Transcript Water Testing

Water Quality and
Testing
Water Quality
• Water quality is the physical, chemical
and biological characteristics of water
• The vast majority of surface water on
the planet is neither potable (fit for
drinking) nor toxic
• Approximately 25% of the world’s
population has no access to potable
water
Water Quality
• No simple property can tell whether
water is polluted or not
• Industrial pollution is a major cause of
water pollution
– Also runoff from agricultural areas, urban
storm water runoff and discharge of
untreated sewage (especially in developing
countries).
Water Contamination
• Contaminants that may be in untreated water
include:
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microorganisms (viruses and bacteria)
inorganic contaminants (salts and metals)
pesticides and herbicides
sediments
organic chemical contaminants from industrial
processes and petroleum use
– radioactive contaminants.
• Water quality depends on the local geology
and ecosystem, as well as human uses
(sewage dispersion, industrial pollution, use
of water bodies as a heat sink)
Water Regulations
• The Environmental Protection Agency (EPA)
regulates limits on the amount of certain
contaminants in the water
• The Food and Drug Administration (FDA)
limits contaminants in bottled water
• Drinking water, including bottled water, may
reasonably be expected to contain at least
small amounts of some contaminants. The
presence of these contaminants does not
necessarily indicate that the water poses a
health risk.
Water Tests
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Electrical conductivity|Conductivity (also see salinity)
Dissolved Oxygen(DO)
pH
Color of water
Turbidity
Total suspended solids (TSS)
Dissolved metals and salts (sodium, chloride, potassium, calcium, manganese,
magnesium)
Chemical oxygen demand (COD)
Biochemical oxygen demand (BOD)
Microorganisms such as fecal coliform bacteria (Escherichia coli),
Cryptosporidium, and Giardia lamblia
Nutrients, such as nitrogen and phosphorus
Dissolved metals and metalloids (lead, Mercury (element),arsenic, etc.)
Dissolved organics: Colored Dissolved Organic Matter (CDOM), Dissolved
Organic Carbon (DOC)
Temperature
Pesticides
Heavy Metals
Pharmaceuticals
Hormone analogs
Temperature
• Determine types of organisms that can live in
water
• Affects how much oxygen water can hold
– Warm water holds less oxygen
• Thermal Pollution (increased water temperature)
– decreasing oxygen supply
– killing fish juveniles which are vulnerable to small
increases in temperature
– affecting ecosystem composition.
Dissolved Oxygen
• Measure of the amount of oxygen dissolved in
water
• Measurement for outdoor bodies of water
– More DO generally relates to “healthier” water
(oxygen necessary for most aquatic species to
breath)
• Related to Biochemical Oxygen Demand (BOD)
– how fast biological organisms use up oxygen in a
body of water
Representative pH values
Substance
pH
• Potential of Hydrogen –
measures hydrogen
concentration in water
• 7.0 is neutral on scale
of 0 – 14
• Can affect how
chemicals dissolve in
water
pH
Hydrochloric Acid, 10M
-1.0
Lead-acid battery
0.5
Gastric acid
1.5 – 2.0
Lemon juice
2.4
Cola
2.5
Vinegar
2.9
Orange or apple juice
3.5
Tomato Juice
4.0
Beer
4.5
Acid Rain
<5.0
Coffee
5.0
Tea or healthy skin
5.5
Urine
6.0
Milk
6.5
Pure Water
7.0
Healthy human saliva
Blood
6.5 – 7.4
7.34 – 7.45
Seawater
7.7 – 8.3
Hand soap
9.0 – 10.0
Household ammonia
11.5
Bleach
12.5
Household lye
13.5
Nutrients
• Eutrophication, strictly speaking, means
an increase in chemical nutrients (typically
nitrogen and phosphorus)
• Resultant increase in primary productivity
– excessive plant growth and decay
• Further impacts, including lack of oxygen
and severe reductions in water quality and
in fish and other animal populations.
Turbidity / Total Suspended Solids
• Amount of particulate matter in water
• Related to sediment, phytoplankton and
nutrients in water
• Turbidity reflects matter visible to naked
eye (measured with Secchi disk)
• TSS collects dissolved material (filtered)
measured as weight
Salinity
• Dissolved salt content in water
• Influences organisms that can live in that area
• Oceans are about 35 ppt or so
Fresh water
< 0.05 %
< 500 ppm
Water salinity
Brackish water
Saline water
0.05 - 3 %
3-5%
Brine
>5%
500 - 30 000 ppm 30 000 - 50 000 ppm > 50 000 ppm
Heavy Metals
• Living organisms require trace amounts of some
heavy metals, including iron, cobalt, copper,
manganese, molybdenum, vanadium,
strontium, and zinc
– excessive levels can be detrimental to the organism.
• Other heavy metals such as mercury, lead and
cadmium are toxic metals
– they have no known vital or beneficial effect on
organisms
– their accumulation over time in the bodies of
mammals can cause serious illness
Microorganisms
• E. coli (fecal coliform bacteria) can generally
cause several intestinal and extra-intestinal
infections
• Cryptosporidium is a protozoan pathogen and
causes a diarrheal illness called cryptosporidiosis
• Giardia lamblia is a flagellated protozoan parasite
that colonises and reproduces in the small
intestine, causing giardiasis. Symptoms of include
diarrhea, malaise, excessive gas, etc
Other Stuff
• Pesticides - bactericides, fungicides
herbicides, insecticides (DDT)
• Radioactive Materials
• A lot of this information pertains to soil
testing as well.
Biotic vs. Abiotic
• Abiotic components are non-living
chemical and physical factors in the
environment.
– The six major aboiotic factors are water,
sunlight, oxygen, temperature, soil and climate.
• Biotic means relating to, produced by, or
caused by living organisms.
Biotic vs. Abiotic
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Salinity
Dissolved Oxygen(DO)
pH
Color of water
Turbidity
Total suspended solids (TSS)
Dissolved metals and salts
Chemical oxygen demand (COD)
Biochemical oxygen demand (BOD)
Nutrients
Dissolved metals
Temperature
Pesticides
Heavy Metals
Pharmaceuticals
Hormone analogs
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Microorganisms such as fecal coliform
bacteria (Escherichia coli),
Cryptosporidium, and Giardia lamblia
Dissolved organics: Colored Dissolved
Organic Matter (CDOM), Dissolved
Organic Carbon (DOC)
Number of species