CHAPTER 16
Synchronous Fluorescence Spectra as Chemical Tracers to Monitor the
Organic Matter Dissolved in North Adriatic Waters
M. Mingazzini
ABSTRACT
The use of synchronous fluorescence spectra as chemical tracers of the DOM in Adriatic Sea
waters is here proposed. Laboratory experiments using both marine diatom cultures and natural phytoplankton provided evidence for the ability of the technique to characterize and quantify the extracellular products. Fluorescence parameters defined on laboratory cultures were
applied to the study of the natural OOM present in the mixing area of the Po River with marine
waters. The results support the effectiveness of the parameters to detect the contribution of the
terrestrial as well as of the newly produced components mixed in seawater OOM. Experimental
evidence was provided for the potential of the technique to trace the accumulation of the EOM
in marine waters.
Introduction
While the cycling of dissolved organic matter
(DOM) in marine systems is the focus of intense
studies, both the low concentration and the chemical complexity of the DOM components which
are mixed in natural waters make difficult to balance the marine carbon budget. Due to the fluorescence properties of the DOM, many of the earliest studies concentrated on using fluorescence
as a chemical tracer of the source, circulation and
mixing of DOM in waters (Mopper and Schultz
1993; De Souza Sierra et al.1994; Coble 1996).
In 1992 a global fluorescence budget was
estimated (Chen and Bada 1992) to assess the
major sources of DOM in seawater. The Authors
concluded that, while rain, rivers and diffusion
from sediments are local sources probably
insignificant on a global scale. the in situ formation is the most likely source for the fluorescence
of seawater. Nevertheless, the same Authors
underlined a lack of information on the last
source. The most recent and in-depth investigations on the nature of the seawater DOM still
pointed out the research need on in situ biological production (Coble 1996). The information on
phytoplankton sources are still related only to
the fluorescence spectral characterization performed by Traganza 30 years ago (Traganza
1969). No more information has been provided
by experimental evidence.
In the case of the Adriatic Sea, where great
amounts of phytoplankton extracellular organic
matter (BOM) are involved in the accumulation
process of massive quantities of mucilage, with
serious economic implications for the Italian
country, the need of a better understanding of
the marine DOM cycling is particularly urgent
(Rinaldi et al.1995; Mingazzini and Thake 1995).
The use of synchronous fluorescence technique
has recently been proposed to characterize the
BOM produced by phytoplankton in Adriatic Sea
waters (Mingazzini et al. 1995). The same technique was also applied to the study of the mixing
DOM in a lagoonal system of the Po River delta
(Ferrari and Mingazzini 1995).
In the present study the synchronous fluorescence technique was used to compare results
obtained both from marine phytoplankton laboratory experiments and from natural Adriatic
samples collected in the transition zone of the Po
River delta. The aim was to determine fluorescence parameters able to characterize the naturally occurring components of DOM as well as to
detect and trace the accumulation of the BOM in
North Adriatic seawaters.
Istituto di Ricerca sulla Acque, CNR, VIa della Mornera 25, 20047 Brugherio (Mi), Italy
RM. Faranda,1. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag Itelia 2001
Synchronous Fluorescence Spectra as Chemical Tracers to Monitor the
Organic Matter Dissolved in North Adriatic Waters
M. Mingazzini
ABSTRACT
The use of synchronous fluorescence spectra as chemical tracers of the DOM in Adriatic Sea
waters is here proposed. Laboratory experiments using both marine diatom cultures and natural phytoplankton provided evidence for the ability of the technique to characterize and quantify the extracellular products. Fluorescence parameters defined on laboratory cultures were
applied to the study of the natural OOM present in the mixing area of the Po River with marine
waters. The results support the effectiveness of the parameters to detect the contribution of the
terrestrial as well as of the newly produced components mixed in seawater OOM. Experimental
evidence was provided for the potential of the technique to trace the accumulation of the EOM
in marine waters.
Introduction
While the cycling of dissolved organic matter
(DOM) in marine systems is the focus of intense
studies, both the low concentration and the chemical complexity of the DOM components which
are mixed in natural waters make difficult to balance the marine carbon budget. Due to the fluorescence properties of the DOM, many of the earliest studies concentrated on using fluorescence
as a chemical tracer of the source, circulation and
mixing of DOM in waters (Mopper and Schultz
1993; De Souza Sierra et al.1994; Coble 1996).
In 1992 a global fluorescence budget was
estimated (Chen and Bada 1992) to assess the
major sources of DOM in seawater. The Authors
concluded that, while rain, rivers and diffusion
from sediments are local sources probably
insignificant on a global scale. the in situ formation is the most likely source for the fluorescence
of seawater. Nevertheless, the same Authors
underlined a lack of information on the last
source. The most recent and in-depth investigations on the nature of the seawater DOM still
pointed out the research need on in situ biological production (Coble 1996). The information on
phytoplankton sources are still related only to
the fluorescence spectral characterization performed by Traganza 30 years ago (Traganza
1969). No more information has been provided
by experimental evidence.
In the case of the Adriatic Sea, where great
amounts of phytoplankton extracellular organic
matter (BOM) are involved in the accumulation
process of massive quantities of mucilage, with
serious economic implications for the Italian
country, the need of a better understanding of
the marine DOM cycling is particularly urgent
(Rinaldi et al.1995; Mingazzini and Thake 1995).
The use of synchronous fluorescence technique
has recently been proposed to characterize the
BOM produced by phytoplankton in Adriatic Sea
waters (Mingazzini et al. 1995). The same technique was also applied to the study of the mixing
DOM in a lagoonal system of the Po River delta
(Ferrari and Mingazzini 1995).
In the present study the synchronous fluorescence technique was used to compare results
obtained both from marine phytoplankton laboratory experiments and from natural Adriatic
samples collected in the transition zone of the Po
River delta. The aim was to determine fluorescence parameters able to characterize the naturally occurring components of DOM as well as to
detect and trace the accumulation of the BOM in
North Adriatic seawaters.
Istituto di Ricerca sulla Acque, CNR, VIa della Mornera 25, 20047 Brugherio (Mi), Italy
RM. Faranda,1. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag Itelia 2001