continuous monitoring of harmful algal blooms | ysi

Stephanie A. Smith, PHD

[email protected]

November 17, 2016 | AWRA , Orlando FL

Continuous Monitoring for Harmful Algal Blooms

Harmful Algal Blooms (HABs)

Scope:

Freshwater cyanobacterial HABs

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Photo credit:

Beagle Bioproducts, Inc.

Photo credit:

Ohio EPA

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For HAB Background:

http://info.xyleminc.com/2016-08-Profiler-Webinar_recording-LP.html

HAB Webinar












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Multiparameter

Water Quality Monitoring

Monitor

Differentiate PTOX from non-PTOX

Identify

Measure for algal toxins (ELISA most common)

Measure

Limit nutrients, algaecides, aeration, etc.

Manage

HAB Control Program

Monitor this… Because…

Chlorophyll Found in almost all algae

Phycocyanin Found specifically in blue-green algae

Temperature High temperatures favor cyanobacteria

pH ↑ pH due to high growth; makes CO2 more bioavailable

Turbidity A surrogate for increased biomass; may also be indicative of

nutrient-bearing suspended solids during runoff events

dO2 Decreases during a bloom; can lead to fish kills

Conductivity Blue-green algae generally thrive in lower conductivity

Algae

identification

Determine whether pigments/turbidity are due to potentially

toxic (PTOX) blue-green algae

Algal toxins Hazardous to human and animal health

Nitrogen and

phosphorus

Growth-limiting nutrients that stimulate blooms when in high

concentrations (eutrophic water)

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HAB Monitoring

• Sensors for

• Turbidity

• pH

• Temperature / Conductivity

• dO2

• Central wiper to protect against

sensor fouling

• Internal or external continuous

data logging

• Total algae sensor (TAL)

• Chlorophyll

• Phycocyanin or phycoerythrin

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HAB Monitoring: EXO Sondes

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Everything that does

photosynthesis has

Chlorophyll

Chlorophyll

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Chlorophyll

Blue-green algae

have

Phycocyanin

Phycocyanin

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HAB Monitoring

Chlorophyll

Chlorophyll Chlorophyll


= MORE ALGAE

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Sample Concentrate Extract Measure

HAB Monitoring: Chlorophyll

• Measure absorbance:

• Peak absorbance at 440

nm,

and lower absorbance

at ~660 nm

• Measure Fluorescence:

• Excitation with 440 nm light

• Peak emission at

~680 nm

Alcohol extraction doesn’t

work for PC & PE…

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Chlorophyll Measurement

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HAB Monitoring: Chlorophyll + PC

Chlorophyll

Phycocyanin



= MORE PTOX

BGA

Phycocyanin Phycocyanin

Phycocyanin Phycocyanin

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Waste heat

6 CO2 + 6 H2O C6H12O6 + 6 O2

Photosynthesis

(Resonance energy transfer)

Other Fates

• Pigment destruction

• Triplet state conversion

• Reactive Oxygen generation

Light

(Fluorescence)

Pigments & Photosynthesis

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FRET = Fluorescence Resonance Energy Transfer


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Pigment Peak Ex ʎ Peak Em ʎ

Phycoerythrin 550 650

Phycocyanin 625 650

Allo-

phycocyanin

615,650 655

Chlorophyll 440, 662 680

Ideal scenario for

photosynthesis:

Where an accessory pigment

emits, chlorophyll absorbs

(FRET)

6-series: pigment-specific

excitation/emission

EXO: leverage FRET

Fluorescent Pigments

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Legacy 6-series:

Chlorophyll and

“BGA” PC or PE

EXO:

Total Algae (TAL)

Smart Sensors

HAB Sensors

• Chlorophyll sensor

• “BGA” sensor for

phycocyanin

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HAB Sensors: Legacy 6-Series

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590 nm

640 ± 40 nm

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470 nm

>590 nm

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470 nm

590 nm

685 nm

650 nm

Solid—excitation

Dotted--emission

HAB Sensors: EXO TAL-PC

HAB Sensors: The EXO Advantages

Feature Legacy 6-series

BGA-PC

EXO TAL-PC EXO Significance

Excitation LED Single (orange) Dual (orange + blue) Chl + PC response

Optical filter 640 ± 40 nm 685 ± 20 nm Less interference

Range 0-280,000 cells/mL

0 to 100 RFU

0 to 100 μg/L:

0 to 100 RFU

Units standardized

for all pigments

Resolution 1 cell/mL

0.1 RFU

0.01 μg/L;

0.01 RFU

10X better

Detection limit 0.1 RFU 0.01 RFU 10X better

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Better specificity + Better sensitivity

=

Earlier Detection

=

Better mitigation & management

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• Biology

• Intracellular pigment concentrations are not standard/constant

• Photoinhibition of chlorophyll

• In 6-series, some excitation of chlorophyll can occur with the PC

probe

• Temperature and fluorescence are inversely proportional

• Turbidity

• Absorbance and scattering in the water matrix

• “But I liked my cfu/mL on the 6-series!!”

All Sensors: What are you really measuring?

• TAL-PC or –PE are ideal for in situ

monitoring

• There is an EXO chlorphyll sensor

• Still better specificity than 6-series

• Know what you’re measuring

• RFUs

• Correlations work, but should be

interpreted with care

• Best management outcomes

leverage the platform

• Temperature, pH and turbidity

• Dissolved oxygen

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EXO Smart Sensors: Recommendations

Questions? [email protected]

+1 (937) 767-2762

Contact us:

continuous monitoring of harmful algal blooms | ysi

Environment