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Surface Water and Sediment
Characteristics
Surface Water
• Discussion restricted to freshwater
• Lentic and Lotic systems
Lentic Systems• Lakes
• Ponds
• Impoundments
• Basins
• Oxbows
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Lentic Systems
• Shoreline pools and mudflats
Lentic Systems• Open water areas of
wetlands
• Bog and fen wetlands– A bog
• a wetland that accumulates peat, a deposit of dead plant material—often mosses, and in a
majority of cases, sphagnum moss
• Acidic water chemistry
– Fens• a wetland usually fed by mineral-rich surface
water or groundwater.
• pH neutral or alkaline water chemistry, with
relatively high dissolved mineral levels but few other plant nutrients.
• They are usually dominated by grasses and sedges, and typically have brown mosses
Lentic Systems
• natural and man-made
• depth varies considerably
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Lotic Systems
• rivers
• streams
• creeks and
brooks
• ditches
• drainageways
Lotic Systems
• mid-sized rivers have pool and riffle
complexes that alternate, runs and glides
also
• mid-sized and larger rivers meander within
their floodplain, unless ‘managed’ by man
Water Quality
• lentic: oligotrophic vs
eutrophic
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Water Quality
• lotic: head waters
versus downstream
areas
Water Quality
• Relationship to groundwater
– Discharge and recharge
• Water column is location of plankton and
nekton communities
• Chemical characteristics, physical
characteristics, and biological diversity are
indicators of water quality
Water Quality
• Possible contaminants are many:
– metals
– VOCs, SVOCs
– GROs and DROs, oil and grease
– pesticides
– pathogens
– invasive species
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Water Quality – Sampling Considerations
• Lentic systems
tend to be
heterogeneous
vertically and
horizontally
– thermocline
– weight of
contaminants
– zones based
on inflow
Water Quality – Sampling Considerations
• Lotic systems tend to be
more homogeneous
– vertically but not
necessarily horizontally
– except for large rivers
which take on some
characteristics of lentic
systems
• Both lotic and lentic vary
temporally
Sediments
• The ‘bottom’ of lentic and lotic systems
• Rock, sand, silts, detritus, clayey
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Sediments
• Depositional areas
around curves and
slow moving pool
areas tend to
accumulate
sediments, scouring
areas lose
Sediment Quality
The result of
deposition from
the ‘water
column,’
underlying
geology, and
biological
activity
Sediment Quality
• Deposition sources
include materials of
– Biological origin
– Urban stormwater run
off
– Industrial and
municipal discharge
– Erosional materials
• Heavier substances
accumulate
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Sediment Quality
• Location of a community of ‘benthic’
organisms:
– periphyton
– bacteria
– fungi
– microscopic worms
– macroinvertebrates
– fish
Sediment Quality
Sediments are both dynamic and historic
• upper layers subject to resuspension
• lower layers tend to stay put and reveal history of deposition
• temporal variation less than surface water
Why Sample?
• Determine ‘use’
– Chemical characteristics
– Biologic communities
– Available habitat
• Characterize water quality
• Support permit applications
• Locate and delineate pollution release
and/or impact
• Monitor clean up activities
• Other reasons?
