Ref. No. [UMCES] CBL 2013-020
ACT VS12-03
BACKGROUND AND OBJECTIVES
Instrument performance verification is necessary so that effective existing technologies
can be recognized and so that promising new technologies can be made available to support
coastal science, resource management and ocean observing systems. To this end, the NOAA-
funded Alliance for Coastal Technologies (ACT) serves as an unbiased, third party testbed for
evaluating sensors and sensor platforms for use in coastal environments. ACT also serves as a
comprehensive data and information clearinghouse on coastal technologies and a forum for
capacity building through workshops on specific technology topics (visit
).
As part of our service to the coastal community, ACT conducted a performance
verification of commercially available, in situ hydrocarbon sensors through the evaluation of
objective and quality assured data. The goal of ACT’s evaluation program is to provide
technology users with an independent and credible assessment of instrument performance in a
variety of environments and applications. Therefore, the data and information on performance
characteristics was focused on the types of information that users most need. ACT surveyed the
broader community to define the data and operational parameters that are valuable in guiding
instrument purchase and deployment decisions.
As oil remains one of the world's most important energy sources, permissible and
unintended release of hydrocarbons into the environment becomes inevitable as oil is explored,
extracted, refined, transported, and consumed. There are a number of challenges in assessing
hydrocarbon concentrations in coastal aquatic systems that point to the value of sustained in situ
observations. This ACT Technology Evaluation examines individual sensor performance both in
the laboratory and across different field conditions in moored and vertically profiled
applications.
The fundamental objectives of this Performance Verification are to: (1) highlight the
potential capabilities of hydrocarbon sensors by demonstrating their utility in a range of coastal
environments, (2) verify manufacturer claims on the performance characteristics of
commercially available hydrocarbon sensors when tested in a controlled laboratory setting, and
(3) verify performance characteristics of commercially available hydrocarbon sensors when
applied in real world applications in a diverse range of coastal environments.
In response to the results of ACT's Customer Needs and Use Assessment Survey the
performance verification focused on both moored and profiling applications. It was also clear
from the user survey that range (i.e., detection limits), reliability, accuracy, and precision are the
most important parameters guiding instrument selection decisions. Given that the majority of
instruments submitted to the verification utilize fluorometry, and that in situ fluorometry is a
relative measurement with no absolute “true value” reference, accuracy cannot be measured
directly. As an alternative to the direct measurement of accuracy, this Performance Verification
will determine response linearity, or stability of the response/calibration factor, to a defined
reference.
INSTRUMENT TECHNOLOGY TESTED
The Turner Designs’ C3 Submersible Fluorometer was configured for this ACT
evaluation with Refined Fuels, Crude Oil, and CDOM sensors used for measuring
in situ
fluorescence of these compounds in water. Each sensor uses a specific LED and filter set
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