Water Quality Measurement and Interpretation

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Water Quality Measurement and Interpretation

• Russ Frydenborg
• Environmental Assessment Section
• Bureau of Laboratories

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Why do we sample water?

• Protect physical, chemical, and biological
  integrity (Clean Water Act)
• Water quality standards, 62-302 FAC
• Interpret biological community results

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Environmental Measurement is a Complicated Process

• Data Quality is Dependent on How Well the Process
  Works

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• Proper location
• Correct equipment
• or bottles
• Prevent contamination
• Proper preservation

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• Sample log-in tracking (1000s per day)
• Preparation steps
• Holding times
• Pairing sample with result and QC elements

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• Calibration maintenance
• Blank contamination
• Spike recovery
• Detection limits
• Statistically, QC failures occur routinely

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How Do You Measure an Analyte?

• Collect sample
• Prepare sample
• Measure analyte
• Compare analyte measurement to known standard

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Typical Measurement Systems Utilized

• Chromatography (separation)
• Spectroscopy (absorption, emission of
  electromagnetic radiation)

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Chromatography Separation
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Chromatography
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SpectroscopyA properly prepared sample absorbs
or emits light at specific wavelengths
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To Ensure the Correct Decision

• DEP must verify that data are useable
• Consistent with DQOs and program requirements
• We have Statutory Authority to reject data!!!

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Data Quality DEP

• If real result is higher than reported
• Environment is not protected
• If real result is lower than reported
• Costly, unneeded treatment requirements
• In either case
• Legal challenges
• Adverse publicity
• Ultimately Results in More Staff Time and

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QA Rule Basics

• Laboratories
• Maintain DoH NELAC Certification
• Field Activities
• Follow DEP Field SOPs
• www.dep.state.fl.us/labs

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QA Rule (continued)

• Can apply for new or alternative procedures
• Extensive reporting requirements
• Location, methods, QA elements (extensive list)
• Audits
• Lab, field, document review, corrective action
• Data validation
• Completeness, data integrity usability
• Data rejection, whole or in part

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Key Sampling Considerations

• Purpose behind sampling (why)
• Study design, Data Quality Objectives
• Representativeness of sample
• What, where, when to sample
• Integrity of sample
• How to sample without changing its
  characteristics
• Material compatibility, preservation, holding
  times
• Blanks to ensure lack of contamination
• Documentation
• Basis for audit checks

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DEP Sampling SOPs

• Naming Conventions
• FA Administrative QS
• FC Field Cleaning
• FD Documentation
• FM Mobilization Laboratory
• FQ Quality Control
• FS Sampling Procedures
• FT Testing
• LD Lab Documentation
• LQ Lab QC
• LT Lab Testing

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Structure
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Factors Affecting Aquatic Biological Communities
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Biochemical Oxygen Demand

• Amount of oxygen consumed by microbial organisms
  during organic matter decomposition
• Sources animal and agricultural waste matter
• Normal, lt1.0 mg/L
• Problematic, gt 2.0 mg/L

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Dissolved Oxygen

• A measure of ecosystem function (P/R ratio)
• Necessary to support aquatic life
• Amount of DO saturated in water depends on
  temperature and conductivity/salinity
• 5 mg/L is freshwater WQ standard, but some
  natural systems (e.g., springs, swamps) are
  lower
• Super-saturation can cause gas bladder disease in
  fish

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Dissolved Oxygen Concentration is a Function of
Ecosystem Processes
Water-Column Dissolved Oxygen
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Nutrient Enrichment Alters these Ecosystem
Processes
Macrophyte Shading
Macrophyte Cover
Atmospheric Exchange
Periphyton Mat and SAV Loss
Water-Column Oxygen Demand (BOD, COD,
Respiration)
Water-Column Dissolved Oxygen
Periphyton-SAV Photosynthesis
Macrophyte Shading
Sediment Oxygen Demand (SOD)
Macrophyte Detritus
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Nutrient Enrichment Depresses Diel Fluctuations

