Major threats to freshwater ecosystems Flashcards
Give an example of a human impact on the nitrogen cycle
Eutrophication
Name two ways in which humans can cause eutrophication in freshwater ecosystems
Fertiliser runoff, sewage discharge
Name a natural mechanism of eutrophication
Erosion of nutrient rich sediments
What can eutrophication result in?
Shift in species composition in the food chain
Name three sources of organic pollution
Domestic sewage, combined sewage overflows, farm waste
Define organic pollution
Large quantities of organic compounds (e.g. proteins, carbohydrates, lipids, nucleic acids)
Describe how domestic sewage can be a source of organic pollution
Waste is discharged into rivers, increasing N and P
Describe two effects farm waste (slurry) as a source of organic pollution
Reduction in O2, anaerobic bacteria decomposes polluting material, increases biochemical oxygen demand (BOD)
Define biochemical oxygen demand (BOD)
The amount of dissolved oxygen consumed by aerobic bacteria
Why does farm waste often end up in freshwater ecosystems?
The farm is near flowing water to dilute leaks
Describe combined sewage overflows (CSO)
Collects runoff in the same system as sewage and industrial wastewater when there is too much for treatment works
What causes CSOs to overflow
Heavy rainfall
What does CSO overflow result in?
Release of organic and industrial pollutants and surface contaminants into water ecosystems
Describe urban stream syndrome
The consistently observed ecological degradation of streams draining urban land.
Looking at the holistic challenges, not in isolation.
Give an example of a solution for the protection of freshwater ecosystems
Stewardship
Give the five processes necessary for the protection of freshwaters
Diagnosis, treatment, prevention of recurrence, management, communication and commitment
Give four responsibilities of environmental agencies in the protection of freshwater
Assess state, identify pressures, assess options, manage environment
What indices can be used to measure the quality of freshwater ecosystems?
WHPT (for organic pollution), biological monitoring working party (BMWP) (for organic pollution), Shannon-Weaver diversity index (for diversity)
What are the responsibilities of wastewater treatment works?
Wastewater treatments, disposed waste causes minimum damage, reduce damage by flooding
Describe the preliminary stage in wastewater treatment
Screening
Describe the primary stage in wastewater treatment
Sedimentation. Removes 70% of suspended solids and 50% of BOD (organic pollution)
Describe the secondary treatment in wastewater treatment
Biological (filter beds) and sedimentation. Removed 95% of suspended solids and 90% of BOD.
Give four roles of partnership groups in the protection of freshwaters
Issues are identified and suggestions for restoration are given. Creates networks and engages the public.
Give seven examples of members of partnership groups.
NGOs, government agencies, water companies, farmers, academics, public
What was the objective of the case study on the River Medlock?
Characterise benthic invertebrates and their relationship between the freshwater conditions (physiochemical, hydrogeomorphological)
What was the hypothesis for the case study on the River Medlock?
Chemical stress, rather than physical is the major determinant of the ecological status of the river.
What did early studies on the River Medlock show?
The river was polluted
What were the results of the case study on the River Medlock?
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.
