Larry Feinson - State of New Jersey

state.nj.us

Larry Feinson - State of New Jersey

USE OF SPECTROPHOTOMETRIC AND

FLUOROMETRIC SENSORS TO MEASURE

IN-STREAM CONSTITUENTS IN

NEW JERSEY

New Jersey Monitoring Summit

November 29, 2012

Lawrence Feinson

USGS New Jersey Water Science Center


USGS NJWSC currently operates 17 water quality monitors

Most collect traditional field parameters:

• Water Temperature

• Specific conductance

• pH

• Dissolved Oxygen Concentration

• Turbidity

Picture

Of

YSI

Here


Spectral Sensors deployed at a select group of stations

Toms River at Toms River, NJ

Passaic river Below Pompton River at

Two Bridges, NJ

Barnegat Bay at Route 528 at

Mantoloking, NJ


S::CAN

Spectrolyzer

bbe Algae Guard

(bench top unit)

Spectral Sensors

Nitrate

Passaic River and Toms River

Chlorophyll

Any use of trade, product, or

firm names is for descriptive

purposes only and does not

imply endorsement by the U.S.

Government.

bbe Fluoroprobe

(submersible unit)

Passaic River Barnegat Bay


Nitrate Sensor

Chlorophyll Sensor

Operating principles

Dissolved compounds (i.e. Nitrogen, DOC) are absorbed at specific

wavelengths of light over the ultraviolet to visible spectrum.

This absorbance can be measured and converted to concentrations of

various compounds (Nitrates, DOC, TOC, Turbidity).

Algae groups have a unique combination of pigments which fluoresce

at different wavelengths.

The intensity of the fluorescence can be measured and converted to

the total chlorophyll concentration.


Operation and Maintenance issues

1. Water matrix effects

• Calibration issues

• Dissolved Organic Carbon

2. Fouling of optical windows


Lab Analyzed NO2+ NO3 (mg/L as N)

7.0

6.0

5.0

4.0

3.0

2.0

1.0

Right Intake (Passaic River)

y = 1.295x - 0.5628

R² = 0.9921

0.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

In-Stream [S::CAN] NO2+NO3 (mg/L as N)

Water matrix effects

Calibration

Any use of trade, product, or

firm names is for descriptive

purposes only and does not

imply endorsement by the

U.S. Government.

Instruments calibrated at the factory, but

may need to be calibrated to local water matrices

Using the equation of the trend line:

Can recalibrate the S::CAN

Internally (bbe?).

Can adjust the data

externally in the USGS

Automated Data Processing

System (ADAPS).


Nitrite +nitrate, mg/L as N

Water matrix effects – High DOC

High Dissolved Organic Carbon

Toms river

23

1.8 2.7

1.6 2.4

1.4 2.1

1.2 1.8

1.5 1

0.8 1.2

0.6 0.9

0.4 0.6

0.2 0.3

0

30

27

24

21

18

15

12

9

6

3

0

DOC, mg/L

Long optical path

35 mm

Shorten optical path length

15 mm


Optical window fouling –

Passaic

Cleaning Jets

Optical window fouling –

Toms River sediment

Optical window fouling –

Barnegat

Fouling of optical windows

DI water

Compressed

Air


Questions?


Passaic River Monitor

Instrument Upgrades

• Sensors installed in 2009 and 2010 respectively.

• First station in NJ to have long-term deployment.

• Unable to convert instrument readings to transmittable formats.

• Local calibration of S::CAN could only be done remotely by

a company technician.

• Length of the S::CAN optical path is permanent; need to send back to

factory for modifications.

Toms River and Barnegat Bay

Any use of trade, product, or

firm names is for descriptive

purposes only and does not

imply endorsement by the

U.S. Government.

• Sensors installed in 2011 – newer generation with improved features.

• Can transmit data over Serial Data Interface (SDI-12)

• Can recalibrate the S::CAN on-site.

• Can reduce the length of the S::CAN optical path by inserting fittings.

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