-

-
Run
End
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pH

• Measure of hydrogen ion activity, based on
  negative log of hydrogen ion concentration
• pH greatly affects biochemical reactions
• Blackwater and surficial aquifer systems are
  usually lt 6 SU
• Springs and estuaries, 7.5 to 8 SU
• Lakes with algae blooms, gt8

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Color

• Brown tint from humic substances dissolved in
  water, usually natural, but can be from pulp
  mills, etc.
• Too much color reduces light transparency
• Clear, lt20 PCU
• Blackwater streams gt100 ug/L
• In estuaries, gt40 ug/L reduces Thallasia growth

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Temperature

• Important factor in chemical interactions and
  biological activities
• Cutting riparian shade trees can increase the
  temperature regime to unacceptable levels
• Values gt 27o C can be problematic

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Specific Conductance

• Measures the ability of water to conduct an
  electric current, from inorganic ions, including
  Na, Cl, Mg, Ca, SO4, etc.
• Surface runoff systems lt 100 umhos/cm
• Springs, 250-500 umhos/cm
• Estuaries gt1500 umhos/cm
• Urban stormwater increases conductivity
• Many sensitive freshwater organisms decline with
  increasing conductivity

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Nutrients

• Narrative standard, In no case shall nutrients
  be altered so as to cause an imbalance in flora
  or fauna
• Currently, must collect biological communities to
  effectively enforce standard
• EPA is mandating numeric standards be adopted in
  2005

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Nutrient Cycling
Food
Wetland
Waste
Residue
Uptake
Soil Organic Matter
Microbial Activity
Nutrient Release
Wetland Soils
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Nitrogen

• Nitrate/nitrite, TKN, ammonia (toxic)
• Excess amounts lead to eutrophication, too much
  organic production, dominance of nuisance species
• Non-problematic concentrations depend on
  aquatic system
• NO2 and ammonia, typically lt 0.05 mg/L
• TKN variable, usually lt 1.0 mg/L

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Denitrification
Atmosphere
Pollutant Input
Wetland
Gas
Wetland Soils (anaerobic condition)
HNO
N2O
NO3-
NO2-
NO
N2
Microbial Processes
Leaching
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Phosphorus

• Ortho-phosphate (bioreactive) and total
  phosphorus
• Excess amounts lead to eutrophication, too much
  organic production, dominance of nuisance species
• Non-problematic concentrations of TP depend on
  aquatic system
• Usually lt 200 ug/L in streams
• Must be lt 10 ug/L to protect Everglades

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Phosphorus Fixation
Pollutant Input
Wetland
Residue
Ortho Phosphorus
Organic Phosphorus
Uptake
Fixed Mineral P, w/ Ca, Mg, Fe, Al, etc.
Wetland Soils
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Chlorophyll a

• Green pigment responsible for photosynthesis
• Measures phytoplankton biomass, algal blooms
• Problematic, gt20 ug/L in streams and lakes, gt11
  ug/L in estuaries

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Secchi Depth

• Depth at which a black and white painted disk
  becomes indistinguishable
• Measures water clarity
• Algae, color, and turbidity can reduce Secchi

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Bacteria

• Indicators of potential human pathogens which may
  cause illness
• Total coliforms, 2400 CFU/100 mL (E. coli,
  Citrobacter, Enterobacter, Klebsiella)
• Fecal coliforms, 800 CFU/100 mL (E. coli,
  Klebsiella)
• New proposed EPA standard Enterococci and E. Coli

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Total Suspended Solids

• Dry weight determination of particulates in the
  water column
• Somewhat redundant with turbidity
• Normal amounts in stream and lakes, lt 7.0 mg/L
  estuaries 20 mg/L

