This slide show examines salinity as a pollutant using an environmental science scaffold, where every pollutant needs to be understood in terms of…. CHARACTERISTICS SOURCE TRANSPORT EFFECTS PERSISTENCE SINKS

1. Characteristics of SALT as a pollutant.
Characteristics of salt (salinity) as a pollutant.
“ A Pollutant is something that when released
into the environment causes some harm or
alters the environment in a negative way.”
Every pollutant needs to be
understood in terms of….
CHARACTERISTICS
SOURCE
TRANSPORT
EFFECTS
PERSISTENCE
SINKS
ABC Salinity News
The term salinity refers to the concentration of dissolved salts in water
or soil and is expressed in terms of concentration (mg/L) or electrical
conductivity (EC).
Salinity management is one of the most significant environmental
challenges facing the Murray–Darling Basin.
If left unmanaged, salinity has serious implications for water quality,
plant growth, biodiversity, land productivity and the supply of water for
critical human needs. MDBA

2. Characteristics of SALT as a pollutant.
General Characteristics
Salinity is a measure of the content of salts in soil or water. Salts are highly
soluble in surface and groundwater and can be transported with water
movement. Large salt deposits are a natural feature of vast areas of the
Australian landscape, stored deep in soils or as surface salt deposits and salt
lakes. This natural distribution of salt in the landscape is referred to as 'primary
salinity'.
In normal circumstances, the deep roots of native plants absorb most water
entering the soil before it reaches the salt contained in groundwater below the
plant root zone. However, widespread vegetation clearance, poor land use,
irrigation and industrial practices have made it easier for salt to be transported to
the soil surface or to waterways. The additional salt from these altered land use
and management practices is referred to as 'secondary salinity'.
Excessive amounts of dissolved salt in water can affect agriculture, drinking
water supplies and ecosystem health. Salinity is a significant issue in south-western
Australia and in some Murray-Darling Basin regions within New South
Wales, Victoria, and South Australia.
http://www.environment.gov.au/water/publications/quality/factsheet-salinity-and-water-
quality

3. Characteristics of SALT as a pollutant.
Chemical characteristics
Salt is formed when a metal reacts with a base. Table salt (NaCl Sodium Chloride) is
an example. Sodium is the metal and chloride is the base.
Salt occur naturally with other metals, including heavy metals such as copper (Cu),
zinc (Zn), magnesium (Mg), calcium (Ca) and many others. These are important to
human health in low levels, but are toxic in high levels.
http://www.manoramaonline.com/advt/palathulli/reportspdf/IISC_KERALA_RESULT1
4_SALINITY.pdf
Fertilisers can also contribute salt to the environment. Most chemical fertilisers have
combinations of nitrogen, phosphorous and Potassium (N:P:K ratio). Used in excess,
salts from chemical fertilisers can pollute waterways.
http://www.dubbo.nsw.gov.au/_literature_32912/Fertilisers_and_soil_conditioners

4. Characteristics of SALT as a pollutant.
Chemical characteristics Synergistic action
An interaction between two or more individual
compounds that produces an effect upon the body
(or an organism) GREATER than either of the
substances alone would have produced. When the
combined result is greater than the sum of it’s
parts.
Example: Smog – combinations of pollutants.
Bioaccumulation and Biomagnification
The effect of salinity is worsened by drought. Plants growing in soils
with shallow salty water tables (ground water) only have shallow roots.
In drought conditions plants access water deep in the soil profile.
Where irrigation salinity, or dryland salinity occurs they are unable to
do this and hence the effect is worsened.
Higher groundwater levels mean more water interacts with
friable, sandy soil and forms the crust of salt that can accelerate
erosion and destroy agricultural productivity.
http://www.smh.com.au/environment/water-issues/higher-rainfall-
holds-key-to-salinity-20090628-
d1az.html#ixzz3A9eGDZ6f

5. Characteristics of SALT as a pollutant.
Sources
POINT
A point source is when the contaminant comes from a single
source – you can pinpoint this location on a map. For
example, a sewerage pipe, a chimney or a leaking oil tank.
They are shown on a map as an x.
Point sources of salt in the natural
environment include,where creeks
with a lot of erosion in their
catchment enter a larger stream, or
which are polluted by human
actions such as littering, industrial
processes and run-off from roads
and rubbish dumps. Point sources
of salinity can also include polluted
drains and sewage pipes.
Although we talk about
sources of salt in the human
diet, these are best refered to
in another section, ‘pathways’
(into the human body), which
would be ingestion (eating and
drinking).

