Real-Time NO3 and PO4 Sensors for Chesapeake Bay

Lora HarrisJeremy Testa

Amanda Moore

UMCES Chesapeake Biological Laboratory

Mark TriceRebecca Burrell

Kristin HeyerJohn ZimmerelliBruce Michael

Ben ColeBrian Smith

Maryland Department of Natural Resources

Why do we need these sensors?

(1) There is a vast amount of nutrient concentration measurements in Chesapeake Bay, but most of these have been measured at a bi-weekly or monthly scales

(2) Event-scale dynamics (floods, wind events) are poorly understood

(3) Nutrient conditions leading to phytoplankton blooms poorly understood

(4) Model simulations made at short time scales that could be better validated

Growing use of in-situ nutrient systems

Pellerin et al. 2016, JAWRA

The WIZ system

• Miniaturized wet chemistry• Won EPA Nutrient Sensor Challenge• Relatively affordable

(10-15k; SUNA=30k+)

Reagentcanister

Internal electronics,colorimetric components

filter

Internal electronics

pump

Reagent canister

Deploying The WIZ system

Solar Panel and Data Logger

Waste and rinse water

WIZ(submerged)

Arundel on the Bay

Deploying The WIZ system

Solar Panel and Data Logger

WIZ(submerged)

Dares Beach

Existing Nitrate Sensor

Solar Panel and Data Logger

WIZ(submerged)

Darlington, MD

Water In site AnalyZer System (WIZ): Real-Time NO3 and PO4 measurements

Miniaturized wet chemistryLong-term deployments, but labor-intensive

0.0

0.5

1.0

1.5

2.0

Oct Nov Dec Jan

NO3m

gL

AOB Nutrient Sensor

DAB Nutrient Sensor

SUNA Sensor

0

20

40

60

Oct Nov Dec Jan2018 - 2019

PO4u

gL

AOB Nutrient Sensor

DAB Nutrient Sensor

0.0

0.5

1.0

1.5

2.0

Oct Nov Dec Jan

NO3m

gL

AOB

Grab

Arundel on the Bay

0

20

40

60

Oct Nov Dec Jan2018 - 2019

PO4u

gL

AOB

Grab

0.0

0.5

1.0

1.5

2.0

Dec 17 Dec 24 Dec 31

NO3m

gL

DAB

Grab

Dare's Beach

0

20

40

60

Dec 17 Dec 24 Dec 312018 - 2019

PO4u

gL

DAB

Grab

Arundel

RMSE = 0.24106

0.0

0.5

1.0

1.5

0.0 0.5 1.0 1.5

LABNO3mg L

WIZN

O3m

gL

Original

Replacement

Arundel on the Bay

RMSE = 22.38322

0

20

40

60

0 20 40 60

LABPO4ug L

WIZP

O4u

gL

Original

Replacement

2018

Susquehanna Flow

Black = Long Term Mean Yellow = IQR Red = 2018

USGS SUNA Nitrate Sensor

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

NO

3 C

onc

(mg/

l)

Arundel on the Bay

IQR

Long-Term Monthly Median (1984-2017)

2018 WIZ Data

NASL Data

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

NO

3 C

onc

(mg/

l)

Dare's Beach

IQR

Long-Term Monthly Median (1984-2017)

2018 WIZ Data

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

PO4

Con

c (m

g/l)

Arundel on the Bay

IQR

Long-Term Monthly Median (1984-2017)

2018 WIZ Data

Susquehanna

NASL Data

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

PO4

Con

c (m

g/l)

Dare's Beach

IQR

Long-Term Monthly Median (1984-2017)

2018 WIZ Data

NASL Data

Wiz Sensors

0

2000

4000

6000

0

2000

4000

6000

Oct Nov Dec Jan

SUS

Flow

m3

sSUS

Flowm

3s

0.0

0.5

1.0

1.5

2.0

0

20

40

60

Oct Nov Dec Jan

NO3m

gL

PO4 ug

L

AOB NO3 AOB PO4

Arundel on the Bay

0.0

2.5

5.0

7.5

10.0

0

10

20

30

40

Oct Nov Dec Jan2018 - 2019

Salin

ity (p

pt)

Chl (ug/L) / Tem

p (C

Chl Salinity WTemp

Arundel on the Bay – Ecological Insights?

Dares Beach– Ecological Insights?

0

2000

4000

6000

0

2000

4000

6000

Dec 17 Dec 24 Dec 31

SUS

Flow

m3

s

SUSFlow

m3

s

0.0

0.5

1.0

1.5

2.0

0

20

40

60

Dec 17 Dec 24 Dec 31

NO3m

gL PO4 ug

L

DAB NO3 DAB PO4

Dare's Beach

0.0

2.5

5.0

7.5

10.0

0

10

20

30

40

Dec 17 Dec 24 Dec 312018 - 2019

Salin

ity (p

pt)

Chl (ug/L) / Tem

p (C

Chl Salinity WTemp

Dares Beach– Ecological Insights?

0

2000

4000

6000

0

2000

4000

6000

Dec 17 Dec 24 Dec 31

SUS

Flow

m3

s

SUSFlow

m3

s

0.0

0.5

1.0

1.5

2.0

0

20

40

60

Dec 17 Dec 24 Dec 31

NO3m

gL PO4 ug

L

DAB NO3 DAB PO4

Dare's Beach

0.0

2.5

5.0

7.5

10.0

0

10

20

30

40

Dec 17 Dec 24 Dec 312018 - 2019

Salin

ity (p

pt)

Chl (ug/L) / Tem

p (C

Chl Salinity WTemp

0

500,000

1,000,000

Jan 2018 Apr 2018 Jul 2018 Oct 2018 Jan 20

Dai

ly L

oad

(kg/

day)

Based on SUNA dataNitrate Loading

flo

0.0

0.5

1.0

1.5

2.0

Oct Nov Dec Jan

NO3m

gL

AOB Nutrient Sensor

DAB Nutrient Sensor

SUNA Sensor

SUNA shifted 8 days

0

1

2

3

0.0

2.5

5.0

7.5

10.0

Oct Nov Dec Jan2018 - 2019

NO3m

gL

Salinity (ppt)AOB NO3 Salinity

Arundel on the Bay

0

1

2

3

0.0

2.5

5.0

7.5

10.0

Oct Nov Dec Jan2018 - 2019

NO3m

gL

Salinity (ppt)

DAB NO3 Salinity

Dare's Beach

Maintenance Insights:CostsChemicals : $445 (for chemicals we didn’t have)Data plan : ? / month (for data transmission)

Site VisitsPlanned Maintenance : 4 based on sampling frequencyMalfunction Response: 9 additional

HoursChemical Prep : 4 hours for initial reagent mixingMaintenance day prep : 3 hours to fill canister and gather equipment/standardsMaintenance Day : 1.5 hours travel each way (75 miles)

2 hours on site for cleanup and calibration checkPost Maintenance Day : 3 hours to empty/clean used canister and waste bagMalfunction Trouble Shooting : 14 (total) additional to normal maintenance on siteTotal hours dedicated : 250 for everything involved

0

50

100

150

200

250

Maintenance MalfunctionReason for Missed Sample

Num

ber o

f Mis

sed

Sam

ples

Ecological Insights:

• Sensors useful for tracking temporal shifts in response to flow events

• Documented variability will be useful for understanding estuarine responses on time scale better suited to modeling and continuous sensor data

• Maintenance is a challenge and calibration data still indicates “proceed with some caution”

• Susquehanna inputs impacted main stem of bay on short time scales this summer (~8 days) – how does this compare to other years with lower flow?

Thank you!