Air, Water and Land Pollution
Chapter 4:
Environmental Sampling Techniques
Copyright © 2010 by DBS
Contents
• General Guidelines of Environmental Sampling Techniques
• Techniques for Sampling Various Media: Practical Approaches and
Tips
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sequence of Sampling Matrices and Analytes
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Project deals with multimedia and/or multiple parameters use following sequence:
– Collect from least to most contaminated sampling locations
– If sediment and water is being collected, collect water first to minimize effects
from suspended bed materials
– For shallow streams, start downstream and work upstream to minimize sediment
effects due to sampling disturbances
– If sampling at different depths, collect surface samples first and then proceed
deeper
– Always collect VOCs first, followed by SVOCs (e.g. pesticides, PCBs, oil, etc.),
then total metals, dissolved metals, microbiological samples, and inorganic
nonmetals
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Amount
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Minimum sample required depends on the concentration of the analytes present
Should take enough for all analyses and additional for any QA/QC work required
Heterogeneous samples generally require larger amounts to be representative of
sample variations
Taking too much sample can lead to problems with storage and transportation
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Amount - Water
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5 mL for total petroleum hydrocarbons (TPHs), 100 mL for metals, 1 L for trace
organics (pesticides)
As a general rule the minimum volume collected should be 3-4 times the amount
required for analysis (EPA, 1995)
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Amount – Soil/Sediment/Solid Waste
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For physiochemical properties (particle size, texture etc.) requires a minimum of
200 g soil
For contaminant analysis 5-100 g is sufficient
More samples are required if the goal is to detect low solubility (hydrophobic) organic
contaminants
Sample volume of waste samples should be kept small to reduce disposal costs
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Amount – Air Samples
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Volume of air required depends on the minimum chemical concentration that can be
detected and the sensitivity of the measurement
Concentration range may be unknown – sample size determined by trial and error
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Amount – Water/Sediment Samples for Toxicity Testing
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20-40 L Water for an effluent toxicity test
15 L sediment for bioaccumulation tests
8-16 L sediment for benthic macroinvertebrate assessments (EPA, 2001)
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Preservation and Storage
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Purpose – minimize physical, chemical and biological changes
3 approaches:
– Refrigeration
– Use of proper sample container
– Addition of preserving chemicals
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Preservation and Storage
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Refrigeration is a universally accepted method to slow down loss processes
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Container choice (material type and headspace) is critical to reduce
– Volatilization
– Adsorption
– Absorption
– Diffusion
– Photodegradation
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Addition of preservatives is critical to reduce losses due to chemical reactions and
bacterial degradation
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Preservation and Storage
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Preservation and Storage
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Maximum Holding Time (MHT) is the length of time a sample can be stored after
collection and prior to analysis
MHTs vary by agency
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Preservation and Storage
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American Public Health Association (APHA) MHTs:
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Sample Preservation and Storage
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Immediate: pH, temperature, salinity, DO
Within 1-2 days: careful pre-planning is required to avoid sampling on Friday,
Saturday or near holidays
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sample Containers
Water
• Glass vs. Plastics:
– Glass may leach boron and silica, metals may stick to walls
– Glass is generally used for organics and plastic for metals, inorganics and
physical properties
– For trace organics cap and liner should be made of inert materials (teflon)
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Headspace vs. no Headspace:
– No headspace is allowed for VOC samples
– 40 mL vial with a teflon-lined septum
– Oil and grease should only be half-filled in wide mouthed glass bottles
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Special containers:
– e.g. BOD/DO bottles and VOC vials
1-33
Standard Methods (1998)
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sample Containers
Soil
• Low temperature storage
• No preservatives except ethanol or sodium bisulfite for VOC analysis (Popek, 2003)
Biological
• Aluminum foil (shiny side out) and closed glass containers with inert seals or cap
liners
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sample Containers
Air
• Various collection media:
– Filter cassettes
– Adsorbent tubes
– Bags
– Canisters
Reeve, 2002
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Surface Water and Wastewater Sampling
• Grab sampler, weighted bottle sampler, Kemmerer bottle
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Groundwater Sampling
• Collected from wells using a bailer or by pumps (peristaltic and bladder)
• Samples do not come into contact with mechanical components of the pump
