|Determination of mercury and thallium in the North Sea and in the Scheldt estuary|
Temmerman, E.; De Ruck, A.; Vandecasteele, C.M.; Dams, R. (1989). Determination of mercury and thallium in the North Sea and in the Scheldt estuary, in: Pichot, G. (Ed.) Progress in Belgian Oceanographic Research 1989: proceedings of the North Sea Symposium held in Ghent, 14 February 1989. pp. 369-392
In: Pichot, G. (Ed.) (1989). Progress in Belgian Oceanographic Research 1989: proceedings of the North Sea Symposium held in Ghent, 14 February 1989. Management Unit of the Mathematical Model of the North Sea and Scheldt Estuary: Brussel. 451 pp., more
|Authors|| || Top |
- Temmerman, E.
- De Ruck, A.
- Vandecasteele, C.M.
- Dams, R.
This article reports the optimization of analytical methods for the determination of mercury and thallium at ultra-low levels (ng.l-1) in sea water. special care was taken to avoid contamination and losses during all stages of the analytical scheme. For this purpose, preliminary experiments were carried out to investigate the stability of the samples and the suitability of the Niskin-samplers for the mercury analyses. The mercury content of the water was determined on the ship hy means of reduction-aeration/amalgamation combined with cold vapour atomic absorption (CVAAS) .The suspended particulate matter and the sediments were analysed in the same way, after acid attack. The mercury concentrations ranged from 0.3 to 1.5 ng.1-1 for Atlantic and North Sea water. Somewhat higher values were found in coastal waters. The significant input from the river Scheldt (appr. 220 kg.y-1) was proven by the analysis of the river water, with values ranging from 10 ng.1-1 in the estuary to 45 ng.1-1 in Antwerpen. 10 to 30% of the mercury was linked to suspended particles in the Scheldt. The mercury concentrations in the sediments were in the North Sea below 100 ng.g-1, but as high as 100 to 500 ng.g-1 in the Scheldt. The measurements indicate that the affinity of the mercury for the suspended particles increases with higher chloride concentration in the river water. The thallium content of the water was determined hy electro-thermal atomic absorption spectrometry (ETAAS) after preconcen- tration on anion exchanger. In the ocean water the concentrations varied from 6 ng.1-1 in the open sea up to 20 ng.1-1 at the mouth of Scheldt and Thames. In the Scheldt much higher concentrations were found (50-150 ng.1-1) of which generally less than 10% was associated with the particulate phase.