11

WATER WATER as as

A ResourceA Resource

Drinking WaterDrinking Water

22

Water ContaminationWater Contamination

How do we know what is “clean water?” In How do we know what is “clean water?” In other words, how do we know if water is other words, how do we know if water is “safe” for humans and wildlife?“safe” for humans and wildlife?

Use “Water Cards” put in order from Use “Water Cards” put in order from unsafe unsafe safe drinking water. safe drinking water.

Read “The Dose Makes the Poison,” Read “The Dose Makes the Poison,” answer questions #1-6 on your paper.answer questions #1-6 on your paper.

Using Bioassays for Using Bioassays for Environmental ResearchEnvironmental Research 33

Water ContaminationWater Contamination

How do we know what is “clean water?” In How do we know what is “clean water?” In other words, how do we know if water is other words, how do we know if water is “safe” for humans and wildlife?“safe” for humans and wildlife?

Charity Water Video Let’s look at Water Quality IndicatorsLet’s look at Water Quality Indicators

Using Bioassays for Using Bioassays for Environmental ResearchEnvironmental Research 44

Units for Measuring Water Units for Measuring Water QualityQuality

PARTS PER MILLIONPARTS PER MILLION

Most dissolved substances Most dissolved substances found in water are measured found in water are measured in parts per million (ppm) or in parts per million (ppm) or even smaller amounts. This even smaller amounts. This

means that for every one means that for every one million parts (units) of water million parts (units) of water there is a certain number of there is a certain number of

parts of the substance.parts of the substance.

It is also expressed as milligrams It is also expressed as milligrams per liter. There are 1000 milliliters per liter. There are 1000 milliliters in a liter and 1000 milligrams in a in a liter and 1000 milligrams in a gram. For example, a dissolved gram. For example, a dissolved oxygen reading of 8 ppm means oxygen reading of 8 ppm means there are 8 milligrams of oxygen there are 8 milligrams of oxygen for every 1000 milliliters of water.for every 1000 milliliters of water.

8/1000 gram 8/1000 gram 1000 milliliters = 1000 milliliters =

8/1,000,000 (8 parts per million)8/1,000,000 (8 parts per million)

Concentrations of certain Concentrations of certain substances are also measured substances are also measured

in parts per billion, parts per in parts per billion, parts per trillion and so on. These are trillion and so on. These are

very small amounts but certain very small amounts but certain substances can be harmful substances can be harmful

even at these very low even at these very low concentrations.concentrations.

Water Quality IndicatorsWater Quality Indicators

We will now take a look We will now take a look at some water quality at some water quality indicators.indicators.

““Water quality” can refer Water quality” can refer to quality for a healthy to quality for a healthy “environment” and/or “environment” and/or healthy for human healthy for human consumptionconsumption

TEMPERATURETEMPERATURE

Most aquatic organisms live Most aquatic organisms live within a temperature range of within a temperature range of 32º F (+0º C) to 90º F (32º C).32º F (+0º C) to 90º F (32º C).

Temperature is measured in Temperature is measured in Fahrenheit and Celsius degrees. Fahrenheit and Celsius degrees. (Temperature, of course, is not a (Temperature, of course, is not a

“dissolved substance”)“dissolved substance”)

Rapid temperature change and Rapid temperature change and temperature extremes can stress temperature extremes can stress

aquatic organisms.aquatic organisms.

TEMPERATURETEMPERATURE

pHpH

pH is the measure of the hydrogen pH is the measure of the hydrogen ion (H+) concentration.ion (H+) concentration.

The pH scale is zero to 14. Seven The pH scale is zero to 14. Seven is neutral, below seven is acidic, is neutral, below seven is acidic,

and above seven is basic (or and above seven is basic (or alkaline).alkaline).

Most aquatic organisms exist Most aquatic organisms exist within a pH range of 5.5 to 9.5.within a pH range of 5.5 to 9.5.

pHpH

pH is usually not a major problem pH is usually not a major problem for aqutic organisms or drinking for aqutic organisms or drinking water except in certain situations water except in certain situations

(acid mine drainage etc.)(acid mine drainage etc.)

SalinitySalinity

Salinity refers to the salt Salinity refers to the salt concentration in water, concentration in water, mostly sodium chloride.mostly sodium chloride.

Salinity is historically Salinity is historically measured in parts measured in parts

per thousand (ppt) or per thousand (ppt) or grams per liter.grams per liter.

