Transcript Mod10/11-A Stream Surveys - Water Quality Assessment

Module 10/11
Stream Surveys
Stream Surveys – February 2004
Part 1 – Water Quality Assessment
Objectives
Students will be able to:
 describe techniques used to determine dissolved oxygen.
 list factors that influence high turbidity and suspended
solids in streams.
 explain methods used to determine total suspended solids.
 evaluate the relationship between total suspended solids
and turbidity.
 identify methods used to determine water clarity in streams.
 assess habitat degradation by determining the degree of
sediment embeddedness in a stream.
 analyze the impact of dissolved salts, pH and temperature
on streams.
 describe accepted sampling methods used in stream
surveys.
Developed by:
Updated:
U5-m21a-s2
Stream assessments
 Water quality
 Habitat
 Hydrologic
 Biological
 Watershed
Developed by:
Updated:
U5-m21a-s3
Water quality parameters
Developed by:
Updated:
U5-m21a-s4
Water Quality Parameters
 Dissolved oxygen
 Suspended sediments (TSS) and turbidity
 Specific conductivity (EC)
 alkalinity
 pH
 Temperature
 Major ions
 All of these parameters are presented in
greater detail in Module 9 – Lake surveys
Developed by:
Updated:
U5-m21a-s5
Dissolved Oxygen
Developed by:
Updated:
U5-m21a-s6
DO – importance and reporting
 Oxygen is produced during photosynthesis
and consumed during respiration and
decomposition.
 Generally < 3 mg/L is stressful to aquatic life.
 Units of measurement are:
 Concentration: mg/L = ppm; concentrations range 0.0 to
20 mg/L
 % saturation – used to determine if water is fully
saturated with oxygen at a particular temperature
Developed by:
Updated:
U5-m21a-s7
DO – techniques
 Probe types and measurement techniques:
 Winkler titration
 Amperometric (polarographic) method, most
commonly used
http://www.lumcon.edu/education/StudentDatabase/gallery.asp
Developed by:
Updated:
U5-m21a-s8
DO – probes
 Most common sensor is the temperature
compensated polarographic membrane-type
(amperometric)
 Temperature sensitive (but virtually all are
compensated).
 The probes actually consume O2 as they work so
measurements require moving water using either
a built-in stirrer (typical in multiparameter sondes
and BOD probes) or “hand jiggling” during the
measurement.
 in situ sensors are prone to fouling by
algal/bacterial slimes and by silt in streams.
Developed by:
Updated:
U5-m21a-s9
DO probes and meters
 The WOW units use either Hydrolab or YSI
multiprobe datasounds, but there are many others
Developed by:
Updated:
U5-m21a-s10
Sedimentation/siltation
 Excessive sedimentation in streams and rivers is
considered to be a major cause of surface water
pollution in the U.S. by the USEPA
Developed by:
Updated:
U5-m21a-s11
Measures of sedimentation
 Suspended sediments
 Turbidity
 Embededdness
Developed by:
Updated:
U5-m21a-s12
High turbidity and suspended solids
 Caused by many factors including:
 soil erosion
 domestic and industrial wastewater discharge
 urban runoff
 flooding
 algal growth due to nutrient enrichment
 dredging operations
 channelization
 removal of riparian vegetation and other stream
bank disturbances
Developed by:
Updated:
U5-m21a-s13
Total suspended solids and turbidity
 Both are indicators of the amount of solids
suspended in the water
 Mineral (e.g., soil particles)
 Organic (e.g., algae, detritus)
 TSS measures the actual weight of material per
volume of water (mg/L)
 Turbidity measures the amount of light
scattered
 Therefore, TSS allows the determination of an
actual concentration or quantity of material
while turbidity does not
Developed by:
Updated:
U5-m21a-s14
Measuring TSS
1. Filter a known amount of
water through a pre-washed,
pre-dried at 103-105 oC, preweighed (~ + 0.5 mg) filter
2. Rinse, dry and reweigh to
calculate TSS in mg/L (ppm)
3. Save filters for other analyses
such as volatile suspended
solids (VSS) that estimate
organic matter
Developed by:
Updated:
U5-m21a-s15
Total suspended solids - method
What type of
filter to use?
