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Ref. No. [UMCES] CBL 2017-050
ACT VS17-05
22
RESULTS of FIELD TESTS
Moored field tests were conducted to examine the performance of the Real-NO3 to
consistently track natural changes in NO
3
over extended field deployments with durations of 31-84
days.
In addition, field tests examined the reliability of the instrument, i.e., the ability to maintain
integrity or stability of data collection over time. Reliability was determined by quantifying the
percent of expected data that was recovered and useable. The performance of the Real-NO3 was
examined in three separate field tests at various ACT Partner sites to include a range of
biogeochemical conditions.
The range and mean for temperature and salinity for each test site is
presented in Table 8.
The reference temperature and conductivity data was measured by RBR
thermistors and a SeaBird SBE 26 or Xylem EXO2 sonde that were mounted at the same sampling
depth as the test instrument.
Immediately before and after each deployment, samples of the on-
board standards were taken from the instrument for comparison against a reference measurement
and to assess their stability over the course of the deployment (Table 9). The Real-NO3 was
calibrated and programmed for deployment by the manufacturer representative.
Table 8. Range and average for temperature, and salinity at each of the test sites during the sensor field
deployments. Temperature and salinity were measured by RBR temperature loggers and a SeaBird SBE 26
or a Xylem EXO2 mounted on the instrument rack or in the tank for the duration of the deployment
.
SITE
(deployment period/duration)
Temperature
(
°
C )
Salinity
(PSU)
Maumee River
Min.
20.1
0.0
26May – 27Jun
Max.
27.7
0.3
(n = 32 days)
Mean
24.3
0.2
Chesapeake Bay
Min.
20.0
12.7
18Jul – 10Oct
Max.
31.1
16.9
(n = 84 days)
Mean
27.2
14.7
Kaneohe Bay
Min.
24.5
27.3
3Oct – 2Nov
Max.
27.9
34.8
(n = 31 days)
Mean
26.3
34.2
Deployment at Maumee River Bowling Green, Ohio
A
32 day deployment occurred from May 26 through June 27 in the Maumee River, at the
facilities of the Bowling Green, Ohio Water Treatment Plant (Figure 8). The deployment site was
located at 41.48° N, 83.74° W, in a flow-through tank located in the water treatment plant pump
house. The pump house is located above the Maumee, approximately 200 m up river from the
water treatment intake and approximately 35 km from the Maumee outflow into Lake Erie. River
water was continuously pumped into a 180 gallon test tank where it was mixed using two
submerged pumps. The residence time in the tank was approximately 10 minutes. The
instrumentation was suspended within the tank with the sampling inlet 0.2 m off the bottom.