4.4 Water pollution Flashcards
List some sources of water pollution (At least 4)
- Domestic sewage
- Industrial discharge
- Agricultural run-off
- Urban run-off
- Land development
- land clearance for building
- Landfill sites
- Disposal of waste on land can lead to leachates entering groundwater or surface waters
- Acid mine drainage
- Emissions from domestic and industrial flues, vehicle exhaust, evaporation or spraying of chemicals
Organic pollution (impact on water)
- sewage effluent, farm runoff and waste from the food and drink industry
- When organic material enters the water, micro-organisms break down the complex organic compounds
- this uses oxygen which creates anoxic conditions
- organisms die from lack of oxygen
- anoxic conditions also produce hydrogen and ammonia
Eutrophication (definition)
Enrichment of waters with plant nutrients is referred to as eutrophication
Try to explain eutrophication
- this increase in primary production leads to further growth, which can block out light
- this means that submerged plants have no sunlgith → loss of overall biodiversity
- When the macrophytes die, they sink to the bottom of the river, lake or seabed and decomposition occurs.
- Oxygen levels may be depleted resulting in anoxic areas (no oxygen areas)
- Eutrophication demonstrates examples of both positive and negative feedback mechanisms as illustrated in the figure below
Draw the eutrophication and its consequences diagram - negative and positive feedback loop
Mira en el docs la foto 7
consequences of eutrophication (HINT: 4)
- Water can become unsuitable for drinking
- Reduced recreation use of the water
- Reduced commercial value of the aquatic ecosystem e.g. due to loss of fisheries or loss of navigation routes used for trade.
- Increase in water related diseases
How is eutrophication a positive and negative feedback loop
eutrophication the positive feedback process by which nutrient enrichment of aquatic systems ultimately results in the death of fish and macroinvertebrates due to suffocation
What is the impact of toxic metal poisoning
- bioaccumulation can ocurr with toxic metals
- Minamata, Japan during the 1950s
- seafood containing mercury
- Concentrations of mercury were found in the seawater within the bay, the plankton and shellfish
- Mercury compounds were found to bioaccumulate within the organisms and levels were biomagnified through the food chain
Impact of PCBs –> polychlorinated biphenyls (HINT: 6 pero fresh saber bien 3)
- Inhibition of phytoplankton growth.
- Inhibition of oyster shell growth.
- Adverse effect on fish reproduction.
- Suppression of the immune system in birds resulting in death.
- Adverse effect on the immune system and endocrine system of mammals linked to reproductive failure.
- Yusho illness in humans which includes acne, darkening of the skin and respiratory problems. PCBs have also been found to cause birth defects and cancer
What are PCB’S
PCBs are a group of compounds historically used widely in electrical equipment, hydraulic fluid, antifouling paints and printing inks
Types of parameters that we can use to determine water quality (only physical and chemical)
- ph
- temperature
- suspended soils
- dissolved oxygen
What are suspended soils
Suspended solids are small particles that can block sunlight penetrating through the water reducing photosynthesis. These small particles can also block the feeding and respiratory systems of some organisms
How to determine amount of suspended soils (process)
- Filtering a known volume of the water sample using pre-weighed filter paper (A).
- Drying out the filter paper and collected residue.
- Weighing the dried filter paper and residue (B).
- Calculating the weight of the dried residue = B-A in micrograms/litre (mg/l).
- A turbidity meter determines the amount of light scattered by the particles in the water. The greater the amount of suspended solids present, the higher the turbidity readings.
- A secchidisk is used to measure water transparency. The greater the amount of suspended solids the lower the light transparency in the water.
How to measure oxygen? (winkler method)
- Filling a bottle completely with the water sample.
- Then adding reagents to the sample to ‘fix’ the oxygen by converting it into an acid, prior to transportation to the laboratory.
- Titrating the sample in which a reagent is gradually added to neutralize the acid until there is a colour change indicating the ‘end point’ (i.e. all the acid has been neutralized).
- The amount of reagent used to reach the end point is used to calculate the amount of dissolved oxygen levels (mg/l) which was present in the water sample.
what is Biochemical oxygen demand
measure of the amount of dissolved oxygen used to breakdown the organic material in a given volume of water through aerobic activity. It provides an indirect measure of the amount organic material that can be oxidised
