can be used to measure the quality of freshwater ecosystems?

Answer 18

WHPT (for organic pollution), biological monitoring working party (BMWP) (for organic pollution), Shannon-Weaver diversity index (for diversity)

Question 19

What are the responsibilities of wastewater treatment works?

Answer 19

Wastewater treatments, disposed waste causes minimum damage, reduce damage by flooding

Question 20

Describe the preliminary stage in wastewater treatment

Answer 20

Screening

Question 21

Describe the primary stage in wastewater treatment

Answer 21

Sedimentation. Removes 70% of suspended solids and 50% of BOD (organic pollution)

Question 22

Describe the secondary treatment in wastewater treatment

Answer 22

Biological (filter beds) and sedimentation. Removed 95% of suspended solids and 90% of BOD.

Question 23

Give four roles of partnership groups in the protection of freshwaters

Answer 23

Issues are identified and suggestions for restoration are given. Creates networks and engages the public.

Question 24

Give seven examples of members of partnership groups.

Answer 24

NGOs, government agencies, water companies, farmers, academics, public

Question 25

What was the objective of the case study on the River Medlock?

Answer 25

Characterise benthic invertebrates and their relationship between the freshwater conditions (physiochemical, hydrogeomorphological)

Question 26

What was the hypothesis for the case study on the River Medlock?

Answer 26

Chemical stress, rather than physical is the major determinant of the ecological status of the river.

Question 27

What did early studies on the River Medlock show?

Answer 27

The river was polluted

Question 28

What were the results of the case study on the River Medlock?

Answer 28

The river does not meet the EU Water Framework Directive for biological and physiochemical variables. The study area is part of a heavily modified water body.