Download - Grade 7 www pollution overview
Water Pollution Indicators of the
Mekong Delta
Grade 7 Science
Saigon South International School
Week Without Walls 2010
Key Questions:
Is the Mekong Delta polluted?Are the waters in HCMC polluted?How do we measure pollution?
What you will learn:
Causes and health affects of pollution Why it’s important to measure pollution What are the two different areas of
measuring/assessing water pollution.
What causes water pollution?
Industrial and municipal sewage systems Pesticide and herbicide run off Illegal dumping Leaking storage tanks
www.neoscience- “Investigating Water pollutants”
Why assess water quality?
Safe for growing crops and livestock? Bioaccumulation may lead to health affects
over long term Can cause ecosystems to change Recreational use
2 Indicators of Water Pollution
Biological What are the living things
that can live here? Are there things that used
to live here, but are not anymore?
(Benthic Macroinvertebrates)
Chemical Are there chemicals
which are dangerous to people in the water?
How do we measure these chemicals?
Are there acceptable amounts?
Benthic Macroinvertebrates
Benthic=Bottom Living Macro=Small Invertebrates=Having no backbone Three classes, some are pollution sensitive,
some are not.
Class 1 Organisms are pollution sensitive. They are associated with good water quality. They do not tolerate pollution well, and large numbers are observed only when good water quality is present.
Class 2 Organisms somewhat pollution tolerant. They tolerate water pollution better than Class 1 organisms. We can expect to see significant numbers of these animals when the water quality ranges from good to moderate.
Class 3 Organisms are pollution tolerant. They are tolerant to even higher levels of pollution than are Class 2. When these animals dominate, poor water quality is generally the reason.
Macroinvertebrates as pollution indicators: Review
Class Class 1-Sensitive to
water pollution and do not tolerate it.
Class 2-More sensitive to water pollution
Class 3-Very tolerant to water pollution. (Can survive in more polluted water)
What does it tell you about pollution levels?
If you find members of all three classes?
If you find members of only class 2, and class 3.
If you find members of only class 3.
You find no members of any class.
Chemical Indicators of Water Quality
Dissolved Oxygen (DO) Nitrates Hardness Phosphates Carbon Dioxide (CO2) Acidity
Dissolved Oxygen
Between 5-6 ppm is optimal to support aquatic ecosystems
Less than 4 ppm = bad 10 < Excellent A key indicator caused naturally by photosynthesis,
oxygen exchanges with the atmosphere Aerobic bacteria from sewage or high amounts of
decomposing plants decrease dissolved oxygen High amounts can cause pipes to corrode
Environmental Affects of Low Dissolved oxygen
Limits suitable habitat for oxygen filtering organisms (fish and amphibians)
Nitrates
NO3
Most common contaminant as nitrates in soil leach down into water table
Industrial fertilizers, herbicides and organic wastes also cause
EPA allows 10 ppm. Some biological
factories can have discharges of 30 < ppm
U.S. Fertilizer Loss Nitrogen runoff
Environmental Consequences of Nitrates
Eutrophocation- “A process whereby water bodies, such as lakes, estuaries, or slow-moving streams receive excess nutrients that stimulate excessive plant growth (algae, periphyton attached algae, and nuisance plants weeds)”
www.usgs
Cause and Impact of Eutrophocation
Causation
Environmental Impact
Agricultural fertilizer run off, factory discharge into rivers
Reduces dissolved oxygen in the process when increased amounts of algae die and decompose.
Hardness
Water Hardness ScaleMg/L (ppm) Classification
Less than 17 Soft
17-60 Slightly Hard
60-120 Moderately Hard
120-180 Hard
Over 180 Very Hard
Health Affects of Hardness
Too much can lead to kidney stones, although the data is inconclusive
Damage machinery Defeats the ability of soap as a cleaning
solution Can cause clothes to feel “stiff” when washed
in hard water.
Phosphates Important in fertilizers
because it is a plant nutrient. Phosphate treated plants
may accumulate in water ways and lead to algae blooms.
Cleaners like soap a domestic contributor
Expressed in mg/l (PPM) 4 ppm or higher have high
levels of bacteria
Carbon Dioxide
Present in low levels due to plant and animal respiration
Used in Photosynthesis
High levels can make water corrosive or toxic to aquatic life (above 10 mg/L) (above 10 ppm)
Outline for Pollution Management
Altering human activity Regulating and reducing quantities of
pollutant released at the point of emission Cleaning up the pollutant and restoring
ecosystems after pollution has occurred.
Acidity
100-120 ppm are acceptable If sample is below 100 pm, an error occurred
and the water should be retested. Over 120 ppm is too acidic.