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Soil Sampling
• Soil depth and whether or not each soil horizon is necessary to sample are main
considerations
• Scoops and trowels, tube sampler, augers, split spoon sampler (drilling)
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Sediment Sampling
• Dredges (Ekman dredge, Peterson dredge,
Ponar dredge)
• Core samplers (Livingstone, Kullenberg, and
Mackereth)
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Sediment Sampling
• Dredges (Ekman dredge, Peterson
dredge, Ponar dredge)
• Core samplers (Livingstone, Kullenberg,
and Mackereth)
Glew et al, 2001
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Hazardous Waste
• Sludges: Dredges, scoops, trowels, buckets
• Composite liquid waste: coliwasa, Thief and Trier samplers
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Biological Sampling
• Very unique and diverse range of equipment
– Mammals - Trapping(live and kill)
– Fish - Electrofishing, gill nets, trawl nets, sein nets, minnow traps
– Benthic macroinvertebrates - Petersen and Ekman dredges
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Air Sampling
• Many direct-reading instruments for monitoring (real-time) levels
• Sampling still needed for trace level analysis (expensive and complex)
e.g. High volume total suspended particulate samplers (TSP), PM-10 samplers, PM2.5 samplers, personal sampling pumps, canister samplers
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Air Sampling
• TSP/PM-10
Question
Calculate the PM-10 concentration for the following conditions:
Filter mass gain = 0.000670 mg
Sample time = 1446 min
Initial sampler flow rate = 1.875 cm3 min-1
Final sampler flow rate = 1.807 cm3 min-1
Average flow rate = 1.841 cm/min
Volume of air = 1.841 cm3/min x 1446 min = 2662 cm3 = 2.662 x10-3 m3
PM concentration = 6.70 x 10-1 μg / 2.662 x 10-3 m3 = 251.7 μg m-3
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Air Sampling
• Summa canister, filter cassettes (particulates), impingers, diffusion tubes, sorbent
tubes, polyurethane foam (PUF)
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Air Sampling
• SUMMA canister
– Electroplated with Ni and Cr oxides to prevent adsorption of VOCs
– Low-ultra low ppt-ppb range concentrations
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Air Sampling
• Palmes diffusion tubes (PDTs)
Environmental Sampling Techniques
General Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Air
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Sampling
Polyurethane Foam Sampler (PUF)
For organics need both solid and vapor phases
Vapor cartridge is placed in-line with quartz fiber filter for
semi-volatile organics
– PUF plug
– Adsorbent resin (XAD-2)
- Pesticides
- PCB’s
- Dioxins
- PAH’s
Environmental Sampling Techniques
Techniques for Sampling
Surface Water and Wastewater Sampling
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Fresh surface waters: flowing waters, static waters and estuaries
Wastewaters: mine drainage, landfill leachate, industrial effluents etc.
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Differ in their characteristics, samples collection is specific for each
Environmental Sampling Techniques
Techniques for Sampling
Surface Water and Wastewater Sampling
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Streams and rivers – size and amount of turbulence impact representativeness of
samples
– Small streams (<20 ft wide) possible to select a location where a grab sample
represents the entire cross-section
– Larger streams and rivers multiple samples across the channel width are
required
(Also at least one vertical composite (surface, middle, bottom))
– Fast moving rivers and streams difficult to collect mid-channel sample
– Ponds and impoundments use a single vertical composite at deepest point
– Estuaries inland fresh water mixes with oceanic saline water have specific
sampling routines
Environmental Sampling Techniques
Techniques for Sampling
Groundwater Sampling
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Requires installation of a sampling well
Well must not change integrity of surrounding waters
Routine groundwater sampling tasks:
– Characterize flow
– Purge and stabilize groundwater prior to sampling
– Minimize cross-contamination due to well materials and sampling devices
Environmental Sampling Techniques
Techniques for Sampling
Groundwater Sampling
Groundwater Flow Direction
• Hydraulic gradient – slope of water table measured from high point to low point
across a site
• Flow is proportional to gradient, in direction of gradient
• Hydraulic head is a vertical measurement from sea level to the water table
Hydraulic gradient = Difference in Hydraulic Head/Distance between two wells
Environmental Sampling Techniques
Techniques for Sampling
Groundwater Sampling
Well Purging
• Used to remove stagnant water in the well borehole and sandpack for representative
sample
• USGS stabilization parameters:
– DO ± 0.3 mg/L
– Turbidity ± 10 % (for samples > 10 NTUs)
– Specific conductivity ± 3%
– ORP ± 10 mV
– pH ± 0.1 unit
– Temp. ± 0.1 oC
Environmental Sampling Techniques
Techniques for Sampling
Groundwater Sampling
Cross Contamination
Environmental Sampling Techniques
Techniques for Sampling
Soil and Sediment Sampling
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Soil sampling at shallow depths relatively easy
Sediments are treated similarly with regard to post-sampling pretreatment
(homogenizing, splitting, drying and sieving)
Horizontal (grab) or vertical (core) sampling
Composite sampling is common (except for VOCs)
Nonsoil/sediment or nonsieved materials should be noted and not discarded
Sediments from lakes, ponds and reservoirs should be collected at the deepest point
(contaminants tend to concentrate in fine grained material in depositional zones)
Environmental Sampling Techniques
Techniques for Sampling
Hazardous Waste Sampling
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Sources: drums, storage tanks, lab packs, impoundments, waste piles, debris
Sampling approach varies considerably
Requires HAZWOPER training
Drums etc.