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Sampling Methods
• Surface waters
– Direct filling of sample
bottle
– Dipper
– Stainless steel bucket
– Bottle sampler
– Kemmerer and Van
Dorn samplers
Sampling Methods
Sediment Surfaces
• Ponar and Eckman
dredges
– tend to stir up the
bottom that may result
in some loss of fines
from sample
– takes 1-3 l of sample
depending on size
Sampling Methods
Sediment
Surfaces
• Ponar and
Eckman
dredges
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Sampling Methods
Sediment coring devices
• maintains sediment layering of inner core
• takes up to 1.5 l of sample
Decontamination
• Soap and water scrub (alconox and brushes, container)
• Water rinse
• Rinses in acid and/or solvent followed by water rinse
• Deionized water rinse
• Protect against recontamination between sites
• Rinse in site water at next site
Sample PreservationCertain parameters done in the field
• likely to change upon collection
– Temp, DO, pH, conductivity, flow, turbidity
Preservation needs: a function of analyte and analytical method
Field preparation
• Addition of fixatives
• Addition of stablizers
• Addition of dechlorinators
• Filtration followed by addition of stabilizers
• Cooling
• Freezing, uncommon
Lab preparation
• More filtering or fixation may be needed
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Drinking Water
Sources
• Potable Wells
• Raw influent water
• Finished water before leaving plant
• Finished water arriving at tap – required
surveillance for PWS
SamplingFirst draw samples
• Water has been sitting in plumbing
• Possible lead and copper leaching from delivery lines and fixtures
Flushed system
• Measures contaminants in finished water and those picked up on the way to the tap
– VOCs
– Bacteria – coliforms
– Pesticides and other organics
Stormwater
Requirement for “facilities who (1) discharge
to waters of the United States or a
separate municipal sewer system and (2)
engage in industrial activities, including
construction activity of over 5 acres of
land”
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Stormwater
First Flush
• Initial runoff from a site/catchment
following the start of a rainfall event
• As runoff travels over a catchment it will
pick up or dissolve pollutants and the "first
flush" portion of the flow may be the most
contaminated as a result
Effluents and Instream Samples
for Toxicity Tests
Point sources
• Require regular periodic sampling for
toxicity-based on permit requirements and
compliance history
• Industrial discharge
• Municipal discharge
Effluents – Sampling Locations
Final effluent
• End of pipe at or near
discharge point into
water way or entry
into sewer system
• Point before end of
pipe that provides
safer access
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Effluents – Sampling Locations
Final effluent
• Manway
• Flume
Effluents – Sampling
Locations• Pre or post
chlorination
Dechlorination Point at WWTP
Sodium Thiosulfate
Sprayers
Purpose for Sampling
1. Provide samples to initiate laboratory
toxicity tests
2. Analytical laboratory samples for
– conventional pollutants
– priority pollutants
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Collecting Samples for Toxicity
Tests - Effluent
• Almost always a
composite sample
using an automatic
sampling device
– 24-hour time
composite very
common
– flow proportional
composite may be
called for
Collecting Samples for Toxicity
Tests - Effluent• Chlorinated effluent
– collect before the point of chlorination
if possible
– in some cases, the
chlorinated/dechlorinated sample is
taken at the outfall
• Keep samples cool during
collection
• All samples to be collected with
no headspace
• Completed samples may be
transferred to suitable container
for shipment Refrigerated sampler
Collecting Samples for Toxicity
Tests - Effluent
• Effluent toxicity
analysis - sample into
Cubitainers® -
“industry standard”
– One-gallon (typical)
polyethylene plastic
collapsible containers
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Collecting Samples for Toxicity
Tests - Effluent
Volume needed
• Varies - one gallon typical
– more or less depending on type of test to be performed
• Acute test - single sampling event
• Chronic test - three sampling events in seven-day period
Collecting Samples for Toxicity
Tests – Supporting Samples
Upstream or Up-Current
• Grab outside of the zone of influence
• Wade and fill Cubitainers directly
• Serves as diluent or simple background
control in testing
• Volume needed depends on use in test
Collecting Samples for Toxicity
Tests – Supporting Samples
Near-field down-
current sample
Submerged outfall sampled
just before entry
Far-field down-current
grab
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Collecting Samples for Toxicity
Tests – Supporting Samples
Near-field down-current sample
• A grab within the mixing zone
• collected in the middle of the effluent plume– five times the water depth at the point of discharge down-
current or if the water is greater than 4 feet deep, 20 feet down-current from the outfall
• effluent plume determined by temperature, conductivity, visual observation, dye study or other method
• No acute toxicity allowed here
Collecting Samples for Toxicity
Tests – Supporting Samples
Far-field downcurrent grab
• Represents complete mixing of effluent with receiving water
– if rapid and complete mixing, collect midstream at distance five times the width at the point of discharge
– if mixing is not rapid and complete, collect mid-plume down current from the outfall at a point five times the stream width at the point of discharge
• for big rivers 2,500 feet down current
– boat may be needed
• document effluent plume as before
• No chronic toxicity allowed here