6. Characteristics of SALT as a pollutant.
Sources
DIFFUSE
Diffuse sources are when the exact location cannot be
determined precisely. For example, exhaust gases on a
highway or methane gases leaking from landfill. They are
shown on a map by shading an area.
Dryland salinity is a diffuse source, because the exact location
cannot be determined accurately; rather it is easier to shade the
contributing area on a map. Dryland salinity happens when deep
rooted vegetation is removed allowing salty ground water to reach
the surface.

7. Characteristics of SALT as a pollutant.
Sources
DIFFUSE
Diffuse sources are when the exact location cannot be
determined precisely. For example, exhaust gases on a
highway or methane gases leaking from landfill. They are
shown on a map by shading an area.
Irrigation salinity is caused when more water is applied to the
soil than can be transported away by ground water flows, or
evaporated by vegetation. It is often associated with flood
irrigation, particularly where deep rooted vegetation, such as
trees and native perennial grasses have been removed.
Irrigation has been more controlled since the Murray Darling
Basin Plan was first introduced in 2010. Some areas of the
Campaspe are no longer irrigated because farmers were not
able to afford the cost of upgrading existing channels.Leaking
channels contributed to rising water tables.

8. Characteristics of SALT as a pollutant.
Sources
DIFFUSE
Diffuse sources are when the exact location cannot be
determined precisely. For example, exhaust gases on a
highway or methane gases leaking from landfill.
Groundwater seepage is the prime
contributing cause of salinity in the
Campaspe Basin. Saline ground
water enters the river in multiple
undetermined locations. Salinity in
groundwater is a natural
occurrence, however levels would
be expected to be higher where
deep rooted vegetation such as
trees and perennial grasses has
been removed.

9. Characteristics of SALT as a pollutant.
Transport
Dispersal and Transport
The way that a pollutant is spread or moves around the
environment. Dispersal can be airborne, water borne or in
soils.
Salt is carried through soil as ground water, in rivers dissolved
in water, and through the air as soil particles and sea spray.
In our Victorian landscape today, there are three
main sources of salt:
1. Many areas, such as the Mallee, were once
covered by an inland sea. When the sea retreated
about 10 million years ago, the sediments it left
behind contained large quantities of salt . Many soils
in the Mallee region have been derived from these
materials.
2. Salt from the sea is carried inland by strong wind,
to fall in rain. As you would expect, salts in rainfall
are highest near the coast, decreasing inland. A
surprising average of 6-8 kilograms/hectare/year falls
on inland Victoria.
3. Salt is one of the products of the weathering of
rocks. Salts are present in rocks and are released by
weathering and dissolved by rainfall. In arid regions,
where there is not enough rainfall to flush the salt
through the soils, the products of rock weathering
accumulate in the soil over millions of years.
(ref: Saltbook 1998 DNRE p1).

10. Characteristics of SALT as a pollutant.
Transport
Dispersal and Transport
The way that a pollutant is spread or moves around the
environment. Dispersal can be airborne, water borne or in
soils.
The salinity of groundwater can vary, even in the one area,
because of the presence of impervious layers which keep
waterbodies separate. When boring for water, the water with
the lowest levels of salinity are targeted. Fracking endangers
these supplies of fresh water because the fractures that are
caused allow the movement of gas, oil and water between
these layers. Ovwerirrigation and the removal of trees lead
to the upward movement of water tables (groundwater)
towards the surface. In Australia, this is often saline and can
reduce the suitability of land for farming.