• Research documentation (labels etc.) for health and safety precautions
• Use proper protective equipment
• Unknown wastes should be opened remotely
• Should not be moved since some chemicals are shock-sensitive, explosive or
reactive
• Sample each phase separately
Environmental Sampling Techniques
Techniques for Sampling
Hazardous Waste Sampling
Waste Impoundments
• Contaminants will be stratified by depth, also horizontally from point of entry
Surface Sampling
• Wipe, chip and dust sampling
Environmental Sampling Techniques
Techniques for Sampling
Biological Sampling
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Biological samples difficult to collect
Species availability - Insufficient sample size may result in invalid statistical inference
Sampling protocol needs to account for size differences between species, tissue
differentiations, growth stage, and habitat
Susceptible to decomposition of organic analytes
Environmental Sampling Techniques
Techniques for Sampling
Air and Stack Emission Sampling
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Ambient air, indoor workplace air and stack/emission exhausts
Concentrations for most atmospheric pollutants are very low
Analysis of organic compounds requires huge volumes
Large variation in analyte concentration due to changes in meteorlogy
Meteorological parameters must be noted
Environmental Sampling Techniques
Techniques for Sampling
Air and Stack Emission Sampling
Indoor Air
• Ventilation systems can alter air flow and add pollutants
• Sampler location will influence the results obtained
• Household chemicals can add compounds to the air
References
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Bodger, K. (2003) Fundamentals of Environmental Sampling, Government Institutes,
Rockville, MD.
Cowgillum (1988) Sampling Waters: The Impact of sample variability on planning and
confidence Levels, In: Keith, L.H. (1988) Principles of Environmental Sampling. American
Chemical Society, Washington, DC.
US EPA (1995) Superfund Program Representative Sampling Guidance: Volume 2, Air
(Short-Term Monitoring), Interim Final, EPA 540-R-95-140, OSWER Directive 9360.4-09,
PB96-963206, December 1995.
US EPA (2001) Methods for Collection, Storage and Manipulation of Sediments for
Chemical and Toxicological Analyses: Technical Manual. EPA-823-B-01-002, October
2001.
Keith, L.H. (1988) Principles of Environmental Sampling. American Chemical Society,
Washington, DC.
Keith, L.H. (1991) Environmental Sampling and Analysis: A Practical Guide. Lewis
Publishers, Boca Raton, Fl.
Reeve, R.N. (2002) Introduction to Environmental Analysis. Wiley.
Popek, E.P. (2003) Sampling and Analysis of Environmental Chemical Pollutants: A
Complete Guide. Academic Press, San Diego, CA.
Questions
2. Which of the following should be monitored in the field: (a) acidity, (b) DO, (c) pesticide,
or (d) hardness.
5. Explain why: (a) HNO3 rather than other acids is used for metal preservation; (b) amber
bottles are preferred for PAHs; (c) zero-head space container for groundwater samples
collected for tetrachloromethylene analysis.
8. Explain why glass containers are generally used for organic compounds whereas PVCtype containers are used for inorganic compounds.
11. The maximum holding time for metal analysis (excluding Cr6+ and dissolved Hg) after
acidification to pH < 2 is most likely: (a) 6 h, (b) 6 days, (c) 6 weeks, (d) 6 months.
18. Suppose you were recently hired as an entry level Environmental Field specialist in a
new firm dealing with groundwater remediation where a sampling and analysis plan (SAP)
has not been developed. You are assigned as an assistant to a Project Manager for
groundwater sampling, and are asked to do the office preparation for this sampling event.
Make a list of items you may need in the field. Exclude containers and sampling tools in
the list.