SalinitySalinity

Salinity of the ocean is Salinity of the ocean is about 33-38 ppt. The about 33-38 ppt. The maximum considered maximum considered

safe for drinking water is safe for drinking water is 1 ppt (1,000 ppm)1 ppt (1,000 ppm)

SalinitySalinitySaltwater can cause drinking water Saltwater can cause drinking water

problems when it replaces fresh problems when it replaces fresh groundwater near the coastal groundwater near the coastal

areas.areas.

DISSOLVED OXYGENDISSOLVED OXYGEN

Dissolved oxygen is a Dissolved oxygen is a product of product of

photosynthesis and photosynthesis and diffusion.diffusion.

Typical range 0 – 14 ppmTypical range 0 – 14 ppm

““Quality” water >6 ppmQuality” water >6 ppm

Diffusion: Diffusion: The movement of molecules, for example oxygen molecules, The movement of molecules, for example oxygen molecules, from an area of higher concentration (e.g. the leaf) to an area of lower from an area of higher concentration (e.g. the leaf) to an area of lower concentration (e.g. the water).concentration (e.g. the water).

DISSOLVED OXYGENDISSOLVED OXYGEN

Most aquatic Most aquatic organisms that organisms that respire using respire using

oxygen need at oxygen need at least 5 or 6 ppm least 5 or 6 ppm

of oxygen in of oxygen in order to survive.order to survive.

BACTERIABACTERIA

Most bacteria are important in Most bacteria are important in nutrient and other organic cycles.nutrient and other organic cycles.

Excess nutrients Excess nutrients cause algal blooms. cause algal blooms. As algae die and As algae die and decay, the high decay, the high bacterial load bacterial load rapidly consumes rapidly consumes dissolved oxygen.dissolved oxygen.

TURBIDITYTURBIDITY

Turbidity refers Turbidity refers to water clarity.to water clarity.

Sediments Sediments suspended in suspended in

the water the water increase increase turbidity.turbidity.

Certain types of bacteria Certain types of bacteria indicate animal and human indicate animal and human

waste pollution.waste pollution.Escherichia coli Escherichia coli are are coliform coliform

bacteriabacteria found in the intestines found in the intestines of warm-blooded organisms. of warm-blooded organisms. Most strains are harmless but Most strains are harmless but one one E.E. coli coli strain can cause strain can cause severe diarrhea and kidney severe diarrhea and kidney

damage.damage.

BacteriaBacteria

The goal for drinking water is The goal for drinking water is “zero” however this is often “zero” however this is often

impossible. impossible.

Therefore, U.S. laws require that Therefore, U.S. laws require that drinking water is treated with a drinking water is treated with a

disinfectant.disinfectant.

Drinking water is periodically Drinking water is periodically tested for bacteriatested for bacteria

NITRATENITRATE

Nitrate is a primary Nitrate is a primary plant nutrient.plant nutrient.

Nitrate is water Nitrate is water soluble and moves soluble and moves easily from surface easily from surface

to groundwater.to groundwater.

Excess nitrate causes algal Excess nitrate causes algal blooms that reduce water quality.blooms that reduce water quality.

Under normal conditions, the Under normal conditions, the nitrogen cycle keeps the amount of nitrogen cycle keeps the amount of available nitrogen in balance with available nitrogen in balance with the demands. the demands.

However, excessive use of fertilizers However, excessive use of fertilizers and nutrient rich sewage release and nutrient rich sewage release have created a surplus of nitrate. have created a surplus of nitrate. The result is The result is eutrophicationeutrophication from from excess algae and bacteria with excess algae and bacteria with reduced dissolved oxygen.reduced dissolved oxygen.

PESTICIDES / HERBICIDESPESTICIDES / HERBICIDES

These chemicals are very These chemicals are very complex.complex.

Effects on aquatic Effects on aquatic organismsorganisms – Moderately – Moderately to highly toxic to to highly toxic to mammals, mollusks, mammals, mollusks, aquatic insects, aquatic insects, amphibians and fish.amphibians and fish.

TOXIC CHEMICALSTOXIC CHEMICALS

Toxic chemicals usually come Toxic chemicals usually come from industry and energy from industry and energy

production.production.

The effects are often not known The effects are often not known until years after they have entered until years after they have entered

the environment.the environment.