11. Characteristics of SALT as a pollutant.
Effects on the environment
Safe levels (EC units).

12. Characteristics of SALT as a pollutant.
Effects on the environment Natural environment.
Declining yields and plants turning reddish, yellowish or brown, or plants with
dead leaf tips or margins are often the first indication of a salt problem. By the
time more salt tolerant plants begin to take over, up to 30% of a farmer’s crop
or pasture production may have been lost!
There are many signs of salinity such as:
• salt tolerant plants
• dying trees
• wilting
• waterlogging
• loss of legumes e.g. clover, medics (so that grasses lack nitrogen)
• reduced yield
• slow germination
• bare patches
As the salt levels in the soil have increased, first the clovers and medics, then
the improved grasses have disappeared and the area has become dominated
by ‘salt indicator plants’ - sea barley grass and spiny rush. Eventually even
these plants may die, leaving patches of bare ground and salt crystals visible
on the surface. Ref: Saltbook DNRE 1998 p10.
Salinity management is one of the most
significant environmental challenges facing the
Murray–Darling Basin. If left unmanaged, salinity
has serious implications for water quality, plant
growth, biodiversity, land productivity and the
supply of water for critical human needs.
High salinity can:
● reduce crop yields
● affect aquatic ecosystems and
vegetation
● damage infrastructure. Ref: MDBA
Researchers in Adelaide are using new
breeding techniques to develop plant
varieties that can better cope with drought
and salinity.
These environmental stresses are
reducing the quality and yields of many of
our grain crops, when with an increasing
population we need production to
dramatically increase.
Catalyst
Increased salinity can reduce crop yields
when it impairs the growth and health of salt-intolerant
crops and may result in corrosion
of machinery and infrastructure such as
fences, roads and bridges. env.gov.au
At the end of the
last drought the
Coorong was
being choked by
salt. ABC Splash

13. Characteristics of SALT as a pollutant.
Effects on the environment
Human environment.
Salinity: Australia’s silent flood. ABC

14. Characteristics of SALT as a pollutant.
Effects on human health
Toxicity
The measure of harm (death or illness) a substance can
cause in humans and other living things. Toxicity is
defined as acute and chronic respectively this refers to
single and repetitive exposure. (Include safe levels).
LD50
Is the term used to describe the dose of a substance
that is sufficient to kill a percentage (50%) of the
specified test animal within a specified period. The
smaller the LD50 dose the more toxic a substance is.
The lethal dose figures refer to acute toxicity and do not
give an indicator of cumulative effects over time.
In most people, the kidneys have trouble keeping up
with the excess sodium in the bloodstream. As sodium
accumulates, the body holds onto water to dilute the
sodium. This increases both the amount of fluid
surrounding cells and the volume of blood in the
bloodstream. Increased blood volume means more work
for the heart and more pressure on blood vessels. Over
time, the extra work and pressure can stiffen blood
vessels, leading to high blood pressure, heart attack,
stroke,. It can also lead to heart failure. There is also
some evidence that too much salt can damage the
heart, aorta, and kidneys without increasing blood
pressure, and that it may be bad for bones, too. Harvard
School of Public Health
Salt is a chemical compound (electrolyte) made up
of sodium and chloride. It is commonly used to
preserve and flavour foods, and is the main source
of sodium in our diet. A small amount of salt is
important for good health – it helps to maintain the
correct volume of circulating blood and tissue fluids
in the body. However, most people consume much
more sodium than they need for good health. The
kidneys are the main regulators of sodium levels in
the body. Too much sodium can cause high blood
pressure and many other health conditions…
Betterhealth.vic.gov.au
Excessive sodium intake has been linked to high
blood pressure, as well as other conditions, such
as:
• heart failure
• kidney problems and kidney stones
• oedema (fluid retention)
• stroke
• stomach cancer
• left ventricular hypertrophy (thickening of heart
muscle)
• osteoporosis.
A high level of salt intake increases the amount of
calcium excreted in the urine, which may also
contribute to osteoporosis and increased risk of
fracture. Betterhealth.vic.gov.au

