2
A. Gianguzza . E. Pelizzetti . S. Sammartano
bon and the nitrogen cycles cannot be considered as independent between them, but,
on the contrary, as interconnected aspects of the whole living cycle. Despite their importance for marine life and the great interest by scientist, there are large gaps in their
understanding. The greatest difficulty in studying the different aspects ofbiogeochemical cycles mainly is in the variability of rates and stoichiometry of the chemical reactions involved ("open systems"), which are dependent on the environmental conditions, such as light, temperature, oxidation state, etc., of the marine ecosystem. Therefore, the most convenient way of determining the overall amounts and fluxes of organic compounds in natural cycles is to use radioactive carbon tracers. For example,
measurements of the variation of the 13C/ 12 C ratio vs. time demonstrate that the ocean
is receiving fossil fuel carbon (Quay et al. 1992; Hedges 1992). The measurements of
DOC in sea water are matters of great controversy. The most used method, based on
high-temperature combustion to CO2, is not yet completely pointed out, as demonstrated by noticeable differences in the results of recent inter-laboratory comparisons
(Sugimura and Suzuki 1988; Martin and Fitzwater 1992). The qualitative and the quantitative analysis of individual organic compounds present in sea water at nanomolar
concentrations represents a challenge for the analytical chemist, and a further obstacle
in the study of natural cycles (Baker and Hites 1999; Tittlemeier et al. 1999; Agrell et al.
1999; Harner et al.1999). Current methodologies require large samples, time-consuming chromatographic separation, preconcentration (Yang et al. 1993) and other sample
handling which are not always easy to carry out on ship cruise. Advances in mass spectrometry and in hyphenated HPLC-MS techniques that provide detection limits in the
picomolar range (Vincenti 1997) allow an expansion in the number of detectable compounds.
The first and most important step ofliving cycles is by far the uptake of atmospheric
CO2 by tlIe oceans. Whereas biologists have focused their attention on tlIe role of carbon
dioxide in photosynthetic processes (Biological Pump), chemists and chemical oceanographers were interested in the participation of carbon dioxide in tlIe major geochemical
cycles and also in the processes that led to the distribution of CO2 and its related chemical forms (HCO;- and CO;-) in the oceans (Solubility Pump), with the aim of building
up chemical models to define the alkalinity and the buffer capacity of sea water.
During the last decades, interest in the carbon dioxide system comes also from its
importance as a major greenhouse gas and its effect on the climate's global change.
Despite the fundamental importance of this chemical system, the CO2 exchange rate
between atmosphere and surface sea water is not yet well known, owing to the difficulty in measuring the net increase of inorganic carbon in the oceans and in distinguishing the fraction of inorganic carbon involved in living processes. Many efforts
are in progress by scientists to develop procedures to detect CO2 partial pressure
by means optical sensors (Millero 1999) and, moreover, to realize routine measurements, to be carried out aboard ship, of alkalinity and pH of sea water within errors
<0.1 %.
Metals and Organometallic Compounds
Analytical Methodologies. Natural concentrations of "heavy metals" are extremely
low in the hydrosphere (Salomons and Forstner 1984; Bruland 1983). Their detection
implies that the following problems have to be solved by an analytical chemist:
A. Gianguzza . E. Pelizzetti . S. Sammartano
bon and the nitrogen cycles cannot be considered as independent between them, but,
on the contrary, as interconnected aspects of the whole living cycle. Despite their importance for marine life and the great interest by scientist, there are large gaps in their
understanding. The greatest difficulty in studying the different aspects ofbiogeochemical cycles mainly is in the variability of rates and stoichiometry of the chemical reactions involved ("open systems"), which are dependent on the environmental conditions, such as light, temperature, oxidation state, etc., of the marine ecosystem. Therefore, the most convenient way of determining the overall amounts and fluxes of organic compounds in natural cycles is to use radioactive carbon tracers. For example,
measurements of the variation of the 13C/ 12 C ratio vs. time demonstrate that the ocean
is receiving fossil fuel carbon (Quay et al. 1992; Hedges 1992). The measurements of
DOC in sea water are matters of great controversy. The most used method, based on
high-temperature combustion to CO2, is not yet completely pointed out, as demonstrated by noticeable differences in the results of recent inter-laboratory comparisons
(Sugimura and Suzuki 1988; Martin and Fitzwater 1992). The qualitative and the quantitative analysis of individual organic compounds present in sea water at nanomolar
concentrations represents a challenge for the analytical chemist, and a further obstacle
in the study of natural cycles (Baker and Hites 1999; Tittlemeier et al. 1999; Agrell et al.
1999; Harner et al.1999). Current methodologies require large samples, time-consuming chromatographic separation, preconcentration (Yang et al. 1993) and other sample
handling which are not always easy to carry out on ship cruise. Advances in mass spectrometry and in hyphenated HPLC-MS techniques that provide detection limits in the
picomolar range (Vincenti 1997) allow an expansion in the number of detectable compounds.
The first and most important step ofliving cycles is by far the uptake of atmospheric
CO2 by tlIe oceans. Whereas biologists have focused their attention on tlIe role of carbon
dioxide in photosynthetic processes (Biological Pump), chemists and chemical oceanographers were interested in the participation of carbon dioxide in tlIe major geochemical
cycles and also in the processes that led to the distribution of CO2 and its related chemical forms (HCO;- and CO;-) in the oceans (Solubility Pump), with the aim of building
up chemical models to define the alkalinity and the buffer capacity of sea water.
During the last decades, interest in the carbon dioxide system comes also from its
importance as a major greenhouse gas and its effect on the climate's global change.
Despite the fundamental importance of this chemical system, the CO2 exchange rate
between atmosphere and surface sea water is not yet well known, owing to the difficulty in measuring the net increase of inorganic carbon in the oceans and in distinguishing the fraction of inorganic carbon involved in living processes. Many efforts
are in progress by scientists to develop procedures to detect CO2 partial pressure
by means optical sensors (Millero 1999) and, moreover, to realize routine measurements, to be carried out aboard ship, of alkalinity and pH of sea water within errors
<0.1 %.
Metals and Organometallic Compounds
Analytical Methodologies. Natural concentrations of "heavy metals" are extremely
low in the hydrosphere (Salomons and Forstner 1984; Bruland 1983). Their detection
implies that the following problems have to be solved by an analytical chemist: