Transcript Water Pollution - University of Arizona

Water Pollution
Distribution of Water Reservoirs
Oceans
97%
Ice Caps and Glaciers
1.725%
Atmosphere
0.01%
Soil Moisture
0.0012%
Rivers, Lakes,
and Inland
Seas
0.141%
Ground Water
0.4 – 1.7%
World Water Supply
97.200% salt water in the oceans
02.014% ice caps and glaciers
00.600% groundwater
00.009% surface water
00.005% soil moisture
00.001% atmospheric moisture
Water Cycle
• Atm. Ocean Land
• Evap. PPT Runoff
Water Pollution
Two major classifications
• Point Source
• Non-point Source
Point Sources
• Single large source
• Can localize it to one spot
– Industrial Plants
- Sewage pipes
Point Source - Example
• LUST - Leaky Underground Storage Tanks
• 22% of the 1.2 million UST are LUST
• Non-point Sources
Diffuse source or many smaller
point sources
• Automobiles
• Fertilizer on fields
Water Pollution: Many Forms
• Disease: In developing nations, 80% of diseases are
water-related.
• Synthetic Organic Compounds
• Inorganic Compounds & Mineral Substances such
as Acids, etc.
• Radioactive substances
• Oxygen-demanding wastes
• Plant Nutrients
• Sediments
• Thermal Discharges
Examples of
Polluted Waters
A very personal look at water
• What happens to your water before you
drink it?
• What happens to your water after you
dispose of it?
– Approximately 99% of Swedes are served by
wastewater treatment plants, 86.5% of
Germans, 74% of Americans, and 57% of
Canadians.
What constitutes quality drinking water?
• Free of pollutants
• Tastes good
– Want Sodium Bicarbonate and Calcium Sulfate in same
concentrations as found in saliva
– 10 oC
– As little chlorination as possible
• Calcium & magnesium account for most water
hardness, death rates (cardiovascular disease)
higher in soft water areas than in hard water areas
• Copper needed to absorb & metabolism iron, but
>1mg/liter makes water unpalatable
• Does taste correlate with presence of toxic
compounds?
Forms of Pollution – Details
• Inorganic – acids, salts, toxic metals
• One gram of lead in 20,000 liters of water
makes it unfit for drinking. Lead is often
found in the pipes of older homes
• What is the safe drinking water limit for
arsenic? For lead? How much does UA
water supply have?
Forms of Pollution – Details
• Organic: sewage, pesticides, plastics, etc.
• One drop of oil can render up to 25 liters of
water unfit for drinking
• One gram of 2,4 D can contaminate 10
million liters of drinking water!
• One gram of PCBs can make 1 billion liters
of water unsuitable for freshwater aquatic
life!
Acid Precipitation:
When Air Pollution Becomes Water Pollution
Acid Rain Effects – Aquatic Systems
When the pH drops below 6.0 species start to die off.
When one species dies, others that depend on it may as well
Acid Neutralization
• How does this work?
• Cation Exchange on
clay minerals
• Role of chemical
weathering...
How does acid kill the fish?
One way is mobilizing metals
• When all base cations are striped from soils
• Acid now reacts with metals e.g. aluminum
– Normally aluminum is immobile
– below pH 5 - mobile aluminum
• Fish breath in the water
– Aluminum comes out of solution
– Clogs gills - suffocate
More Examples: Oxygen and Water
• Biochemical Oxygen Demand – What does
this mean?
– Anything in the water that bacteria can break
down.
– Bacteria will use up oxygen in the water
– Other aerobic organisms will die
Oxygen and Water
• What else can affect the amount of O2 in the
water?
– Temperature
– Speed of water flow
– Roughness of surface
over which water flows
Stories about particular pollutant
forms: Oil
• Both Point and Nonpoint Sources
• Largest source of oil pollution is pipeline
leaks and runoff
– 61% ocean oil pollution river & urban runoff
– 30% intentional discharges from tankers
– 5% accidental spills
from tankers
Stories about particular pollutant
forms: Detergents
The nitrates in fertilizers promote excessive growth of
algae and larger aquatic plants, causing offensive algae
blooms and driving out sport fish.
Phosphates are often thought to culprit, nitrogen is the
“limiting factor” in most aquatic systems.
Stories about particular pollutant
forms: Sediments
• THE largest form of water pollution
• Erosion is source – we’ve sped up rate of
erosion, e.g. during urban construction can
lose up to 43 tons of topsoil/acre/year
• Natural rates of erosion: leads to aquatic
succession
Succession in Aquatic Habitats
Lake
Sediments &
Nutrients
Accumulate
Oligotrophic
Low in nutrients
Eutrophic
High in nutrients
Can sometimes see
Methane gas bubbling up
From sediments – process of
decomposition
Stories about particular pollutant
forms: thermal pollution
• 26% of all water in U.S. is affected by this
• Up to a point of adding heated water, you
can get thermal enrichment
• Adding more heat,
you get
thermal pollution
We can also have cold water pollution
In many areas fish and
Other river organisms are
Adapted to relatively
warm water.
Building a dam results in
very cold water released
Downstream killing
organisms and changing
species
A special case: Groundwater
• What forms of pollution can affect
groundwater?
• All of them except thermal pollution!
• Renewal time of groundwater is important
– Rivers: 12-20 days
– Soil Moisture: 280 days
– Groundwater: 300 years
Groundwater doesn’t stay in one place
Oil Well Drilling & Groundwater
Oil Drilling Protocols
• Well must be cased
from surface to below
freshwater zone
• Casing must also be
for 150 feet above pay
zone
• Logging apparatus
must be retrieved
Oil Drilling Protocols
• Drilling fluids must be
disposed of properly –
e.g. no Midnight
Haulers
• Any spills must be
reported and cleaned
immediately
• Area will be subject to
remediation efforts
Identifying Sources of Pollutants to the Chesapeake Bay
We are going to do the same analysis that scientists did in 1998 to determine what
some of the major sources of pollutants were to the Chesapeake Bay