Developed by:
Updated:
U5-m21a-s16
Total suspended solids
Calculate TSS by using the equation below
TSS (mg/L) = ([A-B]*1000)/C
where
A = final dried weight of the filter (in milligrams = mg)
B = Initial weight of the filter (in milligrams = mg)
C = Volume of water filtered (in Liters)
Developed by:
Updated:
U5-m21a-s17
TSS
 Range of results and what the results mean
 Example:
Suspended solids concentrations at Slate Creek
WA average 150.8 mg/l with a range of 50 to 327
mg/l. It is generally desired to maintain total
suspended solid concentrations below 100 mg/l.
Developed by:
Updated:
U5-m21a-s18
Measuring turbidity
 Turbidity measures the
scattering effect
suspended particles have
on light
 inorganics like clay and silt
 organic material, both fine
and colored
 plankton and other
microscopic organisms
 Transparency or turbidity
tubes
Developed by:
Updated:
Even small amounts of wave action can
erode exposed lakeshore sediments, in
this case a minepit lake from northeastern
Minnesota. Guess the mineral mined here.
U5-m21a-s19
Turbidity
 Field turbidity measurements are made with
 Turbidimeters (bench meter for discrete samples)
 Submersible turbidity sensors (Note - USGS
currently considers this a qualitative method)
Hydrolab turbidity probe
Developed by:
Updated:
U5-m21a-s20
Turbidity - Nephelometric optics
 Nephelometric turbidity estimated by the
scattering effect suspended particles have on
light
 Detector is at 90o from the light source
Developed by:
Updated:
U5-m21a-s21
Turbidity – units and reporting
• Nephelometric Turbidity Units (NTU) standards
are formazin or other certified material
• JTU’s are from an “older” technology in which
a candle flame was viewed through a tube of
water
1 NTU = 1 JTU (Jackson Turbidity Unit)
Developed by:
Updated:
U5-m21a-s22
Turbidity - standards
 Top - a range of
formazin standards
 Bottom –the same
NTU range using a
clay suspension
Developed by:
Updated:
U5-m21a-s23
Turbidity
 Range of results and what the results mean
 Ex: Salmon Creek Watershed (OR/WA border)
TMDL for turbidity is:
"Turbidity shall not exceed 5 NTU over
background turbidity when the background
turbidity is 50 NTU or less. Or more than a 10%
increase in turbidity when the background
turbidity is > 50 NTU”.
Developed by:
Updated:
U5-m21a-s24
How do turbidity and TSS relate?
Developed by:
Updated:
U5-m21a-s25
TSS vs Turbidity relationship
TSS
Turbidity
Yearly
average
Summer range
(May-Oct)
Winter range
(Nov-Apr)
Cedar River
3.6
1.1
0.6-5.0
0.4-1.2
3.5-6.2
1.0-2.0
Newaukum Ck
5.7
2.4
1.6-5.1
0.7-1.5
7.5-8.8
3.1-4.0
Springbrook Ck
19.8
22.0
8.0-26.0
13.0-44.0
6.7-44.0
13.0-35.0
Developed by:
Updated:
U5-m21a-s26
Water clarity – transparency tubes
Developed by:
Updated:
U5-m21a-s27
Water clarity – transparency tubes
• Used in streams, ponds,
wetlands, and some
coastal zones
 Analogous to secchi
depth in lakes: a measure
of the dissolved and
particulate material in the
water
Developed by:
Updated:
U5-m21a-s28
Water clarity – transparency tubes
 Useful for shallow water or fast
moving streams bodies where
a secchi would still be visible
on the bottom
• It is a good measure of
turbidity and suspended
sediment (TSS)
• Used in many volunteer
stream monitoring programs
Developed by:
Updated:
U5-m21a-s29
Horizontal secchi
 Newer method – all-black disk viewed
horizontally
Developed by:
Updated:
U5-m21a-s30
Embeddedness



Measure of fine sediment deposition in the
interstitial spaces between rocks
High embeddedness values indicate habitat
degradation
Visual assessment used to estimate the
degree of embeddedness
Developed by:
Updated:
U5-m21a-s31
Embeddedness – cont.
 The stream-bottom
sediments to the top right
provide spaces for fish to
lay eggs and for
invertebrates to live and
hide.
 Excess erosion has
deposited fine grained
sediments on the stream
bottom to the bottom right.
