also affected by Hg contamination (especially the Nervión estuary). The
Adour and Nervión belong with other polluted rivers, like the Seine,
the Scheldt and the Elbe (Cossa & Ficht, 1999). Highest dissolved Hg(Il)
and MMHg were observed during warm seasons. MMHg usually represents several percents of the total Hg (tab. 1) and is higher during warm
seasons, a possible effect of the increase in methylation rates during
summer (Coquery et al., 1997; Tseng, 2000). Along the salinity gradient,
various spikes in total Hg(II) (dissolved + particulate) concentration (fig.
1, 2) confirm that several anthropogenic inputs take place in the estuarine mixing zone of the Adour (especially at middle salinity approx. 1020), as observed with other heavy metals. As reported for other estuaries
(Coquery et al., 1997; Tseng, 2000), most of the mercury is in the particulate phase (tab. 1) and correlates with the organic carbon content
(POC). Although significant MMHg concentrations in the particles are
observed in the upstream part of the estuary, high MMHg formation or
inputs are occurring seaward in the dissolved phase (fig. 2). It is possible
that a solubilization of the organic matter, occurring in the estuary, is
responsible for the observed MMHg P drop at higher salinity and the
seaward increase of the dissolved MMHg (fig. 2).
This preliminary study demonstrates that Hg contamination in the
Basque coast and particulary in the Adour estuary should now be taken
into consideration and further investigated.
Ackrowledgments
This work is a part of the Ecoman Project, supported by the Aquitaine-Euskadi
Cooperation Fund.
Bibliographic references
Coquery M., Cossa D., Sanjuan J., 1997. Speciation and sorption of
mercup' in two macrotidal estuaries. Mar. Chem., 58(1-2), 213-227.
Cossa D., Ficht A., 1999. La dynamique du mercure. Ed. Ifremer, Progr.
Sci. Seine-Aval, 11, 25 p.
RNO, 1999. Rapport annuel, Ifremer-Matc.
Tseng C.M., De Diego A, Pinaly H., Amouroux D., Donard O.F.X.,
1998. Cryofocussing coupled to atomic absorption spectrometry for
rapid and simple mercury speciation in environmental matrices. J.
Anal. At. Spectrom., 13(8), 755-764.
Tseng C.M., 2000. Développements analytiques et spéciation en milieu
estuarien. Thèse de doctorat, cy cle Biogéochimique du mercure dans
l’environnement, université de Pau et des Pays de l’Adour, 289 p.
30b
Adour and Nervión belong with other polluted rivers, like the Seine,
the Scheldt and the Elbe (Cossa & Ficht, 1999). Highest dissolved Hg(Il)
and MMHg were observed during warm seasons. MMHg usually represents several percents of the total Hg (tab. 1) and is higher during warm
seasons, a possible effect of the increase in methylation rates during
summer (Coquery et al., 1997; Tseng, 2000). Along the salinity gradient,
various spikes in total Hg(II) (dissolved + particulate) concentration (fig.
1, 2) confirm that several anthropogenic inputs take place in the estuarine mixing zone of the Adour (especially at middle salinity approx. 1020), as observed with other heavy metals. As reported for other estuaries
(Coquery et al., 1997; Tseng, 2000), most of the mercury is in the particulate phase (tab. 1) and correlates with the organic carbon content
(POC). Although significant MMHg concentrations in the particles are
observed in the upstream part of the estuary, high MMHg formation or
inputs are occurring seaward in the dissolved phase (fig. 2). It is possible
that a solubilization of the organic matter, occurring in the estuary, is
responsible for the observed MMHg P drop at higher salinity and the
seaward increase of the dissolved MMHg (fig. 2).
This preliminary study demonstrates that Hg contamination in the
Basque coast and particulary in the Adour estuary should now be taken
into consideration and further investigated.
Ackrowledgments
This work is a part of the Ecoman Project, supported by the Aquitaine-Euskadi
Cooperation Fund.
Bibliographic references
Coquery M., Cossa D., Sanjuan J., 1997. Speciation and sorption of
mercup' in two macrotidal estuaries. Mar. Chem., 58(1-2), 213-227.
Cossa D., Ficht A., 1999. La dynamique du mercure. Ed. Ifremer, Progr.
Sci. Seine-Aval, 11, 25 p.
RNO, 1999. Rapport annuel, Ifremer-Matc.
Tseng C.M., De Diego A, Pinaly H., Amouroux D., Donard O.F.X.,
1998. Cryofocussing coupled to atomic absorption spectrometry for
rapid and simple mercury speciation in environmental matrices. J.
Anal. At. Spectrom., 13(8), 755-764.
Tseng C.M., 2000. Développements analytiques et spéciation en milieu
estuarien. Thèse de doctorat, cy cle Biogéochimique du mercure dans
l’environnement, université de Pau et des Pays de l’Adour, 289 p.
30b