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No instrument has yet been devised that can
measure toxicity! Chemical concentrations can be
measured with an instrument but only living
material can measure toxicity. Cairns, John,
Jr. and Mount, Don I The reason this lecture was
stimulated by this quote is that the concept
expressed in the quote is the basis for the water
quality based approach to toxics control that is
reflected in the incorporation of WET tests in
NPDES permits. However, there remains an
extrapolation and that extrapolation is from
effluent toxicity to receiving system impacts.
Stated simply it asks, Does effluent toxicity, as
measured by WET tests, have any relationship to
receiving system impact? It also stimulates the
question, Why extrapolate at all? Why not just
go to the receiving system and measure its
health?
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Diversity Indices and Standards Ecology study
of the interrelationships between plants and
animals and their abiotic environment. Species
individuals that interbreed freely to produce
fertile offspring. Population all the
individuals of the same species in a defined
area. All the Micropeterus salmoides in Lake Ray
Roberts. Community all the populations in a
defined area, or all the fish in Lake Ray
Roberts. Ecosystem Lake Ray Roberts, the
surrounding watershed and all the organisms there
in. Watershed the area of land that catches
precipitation that then if transported along the
surface drains to a common point.
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Historically pollution and organic enrichment
problems were synonymous. Engineers and chemists
used physical and chemical surveys to tell them
about the health of a system. Measured
parameters like pH, dissolved oxygen, BOD5, and
suspended solids. Why cant you use
physical/chemical measurements alone to tell you
about the health of an ecosystem? When
biologists became significantly involved they
tended to provide lists of species they found in
a survey. Species Lists. Head of chironomid
dichotomous key Indicator organisms Diversity
indices Eventually developed a belief that
organisms living in a system are probably the
best indicator of their health.
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In the discussion that follows the letters used
in the listing of organisms represent species A
a species, B a species, etc. The indices that
are used in the following series of slides are
examples of the kinds of indices that have been
developed. There are many variations of these
indices and each has its own inherent strengths
and weaknesses.
If you are using diversity indices you would
never represent your data by a single index!
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.
As i goes from A to J
As i goes from A to J
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For example replace J with L S0.9
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Notice this index tells us nothing about how
the Individuals are distributed among the species
present
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n
Reference Stream
N
Notice this index tells us nothing about which
species are present.
N is the total number of individuals present
while little n is the number in a given species.
For example species A has 25 individuals so n for
species A is 25.
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Study Stream
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Study Stream
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Study Stream
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Study Stream
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Reference Stream
Study Stream
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Bayou Chico
Green Book 1968, Blue Book 1972, Red Book 1976,
Gold1986, Phantom Silver Book, acid soluble
metals vs dissolved vs total
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AF Chronic value divided by the acute
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CCC criteria continuous concentration
CMC criteria maximum concentration
Silver Book??? Acid soluble metals That portion
of the metal concentration that will pass through
a 0.45 um membrane filter after the solution has
been adjusted to within a pH 1.75 0.1 for a
period of 16 hours. Factor for adjusting WQC is
0.960 or 96 of the total metal is in the acid
soluble form.
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n number of samples needed t for n-1 d.f.
alpha 0.05 based on number of
samples used to determine
variance n10, 2.262 s2 variance d difference
you wish to detect In our example n 10,
variance 100 d 2
n t2 x s2 d 2 n 128

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The State criterion in Texas for a given river
might look like the formula below where the 0.960
accounts for the acid soluble function and the
1.60 for the water effects ratio assigned to a
particular receiving system.
(0.960)(1.60)e(0.9422(ln hardness)-1.3844 For
the chronic value for 100 mg/L hardness as CaCO3
Solve the equation above with and without the
modifiers
Answer is
29.5 ug/L copper without the 0.960 and the 1.60
the standard would be 19.2 ug/L
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Note the antidegradation policy for Outstanding
National Resource Waters
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Texas Water Quality Standards for Red River and
Major Tributaries
Segment Segment Name USES USES USES USES Criteria Criteria Criteria Criteria Criteria Criteria Criteria
Number Recreation Aquatic Domestic Other Cl-1 SO4-2 TDS D.O. pH Indicator Temp.
Life Water mg/L mg/L mg/L mg/L Range Bacteria (oF)
Supply (SU) /100mL
0202 R.R. Below Lake Texoma CR H PS 375 250 1,100 5.0 6.5-9.0 126/200 93
0203 Lake Texoma CR H PS 600 300 1,500 5.0 6.5-9.0 126/200 92
0204 R.R. Above Lake Texoma CR H 2,000 1,200 6,000 5.0 6.5-9.0 126/200 93
0205 R.R. Below Pease River CR H 5,000 2,000 10,000 5.0 6.5-9.0 126/200 93
0206 R.R. Above Pease River CR H 12,000 4,000 25,000 5.0 6.5-9.0 126/200 93
0207 Lower Prarie Dog Town Fork R.R. CR H 37,000 5,300 46,200 5.0 6.5-9.0 126/200 93