There are no spaces
available for fish spawning
or for invertebrate habitat.
Developed by:
Updated:
U5-m21a-s32
Embededdness – visual assessment

Embeddedness: General guidelines





0% = no fine sediments even at base of top
layer of gravel/cobble
25% = rocks are half surrounded by sediment
50% = rocks are completely surrounded by
sediment but their tops are clean
75% = rocks are completely surrounded by
sediment and half covered
100% = rocks are completely covered by
sediment
Developed by:
Updated:
U5-m21a-s33
Specific electrical conductivity = EC25
Developed by:
Updated:
U5-m21a-s34
EC25 - importance
 Cheap, easy way to characterize the total
dissolved salt concentration of a water sample
 For tracing water masses and defining mixing
zones
 Groundwater plumes
 Stream flowing into another stream or into a lake or
reservoir
Developed by:
Updated:
U5-m21a-s35
EC25 – units and reporting
Principle of measurement
• A small voltage is applied between 2 parallel
metal rod shaped electrodes, usually 1 cm apart
• Measured current flow is proportional to the
dissolved ion content of the water
• If the sensor is temperature compensated to
25oC, EC is called “specific” EC (EC25)
Developed by:
Updated:
U5-m21a-s36
EC25 - units
 What in the world are
microSiemens per centimeter (µS/cm)?
• Units for EC and EC25 are mS/cm or μS/cm
@25oC. The WOW site reports it as EC @25oC (in
μS/cm).
• Usually report to 2 or 3 significant figures (to + ~ 15 μS/cm)
 More details can be found in Module 9
Developed by:
Updated:
U5-m21a-s37
EC25
 EC25 values in streams reflect primarily a combination
of watershed sources of salts and the hydrology of the
system
 wastewater from sewage treatment plants and
industrial discharge
 wastewater from on-site wastewater treatment and
dispersal systems (septic systems and drainfields)
 urban runoff
 agricultural runoff
 acid mine drainage
 atmospheric inputs
Developed by:
Updated:
U5-m21a-s38
Snowmelt runoff example
Developed by:
Updated:
U5-m21a-s39
pH
Image courtesy of USGS at http://www.usgs.gov/
Developed by:
Updated:
U5-m21a-s40
pH – importance in aquatic systems
 The pH of a sample of water is a measure of the
concentration of hydrogen ions.
 pH determines the solubility and biological
availability of chemical constituents such as
nutrients (phosphorus, nitrogen, and carbon)
and heavy metals (lead, copper, cadmium, etc.).
Developed by:
Updated:
U5-m21a-s41
pH - reporting
 pH can be measured electrometrically or
colorimetrically (pH paper) BUT ONLY the
former technique is approved by the EPA and
USGS for natural waters.
 The electrometric method uses a hydrogen ion
electrode.
 pH meters require extensive care in handling
and operation.
 Report to the nearest 0.1 standard pH unit
Developed by:
Updated:
U5-m21a-s42
pH – probes
 Field probe types:
 Combination probes (e.g.YSI)
 Less expensive; more rugged design
 Less precise
 Shorter life because reference solution cannot be
replenished
 Separate reading and reference electrodes (e.g.,
Hydrolab)
 Costs more
 More precise; faster response time
 Allows user maintenance; Teflon junction and electrolyte
can be replaced
Developed by:
Updated:
U5-m21a-s43
pH – probes
 Or, alternatively, a bench or hand-held meter
and probe can be used in a fresh subsample if
you don’t have a field meter with a pH probe.
Developed by:
Updated:
U5-m21a-s44
Temperature
Developed by:
Updated:
U5-m21a-s45
Temperature importance
 Temperature affects:
 the oxygen content of the water (oxygen levels
become lower as temperature increases)
 the rate of photosynthesis by aquatic plants
 the metabolic rates of aquatic organisms
 the sensitivity of organisms to toxic wastes,
parasites, and diseases
Developed by:
Updated:
U5-m21a-s46
Temperature measurement - probes
 Types of probes
 Liquid-in-glass
 Thermistor: based on measuring changes in electrical
resistance of a semi-conductor with increasing
temperature.
thermistor on a YSI sonde
Developed by:
Updated:
U5-m21a-s47
Temperature changes
 Causes of temperature change include:
 weather
 removal of shading streambank vegetation,
 impoundments (a body of water confined by a
barrier, such as a dam)
 discharge of cooling water
 urban storm water
 groundwater inflows to the stream
Developed by:
Updated:
U5-m21a-s48
Temperature changes - continued
Graph showing
factors that
influence
stream
temperature,
from Bartholow
(1989).
