Transcript pH - Summit School District / Overview

pH
• The concentration of
hydrogen ions in a
solution
• Low pH corresponds to
high hydrogen ion
concentration
• A substance that reduces
the concentration of
hydrogen ions (raises the
pH) is called a base.
Living Range
• At pHs lower than 5
most fish eggs will
not hatch and lower
pHs can kill adult
fish.
• As lakes and rivers
become more acidic
biodiversity is
reduced
Alkalinity
• measures the ability of a
solution to neutralize
acids (carbonate and
bicarbonate)
• carbonate rock is
composed of CaCO3
• CO32- = carbonate, the
carbonate ion has the
potential to absorb two
hydrogen ions H+
Therefore, it causes a net
increase in pH.
Hardness
• Hardness is a
measurement of
compounds of
calcium (Ca2+) and
magnesium (Mg2+)
• These ions react
with heavy metals to
reduce the toxicity
of the metals like
copper, zinc and
lead.
Dissolved Oxygen (DO)
• DO is a relative
measure of the
amount of oxygen
that is dissolved or
carried in water.
• Insufficient oxygen
may occur in bodies
of water such as
ponds and rivers
causing fish and
insects to die.
DO Continued
• Fish, invertebrates, plants, and aerobic
bacteria all require oxygen for respiration.
• Much of the dissolved oxygen in water
comes from the atmosphere. Algae and
rooted aquatic plants also deliver oxygen to
water through photosynthesis.
• The main factor contributing to changes in
dissolved oxygen levels is the decay of
organic wastes. Depletions in dissolved
oxygen can cause major shifts in the kinds of
aquatic organisms found in water bodies.
• Temperature, pressure, and salinity affect the
dissolved oxygen capacity of water.
NITRATES
• Nitrates are an
oxidized state of
Nitrogen needed by
organisms that
photosynthesize.
• To much Nitrogen in
water systems
causes
Eutrophication.
• Comes from
fertilizers, animal
and human poop
and decomposition.
Nitrates Cont.
• Levels above 10
mg/l can cause
human health
problems like “blue
baby” syndrome.
• Large amounts of
Nitrogen in
waterways can
cause “Dead Zones”
along coastlines.
• 7,722 mi2 in the Gulf
of Mexico in 2011
PHOSPHATES
• Oxidized
Phosphorous that is
needed by
photosynthesizing
organisms.
• Comes from
fertilizers, human
and animal poop
and detergents.
• Also causes
Eutrophication.
Phosphate Cont.
• 0.01 - 0.03 mg/L - the
level in uncontaminated
lakes
• 0.025 - 0.1 mg/L - level
at which plant growth is
stimulated
• 0.1 mg/L - maximum
acceptable to avoid
accelerated
Eutrophication
• > 0.1 mg/L - accelerated
growth and consequent
problems
Biochemical Oxygen Demand
(B.O.D)
• This is the measure
of the amount of
oxygen used up by
aerobic bacteria in a
water sample over a
5 day period.
• If the B.O.D is
greater than the rate
at which O2 is
naturally replaced
than aquatic
organisms may die.