FAU Harbor Branch's LOBO Network
Quality Assurance/Quality Control (QA/QC) for FAU Harbor Branch's
Land/Ocean Biogeochemical Observatory (LOBO) Units
Quality Assurance/Quality Control (QA/QC) refers to:
the process or set of processes used to measure and assure the quality
of a product (QA) and the process of meeting products and services to
consumer expectations (QC). This is an overview of the QA/QC actively
used for FAU Harbor Branch's Land/Ocean Biogeochemical Observatory
Calibration and Verification of the Instrumentation
All instruments are factory calibrated by the manufacturers every 12
months. In addition, the instruments are retrieved by FAU Harbor Branch
scientists for verification of sensor performance every six months. The
purpose of the verification is to confirm that the individual sensors in
the LOBO unit are performing within factory specifications. Corrective
actions are taken whenever needed.
The water quality monitor (WQMX) integrates
conductivity, temperature, depth (pressure) and dissolved oxygen sensors
(CTD-DO) from Sea-Bird Electronics with a chlorophyll fluorescence,
CDOM, and turbidity sensor (ECO-BBFL2) from WET Labs, Inc. to make
highly accurate measurements in estuarine applications. The WQMX is
factory calibrated after every twelve months of in-water use. In
addition, further characterization is performed by FAU Harbor Branch
scientists on a semi-annual basis to ensure sensors are performing
- Verification for the CTD-DO sensors includes taking measurements in
air to ensure values are within expected ranges as well as comparison to
factory calibration values.
- Performance for the ECO-BBFL2 sensor is verified by measuring and
updating offsets as necessary and confirming sensor saturation for each
parameter. Further, turbidity standards including an ultrapure water
blank, 2.5, 5.0, 10.0 and 20.0 NTU are evaluated (three runs) to
determine calibration and evaluation of the sensor over a range of
values common in the Indian River Lagoon (IRL).
- Characterization of the chlorophyll sensor includes comparison of
the measured value of an IRL grab sample to the extracted value from
standard spectrophotometric analysis (Method #10200H, APHA, Standard
Methods for the Examination of Water and Wastewater, 19th edition).
The Cycle-PO4 (WETLabs, Inc.) is an in situ
instrument that uses wet chemistry to measure phosphate (PO4)
colorimetrically with methods modified from Murphy and Riley (1962) and
EPA method 365.5 (1997). The Cycle-PO4 is fully calibrated at WETLabs on
an annual basis with documentation of optical, electronic and fluidic
parameter values. Further, the Cycle-PO4 is then subjected to
environmental stress and leak tests. On a semi-annual basis, FAU Harbor
Branch runs a standard curve to determine calibration and verify the
instrument is operating within specifications. Standards include
ultrapure DI water blank, 0.5, 2.6 and 5.3 µM (three runs).
The submersible ultraviolet nitrate analyzer (SUNA;
Satlantic, Inc.) is an optical sensor for high resolution
ultraviolet spectrophotometry of nitrate in coastal waters. The SUNA is
fully characterized at Satlantic on an annual basis. In addition,
instrument performance is checked semi-annually by FAU Harbor Branch to
ensure optimized accuracy of data. The concentration of nitrate in
ultrapure DI water is measured before and after cleaning the optical
window. If the nitrate concentration does not read 0.00 ± 2 µM
instrument's calibration will be updated following protocols established
by Satlantic. Next, nitrate standards, including an ultrapure water
blank, 0.71, 1.71, 3.57, 7.14 and 14.28 µMare evaluated (three runs)
to determine calibration and evaluation of the sensor over a range of
values common in the IRL.
FAU Harbor Branch researchers visit the LOBOs every four to six weeks
(depending on season/biofouling) to collect discrete samples to be used
to QA/QC sensor data and document drift. Discrete samples are collected
with a five-liter Niskin bottle lowered separately and concurrently with
a Seabird CTD to the depth of the LOBO. Once the CTD and Niskin bottle
are at the same depth, the CTD is run for 60 seconds to equilibrate the
sensors. The messenger on the Niskin line is released at 90 seconds and
CTD sampling continues through 120 seconds. The Niskin is brought on
board the vessel and samples for dissolved oxygen are taken, followed by
samples collected for analysis of nutrients, turbidity, and chlorophyll
concentrations. The CTD data are downloaded in the laboratory upon
return and used to QA/QC the real-time sensor readings.
for oxygen will be collected directly in pre-cleaned containers and
fixed according to Labasque et al. (2004). Oxygen samples are shaken
twice with an intermediate settling, and then maintained in the dark
with deionized water filling the bottle top. Pre-cleaned syringes used
for sample collection will be rinsed with ambient water three times
before filtering and repeated for each LOBO. Nutrient samples will be
collected in 500-mL pre-cleaned high-density polyethylene (HDPE)
bottles, filtered (25 mm Whatman GF/F filters) into pre-cleaned 125-mL
HDPE bottles, and frozen until analyzed. Water samples for chlorophyll
and turbidity will be collected into two pre-cleaned HDPE 1-L bottles.
Chlorophyll, turbidity, and nutrient samples are immediately placed on
ice and kept in the dark. Samples are stored according to established
protocols (see Table 1). All samples are transported back to FAU Harbor
Branch the same day as collection for analysis.
Table 1. FAU Harbor Branch laboratory measurement procedures
||Filter and freeze
||Filter and freeze
||Labasque et al.
||Filter and freeze
Data Use and Metadata
The data made available on this website should be considered provisional
for any use. Each year metadata files will be made available to all
interested parties. The term metadata refers to "data about data".
Metadata are helpful to interpret ecological and environmental data.
Annual metadata reports will be drafted at the end of each calendar year
to document research objectives and methods, site location information,
the data collection period, the QA/QC process, sensor resolution and
accuracy, and anomalous data. To receive metadata reports or request any
other information, please contact FAU Harbor at:
APHA. 1995. Standard Methods for the Examination of Water and
Wastewater. 19th ed. Washington, DC: American Public Health
EPA. 1997. Method 365.5 determination of orthophosphate in estuarine and
coastal waters by automated colorimetric analysis. Cincinnati: National
Exposure Research Laboratory Office of Research and Development U.S.
Environmental Protection Agency.
Labasque, T., C. Chaumery, A. Aminot, and G. Keroat. 2004.
Spectrophotometric Winkler determination of dissolved oxygen:
re-examination of critical factors and reliability. Mar. Chem. 88:53-60.
Murphy, J. and J.R. Riley. 1962. A modified single solution method for
the determination of phosphate in natural waters. Anal. Chem. 27:31-36.