Developed by:
Updated:
U5-m21a-s49
Temperature criteria – example
Here’s an example of a temperature TMDL for a California
stream
Developed by:
Updated:
U5-m21a-s50
Temperature criteria – cont.
Developed by:
Updated:
U5-m21a-s51
Temperature – summer rain storm
Bump in stream temp (and
turbidity)
Summer rainfall event
Developed by:
Updated:
U5-m21a-s52
Other Water Quality Parameters





Nutrients – nitrogen and phosphorus
Fecal coliforms
Biochemical oxygen demand (BOD)
Metals
Toxic contaminants
 Details on analyzing these parameters are in
Module 9 – Lake Surveys
Developed by:
Updated:
U5-m21a-s53
Fecal coliforms
 Pathogens are number one
Developed by:
Updated:
U5-m21a-s54
Water sampling - microbes
 Sterile technique:
 Containers must be
sterilized by autoclaving
or with gas used to kill
microbes
 Take care not to
contaminate the
container
 Water samplers should
be swabbed with 70 %
alcohol
Developed by:
Updated:
U5-m21a-s55
Bacteria – E. coli and fecal coliforms
 Fecal bacteria are used as indicators of
possible sewage contamination
 These bacteria indicate the possible presence
of disease-causing bacteria, viruses, and
protozoans that also live in human and animal
digestive systems
 E. coli is currently replacing the fecal coliform
assay in most beach monitoring programs
See Module 9 for a detailed discussion of
measuring pathogens
Developed by:
Updated:
U5-m21a-s56
Water sample collection – grab samples
Grab samples for fecal
coliforms are taken with
sterile containers
Developed by:
Updated:
U5-m21a-s57
Water sample collection
 General considerations:
 Sample in the main
current
 Avoid disturbing bottom
sediments
 Collect the water sample
on your upstream side
 A detailed discussion on how to manually collect stream
and river water can be found in the USGS Field Manual
Chapter 4: Collection of Water Samples
Developed by:
Updated:
U5-m21a-s58
Suggested sample volumes
Analyte
chlorophyll
Volume needed
>500 mLs
TSS
Often > 1 L
total phosphorus
total nitrogen
anions
200 to 500 mLs
Dissolved nutrients
Total and dissolved carbon
~ 100mLs
~60 mLs
Metals
~60 mLs
color, DOC
~60 mLs
Developed by:
Updated:
U5-m21a-s59
Stream sampling– sample labeling
 An unlabeled sample
may as well just be
dumped down the
drain.
Developed by:
 Use good labels not
masking tape, etc.
Poor labels often fall
off when frozen
samples are thawed.
 Use permanent
markers NOT ball
point pens, pencils in
a pinch
Updated:
U5-m21a-s60
Lake sampling
Stream
sampling
– sample
– sample
labeling
labeling
 A simple sample label with the minimum amount of
information needed…
project
WOW
Tischer Creek 7/26/02
Reach 3
Site,
date,
location
RAW, frozen
Sample processing and
preservation info
Often, much more information may be needed by the laboratory
performing your analyses. You will also need to supply a chain of
custody form.
Developed by:
Updated:
U5-m21a-s61
Automated stream monitoring
Developed by:
Updated:
U5-m21a-s62
Water sampling - automated
 Automated stream
sampling stations
provide continuous
monitoring of a variety of
parameters
 These units are capable
of both collecting water
samples and measure
various water quality
parameters
Developed by:
Updated:
U5-m21a-s63
Automated stream samplers
 Flow weighted composites
 Flow weighted discrete
 Sampling triggered by predetermined set point
such as:
 Flow
 Precipitation
 Any other parameter measured by in-stream
sensors
Developed by:
Updated:
U5-m21a-s64
Automated sampling – Duluth Streams
 These stream monitoring units are not “state of the art”
but provide near real-time data for delivery into the data
visualization tools
Developed by:
Updated:
U5-m21a-s65