9/23/2016

1

HydroCycle-PO4: Continuous, real-time, nutrient monitoring for non-point sources

Corey Koch, Michael Dewey, Bruce Rhoades, Nichole Halsey, Doug Wilson*

The National Non-Point Source Monitoring Workshop, Salt Lake City, Aug 2016

Rio Grande in Albuquerque *Caribbean Wind LLC

Overview• Instrument Overview

• Univ. Florida tomato farm application

• Snake River Loads

• Stream Reach Slug Injection

• Real-time QC flags

• Bubbles and Sediment Performance

• USDA experimental pasture runoff

• Florida HAB nutrient sources

9/23/2016

2

Performance Specifications

• Soluble reactive ortho-phosphate

• 7.5 um pore size filter

• LOD, IDL: 3* 0.0023 mgP/L (75 nM PO₄)

• Range: 0-0.3 mgP/L (0-10 µM PO4)

• linear to ~1.2mgP/L

• Maximum 4 samples per hour

• 1500 runs per deployment

• 0-35C, 0-200 meters

• On-board memory, but needs a battery

3

3 years of in-situ phosphate monitoring

0.16 mgP/L

0.03 mgP/L

9/23/2016

3

Instrument and Chemistry

5

Based on:-Murphy, J.; Riley J.P. Anal. Chim. Acta. (1962)

-US EPA method 365.5

• On board reagent cartridges (5 month lifetime)• On-board spike calibration (NIST Traceable

Standard)• NIST Standard 10-25C

Analysis of a Sample

4. Sample reaction: product formation*

5. Reaction completed, slope inflection point identified

6. Flush and rinse with ambient

~ 12-20 min/sample depending on temp

1. Ambient sample flush/rinse 2. Baseline (ambient) measurement3. Mixing: reagents added, pumps sample

to optical cell

Concentration PO4 absorption

1 2

3

6

4

5

9/23/2016

4

Tomato Farming

• Experimental tomato farm

– UF: Best Management Practices research

– DEQ: nutrient loading from Ag

• Challenges

– Intermittent water

– High values

• Now sampling from Lysimeter under tomato rows (sensor buried)

Brownlee Reservoir Loads• Snake River(107,500 mi2) as it enters

system of dams.

• Real-time phosphate yields more accurate loadings

• Load estimations are highly sensitive to sampling frequency.

• Typical loadings methods:

1)Linear Interpolation of grab samples

2)Linear regression of grab samples with discharge.

HoelscherB_MyersR_July2003

9/23/2016

5

Brownlee Reservoir Loads

Traditional loadings models over-or-

under estimate loads

• Interpolation results in smoothing

events

• Regression relationships do not

have strong correlations due to

complexity of phosphate-

discharge relationships.

Instrument-to-Instrument Agreement

• Several sensors deployed side-by-side• Demonstrate sensor-sensor data quality• Changes 0.002 mgP/L coherent

between instruments• Ability to swap/compare

9/23/2016

6

Haggard B.E., L.B. Massey, C.R. Koch, J.T. Scott, M.A. Evans-White, B.J. Austin, E.E. Scott, and D. Procyk University of Arkansas System.

Phosphorus Slug Dynamics in an Urban Stream

Upstream Cycle P

Downstream Cycle PO4

P Injection Point

Upstream Cycle P

Downstream Cycle PO4

P Injection Point

Phosphorus Slug Dynamics in an Urban Stream

9/23/2016

7

Sensor Specific QC flags• Real-time data assigned QC flag, software plot

color-coded• Overall flag composite of the six individual quality

flags:• out-of-range, optical noise, low signal,

bubbles, mixing errors. • Ability to change thresholds and post-process data

sets• Save analysis reports with data statistics and

embedded links to files for database creation

UNESCO Flag levels, adopted by IOOS

Sherson and Van Horn; Jemez River, NM after fire flushes. Suspect due to out of range, low signal leads to bad data

Software % of data flagged table

Simulated Mud Puddles

• Tested at riverine, estuarine resuspension, and high algae sites

• Single filter disc with 7.5 um avg pore size

• Data quality in fine sediment– 500 NTU sample resulted in 3 NTU filtrate

• Uniform caking and larger area lead to longer filter life

• May get at labile or surface bound particulate P

• HydroCycle-PO4 can do ~100 runs at NTUs varying from 100-500 NTU.

• Expected to survive a few short duration (day) high sediment events

• Tank tests with Elliot Silt Loam, Maumee, Rio Grande, Murkderkill estuary, and Missouri River Sediment

9/23/2016

8

• Bubbles can compromise fluidic volumes and cause catastrophic optical noise.

• HydroCycle-PO4 tested extensively in a bubble tank with saturated water

– filled with macro and micro bubbles, allowed to collect under and on filter surface

– Tested in the field at estuarine and riverine sites

• Can continue to make measurements in presence of micro / macro bubbles in the sample

– Patent application submitted

Bring on the Bubbles

• Lake discharges often associated with large HAB events

• High nutrient sources likely runoff from Urban and Ag areas

Florida HABs Nutrient Sources

Data retrieved from The Indian River Lagoon

Observatory Network of Environmental Sensors (http://fau.loboviz.com/) on 8/16/16)Contact:HBOI_IRLO@fau.edu

Credit: Rick Solveson

9/23/2016

9

Florida HABs Nutrient Sources

Lake Okeechobee Canal discharge and PO4 at St.

Lucie estuary 6/17/16 to 8/16/16

• Several Nutrient Observatories (LOBO) bracket St. Lucie Estuary

• Lake O. discharges may increase residence times in the estuary to exacerbate HABs

• High Nutrient concentrations and HAB sustainment from different sources

0

Data retrieved from IRLON (http://fau.loboviz.com/) on 8/16/16)

Discharge data courtesy of U.S. Geological Survey

Kyle Elkin, Ray Bryant and Terry Troutman, USDA ARS

Experimental Pasture Runoff

• USDA ARS experimental farm WE-38 in Pennsylvania

• Need to use validated SWAT model to confidently guide BMP

• SWAT models and grab samples don’t agree well• Need high frequency data• Capture key transient events• Model has daily resolution• “Missed every weekend storm

since 1984 when we started…”

9/23/2016

10

• Nutrients respond to runoff• Phosphate likely leaching from mobilized soil

• Subsurface flow may contribute to long decay• Aquifers high in nitrate get activated after

surface runoff pulse

Kyle Elkin, Ray Bryant and Terry Troutman, USDA ARS

Experimental Pasture Runoff

Rai

n

• Acknowledgements:– SeaBird team: Jeff Pauk, Ian Walsh, Kate Threlfall, Gabe Ryan, Adam

Dutton

– Justin Reale (CoE), Dave Van Horn (UNM)

– Kevin Locher (Locher Environmental) and Kelly Morgan (Univ. Florida)

– Charles Hoovestol and Jesse Naymik (Idaho Power)

– Brian Haggard and Leslie Massey (University of Arkansas)

– Indian River Lagoon Observatory Network

– Kyle Elkin, Ray Bryant, and Terry Troutman (USDA ARS)