Geoscience Reference
In-Depth Information
4
Sampling Design for Organic Matter
Fluorescence Analysis
Robert G. M. Spencer and Paula G. Coble
4.1 Introduction
The development of a robust and appropriate sampling design is fundamental to the suc-
cess of any study involving the collection of field samples, and many of the aspects are
also applicable to laboratory studies. The importance of careful sample collection and pro-
cessing is imperative to underscore, as these are the first steps undertaken in studies based
in aquatic ecosystems. Clearly any issues introduced during these early stages result in a
wasted effort as data quality is compromised from the outset of the study.
In the vast majority of studies in aquatic ecosystems that utilize absorbance and fluo-
rescence analyses to examine dissolved organic matter (DOM), the goal of the study is to
relate the measurements to the actual value in the natural environment. Therefore, such
studies are interested in producing accurate data, and the primary aim of this chapter is
to outline strategies that support this goal. For researchers aiming to relate measurements
made in the laboratory back to aquatic ecosystems two points are fundamental for DOM
sampling: first, collection of a representative sample and second, avoidance of any con-
tamination (U.S. Geological Survey,
2006
). Collection of a representative sample is deter-
mined by study objectives and the expected or known spatial and temporal variability of
DOM at the study location. Contamination of a sample via the procedures of collection,
processing, and storage and contamination avoidance are discussed in detail in this chapter.
As with all measurements in analytical chemistry, quality assurance and control protocols
should be implemented to ensure high-quality data and this chapter aims to outline useful
information to aid with sample collection and processing.
4.2 Sample Collection
4.2.1 Contamination Sources
There are three main types of contamination to be aware of when collecting samples.
The first are airborne and waterborne contaminants such as tobacco smoke, dust, exhaust
fumes, cleaning and lubricating solutions as well as hydrocarbons from a research vessel
or other vessels in the water. This category of contaminant can normally be avoided by
paying careful attention to the sampling site and sampling upwind (or on the lee side of a
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