15. Characteristics of SALT as a pollutant.
Effects on human health
Exposure
The degree of time spent near or in contact with the
pollutant. The level of exposure is related to the properties
of the pollutant.
Pathways
● Inhalation: when toxicants make their way into
the human body through the lungs.
● Ingestion: when toxicants make their way into
the human body through the stomach.
● Absorption: when toxicants make their way into
the human body through the skin.
Types of exposure and toxicity.
● Chronic Exposure/Chronic Toxicity: repeated
exposure and/or absorption over a long period of
time.
● Acute Exposure/Acute Toxicity: a single, severe
case of exposure, absorption and harm caused.
Around 75 per cent of the salt in our diet comes from
processed foods. Nutritionists recognise that it may
be difficult for many people to reduce their salt intake
to the ideal level, given our current food supply. Heart
Foundation advice is that all Australians should at
least reduce their salt intake to less than 6 g of salt a
day (approximately 2,300 mg of sodium a day) as a
first step towards reaching the recommended levels.
This is approximately 1½ teaspoons of salt.
Betterhealth.vic.gov.au

16. Characteristics of SALT as a pollutant.
Persistence
Persistence
A property of a pollutant which relates to the time that the pollutant takes to break
down. Substances that are not easily broken down are said to be persistent. A
pollutant is degradable if it breaks down with sunlight, soil, water or in chemical
reactions.
Regulation in the human body
Persistence in the environment
Repairing salinity affected environments
Environmental flows to remove saline water from rivers.
Salt is readily excreted from the human body and as such is not persistent. It is
removed from the blood by the kidneys and excreted in the urine and through
pores in our skin as sweat. In the environment salt can be more persistent, not
because it cannot be broken down, but because it can be more difficult to remove
- especially in the case of dryland and irrigation salinity. To remove salinity from
these environments, ground water levels need to be reduced. This means
planting deep rooted, salt tolerant natives such as perennial native grasses, salt
bush and river red gums. In the case of irrigation salinity, it also means using less
water. Salinity in waterways can be flushed out using environmental flows, or
natural floods, diluting the saline water and transporting it to the sea.

17. Characteristics of SALT as a pollutant.
Sinks
Pollution Sinks
A place or process that removes, stores or absorbs the
pollutant. Wetlands are a pollutant sink for heavy metals and
other materials. Atmospheric carbon dioxide dissolves in sea
and is stored in organic matter such as plants and vegetation.
Salt interception schemes
The MDBC operates eight jointly funded salt interception
schemes (SIS) along the Murray River, from Waikerie in
South Australia to Pyramid Creek in Victoria. These schemes
intercept saline groundwater flows and saline surface
drainage that would have otherwise entered the River.
Barr Creek Drainage Disposal Scheme (Victoria)
There are three types of sinks for salinity in inland Australia: salt lakes
(groundwater evaporation), salt interception schemes (pumping away
from rivers) and export to the sea.
The Barr Creek Drainage Diversion Scheme has once again been effective in reducing
base salt loads in the Murray River by diverting drainage flows and intercepting saline
groundwater from the Barr Creek to the Tutchewop disposal basins. During the year the
scheme operated according to the agreed rules and diverted approximately 11 078 ML of
drainage water, containing approximately 54 112 tonnes of salt, to the disposal basins.
This represents approximately 96 per cent of the flow and salt load in the Barr Creek
catchment that would otherwise have reached the Murray River.
The $13 million salt interception scheme on the
upper reaches of Pyramid Creek will lower the
adjacent groundwater table, preventing about
22 000 tonnes of salt from entering the creek
each year. This will result in reduced salinity in
downstream waterways including the Loddon
River, the Ramsar-listed Kerang Lakes and the
Murray River.