Transcript Water Chemistry and Pollution

Water Chemistry and
Pollution
Why we measure water quality?
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When a body of
water is overfed
with nutrients it
can create massive
algal blooms which
causes very low
levels of DO killing
off many aquatic
organisms.
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www.thebutlerchain.com/introd
uction.htm
Pfiesteria
Found in waters high in nutrients
-Harmful Algal Bloom (HABs)
www.sierraclub.org
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A fertilized lake
designated "Lake 227"
in northwest Ontario,
Canada, (foreground)
with increased algae,
whose growth has been
found unpredictable,
pictured next to a lake
that hasn't been
manipulated for
research. (Photo by
Karen J. Scott
www.monitor.net)
Would you want to swim at
this beach?
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“Under the belief that water
could dilute any substance,
industries and individuals
during the 18th and 19th
centuries often used rivers
and lakes as garbage cans.
Industrial effluent, raw
sewage and animal
carcasses would often be
dumped into waterways,
without much thought of
contamination and
downstream neighbors.”
http://www.great-lakes.net/teach/pollution/water/water2.html
Eutrophication
 Excessive
Nutrients: N>3ppm P>.01ppm
 Causes excessive growth of marine
autotrophs (large algal blooms)
 Die off of Marine Plants = Lack of Light
 Decomposition of marine plants uses more
oxygen which can lead to an “oxygen sag”
in an aquatic environment
The Dead Zone
 Oxygen
minimum zone that develops
annually in response to nutrient and other
inputs to the Gulf of Mexico.
 Hypoxic - <2.0mg/l of dissolved oxygen
 Anoxic – 0.0mg/l of dissolved oxygen
 To
determine the health of a body of water,
many parameters or guidelines are
monitored including
Coliform Bacteria, Dissolved Oxygen
(DO), Nitrate/Nitrite, Phosphate, pH,
Temperature, & Turbidity
Coliform Bacteria
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EPA standards: One coliform colony / I00 mL of
water is cause for concern
Four colonies per 100 mL requires direct action
The appearance of coliform bacteria indicates the
presence of raw sewage. Raw sewage may contain
disease-producing bacteria.
Coliform is an indicator species.
A coliform test measures the amount of E. coli
present in the water supply
Dissolved Oxygen
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DO is dependent on a
number of factors
including salinity,
temperature,
photosynthesis rates
atmospheric
pressure, and the
amount of wind &
wave turbulence.
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The suitability of a body
of water for organisms to
live can be determined by
the amount of DO in the
water.
Fish require 4-5 mg
O2/liter of water while air
breathing aquatic
organisms require less.
Nitrates/Nitrites
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EPA standards: Nitrate
cannot exceed 10 mg/L
Excess levels of nitrates
can cause hypoxia.
Excess nitrite can cause
the “blue baby syndrome”
and is toxic to warmblooded organisms.
Natural levels of nitrates
in surface water is
<1mg/L.
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Essential nutrient for
plants & animals.
Sources of nitrates come
from the atmosphere
(automobile exhaust),
fertilizer runoff from land,
animal excrement,
sewage wastes, and
plant debris.
Wastewater treatment
plants can have nitrate
levels as high as 30mg/L.
Phosphates
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Phosphorus is also an essential nutrient for the plants
and animals that make up the aquatic food web.
Phosphorus is naturally available in low concentrations
and is often limited.
Small increases can result in accelerated plant growth,
algae blooms, low dissolved oxygen, and the death of
certain fish, and other aquatic animals.
Sources of phosphorus include soil and rocks,
wastewater treatment, fertilizer runoff, failing septic
systems, runoff from animal manure, disturbed land
areas, drained wetlands, and commercial cleaning
preparations.
pH
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pH describes how acidic or alkaline a substance is.
Acidity increases as the pH gets lower (pH of 7 being
neutral).
pH affects many chemical and biological processes in
the water.
Most aquatic organisms prefer a range of 6.5-8.0. Water
higher or lower than the range decreases biodiversity, &
reduce reproduction.
Low pH can also allow toxic elements to become mobile
& “available” for uptake by aquatic plants. This can be
particularly dangerous to sensitive species like rainbow
trout.
Changes in pH occur from acid rain, wastewater
treatment plants, and leaching from surrounding rock
beds.
Turbidity
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Turbidity measures the amount of particles suspended in
a body of water such as soil particles (clay, silt, sand),
algae, plankton, microbes, and etc.
 Higher turbidity increases water temperatures because
the particles absorb more heat reducing the amount of
DO. Warm water holds less DO than cold. Higher
turbidity reduces the amount of light penetrating the
water, and reduces photosynthesis. Suspended
materials can clog fish gills, decrease resistance to
disease & affect egg/larval development
 Sources include soil erosion & runoff, waste discharge,
eroding stream banks, bottom feeders (carp). Turbidity
has no direct human health effects but can provide a
medium for microbial growth.
Indicators vs. actual chemicals
 Ecotoxicology-
pollutants in the ocean
 Eating too much of certain seafood is
harmful
 We looked at the chemistry of the water.
Now we will look at the chemistry of the
animals in the water
Why are we concerned about
ocean pollution?
 Transportation
 Coastal
ocean is used most heavily-76%
of fisheries!!
 recreation- jet skis, cruise ships
Causes
 Natural
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(not all are human-caused)
Volcanoes- atmospheric pollutants (ash, SO2)
Underwater seeps
 Anthropogenic
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Anthro=humans
Industry, mining, agriculture, transportation
Recreation
4 main pollutants
 Petroleum-least
damaging, can be broken
down naturally
 Sewage sludge-water treatment does not
treat for chemicals, only treats waste
 Toxic chemicals
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DDT (banned), PCB’s, PAH’s
Still in environment today
 Heavy
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metals
Lead, mercury, methylmercury
What is mercury?
 Heavy,
silvery-white liquid
 Only metal that is liquid at ambient temp.
 Mad as a hatter
 Naturally in environment from volcanic
eruptions and weathering of rocks- but
miniscule compared to human-caused
 Environmental neurotoxin affects growth,
reproductive success, and development in
plants and animals
Uses of mercury
 Electrical
products-switches, wiring,
thermostats, batteries, etc.
 Dentistry
 Medical products-antiseptics, laxatives
 Thermometers
 Pharmaceutical preservatives- thimerosal
 Industrial processes- byproduct of coalburning power plants, fossil fuel
combustion
Effects of Mercury
 Neurological
complications on a
developing fetus
 Sensory disturbances (blindness)
 Lack of coordination (slurred speech)
 Reproductive failure
 Impaired growth
 Loss of motor skills
 Loss of IQ points
 Cardiovascular problems
Different forms of mercury
 Elemental
mercury-does not affect
humans
 Inorganic mercury-does not affect
humans, gets transformed by bacteria into
methylmercury
 Methylmercury-also called organic
mercury, poisonous, absorbed into tissue
 Bioaccumulation:
build-up in concentration
of something with each step of the food
chain
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Crosses the blood/brain barrier and placenta
Eliminated from living tissue very slowly
Is contained in fish flesh and is not reduced or
removed by cleaning, trimming or cooking
 Bioconcentration:
comparison between
creature’s concentration and concentration
in environment (i.e. seawater)