Water & Enviro Week 8

Suspended solids

Organic and inorganic particles discharged into water courses

Inert solids

Produced by mining activity, coal washing, construction sites, dredging

Effect of inert suspended solids

1. Settles suspended solids alters plants & animals found due to change of riverbed

2. Can cog filter feeders & gills

3. Fish breeding -- suffocate eggs

4. Reduced sunlight - depresses photosynthesis

Salmon eggs only develop/hatch in

Loose gravel stream beds

Indirect effect of inert suspended solids

1. Reduction in number of species that feed on eliminated organisms

2. Loss of shelter - reduces habitat diversity

Oxidisable solids

Settle like inert solids but the decompose resulting in reduction of dissolve O2

Most fish become distressed when dissolve oxygen falls to _____. Mortality occurs at ____-

2-4 mg/l, <2 mg/L

Industries that produce oxygen demanding pollution

Breweries (nooo), dairy, food, processing, agriculture

Sewage fungi thrive when

O2 is low at discharge point

Affected river broken down into

Clean zone, decomposition zone, septic zone, recovery zone, return to clean water

Thermal pollution

Temperature change in water can be harmful to aquatic life

Point source of thermal pollution

Overflow from dams, cold water from reservoir bottom released

Non point sources of thermal pollution

Runoff from warm services, soil erosion increases turbidity which increases absorption of solar energy, deforestation

Effect of thermal pollution (Temperature Increase)

1. Reduces O2 saturation

2. Increases photosynthesis & aquatic plant growth

3. Increases metabolic process of aquatic organisms

4. Swimming speeds decline in some species

5. Fish more vulnerable to toxic compounds

6. Causes thermal stratification

Eutrophication

Natural aging process due to weathering of rocks/soils from catchment area - accumulation of nutrients/sediment in water.

Transforms aquatic environments into terrestrial habitats

Oligotropic lake

Young lakes/man-made reservoirs - low nutrient levels - low biological activity

Mesotrophic lakes

Lakes in transition - nutrient levels & biological activity increasing

Eutrophic lake

Old lakes - high nutrient levels - high biological activity levels

Cultural/Artificial Eutrophication

High nutrient input from humans increase rate significantly

Main sources of eutrophication

1. Nitrogen

2. Phosphorus

3. Fertiliser

4. Sewage

5. Wastewater