Some toxic chemicals include Some toxic chemicals include petroleum products (oil), heavy petroleum products (oil), heavy metals (lead, mercury etc.), and metals (lead, mercury etc.), and

organic compounds (DDT, organic compounds (DDT, PCB).PCB).

Stop: Activity

Use “Water Cards” put in order Use “Water Cards” put in order from unsafe from unsafe safe drinking safe drinking water.water.

Using Bioassays for Using Bioassays for Environmental ResearchEnvironmental Research 3030

BIOASSAYSBIOASSAYS

Dose/Response Bioassays are used to:Dose/Response Bioassays are used to: Estimate toxicity to humans.Estimate toxicity to humans. Estimate maximum concentrations of specific Estimate maximum concentrations of specific

chemicals allowed to discharge into bodies of chemicals allowed to discharge into bodies of water.water.

Investigate hazardous waste sites. Investigate hazardous waste sites.

3131

Bioassay SpeciesBioassay Species

3 organisms are often used3 organisms are often used DaphniaDaphnia DuckweedDuckweed Lettuce SeedsLettuce Seeds

Expose organisms to chemicals and Expose organisms to chemicals and measure how they respond.measure how they respond.

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Bioassay SpeciesBioassay Species

Lettuce SeedsLettuce Seeds In Petri dishes with test samplesIn Petri dishes with test samples Sensitive to pesticides, solvents and organic Sensitive to pesticides, solvents and organic

compoundscompounds After 5 day check for:After 5 day check for:

• germinationgermination• radicle lengthradicle length

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CCONCENTRATION VS. DOSEONCENTRATION VS. DOSE

LDLD5050 the the DDose that is ose that is LLethal for 50% of the ethal for 50% of the

test organisms. test organisms. Used for DaphniaUsed for Daphnia

TCTC50 50 the the CConcentration that causes a 50% oncentration that causes a 50%

drop in growth or health of the test drop in growth or health of the test organisms (organisms (TToxic oxic CConcentration).oncentration). Used for seeds (they may not die, just not Used for seeds (they may not die, just not

sprout) sprout)

Using Bioassays for Using Bioassays for Environmental ResearchEnvironmental Research 3434

An Introduction To Experimental DesignAn Introduction To Experimental Design

The The TreatmentsTreatments in an experiment in an experiment represent the factor that you vary while represent the factor that you vary while keeping everything else constant.keeping everything else constant.

Using Bioassays for Using Bioassays for Environmental ResearchEnvironmental Research 3535

An Introduction To Experimental DesignAn Introduction To Experimental Design

The The control control is the untreated group, used is the untreated group, used for comparison with the treatment groups.for comparison with the treatment groups.

Using Bioassays for Using Bioassays for Environmental ResearchEnvironmental Research 3636

An Introduction To Experimental DesignAn Introduction To Experimental Design

ReplicatesReplicates are groups of organisms are groups of organisms exposed to identical conditions.exposed to identical conditions. The more replicates the better.The more replicates the better.

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INTERPRETING BIOASSAY RESULTSINTERPRETING BIOASSAY RESULTS

How do interpret LD How do interpret LD 5050’s and LC ’s and LC 5050’s?’s?

What conclusions are valid about What conclusions are valid about environmental impacts of the compounds environmental impacts of the compounds being tested?being tested?

Using Bioassays for Using Bioassays for Environmental ResearchEnvironmental Research 3838

INTERPRETING BIOASSAY RESULTSINTERPRETING BIOASSAY RESULTS

Bioassays DO NOT specify what Bioassays DO NOT specify what chemicals are present in the samples.chemicals are present in the samples.

They measure the combined toxicity of They measure the combined toxicity of whatever is in the sample. whatever is in the sample.

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INTERPRETING BIOASSAY RESULTSINTERPRETING BIOASSAY RESULTS

Bioassays give us a standard technique to Bioassays give us a standard technique to compare:compare:

Samples taken at different times and Samples taken at different times and places.places.

Samples of environmental samples to Samples of environmental samples to known samples.known samples.

Using Bioassays for Using Bioassays for Environmental ResearchEnvironmental Research 4040

TIPS FOR PLANNING AN TIPS FOR PLANNING AN EXPERIMENTEXPERIMENT

GO TOGO TO http://ei.cornell.edu/student/exptdesign.asphttp://ei.cornell.edu/student/exptdesign.asp