| Substance |
Sources
|
Fate and Behaviour
|
Effects
|
|
Point
|
Diffuse
|
Partitioning to air, water
and sediments
|
|
| Nitrogen |
Sewage
discharges;
Industrial discharges
|
Atmospheric
deposition,
Coastal water inputs,
Agricultural run-off
|
Cycles
between sediment, water and the atmosphere.
Can accumulate in sediment as organic matter
increases (with greater N-load) then dies entering
sediment |
Can
be toxic to invertebrates and fish (NH3);
Can contribute to deoxygenation of the water
column and sediments (nitrification and eutrophication);
Can contribute to stimulation of algal growth
(eutrophication).
|
| Phosphorus |
Sewage
discharges; Industrial discharges |
Coastal
water inputs;
Agricultural run-off;
Natural catchment run-off; Some input from
wind-blown pollen and dust.
|
Cycles
between sediment and water.
Accumulates in sediments
|
Can
contribute to stimulation of algal growth (eutrophication);
Can contribute to deoxygenation of water
column and sediments (eutrophication).
|
| Silicon |
Has
been associated with detergent manufacture |
Soil
erosion;
Weathering of rocks;
Sediment mineralisation
|
Accumulates
in sediments. Cycles between water and sediments;
never reaches saturation point in water. Spring
diatom blooms may strip silicon from the water
column.
|
Can contribute to stimulation of algal growth
(eutrophication);
Can contribute to deoxygenation of water
column and sediments (eutrophication).
|
| Organic
carbon |
Sewage
discharges; Industrial discharges |
Agricultural
run-off;
Natural catchment run-off;
Primary productivity within the aquatic environment
|
Cycles
between water column, sediments, and atmosphere
through biological and chemical processes.
Can accumulate in sediments.
|
Can
contribute to stimulation of production of primary
consumers (organic enrichment);
Can contribute to deoxygenation of water
column and sediments (organic pollution)
|
| Oxygen
depleting substances |
Sewage
discharges; Industrial discharges |
Water
column:
Bacterial and algal respiration.
Chemical oxidation
Sediments:
Agricultural run-off;Natural catchment run-off;
Primary production;
Decaying algal blooms.
|
Dissolved
and particulate organic matter can deplete oxygen
in the water column (measured as BOD).
Particlulate organic matter can accumulate
in sediments and delete oxygen (measured as
SOD)
Nitrification in sediments (measured as SOD)
|
Can
be toxic to invertebrates and fish at low concentrations; |
|
pH
|
Industrial
discharges |
Atmospheric
deposition (acid rain |
pH
can be decreased in the water column. |
Can
contribute to transient changes in water chemistry. |
| Salinity |
Major
sewage and industrial discharges discharges
(reduce salinity) |
Coastal
water inputs (increase salinity);
River inputs (reduce salinity;
Atmospheric inputs (reduce salinity).
|
Salinity
can be increased or reduced in the water column
and sediments. |
Reduced
salinity can have lethal and sub-lethal effects
on marine organisms;
Can influence toxicity of ammonia;
|
| Turbidity |
Sewage
discharges;
Industrial discharges. Dredging operations
|
Sediment
resuspension; Coastal erosion; Phytoplankton;
Coastal water inputs; Dissolved and particulate
organic matter.
|
Can
remain in water column or accumulate in sediments. |
Can
contribute to reduction in light penetration;
Can reduce primary productivity;
Can adversely affect filter feeding organisms.
|
