5. discussion review method
TRANSCRIPT
DISCUSSION -
REVIEW
METHOD
CN505/DCN5051 -ENVIRONMENTAL PROJECT 1
RESEARCH METHODOLOGY
RESEARCH HYPOTHESIS
Operationalization
• Operationalization is the process of strictly defining variables into
measurable factors. The process defines fuzzy concepts and
allows them to be measured, empirically and quantitatively.
• Operationalization also sets down exact definitions of each
variable, increasing the quality of the results, and improving the
robustness of the design.
Introduction to Validity
Validity: the best available approximation to the
truth of a given proposition, inference, or conclusion
Introduction to Validity (cont..)
Introduction to Validity (cont..)
SamplingSampling is the process of selecting units (e.g., people,
organizations) from a population of interest so that by
studying the sample we may fairly generalize our results back
to the population from which they were chosen.
Types of Sampling
Sampling and Analysis of Waters, Wastewaters, Soils and Wastes
Steps needed in any environmental monitoring
program should include, but are not limited to:
i. determining the objectives of the monitoring program
ii. selecting and accurately analyzing chemical,
physical or biological indicators which are relevant to the objectives of the monitoring program
iii. selecting the appropriate sampling equipment
Sampling and Analysis of Waters, Wastewaters, Soils and Wastes
iv. mapping out the location and site to
determine the number and type of samples needed
v. obtaining a representative sample or samples
vi. accurately recording site observations and
measurements
vii. appropriate labelling, preserving, storing and transporting of sample for analysis
viii. reporting results accurately and completely
ix. providing informed interpretation.
Sample Handling and Preparation Checklist
‰ Determine precautions to be taken in the field.
‰ Observe all safety precautions during sampling,
in particular taking care to avoid contact with contaminated samples.
‰ Ensure sample container selection, preservation
procedures and holding times stipulated here are followed.
‰Where reagents are added to the sample or the
sample is filtered, ensure that blanks are collected for analysis.
Sample Handling and Preparation Checklist
‰Ensure samples are not contaminated in the field,
or in transit and are secured during transport to avoid damage.
Complete the identification and description of
sample on the submission sheet, including any treatment of the sample undertaken in the field.
‰ Transport sample(s) to laboratory as soon as possible
‰ Preserve and/or analyze samples as soon as possible
Sampling techniqueSampling procedure from dug wells and similar sources
Sampling procedure from a tap
or pump outlet
Sampling procedure from a
watercourse or reservoir
Environmental Sampling Techniques-
General Guidelines of Environmental Sampling
Techniques
Sequence of Sampling Matrices and Analyses
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
Minimum sample required depends on the
concentration of the analyses 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 Sample Amount –
Soil/Sediment/Solid Waste
• 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)
• 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 Sample Amount –
Water/Sediment Samples for
Toxicity Testing
• 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
• 20-40 L Water for an effluent
toxicity test
• 15 L sediment for
bioaccumulation tests
• 8-16 L sediment for benthic
macro invertebrate
assessments (EPA, 2001)
Environmental Sampling Techniques General Guidelines of Environmental Sampling Techniques
Sample Preservation and Storage
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
Refrigeration is a universally accepted method to slow down loss
processes
Container choice (material type and headspace) is critical to
reduce
Volatilization
Adsorption
Absorption
Diffusion
Photodegradation
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
Maximum Holding Time (MHT) is the length of time a sample can
be stored after collection and prior to analysis
MHTs vary by agency
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
Sample Preservation and Storage
American Public Health Association (APHA) MHTs:
Environmental Sampling TechniquesGeneral 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)
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
Special containers:
e.g. BOD/DO bottles and VOC vials
1-33
Standard Methods (1998)
Environmental Sampling TechniquesGeneral Guidelines of Environmental Sampling Techniques
Selection of Sample Containers
Soil Biological
• Low temperature storage
• No preservatives except
ethanol or sodium bisulfite
for VOC analysis (Popek,
2003)
• Aluminum foil (shiny side
out) and closed glass
containers with inert seals
or cap liners
Environmental Sampling TechniquesGeneral Guidelines of Environmental Sampling Techniques
Selection of Sample Containers
Air
Various collection media:
Filter cassettes
Adsorbent tubes
Bags
Canisters
Reeve, 2002
Environmental Sampling TechniquesGeneral Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment
Surface Water and Wastewater Sampling
Grab sampler, weighted bottle sampler,
Kemmerer bottle
Environmental Sampling TechniquesGeneral 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 TechniquesGeneral 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 TechniquesGeneral 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 TechniquesGeneral 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 TechniquesGeneral 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 TechniquesGeneral 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 TechniquesGeneral 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, PM-2.5 samplers, personal sampling pumps,
canister samplers
Environmental Sampling TechniquesGeneral Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment -Air 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)
SUMMA canister
• Electroplated with Ni and Cr
oxides to prevent adsorption of
VOCs
• Low-ultra low ppt-ppb range concentrations
Environmental Sampling TechniquesGeneral Guidelines of Environmental Sampling Techniques
Selection of Sampling Equipment -Air Sampling
Palmes diffusion tubes (PDTs) TSP/ PM10
Environmental Sampling Techniques -Techniques for Sampling
Surface Water and Wastewater Sampling
Fresh surface waters: flowing waters, static waters and estuaries
Wastewaters: mine drainage, landfill leachate, industrial effluents etc.
Differ in their characteristics, samples collection is specific for each
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
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
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 SamplingCross Contamination
Environmental Sampling Techniques - Techniques for Sampling
Soil and Sediment Sampling
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)
Non-soil/sediment or no sieved 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
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
Biological Sampling
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 analyses
Environmental Sampling Techniques - Techniques for Sampling
Air and Stack Emission Sampling
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 analyze concentration due to changes in
meteorology
Meteorological parameters must be noted
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
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.