Transcript Lecture 5 ppt

“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?
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.
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 can’t 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.
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!
.
Stream of Concern
Reference Stream
As i goes from A to J
As i goes from A to J
For example replace J with L
S=0.9
Notice this index tells us nothing about how the
Individuals are distributed among the species present
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.
Study Stream
Study Stream
Study Stream
Study Stream
Reference Stream
Study Stream
Bayou Chico
Green Book 1968, Blue Book 1972, Red Book 1976, Gold1986,
Phantom Silver Book, acid soluble metals vs dissolved vs total
AF = Chronic
value divided
by the acute
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.
n = t 2 x s2
d2
n = 128
n = number of samples needed
t for n-1 d.f. alpha = 0.05 based on number of
samples used to determine
variance n=10, 2.262
s2 = variance
d = difference you wish to detect
In our example n = 10, variance = 100
d=2
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
Note the antidegradation policy for Outstanding National Resource
Waters
Texas Water Quality Standards for Red River and Major Tributaries
Segment Segment Name
Number
R.R. Below Lake
0202 Texoma
0203Lake Texoma
R.R. Above Lake
0204 Texoma
R.R. Below Pease
0205 River
R.R. Above Pease
0206 River
Lower Prarie Dog
0207 Town Fork R.R.
USES
Recreation Aquatic Domestic Other Cl-1
Life
Water
mg/L
Supply
CR
CR
H
H
CR
PS
PS
SO4-2
mg/L
TDS
mg/L
Criteria
D.O.
pH
Indicator Temp.
mg/L
Range Bacteria (oF)
(SU)
#/100mL
375
600
250
300
1,100
1,500
5.0
5.0
6.5-9.0 126/200
6.5-9.0 126/200
93
92
H
2,000
1,200
6,000
5.0
6.5-9.0 126/200
93
CR
H
5,000
2,000 10,000
5.0
6.5-9.0 126/200
93
CR
H
12,000
4,000 25,000
5.0
6.5-9.0 126/200
93
CR
H
37,000
5,300 46,200
5.0
6.5-9.0 126/200
93