CHAPTER 13
Concentrations of Trace Metals (Cd, Cu, Fe, Pb) in Posidonia oceanica
Seagrass of Usda Bay, Sardinia (Italy)
M. BarolP, A. CristinP, A. Cossu 3 ) G. De Falco!) V. Gazale\ C. Pergent-Martini s , and G. Pergent S
ABSTRACT
Heavy metal concentrations were measured in Posidonia oceanica seagrass from a
Mediterranean site (Uscia bay, N Sardinia, Italy) in order to assess the degree of metal pollution
in the area. Metals Cd, Cu, Fe and Pb were measured in sheaths and rhizomes dated and dissected by lepidochronology procedures, which may offer a timeseries of metal concentrations
in the environment (Pergent 1990; Romeo et at. 1995).
Comparison between metal concentrations according to lepidochronological years in
sheaths and rhizomes produced significant differences: Cd and Cu concentrations were similar
in the two tissues, while Fe and Pb showed higher values in sheaths, with differences up to 2
orders of magnitude. Rhizome concentrations showed no trend related to lepidochronological
years, whereas Cu, Fe and Pb tended to decrease over time in sheaths.
Values detected in sheaths and rhizomes of P. oceanica from Liscia bay were generally low,
compared with other Mediterranean sites, with the exception of Fe: this confirms that the site is
a clean area without anthropogenic enrichment and with metal concentrations representing
background values.
Introduction
Posidonia oceanica is a long-lived benthic species
widespread in the Mediterranean. It is the only
marine phanerogam capable of forming durable
structures ("matte"), it may absorb metals
directly from the water column or from interstitial water in sediments, and has a high capacity
for concentrating chemical pollutants and to
accumulate trace metals occurring in the environment during its life cycle (Calmet et al. 1988;
Malea and Haritonidis 1989). In fact, in the last
10 years P. oceanica has been used as a biological
«recorder" of marine environmental quality
(Augier 1985; Maserti et al. 1988). The capability
of P. oceanica to concentrate a range of pollutants
such as trace metals has been clearly established
(Augier et al. 1977; Maserti et al. 1988; Malea and
Haritonidis 1989).
When P. oceanica leaves die only the blade
falls away and the sheathing base remains fixed
to the rhizome (Giraud 1977; Pergent 1987).
Sheaths and rhizomes decay extremely slowly
and may persist within a "matte" for millennia
(Boudouresque et al. 1983). Sheath thickness has
been shown to vary cyclically according to position along the rhizome (erouzet 1981; Pergent
1990). These cyclical variations have a chronological significance with each cycle, defined by
two thickness minima, corresponding to a oneyear period of growth (Pergent 1990). Recent
works show that P. oceanica can memorise trace
metal contents over several decades (Romeo et
al. 1995; Pergent-Martini 1998).
The aim of the present work was to measure
heavy metal concentrations in P. oceanica seagrass from a Mediterranean site (Liscia bay, N
Sardinia, Italy, Fig. 1) in order to assess the
1 Centro Marino Internazionale, Loc. Sa Mardini, 09072 Thrregrande-Oristano, Italy
2 Dipartimento di Scienze della Terra, Universita di Cagliari, Via Trentino 51, Cagliari, Italy
3 Dipartimento di Botanica ed Ecologia Vegetale, Universita di Sassari, Via Muroni 25, Sassari. Italy
4 Battelle-Medsar, Tramariglio-Alghero, Italy
5 Eq.E.L., Universite de Corse, Faculte des Sciences, BP 52, 20250 Corte, France
EM. Faranda. L. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag ltalia Z001
Concentrations of Trace Metals (Cd, Cu, Fe, Pb) in Posidonia oceanica
Seagrass of Usda Bay, Sardinia (Italy)
M. BarolP, A. CristinP, A. Cossu 3 ) G. De Falco!) V. Gazale\ C. Pergent-Martini s , and G. Pergent S
ABSTRACT
Heavy metal concentrations were measured in Posidonia oceanica seagrass from a
Mediterranean site (Uscia bay, N Sardinia, Italy) in order to assess the degree of metal pollution
in the area. Metals Cd, Cu, Fe and Pb were measured in sheaths and rhizomes dated and dissected by lepidochronology procedures, which may offer a timeseries of metal concentrations
in the environment (Pergent 1990; Romeo et at. 1995).
Comparison between metal concentrations according to lepidochronological years in
sheaths and rhizomes produced significant differences: Cd and Cu concentrations were similar
in the two tissues, while Fe and Pb showed higher values in sheaths, with differences up to 2
orders of magnitude. Rhizome concentrations showed no trend related to lepidochronological
years, whereas Cu, Fe and Pb tended to decrease over time in sheaths.
Values detected in sheaths and rhizomes of P. oceanica from Liscia bay were generally low,
compared with other Mediterranean sites, with the exception of Fe: this confirms that the site is
a clean area without anthropogenic enrichment and with metal concentrations representing
background values.
Introduction
Posidonia oceanica is a long-lived benthic species
widespread in the Mediterranean. It is the only
marine phanerogam capable of forming durable
structures ("matte"), it may absorb metals
directly from the water column or from interstitial water in sediments, and has a high capacity
for concentrating chemical pollutants and to
accumulate trace metals occurring in the environment during its life cycle (Calmet et al. 1988;
Malea and Haritonidis 1989). In fact, in the last
10 years P. oceanica has been used as a biological
«recorder" of marine environmental quality
(Augier 1985; Maserti et al. 1988). The capability
of P. oceanica to concentrate a range of pollutants
such as trace metals has been clearly established
(Augier et al. 1977; Maserti et al. 1988; Malea and
Haritonidis 1989).
When P. oceanica leaves die only the blade
falls away and the sheathing base remains fixed
to the rhizome (Giraud 1977; Pergent 1987).
Sheaths and rhizomes decay extremely slowly
and may persist within a "matte" for millennia
(Boudouresque et al. 1983). Sheath thickness has
been shown to vary cyclically according to position along the rhizome (erouzet 1981; Pergent
1990). These cyclical variations have a chronological significance with each cycle, defined by
two thickness minima, corresponding to a oneyear period of growth (Pergent 1990). Recent
works show that P. oceanica can memorise trace
metal contents over several decades (Romeo et
al. 1995; Pergent-Martini 1998).
The aim of the present work was to measure
heavy metal concentrations in P. oceanica seagrass from a Mediterranean site (Liscia bay, N
Sardinia, Italy, Fig. 1) in order to assess the
1 Centro Marino Internazionale, Loc. Sa Mardini, 09072 Thrregrande-Oristano, Italy
2 Dipartimento di Scienze della Terra, Universita di Cagliari, Via Trentino 51, Cagliari, Italy
3 Dipartimento di Botanica ed Ecologia Vegetale, Universita di Sassari, Via Muroni 25, Sassari. Italy
4 Battelle-Medsar, Tramariglio-Alghero, Italy
5 Eq.E.L., Universite de Corse, Faculte des Sciences, BP 52, 20250 Corte, France
EM. Faranda. L. Guglielmo, G. Spezie (eds)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag ltalia Z001