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.