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Turbidity

• Measures light dispersion caused by suspended
  particulates in water column
• Turbidity can reduce light penetration and clog
  gills of fish and invertebrates
• As turbid particles settle, they smother habitat,
  reducing substrate quality and preventing fish
  spawning
• 29 NTU above background is WQ standard
• Different technologies will yield different
  results

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Turbidity Sampling Schematic Tidal Direction
Example 1
1500 m
Test Turbidity Transects
Channel
150 m
Dredge
Turbidity Transects Are Perpendicular to Tidal
Flow
150 m
Reference Turbidity Transect
Tidal Flow (direction varies)
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Turbidity Sampling SchematicTidal Direction
Example 2
Channel
Reference Turbidity Transect
150 m
150 m
Dredge
Test Turbidity Transect
Tidal Flow (direction varies)
1500 m
Turbidity Transects Are Perpendicular to Tidal
Flow
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Data EvaluationIn Compliance Scenario
95 Confidence Intervals Overlap
Geometric Mean
Test Data
Ref Data
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Data EvaluationNon-Compliance Scenario
95 Confidence Intervals DO NOT Overlap
Geometric Mean
Test Data
Ref Data
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Turbidity Adaptive Management Concept
If non-compliance scenario arises, use best
professional judgment to modify dredge
operations, to lower risk of increased
turbidities during the next week of
operation. If adaptive management goes as
planned, by the end of the project, cumulative
reference and test data distributions should not
be statistically different.
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Heavy Metals

• Toxic to plants, invertebrates, and fish
• Strong affinity to particulates
• Dissolved portion most toxic
• Sediment Quality Guidelines
• Higher bio-availability in lower pH waters
• Freshwater quality standards based on hardness
  for Cd, Cr, Cu, Pb, Ni, Zn

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Hardness Dependent Metals Standards (Class III)
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Marine Metals Standards (Class III)

• Cr (hexavalent)- 50 ug/L
• Cd- 9.3 ug/L
• Cu- 3.7 ug/L
• Pb- 8.5 ug/L
• Ni- 8.3 ug/L
• Zn- 86 ug/L
• Fe- 300 ug/L

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Some Cautions

• Dont disturb bottom when sampling
• Turbidity, metals, nutrients in this bad sample
  will be higher than actual
• Copper in seawater needs special preparation step
  (MIBK)
• See SLER Table1501-4

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Oil Grease, PAHs, FL-PRO, and TPRH

• Should be direct grab sample
• Sticks to intermediate surfaces, giving false low
  readings
• Oil and grease shall not exceed 5 mg/L
• PAHs, for gasoline contamination
• WQ standards for individual PAHs
• FL-PRO, for diesel and motor oil
• TPRH, least sensitive method
• No WQ standards for FL-PRO and TPRH

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SLER 1500 Contents

• Sampling and analysis procedures
• Data reporting, validation, and review for
  compliance determination
• WQ sampling for specific permitting applications

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Designing Sampling Plans

• Random design
• Statistically most defensible, but expensive
• Professional judgment design
• Practical, simple, less expensive, but care must
  made to ensure defensibility
• Authoritative design
• Biased to include background and worst-case
• Recommended by SLER 1500 for regulatory decisions

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Recommended Analytes

• Dissolved oxygen, pH, conductivity, temperature
• Turbidity
• Copper, Chromium, Arsenic, Cadmium, Mercury, Lead
• Oil and grease
• PAH, FL-PRO, TRPH
• Total and fecal coliform bacteria
• Total nitrogen
• Total phosphorus

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Data Validation and Review

• Check sampling design, field procedures, validate
  QC of laboratory data
• Determine if any analytical data should be
  discarded
• Exercise profession judgment
• Qualified data may still be useable
• Interpret in context of Water Quality Standards,
  Rule 62-302 FAC

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Remember

• Quality of analytical results must be suitable
  for DEP decisions
• A single sample is a snapshot in time,
  additional data may be needed for full picture
• WQ Standards are ultimately designed to protect
  aquatic biota and human health